<?php
/* For licensing terms, see /license.txt */

use ChamiloSession as Session;

/**
 *  Class DocumentManager
 *  This is the document library for Chamilo.
 *  It is / will be used to provide a service layer to all document-using tools.
 *  and eliminate code duplication fro group documents, scorm documents, main documents.
 *  Include/require it in your code to use its functionality.
 *
 * @package chamilo.library
 */
class DocumentManager
{
    /**
     * Construct.
     */
    private function __construct()
    {
    }

    /**
     * @param string $course_code
     *
     * @return int the document folder quota for the current course in bytes
     *             or the default quota
     */
    public static function get_course_quota($course_code = null)
    {
        if (empty($course_code)) {
            $course_info = api_get_course_info();
        } else {
            $course_info = api_get_course_info($course_code);
        }

        $course_quota = null;
        if (empty($course_info)) {
            return DEFAULT_DOCUMENT_QUOTA;
        } else {
            $course_quota = $course_info['disk_quota'];
        }
        if (is_null($course_quota) || empty($course_quota)) {
            // Course table entry for quota was null, then use default value
            $course_quota = DEFAULT_DOCUMENT_QUOTA;
        }

        return $course_quota;
    }

    /**
     * Get the content type of a file by checking the extension
     * We could use mime_content_type() with php-versions > 4.3,
     * but this doesn't work as it should on Windows installations.
     *
     * @param string $filename or boolean TRUE to return complete array
     *
     * @author ? first version
     * @author Bert Vanderkimpen
     *
     * @return string
     */
    public static function file_get_mime_type($filename)
    {
        // All MIME types in an array (from 1.6, this is the authorative source)
        // Please, keep this alphabetical if you add something to this list!
        $mime_types = [
            'ai' => 'application/postscript',
            'aif' => 'audio/x-aiff',
            'aifc' => 'audio/x-aiff',
            'aiff' => 'audio/x-aiff',
            'asf' => 'video/x-ms-asf',
            'asc' => 'text/plain',
            'au' => 'audio/basic',
            'avi' => 'video/x-msvideo',
            'bcpio' => 'application/x-bcpio',
            'bin' => 'application/octet-stream',
            'bmp' => 'image/bmp',
            'cdf' => 'application/x-netcdf',
            'class' => 'application/octet-stream',
            'cpio' => 'application/x-cpio',
            'cpt' => 'application/mac-compactpro',
            'csh' => 'application/x-csh',
            'css' => 'text/css',
            'dcr' => 'application/x-director',
            'dir' => 'application/x-director',
            'djv' => 'image/vnd.djvu',
            'djvu' => 'image/vnd.djvu',
            'dll' => 'application/octet-stream',
            'dmg' => 'application/x-diskcopy',
            'dms' => 'application/octet-stream',
            'doc' => 'application/msword',
            'docm' => 'application/vnd.ms-word.document.macroEnabled.12',
            'docx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.document',
            'dotx' => 'application/vnd.openxmlformats-officedocument.wordprocessingml.template',
            'dvi' => 'application/x-dvi',
            'dwg' => 'application/vnd.dwg',
            'dwf' => 'application/vnd.dwf',
            'dxf' => 'application/vnd.dxf',
            'dxr' => 'application/x-director',
            'eps' => 'application/postscript',
            'epub' => 'application/epub+zip',
            'etx' => 'text/x-setext',
            'exe' => 'application/octet-stream',
            'ez' => 'application/andrew-inset',
            'flv' => 'video/flv',
            'gif' => 'image/gif',
            'gtar' => 'application/x-gtar',
            'gz' => 'application/x-gzip',
            'hdf' => 'application/x-hdf',
            'hqx' => 'application/mac-binhex40',
            'htm' => 'text/html',
            'html' => 'text/html',
            'ice' => 'x-conference-xcooltalk',
            'ief' => 'image/ief',
            'iges' => 'model/iges',
            'igs' => 'model/iges',
            'jar' => 'application/java-archiver',
            'jpe' => 'image/jpeg',
            'jpeg' => 'image/jpeg',
            'jpg' => 'image/jpeg',
            'js' => 'application/x-javascript',
            'kar' => 'audio/midi',
            'lam' => 'application/vnd.ms-excel.addin.macroEnabled.12',
            'latex' => 'application/x-latex',
            'lha' => 'application/octet-stream',
            'log' => 'text/plain',
            'lzh' => 'application/octet-stream',
            'm1a' => 'audio/mpeg',
            'm2a' => 'audio/mpeg',
            'm3u' => 'audio/x-mpegurl',
            'man' => 'application/x-troff-man',
            'me' => 'application/x-troff-me',
            'mesh' => 'model/mesh',
            'mid' => 'audio/midi',
            'midi' => 'audio/midi',
            'mov' => 'video/quicktime',
            'movie' => 'video/x-sgi-movie',
            'mp2' => 'audio/mpeg',
            'mp3' => 'audio/mpeg',
            'mp4' => 'video/mpeg4-generic',
            'mpa' => 'audio/mpeg',
            'mpe' => 'video/mpeg',
            'mpeg' => 'video/mpeg',
            'mpg' => 'video/mpeg',
            'mpga' => 'audio/mpeg',
            'ms' => 'application/x-troff-ms',
            'msh' => 'model/mesh',
            'mxu' => 'video/vnd.mpegurl',
            'nc' => 'application/x-netcdf',
            'oda' => 'application/oda',
            'oga' => 'audio/ogg',
            'ogg' => 'application/ogg',
            'ogx' => 'application/ogg',
            'ogv' => 'video/ogg',
            'pbm' => 'image/x-portable-bitmap',
            'pct' => 'image/pict',
            'pdb' => 'chemical/x-pdb',
            'pdf' => 'application/pdf',
            'pgm' => 'image/x-portable-graymap',
            'pgn' => 'application/x-chess-pgn',
            'pict' => 'image/pict',
            'png' => 'image/png',
            'pnm' => 'image/x-portable-anymap',
            'potm' => 'application/vnd.ms-powerpoint.template.macroEnabled.12',
            'potx' => 'application/vnd.openxmlformats-officedocument.presentationml.template',
            'pps' => 'application/vnd.ms-powerpoint',
            'ppam' => 'application/vnd.ms-powerpoint.addin.macroEnabled.12',
            'ppsm' => 'application/vnd.ms-powerpoint.slideshow.macroEnabled.12',
            'ppsx' => 'application/vnd.openxmlformats-officedocument.presentationml.slideshow',
            'pptm' => 'application/vnd.ms-powerpoint.presentation.macroEnabled.12',
            'pptx' => 'application/vnd.openxmlformats-officedocument.presentationml.presentation',
            'ppm' => 'image/x-portable-pixmap',
            'ppt' => 'application/vnd.ms-powerpoint',
            'pps' => 'application/vnd.ms-powerpoint',
            'ps' => 'application/postscript',
            'qt' => 'video/quicktime',
            'ra' => 'audio/x-realaudio',
            'ram' => 'audio/x-pn-realaudio',
            'rar' => 'image/x-rar-compressed',
            'ras' => 'image/x-cmu-raster',
            'rgb' => 'image/x-rgb',
            'rm' => 'audio/x-pn-realaudio',
            'roff' => 'application/x-troff',
            'rpm' => 'audio/x-pn-realaudio-plugin',
            'rtf' => 'text/rtf',
            'rtx' => 'text/richtext',
            'sgm' => 'text/sgml',
            'sgml' => 'text/sgml',
            'sh' => 'application/x-sh',
            'shar' => 'application/x-shar',
            'silo' => 'model/mesh',
            'sib' => 'application/X-Sibelius-Score',
            'sit' => 'application/x-stuffit',
            'skd' => 'application/x-koan',
            'skm' => 'application/x-koan',
            'skp' => 'application/x-koan',
            'skt' => 'application/x-koan',
            'smi' => 'application/smil',
            'smil' => 'application/smil',
            'snd' => 'audio/basic',
            'so' => 'application/octet-stream',
            'spl' => 'application/x-futuresplash',
            'src' => 'application/x-wais-source',
            'sv4cpio' => 'application/x-sv4cpio',
            'sv4crc' => 'application/x-sv4crc',
            'svf' => 'application/vnd.svf',
            'svg' => 'image/svg+xml',
            //'svgz' => 'image/svg+xml',
            'swf' => 'application/x-shockwave-flash',
            'sxc' => 'application/vnd.sun.xml.calc',
            'sxi' => 'application/vnd.sun.xml.impress',
            'sxw' => 'application/vnd.sun.xml.writer',
            't' => 'application/x-troff',
            'tar' => 'application/x-tar',
            'tcl' => 'application/x-tcl',
            'tex' => 'application/x-tex',
            'texi' => 'application/x-texinfo',
            'texinfo' => 'application/x-texinfo',
            'tga' => 'image/x-targa',
            'tif' => 'image/tif',
            'tiff' => 'image/tiff',
            'tr' => 'application/x-troff',
            'tsv' => 'text/tab-seperated-values',
            'txt' => 'text/plain',
            'ustar' => 'application/x-ustar',
            'vcd' => 'application/x-cdlink',
            'vrml' => 'model/vrml',
            'wav' => 'audio/x-wav',
            'wbmp' => 'image/vnd.wap.wbmp',
            'wbxml' => 'application/vnd.wap.wbxml',
            'wml' => 'text/vnd.wap.wml',
            'wmlc' => 'application/vnd.wap.wmlc',
            'wmls' => 'text/vnd.wap.wmlscript',
            'wmlsc' => 'application/vnd.wap.wmlscriptc',
            'wma' => 'audio/x-ms-wma',
            'wmv' => 'video/x-ms-wmv',
            'wrl' => 'model/vrml',
            'xbm' => 'image/x-xbitmap',
            'xht' => 'application/xhtml+xml',
            'xhtml' => 'application/xhtml+xml',
            'xls' => 'application/vnd.ms-excel',
            'xlsb' => 'application/vnd.ms-excel.sheet.binary.macroEnabled.12',
            'xlsm' => 'application/vnd.ms-excel.sheet.macroEnabled.12',
            'xlsx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet',
            'xltm' => 'application/vnd.ms-excel.template.macroEnabled.12',
            'xltx' => 'application/vnd.openxmlformats-officedocument.spreadsheetml.template',
            'xml' => 'text/xml',
            'xpm' => 'image/x-xpixmap',
            'xsl' => 'text/xml',
            'xwd' => 'image/x-windowdump',
            'xyz' => 'chemical/x-xyz',
            'zip' => 'application/zip',
        ];

        if ($filename === true) {
            return $mime_types;
        }

        //get the extension of the file
        $extension = explode('.', $filename);

        //$filename will be an array if a . was found
        if (is_array($extension)) {
            $extension = strtolower($extension[sizeof($extension) - 1]);
        } else {
            //file without extension
            $extension = 'empty';
        }

        //if the extension is found, return the content type
        if (isset($mime_types[$extension])) {
            return $mime_types[$extension];
        }
        //else return octet-stream
        return 'application/octet-stream';
    }

    /**
     * This function streams a file to the client.
     *
     * @param string $full_file_name
     * @param bool   $forced
     * @param string $name
     * @param bool   $fixLinksHttpToHttps change file content from http to https
     *
     * @return false if file doesn't exist, true if stream succeeded
     */
    public static function file_send_for_download(
        $full_file_name,
        $forced = false,
        $name = '',
        $fixLinksHttpToHttps = false
    ) {
        session_write_close(); //we do not need write access to session anymore
        if (!is_file($full_file_name)) {
            return false;
        }
        $filename = $name == '' ? basename($full_file_name) : api_replace_dangerous_char($name);
        $len = filesize($full_file_name);
        // Fixing error when file name contains a ","
        $filename = str_replace(',', '', $filename);
        $sendFileHeaders = api_get_configuration_value('enable_x_sendfile_headers');

        // Allows chrome to make videos and audios seekable
        header('Accept-Ranges: bytes');

        if ($forced) {
            // Force the browser to save the file instead of opening it
            if (isset($sendFileHeaders) &&
                !empty($sendFileHeaders)) {
                header("X-Sendfile: $filename");
            }

            header('Content-type: application/octet-stream');
            header('Content-length: '.$len);
            if (preg_match("/MSIE 5.5/", $_SERVER['HTTP_USER_AGENT'])) {
                header('Content-Disposition: filename= '.$filename);
            } else {
                header('Content-Disposition: attachment; filename= '.$filename);
            }
            if (strpos($_SERVER['HTTP_USER_AGENT'], 'MSIE')) {
                header('Pragma: ');
                header('Cache-Control: ');
                header('Cache-Control: public'); // IE cannot download from sessions without a cache
            }
            header('Content-Description: '.$filename);
            header('Content-Transfer-Encoding: binary');

            if (function_exists('ob_end_clean') && ob_get_length()) {
                // Use ob_end_clean() to avoid weird buffering situations
                // where file is sent broken/incomplete for download
                ob_end_clean();
            }

            $res = fopen($full_file_name, 'r');
            fpassthru($res);

            return true;
        } else {
            // no forced download, just let the browser decide what to do according to the mimetype
            $lpFixedEncoding = api_get_configuration_value('lp_fixed_encoding');

            // Commented to let courses content to be cached in order to improve performance:
            //header('Expires: Wed, 01 Jan 1990 00:00:00 GMT');
            //header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');

            // Commented to avoid double caching declaration when playing with IE and HTTPS
            //header('Cache-Control: no-cache, must-revalidate');
            //header('Pragma: no-cache');
            $contentType = self::file_get_mime_type($filename);
            switch ($contentType) {
                case 'text/html':
                    if (isset($lpFixedEncoding) && $lpFixedEncoding === 'true') {
                        $contentType .= '; charset=UTF-8';
                    } else {
                        $encoding = @api_detect_encoding_html(file_get_contents($full_file_name));
                        if (!empty($encoding)) {
                            $contentType .= '; charset='.$encoding;
                        }
                    }
                    break;
                case 'text/plain':
                    if (isset($lpFixedEncoding) && $lpFixedEncoding === 'true') {
                        $contentType .= '; charset=UTF-8';
                    } else {
                        $encoding = @api_detect_encoding(strip_tags(file_get_contents($full_file_name)));
                        if (!empty($encoding)) {
                            $contentType .= '; charset='.$encoding;
                        }
                    }
                    break;
                case 'application/vnd.dwg':
                case 'application/vnd.dwf':
                    header('Content-type: application/octet-stream');
                    break;
            }

            header('Content-type: '.$contentType);
            header('Content-Length: '.$len);
            $user_agent = strtolower($_SERVER['HTTP_USER_AGENT']);
            if (strpos($user_agent, 'msie')) {
                header('Content-Disposition: ; filename= '.$filename);
            } else {
                header('Content-Disposition: inline; filename= '.$filename);
            }

            if ($fixLinksHttpToHttps) {
                $content = file_get_contents($full_file_name);
                $content = str_replace(
                    ['http%3A%2F%2F', 'http://'],
                    ['https%3A%2F%2F', 'https://'],
                    $content
                );
                echo $content;
            } else {
                if (function_exists('ob_end_clean') && ob_get_length()) {
                    // Use ob_end_clean() to avoid weird buffering situations
                    // where file is sent broken/incomplete for download
                    ob_end_clean();
                }

                readfile($full_file_name);
            }

            return true;
        }
    }

    /**
     * Session folder filters.
     *
     * @param string $path
     * @param int    $sessionId
     *
     * @return null|string
     */
    public static function getSessionFolderFilters($path, $sessionId)
    {
        $sessionId = intval($sessionId);
        $condition = null;

        if (!empty($sessionId)) {
            // Chat folder filter
            if ($path == '/chat_files') {
                $condition .= " AND (docs.session_id = '$sessionId') ";
            }
            // share_folder filter
            $condition .= " AND docs.path != '/shared_folder' ";
        }

        return $condition;
    }

    /**
     * Fetches all document data for the given user/group.
     *
     * @param array  $courseInfo
     * @param string $path
     * @param int    $toGroupId       iid
     * @param int    $toUserId
     * @param bool   $canSeeInvisible
     * @param bool   $search
     * @param int    $sessionId
     *
     * @return array with all document data
     */
    public static function getAllDocumentData(
        $courseInfo,
        $path = '/',
        $toGroupId = 0,
        $toUserId = null,
        $canSeeInvisible = false,
        $search = false,
        $sessionId = 0
    ) {
        $tblItemProperty = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $tblDocument = Database::get_course_table(TABLE_DOCUMENT);

        $userGroupFilter = '';
        if (!is_null($toUserId)) {
            $toUserId = intval($toUserId);
            $userGroupFilter = "last.to_user_id = $toUserId";
            if (empty($toUserId)) {
                $userGroupFilter = " (last.to_user_id = 0 OR last.to_user_id IS NULL) ";
            }
        } else {
            $toGroupId = intval($toGroupId);
            $userGroupFilter = "last.to_group_id = $toGroupId";
            if (empty($toGroupId)) {
                $userGroupFilter = "( last.to_group_id = 0 OR last.to_group_id IS NULL) ";
            }
        }

        // Escape underscores in the path so they don't act as a wildcard
        $originalPath = $path;
        $path = str_replace('_', '\_', $path);

        $visibilityBit = ' <> 2';

        // The given path will not end with a slash, unless it's the root '/'
        // so no root -> add slash
        $addedSlash = $path == '/' ? '' : '/';

        // Condition for the session
        $sessionId = $sessionId ?: api_get_session_id();
        $conditionSession = " AND (last.session_id = '$sessionId' OR (last.session_id = '0' OR last.session_id IS NULL) )";
        $conditionSession .= self::getSessionFolderFilters($originalPath, $sessionId);

        $sharedCondition = null;
        if ($originalPath == '/shared_folder') {
            $students = CourseManager::get_user_list_from_course_code($courseInfo['code'], $sessionId);
            if (!empty($students)) {
                $conditionList = [];
                foreach ($students as $studentInfo) {
                    $conditionList[] = '/shared_folder/sf_user_'.$studentInfo['user_id'];
                }
                $sharedCondition .= ' AND docs.path IN ("'.implode('","', $conditionList).'")';
            }
        }

        $sql = "SELECT
                    docs.id,
                    docs.filetype,
                    docs.path,
                    docs.title,
                    docs.comment,
                    docs.size,
                    docs.readonly,
                    docs.session_id,
                    last.session_id item_property_session_id,
                    last.lastedit_date,
                    last.visibility,
                    last.insert_user_id
                FROM $tblItemProperty AS last
                INNER JOIN $tblDocument AS docs
                ON (
                    docs.id = last.ref AND
                    docs.c_id = last.c_id
                )
                WHERE                                
                    last.tool = '".TOOL_DOCUMENT."' AND 
                    docs.c_id = {$courseInfo['real_id']} AND
                    last.c_id = {$courseInfo['real_id']} AND
                    docs.path LIKE '".Database::escape_string($path.$addedSlash.'%')."' AND
                    docs.path NOT LIKE '".Database::escape_string($path.$addedSlash.'%/%')."' AND
                    docs.path NOT LIKE '%_DELETED_%' AND
                    $userGroupFilter AND
                    last.visibility $visibilityBit
                    $conditionSession
                    $sharedCondition
                ORDER BY last.iid DESC, last.session_id DESC
                ";
        $result = Database::query($sql);

        $documentData = [];
        $isAllowedToEdit = api_is_allowed_to_edit(null, true);
        $isCoach = api_is_coach();
        if ($result !== false && Database::num_rows($result) != 0) {
            $rows = [];

            $hideInvisibleDocuments = api_get_configuration_value('hide_invisible_course_documents_in_sessions');

            while ($row = Database::fetch_array($result, 'ASSOC')) {
                if (isset($rows[$row['id']])) {
                    continue;
                }

                // If we are in session and hide_invisible_course_documents_in_sessions is enabled
                // Then we avoid the documents that have visibility in session but that they come from a base course
                if ($hideInvisibleDocuments && $sessionId) {
                    if ($row['item_property_session_id'] == $sessionId && empty($row['session_id'])) {
                        continue;
                    }
                }

                $rows[$row['id']] = $row;
            }

            // If we are in session and hide_invisible_course_documents_in_sessions is enabled
            // Or if we are students
            // Then don't list the invisible or deleted documents
            if (($sessionId && $hideInvisibleDocuments) || (!$isCoach && !$isAllowedToEdit)) {
                $rows = array_filter($rows, function ($row) {
                    if (in_array($row['visibility'], ['0', '2'])) {
                        return false;
                    }

                    return true;
                });
            }

            foreach ($rows as $row) {
                if ($row['filetype'] == 'file' &&
                    pathinfo($row['path'], PATHINFO_EXTENSION) == 'html'
                ) {
                    // Templates management
                    $tblTemplate = Database::get_main_table(TABLE_MAIN_TEMPLATES);
                    $sql = "SELECT id FROM $tblTemplate
                            WHERE
                                course_code = '".$courseInfo['code']."' AND
                                user_id = '".api_get_user_id()."' AND
                                ref_doc = '".$row['id']."'";
                    $templateResult = Database::query($sql);
                    $row['is_template'] = (Database::num_rows($templateResult) > 0) ? 1 : 0;
                }
                $row['basename'] = basename($row['path']);
                // Just filling $document_data.
                $documentData[$row['id']] = $row;
            }

            // Only for the student we filter the results see BT#1652
            if (!$isCoach && !$isAllowedToEdit) {
                // Checking parents visibility.
                $finalDocumentData = [];
                foreach ($documentData as $row) {
                    $isVisible = self::check_visibility_tree(
                        $row['id'],
                        $courseInfo['code'],
                        $sessionId,
                        api_get_user_id(),
                        $toGroupId
                    );
                    if ($isVisible) {
                        $finalDocumentData[$row['id']] = $row;
                    }
                }
            } else {
                $finalDocumentData = $documentData;
            }

            return $finalDocumentData;
        } else {
            return [];
        }
    }

    /**
     * Gets the paths of all folders in a course
     * can show all folders (except for the deleted ones) or only visible ones.
     *
     * @param array  $_course
     * @param int    $groupIid          iid
     * @param bool   $can_see_invisible
     * @param bool   $getInvisibleList
     * @param string $path              current path
     *
     * @return array with paths
     */
    public static function get_all_document_folders(
        $_course,
        $groupIid = 0,
        $can_see_invisible = false,
        $getInvisibleList = false,
        $path = ''
    ) {
        $TABLE_ITEMPROPERTY = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);
        $groupIid = intval($groupIid);
        $document_folders = [];

        $students = CourseManager::get_user_list_from_course_code(
            $_course['code'],
            api_get_session_id()
        );

        $conditionList = [];
        if (!empty($students)) {
            foreach ($students as $studentId => $studentInfo) {
                $conditionList[] = '/shared_folder/sf_user_'.$studentInfo['user_id'];
            }
        }

        $groupCondition = " last.to_group_id = $groupIid";
        if (empty($groupIid)) {
            $groupCondition = " (last.to_group_id = 0 OR last.to_group_id IS NULL)";
        }

        $show_users_condition = '';
        if (api_get_setting('show_users_folders') === 'false') {
            $show_users_condition = " AND docs.path NOT LIKE '%shared_folder%'";
        }

        if ($can_see_invisible) {
            // condition for the session
            $session_id = api_get_session_id();
            //$condition_session = api_get_session_condition($session_id, true, false, 'docs.session_id');

            $session_id = $session_id ?: api_get_session_id();
            $condition_session = " AND (last.session_id = '$session_id' OR (last.session_id = '0' OR last.session_id IS NULL) )";
            $condition_session .= self::getSessionFolderFilters($path, $session_id);

            if ($groupIid != 0) {
                $sql = "SELECT DISTINCT docs.id, path
                       FROM $TABLE_ITEMPROPERTY  AS last
                       INNER JOIN $TABLE_DOCUMENT  AS docs
                       ON (
                            docs.id = last.ref AND
                            docs.c_id = last.c_id
                       )
                       WHERE                       
                            last.tool = '".TOOL_DOCUMENT."' AND
                            last.c_id = {$_course['real_id']} AND
                            docs.c_id = {$_course['real_id']} AND
                            docs.filetype = 'folder' AND
                            $groupCondition AND
                            docs.path NOT LIKE '%shared_folder%' AND
                            docs.path NOT LIKE '%_DELETED_%' AND
                            last.visibility <> 2                            
                            $condition_session ";
            } else {
                $sql = "SELECT DISTINCT docs.id, path
                        FROM $TABLE_ITEMPROPERTY  AS last
                        INNER JOIN $TABLE_DOCUMENT  AS docs
                        ON (
                            docs.id = last.ref AND
                            docs.c_id = last.c_id                          
                        )
                        WHERE
                            last.tool = '".TOOL_DOCUMENT."' AND
                            last.c_id = {$_course['real_id']} AND
                            docs.c_id = {$_course['real_id']} AND
                            docs.filetype = 'folder' AND
                            docs.path NOT LIKE '%_DELETED_%' AND
                            $groupCondition AND
                            last.visibility <> 2
                            $show_users_condition 
                            $condition_session 
                        ";
            }
            $result = Database::query($sql);

            if ($result && Database::num_rows($result) != 0) {
                while ($row = Database::fetch_array($result, 'ASSOC')) {
                    if (self::is_folder_to_avoid($row['path'])) {
                        continue;
                    }

                    if (strpos($row['path'], '/shared_folder/') !== false) {
                        if (!in_array($row['path'], $conditionList)) {
                            continue;
                        }
                    }

                    $document_folders[$row['id']] = $row['path'];
                }

                if (!empty($document_folders)) {
                    natsort($document_folders);
                }

                return $document_folders;
            } else {
                return false;
            }
        } else {
            // No invisible folders
            // Condition for the session
            $session_id = api_get_session_id();
            $condition_session = api_get_session_condition(
                $session_id,
                true,
                false,
                'docs.session_id'
            );

            $visibilityCondition = 'last.visibility = 1';
            $fileType = "docs.filetype = 'folder' AND";
            if ($getInvisibleList) {
                $visibilityCondition = 'last.visibility = 0';
                $fileType = '';
            }

            //get visible folders
            $sql = "SELECT DISTINCT docs.id, path
                    FROM
                    $TABLE_ITEMPROPERTY AS last 
                    INNER JOIN $TABLE_DOCUMENT AS docs
                    ON (docs.id = last.ref AND last.c_id = docs.c_id)
                    WHERE
                        $fileType
                        last.tool = '".TOOL_DOCUMENT."' AND
                        $groupCondition AND
                        $visibilityCondition
                        $show_users_condition
                        $condition_session AND
                        last.c_id = {$_course['real_id']}  AND
                        docs.c_id = {$_course['real_id']} ";

            $result = Database::query($sql);

            $visibleFolders = [];
            while ($row = Database::fetch_array($result, 'ASSOC')) {
                $visibleFolders[$row['id']] = $row['path'];
            }

            if ($getInvisibleList) {
                return $visibleFolders;
            }

            //get invisible folders
            $sql = "SELECT DISTINCT docs.id, path
                    FROM $TABLE_ITEMPROPERTY AS last 
                    INNER JOIN $TABLE_DOCUMENT AS docs
                    ON (docs.id = last.ref AND last.c_id = docs.c_id)
                    WHERE                        
                        docs.filetype = 'folder' AND
                        last.tool = '".TOOL_DOCUMENT."' AND
                        $groupCondition AND
                        last.visibility = 0 $condition_session AND
                        last.c_id = {$_course['real_id']} AND
                        docs.c_id = {$_course['real_id']} ";
            $result = Database::query($sql);
            $invisibleFolders = [];
            while ($row = Database::fetch_array($result, 'ASSOC')) {
                //get visible folders in the invisible ones -> they are invisible too
                $sql = "SELECT DISTINCT docs.id, path
                        FROM $TABLE_ITEMPROPERTY AS last 
                        INNER JOIN $TABLE_DOCUMENT AS docs
                        ON (docs.id = last.ref AND docs.c_id = last.c_id)
                        WHERE                            
                            docs.path LIKE '".Database::escape_string($row['path'].'/%')."' AND
                            docs.filetype = 'folder' AND
                            last.tool = '".TOOL_DOCUMENT."' AND
                            $groupCondition AND
                            last.visibility = 1 $condition_session AND
                            last.c_id = {$_course['real_id']} AND
                            docs.c_id = {$_course['real_id']}  ";
                $folder_in_invisible_result = Database::query($sql);
                while ($folders_in_invisible_folder = Database::fetch_array($folder_in_invisible_result, 'ASSOC')) {
                    $invisibleFolders[$folders_in_invisible_folder['id']] = $folders_in_invisible_folder['path'];
                }
            }

            // If both results are arrays -> //calculate the difference between the 2 arrays -> only visible folders are left :)
            if (is_array($visibleFolders) && is_array($invisibleFolders)) {
                $document_folders = array_diff($visibleFolders, $invisibleFolders);
                natsort($document_folders);

                return $document_folders;
            } elseif (is_array($visibleFolders)) {
                natsort($visibleFolders);

                return $visibleFolders;
            } else {
                //no visible folders found
                return false;
            }
        }
    }

    /**
     * This check if a document has the readonly property checked, then see if the user
     * is the owner of this file, if all this is true then return true.
     *
     * @param array  $_course
     * @param int    $user_id     id of the current user
     * @param string $file        path stored in the database (if not defined, $documentId must be used)
     * @param int    $document_id in case you dont have the file path ,
     *                            insert the id of the file here and leave $file in blank ''
     * @param bool   $to_delete
     * @param int    $sessionId
     *
     * @return bool true/false
     * */
    public static function check_readonly(
        $_course,
        $user_id,
        $file = null,
        $document_id = 0,
        $to_delete = false,
        $sessionId = null,
        $documentId = null
    ) {
        if (empty($sessionId)) {
            $sessionId = api_get_session_id();
        } else {
            $sessionId = intval($sessionId);
        }

        if (empty($document_id) || !is_numeric($document_id)) {
            $document_id = self::get_document_id($_course, $file, $sessionId);
        } else {
            $document_id = intval($document_id);
        }

        $TABLE_PROPERTY = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);
        $course_id = $_course['real_id'];

        if ($to_delete) {
            if (self::is_folder($_course, $document_id)) {
                if (!empty($file)) {
                    $path = Database::escape_string($file);
                    // Check
                    $sql = "SELECT td.id, readonly, tp.insert_user_id
                            FROM $TABLE_DOCUMENT td 
                            INNER JOIN $TABLE_PROPERTY tp
                            ON (td.c_id = tp.c_id AND tp.ref= td.id)
                            WHERE
                                td.c_id = $course_id AND
                                tp.c_id = $course_id AND
                                td.session_id = $sessionId AND                                
                                (path='".$path."' OR path LIKE BINARY '".$path."/%' ) ";
                    // Get all id's of documents that are deleted
                    $what_to_check_result = Database::query($sql);

                    if ($what_to_check_result && Database::num_rows($what_to_check_result) != 0) {
                        // file with readonly set to 1 exist?
                        $readonly_set = false;
                        while ($row = Database::fetch_array($what_to_check_result)) {
                            //query to delete from item_property table
                            if ($row['readonly'] == 1) {
                                if (!($row['insert_user_id'] == $user_id)) {
                                    $readonly_set = true;
                                    break;
                                }
                            }
                        }

                        if ($readonly_set) {
                            return true;
                        }
                    }
                }

                return false;
            }
        }

        if (!empty($document_id)) {
            $sql = "SELECT a.insert_user_id, b.readonly
                   FROM $TABLE_PROPERTY a 
                   INNER JOIN $TABLE_DOCUMENT b
                   ON (a.c_id = b.c_id AND a.ref= b.id)
                   WHERE
            			a.c_id = $course_id AND
                        b.c_id = $course_id AND
            			a.ref = $document_id 
                    LIMIT 1";
            $result = Database::query($sql);
            $doc_details = Database::fetch_array($result, 'ASSOC');

            if ($doc_details['readonly'] == 1) {
                return !($doc_details['insert_user_id'] == $user_id || api_is_platform_admin());
            }
        }

        return false;
    }

    /**
     * This check if a document is a folder or not.
     *
     * @param array $_course
     * @param int   $id      document id
     *
     * @return bool true/false
     * */
    public static function is_folder($_course, $id)
    {
        $table = Database::get_course_table(TABLE_DOCUMENT);
        if (empty($_course)) {
            return false;
        }
        $course_id = $_course['real_id'];
        $id = (int) $id;
        $sql = "SELECT filetype FROM $table
                WHERE c_id = $course_id AND id= $id";
        $result = Database::fetch_array(Database::query($sql), 'ASSOC');

        return $result['filetype'] == 'folder';
    }

    /**
     * @param int   $document_id
     * @param array $course_info
     * @param int   $session_id
     * @param bool  $remove_content_from_db
     */
    public static function deleteDocumentFromDb(
        $document_id,
        $course_info = [],
        $session_id = 0,
        $remove_content_from_db = false
    ) {
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);
        $TABLE_ITEMPROPERTY = Database::get_course_table(TABLE_ITEM_PROPERTY);

        // Deleting from the DB
        $user_id = api_get_user_id();
        $document_id = intval($document_id);

        if (empty($course_info)) {
            $course_info = api_get_course_info();
        }

        if (empty($session_id)) {
            $session_id = api_get_session_id();
        }
        // Soft DB delete
        api_item_property_update(
            $course_info,
            TOOL_DOCUMENT,
            $document_id,
            'delete',
            $user_id,
            null,
            null,
            null,
            null,
            $session_id
        );
        self::delete_document_from_search_engine($course_info['code'], $document_id);
        self::unset_document_as_template($document_id, $course_info['code'], $user_id);

        //Hard DB delete
        if ($remove_content_from_db) {
            $sql = "DELETE FROM $TABLE_ITEMPROPERTY
                    WHERE
                        c_id = {$course_info['real_id']} AND
                        ref = ".$document_id." AND
                        tool='".TOOL_DOCUMENT."'";
            Database::query($sql);

            $sql = "DELETE FROM $TABLE_DOCUMENT
                    WHERE c_id = {$course_info['real_id']} AND id = ".$document_id;
            Database::query($sql);
        }
    }

    /**
     * This deletes a document by changing visibility to 2, renaming it to filename_DELETED_#id
     * Files/folders that are inside a deleted folder get visibility 2.
     *
     * @param array  $_course
     * @param string $path          Path stored in the database
     * @param string $base_work_dir Path to the documents folder (if not defined, $documentId must be used)
     * @param int    $sessionId     The ID of the session, if any
     * @param int    $documentId    The document id, if available
     * @param int    $groupId       iid
     *
     * @return bool true/false
     *
     * @todo now only files/folders in a folder get visibility 2, we should rename them too.
     * @todo We should be able to get rid of this later when using only documentId (check further usage)
     */
    public static function delete_document(
        $_course,
        $path = null,
        $base_work_dir = null,
        $sessionId = null,
        $documentId = null,
        $groupId = 0
    ) {
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);

        $groupId = intval($groupId);
        if (empty($groupId)) {
            $groupId = api_get_group_id();
        }

        $sessionId = intval($sessionId);
        if (empty($sessionId)) {
            $sessionId = api_get_session_id();
        }

        $course_id = $_course['real_id'];

        if (empty($course_id)) {
            return false;
        }

        if (empty($base_work_dir)) {
            return false;
        }

        if (empty($documentId)) {
            $documentId = self::get_document_id($_course, $path, $sessionId);
            $docInfo = self::get_document_data_by_id(
                $documentId,
                $_course['code'],
                false,
                $sessionId
            );
            $path = $docInfo['path'];
        } else {
            $docInfo = self::get_document_data_by_id(
                $documentId,
                $_course['code'],
                false,
                $sessionId
            );
            if (empty($docInfo)) {
                return false;
            }
            $path = $docInfo['path'];
        }

        $documentId = intval($documentId);

        if (empty($path) || empty($docInfo) || empty($documentId)) {
            return false;
        }

        $itemInfo = api_get_item_property_info(
            $_course['real_id'],
            TOOL_DOCUMENT,
            $documentId,
            $sessionId,
            $groupId
        );

        if (empty($itemInfo)) {
            return false;
        }

        // File was already deleted.
        if ($itemInfo['lastedit_type'] == 'DocumentDeleted' ||
            $itemInfo['lastedit_type'] == 'delete' ||
            $itemInfo['visibility'] == 2
        ) {
            return false;
        }

        // Filtering by group.
        if ($itemInfo['to_group_id'] != $groupId) {
            return false;
        }

        $document_exists_in_disk = file_exists($base_work_dir.$path);
        $new_path = $path.'_DELETED_'.$documentId;

        $file_deleted_from_db = false;
        $file_deleted_from_disk = false;
        $file_renamed_from_disk = false;

        if ($documentId) {
            // Deleting doc from the DB.
            self::deleteDocumentFromDb($documentId, $_course, $sessionId);
            // Checking
            // $file_exists_in_db = self::get_document_data_by_id($documentId, $_course['code']);
            $file_deleted_from_db = true;
        }

        // Looking for children.
        if ($docInfo['filetype'] == 'folder') {
            $cleanPath = Database::escape_string($path);

            // Deleted files inside this folder.
            $sql = "SELECT id FROM $TABLE_DOCUMENT
                    WHERE
                        c_id = $course_id AND
                        session_id = $sessionId AND
                        path LIKE BINARY '".$cleanPath."/%'";

            // Get all id's of documents that are deleted.
            $result = Database::query($sql);

            if ($result && Database::num_rows($result) != 0) {
                // Recursive delete.
                while ($row = Database::fetch_array($result)) {
                    self::delete_document(
                        $_course,
                        null,
                        $base_work_dir,
                        $sessionId,
                        $row['id'],
                        $groupId
                    );
                }
            }
        }

        if ($document_exists_in_disk) {
            if (api_get_setting('permanently_remove_deleted_files') === 'true') {
                // Delete documents, do it like this so metadata gets deleted too
                my_delete($base_work_dir.$path);
                // Hard delete.
                self::deleteDocumentFromDb($documentId, $_course, $sessionId, true);
                $file_deleted_from_disk = true;
            } else {
                // Set visibility to 2 and rename file/folder to xxx_DELETED_#id (soft delete)
                if (is_file($base_work_dir.$path) || is_dir($base_work_dir.$path)) {
                    if (rename($base_work_dir.$path, $base_work_dir.$new_path)) {
                        $new_path = Database::escape_string($new_path);

                        $sql = "UPDATE $TABLE_DOCUMENT
                                SET path = '".$new_path."'
                                WHERE
                                    c_id = $course_id AND
                                    session_id = $sessionId AND
                                    id = ".$documentId;
                        Database::query($sql);

                        // Soft delete.
                        self::deleteDocumentFromDb($documentId, $_course, $sessionId);

                        // Change path of sub folders and documents in database.
                        $old_item_path = $docInfo['path'];
                        $new_item_path = $new_path.substr($old_item_path, strlen($path));
                        $new_item_path = Database::escape_string($new_item_path);

                        $sql = "UPDATE $TABLE_DOCUMENT
                                SET path = '".$new_item_path."'
                                WHERE
                                    c_id = $course_id AND
                                    session_id = $sessionId AND
                                    id = ".$documentId;
                        Database::query($sql);

                        $file_renamed_from_disk = true;
                    } else {
                        // Couldn't rename - file permissions problem?
                        error_log(
                            __FILE__.' '.__LINE__.': Error renaming '.$base_work_dir.$path.' to '.$base_work_dir.$new_path.'. This is probably due to file permissions',
                            0
                        );
                    }
                }
            }
        }
        // Checking inconsistency
        //error_log('Doc status: (1 del db :'.($file_deleted_from_db?'yes':'no').') - (2 del disk: '.($file_deleted_from_disk?'yes':'no').') - (3 ren disk: '.($file_renamed_from_disk?'yes':'no').')');
        if ($file_deleted_from_db && $file_deleted_from_disk ||
            $file_deleted_from_db && $file_renamed_from_disk
        ) {
            return true;
        } else {
            //Something went wrong
            //The file or directory isn't there anymore (on the filesystem)
            // This means it has been removed externally. To prevent a
            // blocking error from happening, we drop the related items from the
            // item_property and the document table.
            error_log(
                __FILE__.' '.__LINE__.': System inconsistency detected. The file or directory '.$base_work_dir.$path.' seems to have been removed from the filesystem independently from the web platform. To restore consistency, the elements using the same path will be removed from the database',
                0
            );

            return false;
        }
    }

    /**
     * Removes documents from search engine database.
     *
     * @param string $course_id   Course code
     * @param int    $document_id Document id to delete
     */
    public static function delete_document_from_search_engine($course_id, $document_id)
    {
        // remove from search engine if enabled
        if (api_get_setting('search_enabled') === 'true') {
            $tbl_se_ref = Database::get_main_table(TABLE_MAIN_SEARCH_ENGINE_REF);
            $sql = 'SELECT * FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_high_level=%s LIMIT 1';
            $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_DOCUMENT, $document_id);
            $res = Database::query($sql);
            if (Database::num_rows($res) > 0) {
                $row2 = Database::fetch_array($res);
                $di = new ChamiloIndexer();
                $di->remove_document($row2['search_did']);
            }
            $sql = 'DELETE FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_high_level=%s LIMIT 1';
            $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_DOCUMENT, $document_id);
            Database::query($sql);

            // remove terms from db
            require_once api_get_path(LIBRARY_PATH).'specific_fields_manager.lib.php';
            delete_all_values_for_item($course_id, TOOL_DOCUMENT, $document_id);
        }
    }

    /**
     * Gets the id of a document with a given path.
     *
     * @param array  $courseInfo
     * @param string $path
     * @param int    $sessionId
     *
     * @return int id of document / false if no doc found
     */
    public static function get_document_id($courseInfo, $path, $sessionId = null)
    {
        $table = Database::get_course_table(TABLE_DOCUMENT);
        $courseId = $courseInfo['real_id'];

        if (!isset($sessionId)) {
            $sessionId = api_get_session_id();
        } else {
            $sessionId = intval($sessionId);
        }

        $path = Database::escape_string($path);
        if (!empty($courseId) && !empty($path)) {
            $sql = "SELECT id FROM $table
                    WHERE
                        c_id = $courseId AND
                        path LIKE BINARY '$path' AND
                        session_id = $sessionId
                    LIMIT 1";

            $result = Database::query($sql);
            if (Database::num_rows($result)) {
                $row = Database::fetch_array($result);

                return intval($row['id']);
            }
        }

        return false;
    }

    /**
     * Gets the document data with a given id.
     *
     * @param int    $id           Document Id (id field in c_document table)
     * @param string $course_code  Course code
     * @param bool   $load_parents load folder parents
     * @param int    $session_id   The session ID,
     *                             0 if requires context *out of* session, and null to use global context
     *
     * @return array document content
     */
    public static function get_document_data_by_id(
        $id,
        $course_code,
        $load_parents = false,
        $session_id = null
    ) {
        $course_info = api_get_course_info($course_code);
        $course_id = $course_info['real_id'];

        if (empty($course_info)) {
            return false;
        }

        $session_id = empty($session_id) ? api_get_session_id() : intval($session_id);
        $www = api_get_path(WEB_COURSE_PATH).$course_info['path'].'/document';
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);
        $id = intval($id);
        $sessionCondition = api_get_session_condition($session_id, true, true);

        $sql = "SELECT * FROM $TABLE_DOCUMENT
                WHERE c_id = $course_id $sessionCondition AND id = $id";

        $result = Database::query($sql);
        if ($result && Database::num_rows($result) == 1) {
            $row = Database::fetch_array($result, 'ASSOC');
            //@todo need to clarify the name of the URLs not nice right now
            $url_path = urlencode($row['path']);
            $path = str_replace('%2F', '/', $url_path);
            $pathinfo = pathinfo($row['path']);

            $row['url'] = api_get_path(WEB_CODE_PATH).'document/showinframes.php?cidReq='.$course_code.'&id='.$id;
            $row['document_url'] = api_get_path(WEB_CODE_PATH).'document/document.php?cidReq='.$course_code.'&id='.$id;
            $row['absolute_path'] = api_get_path(SYS_COURSE_PATH).$course_info['path'].'/document'.$row['path'];
            $row['absolute_path_from_document'] = '/document'.$row['path'];
            $row['absolute_parent_path'] = api_get_path(SYS_COURSE_PATH).$course_info['path'].'/document'.$pathinfo['dirname'].'/';
            $row['direct_url'] = $www.$path;
            $row['basename'] = basename($row['path']);

            if (dirname($row['path']) == '.') {
                $row['parent_id'] = '0';
            } else {
                $row['parent_id'] = self::get_document_id($course_info, dirname($row['path']), $session_id);
            }
            $parents = [];

            //Use to generate parents (needed for the breadcrumb)
            //@todo sorry but this for is here because there's not a parent_id in the document table so we parsed the path!!
            if ($load_parents) {
                $dir_array = explode('/', $row['path']);
                $dir_array = array_filter($dir_array);
                $array_len = count($dir_array) + 1;
                $real_dir = '';

                for ($i = 1; $i < $array_len; $i++) {
                    $real_dir .= '/'.(isset($dir_array[$i]) ? $dir_array[$i] : '');
                    $parent_id = self::get_document_id($course_info, $real_dir);
                    if ($session_id != 0 && empty($parent_id)) {
                        $parent_id = self::get_document_id($course_info, $real_dir, 0);
                    }
                    if (!empty($parent_id)) {
                        $sub_document_data = self::get_document_data_by_id(
                            $parent_id,
                            $course_code,
                            false,
                            $session_id
                        );
                        if ($session_id != 0 and !$sub_document_data) {
                            $sub_document_data = self::get_document_data_by_id(
                                $parent_id,
                                $course_code,
                                false,
                                0
                            );
                        }
                        //@todo add visibility here
                        $parents[] = $sub_document_data;
                    }
                }
            }
            $row['parents'] = $parents;

            return $row;
        }

        return false;
    }

    /**
     * Allow to set a specific document as a new template for CKeditor
     * for a particular user in a particular course.
     *
     * @param string $title
     * @param string $description
     * @param int    $document_id_for_template the document id
     * @param string $course_code
     * @param int    $user_id
     * @param string $image
     *
     * @return bool
     */
    public static function set_document_as_template(
        $title,
        $description,
        $document_id_for_template,
        $course_code,
        $user_id,
        $image
    ) {
        // Database table definition
        $table_template = Database::get_main_table(TABLE_MAIN_TEMPLATES);
        $params = [
            'title' => $title,
            'description' => $description,
            'course_code' => $course_code,
            'user_id' => $user_id,
            'ref_doc' => $document_id_for_template,
            'image' => $image,
        ];
        Database::insert($table_template, $params);

        return true;
    }

    /**
     * Unset a document as template.
     *
     * @param int    $document_id
     * @param string $course_code
     * @param int    $user_id
     */
    public static function unset_document_as_template(
        $document_id,
        $course_code,
        $user_id
    ) {
        $table_template = Database::get_main_table(TABLE_MAIN_TEMPLATES);
        $course_code = Database::escape_string($course_code);
        $user_id = intval($user_id);
        $document_id = intval($document_id);
        $sql = 'SELECT id FROM '.$table_template.'
                WHERE
                    course_code="'.$course_code.'" AND
                    user_id="'.$user_id.'" AND
                    ref_doc="'.$document_id.'"';
        $result = Database::query($sql);
        $template_id = Database::result($result, 0, 0);

        my_delete(api_get_path(SYS_CODE_PATH).'upload/template_thumbnails/'.$template_id.'.jpg');

        $sql = 'DELETE FROM '.$table_template.'
                WHERE
                    course_code="'.$course_code.'" AND
                    user_id="'.$user_id.'" AND
                    ref_doc="'.$document_id.'"';

        Database::query($sql);
    }

    /**
     * Return true if the documentpath have visibility=1 as
     * item_property (you should use the is_visible_by_id).
     *
     * @param string $doc_path the relative complete path of the document
     * @param array  $course   the _course array info of the document's course
     * @param int
     * @param string
     *
     * @return bool
     */
    public static function is_visible(
        $doc_path,
        $course,
        $session_id = 0,
        $file_type = 'file'
    ) {
        $docTable = Database::get_course_table(TABLE_DOCUMENT);
        $propTable = Database::get_course_table(TABLE_ITEM_PROPERTY);

        $course_id = $course['real_id'];
        // note the extra / at the end of doc_path to match every path in
        // the document table that is part of the document path

        $session_id = intval($session_id);
        $condition = "AND d.session_id IN  ('$session_id', '0') ";
        // The " d.filetype='file' " let the user see a file even if the folder is hidden see #2198

        /*
          When using hotpotatoes files, a new html files are generated
          in the hotpotatoes folder to display the test.
          The genuine html file is copied to math4.htm(user_id).t.html
          Images files are not copied, and keep same name.
          To check the html file visibility, we don't have to check file math4.htm(user_id).t.html but file math4.htm
          In this case, we have to remove (user_id).t.html to check the visibility of the file
          For images, we just check the path of the image file.

          Exemple of hotpotatoes folder :
          A.jpg
          maths4-consigne.jpg
          maths4.htm
          maths4.htm1.t.html
          maths4.htm52.t.html
          maths4.htm654.t.html
          omega.jpg
          theta.jpg
         */

        if (strpos($doc_path, 'HotPotatoes_files') && preg_match("/\.t\.html$/", $doc_path)) {
            $doc_path = substr($doc_path, 0, strlen($doc_path) - 7 - strlen(api_get_user_id()));
        }

        if (!in_array($file_type, ['file', 'folder'])) {
            $file_type = 'file';
        }
        $doc_path = Database::escape_string($doc_path).'/';

        $sql = "SELECT visibility
                FROM $docTable d
                INNER JOIN $propTable ip
                ON (d.id = ip.ref AND d.c_id = ip.c_id)
        		WHERE
        		    d.c_id  = $course_id AND 
        		    ip.c_id = $course_id AND
        		    ip.tool = '".TOOL_DOCUMENT."' $condition AND
        			filetype = '$file_type' AND
        			locate(concat(path,'/'), '$doc_path')=1
                ";

        $result = Database::query($sql);
        $is_visible = false;
        if (Database::num_rows($result) > 0) {
            $row = Database::fetch_array($result, 'ASSOC');
            if ($row['visibility'] == 1) {
                $is_visible = api_is_allowed_in_course() || api_is_platform_admin();
            }
        }

        /* improved protection of documents viewable directly through the url:
            incorporates the same protections of the course at the url of
            documents:
            access allowed for the whole world Open, access allowed for
            users registered on the platform Private access, document accessible
            only to course members (see the Users list), Completely closed;
            the document is only accessible to the course admin and
            teaching assistants.*/
        //return $_SESSION ['is_allowed_in_course'] || api_is_platform_admin();
        return $is_visible;
    }

    /**
     * Return true if user can see a file.
     *
     * @param   int     document id
     * @param   array   course info
     * @param   int
     * @param   int
     * @param bool
     *
     * @return bool
     */
    public static function is_visible_by_id(
        $doc_id,
        $course_info,
        $session_id,
        $user_id,
        $admins_can_see_everything = true,
        $userIsSubscribed = null
    ) {
        $user_in_course = false;

        //1. Checking the course array
        if (empty($course_info)) {
            $course_info = api_get_course_info();
            if (empty($course_info)) {
                return false;
            }
        }

        $doc_id = intval($doc_id);
        $session_id = intval($session_id);

        //2. Course and Session visibility are handle in local.inc.php/global.inc.php
        //3. Checking if user exist in course/session
        if ($session_id == 0) {
            if (is_null($userIsSubscribed)) {
                $userIsSubscribed = CourseManager::is_user_subscribed_in_course(
                    $user_id,
                    $course_info['code']
                );
            }

            if ($userIsSubscribed === true || api_is_platform_admin()) {
                $user_in_course = true;
            }

            // Check if course is open then we can consider that the student is registered to the course
            if (isset($course_info) &&
                in_array(
                    $course_info['visibility'],
                    [COURSE_VISIBILITY_OPEN_PLATFORM, COURSE_VISIBILITY_OPEN_WORLD]
                )
            ) {
                $user_in_course = true;
            }
        } else {
            $user_status = SessionManager::get_user_status_in_course_session(
                $user_id,
                $course_info['real_id'],
                $session_id
            );

            if (in_array($user_status, ['0', '2', '6'])) {
                //is true if is an student, course session teacher or coach
                $user_in_course = true;
            }

            if (api_is_platform_admin()) {
                $user_in_course = true;
            }
        }

        // 4. Checking document visibility (i'm repeating the code in order to be more clear when reading ) - jm
        if ($user_in_course) {
            // 4.1 Checking document visibility for a Course
            if ($session_id == 0) {
                $item_info = api_get_item_property_info(
                    $course_info['real_id'],
                    'document',
                    $doc_id,
                    0
                );

                if (isset($item_info['visibility'])) {
                    // True for admins if document exists
                    if ($admins_can_see_everything && api_is_platform_admin()) {
                        return true;
                    }
                    if ($item_info['visibility'] == 1) {
                        return true;
                    }
                }
            } else {
                // 4.2 Checking document visibility for a Course in a Session
                $item_info = api_get_item_property_info(
                    $course_info['real_id'],
                    'document',
                    $doc_id,
                    0
                );

                $item_info_in_session = api_get_item_property_info(
                    $course_info['real_id'],
                    'document',
                    $doc_id,
                    $session_id
                );

                // True for admins if document exists
                if (isset($item_info['visibility'])) {
                    if ($admins_can_see_everything && api_is_platform_admin()) {
                        return true;
                    }
                }

                if (isset($item_info_in_session['visibility'])) {
                    if ($item_info_in_session['visibility'] == 1) {
                        return true;
                    }
                } else {
                    if ($item_info['visibility'] == 1) {
                        return true;
                    }
                }
            }
        } elseif ($admins_can_see_everything && api_is_platform_admin()) {
            return true;
        }

        return false;
    }

    /**
     * Allow attach a certificate to a course.
     *
     * @todo move to certificate.lib.php
     *
     * @param string $course_id
     * @param int    $document_id
     * @param int    $session_id
     */
    public static function attach_gradebook_certificate($course_id, $document_id, $session_id = 0)
    {
        $tbl_category = Database::get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $session_id = intval($session_id);
        if (empty($session_id)) {
            $session_id = api_get_session_id();
        }

        if (empty($session_id)) {
            $sql_session = 'AND (session_id = 0 OR isnull(session_id)) ';
        } elseif ($session_id > 0) {
            $sql_session = 'AND session_id='.intval($session_id);
        } else {
            $sql_session = '';
        }
        $sql = 'UPDATE '.$tbl_category.' SET document_id="'.intval($document_id).'"
                WHERE course_code="'.Database::escape_string($course_id).'" '.$sql_session;
        Database::query($sql);
    }

    /**
     * get the document id of default certificate.
     *
     * @todo move to certificate.lib.php
     *
     * @param string $course_id
     * @param int    $session_id
     *
     * @return int The default certificate id
     */
    public static function get_default_certificate_id($course_id, $session_id = 0)
    {
        $tbl_category = Database::get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
        $session_id = intval($session_id);
        if (empty($session_id)) {
            $session_id = api_get_session_id();
        }

        if (empty($session_id)) {
            $sql_session = 'AND (session_id = 0 OR isnull(session_id)) ';
        } elseif ($session_id > 0) {
            $sql_session = 'AND session_id='.intval($session_id);
        } else {
            $sql_session = '';
        }
        $sql = 'SELECT document_id FROM '.$tbl_category.'
                WHERE course_code="'.Database::escape_string($course_id).'" '.$sql_session;

        $rs = Database::query($sql);
        $num = Database::num_rows($rs);
        if ($num == 0) {
            return null;
        }
        $row = Database::fetch_array($rs);

        return $row['document_id'];
    }

    /**
     * Allow replace user info in file html.
     *
     * @param int    $user_id
     * @param string $course_code
     * @param int    $sessionId
     * @param bool   $is_preview
     *
     * @return array
     */
    public static function replace_user_info_into_html(
        $user_id,
        $course_code,
        $sessionId,
        $is_preview = false
    ) {
        $user_id = intval($user_id);
        $course_info = api_get_course_info($course_code);
        $tbl_document = Database::get_course_table(TABLE_DOCUMENT);
        $course_id = $course_info['real_id'];

        $document_id = self::get_default_certificate_id(
            $course_code,
            $sessionId
        );

        $my_content_html = null;
        if ($document_id) {
            $sql = "SELECT path FROM $tbl_document
                    WHERE c_id = $course_id AND id = $document_id";
            $rs = Database::query($sql);
            $new_content = '';
            $all_user_info = [];
            if (Database::num_rows($rs)) {
                $row = Database::fetch_array($rs);
                $filepath = api_get_path(SYS_COURSE_PATH).$course_info['path'].'/document'.$row['path'];
                if (is_file($filepath)) {
                    $my_content_html = file_get_contents($filepath);
                }
                $all_user_info = self::get_all_info_to_certificate(
                    $user_id,
                    $course_code,
                    $is_preview
                );

                $info_to_be_replaced_in_content_html = $all_user_info[0];
                $info_to_replace_in_content_html = $all_user_info[1];
                $new_content = str_replace(
                    $info_to_be_replaced_in_content_html,
                    $info_to_replace_in_content_html,
                    $my_content_html
                );
            }

            return [
                'content' => $new_content,
                'variables' => $all_user_info,
            ];
        }

        return [];
    }

    /**
     * Return all content to replace and all content to be replace.
     *
     * @param int  $user_id
     * @param int  $course_id
     * @param bool $is_preview
     *
     * @return array
     */
    public static function get_all_info_to_certificate($user_id, $course_id, $is_preview = false)
    {
        $info_list = [];
        $user_id = intval($user_id);
        $course_info = api_get_course_info($course_id);

        // Portal info
        $organization_name = api_get_setting('Institution');
        $portal_name = api_get_setting('siteName');

        // Extra user data information
        $extra_user_info_data = UserManager::get_extra_user_data(
            $user_id,
            false,
            false,
            false,
            true
        );

        // get extra fields
        $extraField = new ExtraField('user');
        $extraFields = $extraField->get_all(['filter = ? AND visible_to_self = ?' => [1, 1]]);

        // Student information
        $user_info = api_get_user_info($user_id);
        $first_name = $user_info['firstname'];
        $last_name = $user_info['lastname'];
        $official_code = $user_info['official_code'];

        // Teacher information
        $info_teacher_id = UserManager::get_user_id_of_course_admin_or_session_admin($course_info);
        $teacher_info = api_get_user_info($info_teacher_id);
        $teacher_first_name = $teacher_info['firstname'];
        $teacher_last_name = $teacher_info['lastname'];

        // info gradebook certificate
        $info_grade_certificate = UserManager::get_info_gradebook_certificate($course_id, $user_id);
        $date_certificate = $info_grade_certificate['created_at'];
        $date_long_certificate = '';

        $date_no_time = api_convert_and_format_date(api_get_utc_datetime(), DATE_FORMAT_LONG_NO_DAY);
        if (!empty($date_certificate)) {
            $date_long_certificate = api_convert_and_format_date($date_certificate);
            $date_no_time = api_convert_and_format_date($date_certificate, DATE_FORMAT_LONG_NO_DAY);
        }

        if ($is_preview) {
            $date_long_certificate = api_convert_and_format_date(api_get_utc_datetime());
            $date_no_time = api_convert_and_format_date(api_get_utc_datetime(), DATE_FORMAT_LONG_NO_DAY);
        }

        $url = api_get_path(WEB_PATH).'certificates/index.php?id='.$info_grade_certificate['id'];
        $externalStyleFile = api_get_path(SYS_CSS_PATH).'themes/'.api_get_visual_theme().'/certificate.css';
        $externalStyle = '';
        if (is_file($externalStyleFile)) {
            $externalStyle = file_get_contents($externalStyleFile);
        }

        // Replace content
        $info_to_replace_in_content_html = [
            $first_name,
            $last_name,
            $organization_name,
            $portal_name,
            $teacher_first_name,
            $teacher_last_name,
            $official_code,
            $date_long_certificate,
            $date_no_time,
            $course_id,
            $course_info['name'],
            $info_grade_certificate['grade'],
            $url,
            '<a href="'.$url.'" target="_blank">'.get_lang('CertificateOnlineLink').'</a>',
            '((certificate_barcode))',
            $externalStyle,
        ];

        $tags = [
            '((user_firstname))',
            '((user_lastname))',
            '((gradebook_institution))',
            '((gradebook_sitename))',
            '((teacher_firstname))',
            '((teacher_lastname))',
            '((official_code))',
            '((date_certificate))',
            '((date_certificate_no_time))',
            '((course_code))',
            '((course_title))',
            '((gradebook_grade))',
            '((certificate_link))',
            '((certificate_link_html))',
            '((certificate_barcode))',
            '((external_style))',
        ];

        if (!empty($extraFields)) {
            foreach ($extraFields as $extraField) {
                $valueExtra = isset($extra_user_info_data[$extraField['variable']]) ? $extra_user_info_data[$extraField['variable']] : '';
                $tags[] = '(('.strtolower($extraField['variable']).'))';
                $info_to_replace_in_content_html[] = $valueExtra;
            }
        }

        $info_list[] = $tags;
        $info_list[] = $info_to_replace_in_content_html;

        return $info_list;
    }

    /**
     * Remove default certificate.
     *
     * @param string $course_id              The course code
     * @param int    $default_certificate_id The document id of the default certificate
     */
    public static function remove_attach_certificate($course_id, $default_certificate_id)
    {
        if (empty($default_certificate_id)) {
            return false;
        }

        $default_certificate = self::get_default_certificate_id($course_id);
        if ((int) $default_certificate == (int) $default_certificate_id) {
            $tbl_category = Database::get_main_table(TABLE_MAIN_GRADEBOOK_CATEGORY);
            $session_id = api_get_session_id();
            if ($session_id == 0 || is_null($session_id)) {
                $sql_session = 'AND (session_id='.intval($session_id).' OR isnull(session_id)) ';
            } elseif ($session_id > 0) {
                $sql_session = 'AND session_id='.intval($session_id);
            } else {
                $sql_session = '';
            }

            $sql = 'UPDATE '.$tbl_category.' SET document_id = null
                    WHERE
                        course_code = "'.Database::escape_string($course_id).'" AND
                        document_id="'.$default_certificate_id.'" '.$sql_session;
            Database::query($sql);
        }
    }

    /**
     * Create directory certificate.
     *
     * @param array $courseInfo
     */
    public static function create_directory_certificate_in_course($courseInfo)
    {
        if (!empty($courseInfo)) {
            $to_group_id = 0;
            $to_user_id = null;
            $course_dir = $courseInfo['path']."/document/";
            $sys_course_path = api_get_path(SYS_COURSE_PATH);
            $base_work_dir = $sys_course_path.$course_dir;
            $dir_name = '/certificates';
            $post_dir_name = get_lang('CertificatesFiles');
            $visibility_command = 'invisible';

            $id = self::get_document_id_of_directory_certificate();

            if (empty($id)) {
                create_unexisting_directory(
                    $courseInfo,
                    api_get_user_id(),
                    api_get_session_id(),
                    $to_group_id,
                    $to_user_id,
                    $base_work_dir,
                    $dir_name,
                    $post_dir_name,
                    null,
                    false,
                    false
                );

                $id = self::get_document_id_of_directory_certificate();

                if (empty($id)) {
                    $id = add_document(
                        $courseInfo,
                        $dir_name,
                        'folder',
                        0,
                        $post_dir_name,
                        null,
                        0,
                        true,
                        $to_group_id,
                        0,
                        0,
                        false
                    );
                }

                if (!empty($id)) {
                    api_item_property_update(
                        $courseInfo,
                        TOOL_DOCUMENT,
                        $id,
                        $visibility_command,
                        api_get_user_id()
                    );
                }
            }
        }
    }

    /**
     * Get the document id of the directory certificate.
     *
     * @return int The document id of the directory certificate
     *
     * @todo move to certificate.lib.php
     */
    public static function get_document_id_of_directory_certificate()
    {
        $tbl_document = Database::get_course_table(TABLE_DOCUMENT);
        $course_id = api_get_course_int_id();
        $sql = "SELECT id FROM $tbl_document 
                WHERE c_id = $course_id AND path='/certificates' ";
        $rs = Database::query($sql);
        $row = Database::fetch_array($rs);

        return $row['id'];
    }

    /**
     * Check if a directory given is for certificate.
     *
     * @todo move to certificate.lib.php
     *
     * @param string $dir path of directory
     *
     * @return bool true if is a certificate or false otherwise
     */
    public static function is_certificate_mode($dir)
    {
        // I'm in the certification module?
        $is_certificate_mode = false;
        $is_certificate_array = explode('/', $dir);
        array_shift($is_certificate_array);
        if (isset($is_certificate_array[0]) && $is_certificate_array[0] == 'certificates') {
            $is_certificate_mode = true;
        }

        return $is_certificate_mode || (isset($_GET['certificate']) && $_GET['certificate'] === 'true');
    }

    /**
     * Gets the list of included resources as a list of absolute or relative paths from a html file or string html
     * This allows for a better SCORM export or replace urls inside content html from copy course
     * The list will generally include pictures, flash objects, java applets, or any other
     * stuff included in the source of the current item. The current item is expected
     * to be an HTML file or string html. If it is not, then the function will return and empty list.
     *
     * @param    string  source html (content or path)
     * @param    bool    is file or string html
     * @param    string    type (one of the app tools) - optional (otherwise takes the current item's type)
     * @param    int        level of recursivity we're in
     *
     * @return array List of file paths. An additional field containing 'local' or 'remote' helps determine
     *               if the file should be copied into the zip or just linked
     */
    public static function get_resources_from_source_html(
        $source_html,
        $is_file = false,
        $type = null,
        $recursivity = 1
    ) {
        $max = 5;
        $attributes = [];
        $wanted_attributes = [
            'src',
            'url',
            '@import',
            'href',
            'value',
            'flashvars',
            'poster',
        ];
        $explode_attributes = ['flashvars' => 'file'];
        $abs_path = '';

        if ($recursivity > $max) {
            return [];
        }

        if (!isset($type)) {
            $type = TOOL_DOCUMENT;
        }

        if (!$is_file) {
            $attributes = self::parse_HTML_attributes(
                $source_html,
                $wanted_attributes,
                $explode_attributes
            );
        } else {
            if (is_file($source_html)) {
                $abs_path = $source_html;
                //for now, read the whole file in one go (that's gonna be a problem when the file is too big)
                $info = pathinfo($abs_path);
                $ext = $info['extension'];
                switch (strtolower($ext)) {
                    case 'html':
                    case 'htm':
                    case 'shtml':
                    case 'css':
                        $file_content = file_get_contents($abs_path);
                        // get an array of attributes from the HTML source
                        $attributes = self::parse_HTML_attributes(
                            $file_content,
                            $wanted_attributes,
                            $explode_attributes
                        );
                        break;
                    default:
                        break;
                }
            } else {
                return false;
            }
        }

        $files_list = [];
        switch ($type) {
            case TOOL_DOCUMENT:
            case TOOL_QUIZ:
            case 'sco':
                foreach ($wanted_attributes as $attr) {
                    if (isset($attributes[$attr])) {
                        //find which kind of path these are (local or remote)
                        $sources = $attributes[$attr];
                        foreach ($sources as $source) {
                            //skip what is obviously not a resource
                            if (strpos($source, '+this.')) {
                                continue; //javascript code - will still work unaltered
                            }
                            if (strpos($source, '.') === false) {
                                continue; //no dot, should not be an external file anyway
                            }
                            if (strpos($source, 'mailto:')) {
                                continue; //mailto link
                            }
                            if (strpos($source, ';') && !strpos($source, '&amp;')) {
                                continue; //avoid code - that should help
                            }

                            if ($attr == 'value') {
                                if (strpos($source, 'mp3file')) {
                                    $files_list[] = [
                                        substr($source, 0, strpos($source, '.swf') + 4),
                                        'local',
                                        'abs',
                                    ];
                                    $mp3file = substr($source, strpos($source, 'mp3file=') + 8);
                                    if (substr($mp3file, 0, 1) == '/') {
                                        $files_list[] = [$mp3file, 'local', 'abs'];
                                    } else {
                                        $files_list[] = [$mp3file, 'local', 'rel'];
                                    }
                                } elseif (strpos($source, 'flv=') === 0) {
                                    $source = substr($source, 4);
                                    if (strpos($source, '&') > 0) {
                                        $source = substr($source, 0, strpos($source, '&'));
                                    }
                                    if (strpos($source, '://') > 0) {
                                        if (strpos($source, api_get_path(WEB_PATH)) !== false) {
                                            //we found the current portal url
                                            $files_list[] = [$source, 'local', 'url'];
                                        } else {
                                            //we didn't find any trace of current portal
                                            $files_list[] = [$source, 'remote', 'url'];
                                        }
                                    } else {
                                        $files_list[] = [$source, 'local', 'abs'];
                                    }
                                    /* skipping anything else to avoid two entries
                                    (while the others can have sub-files in their url, flv's can't)*/
                                    continue;
                                }
                            }
                            if (strpos($source, '://') > 0) {
                                //cut at '?' in a URL with params
                                if (strpos($source, '?') > 0) {
                                    $second_part = substr($source, strpos($source, '?'));
                                    if (strpos($second_part, '://') > 0) {
                                        //if the second part of the url contains a url too, treat the second one before cutting
                                        $pos1 = strpos($second_part, '=');
                                        $pos2 = strpos($second_part, '&');
                                        $second_part = substr($second_part, $pos1 + 1, $pos2 - ($pos1 + 1));
                                        if (strpos($second_part, api_get_path(WEB_PATH)) !== false) {
                                            //we found the current portal url
                                            $files_list[] = [$second_part, 'local', 'url'];
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $second_part,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } else {
                                            //we didn't find any trace of current portal
                                            $files_list[] = [$second_part, 'remote', 'url'];
                                        }
                                    } elseif (strpos($second_part, '=') > 0) {
                                        if (substr($second_part, 0, 1) === '/') {
                                            //link starts with a /, making it absolute (relative to DocumentRoot)
                                            $files_list[] = [$second_part, 'local', 'abs'];
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $second_part,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } elseif (strstr($second_part, '..') === 0) {
                                            //link is relative but going back in the hierarchy
                                            $files_list[] = [$second_part, 'local', 'rel'];
                                            //$dir = api_get_path(SYS_CODE_PATH);//dirname($abs_path);
                                            //$new_abs_path = realpath($dir.'/'.$second_part);
                                            $dir = '';
                                            if (!empty($abs_path)) {
                                                $dir = dirname($abs_path).'/';
                                            }
                                            $new_abs_path = realpath($dir.$second_part);
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $new_abs_path,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } else {
                                            //no starting '/', making it relative to current document's path
                                            if (substr($second_part, 0, 2) == './') {
                                                $second_part = substr($second_part, 2);
                                            }
                                            $files_list[] = [$second_part, 'local', 'rel'];
                                            $dir = '';
                                            if (!empty($abs_path)) {
                                                $dir = dirname($abs_path).'/';
                                            }
                                            $new_abs_path = realpath($dir.$second_part);
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $new_abs_path,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        }
                                    }
                                    //leave that second part behind now
                                    $source = substr($source, 0, strpos($source, '?'));
                                    if (strpos($source, '://') > 0) {
                                        if (strpos($source, api_get_path(WEB_PATH)) !== false) {
                                            //we found the current portal url
                                            $files_list[] = [$source, 'local', 'url'];
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $source,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } else {
                                            //we didn't find any trace of current portal
                                            $files_list[] = [$source, 'remote', 'url'];
                                        }
                                    } else {
                                        //no protocol found, make link local
                                        if (substr($source, 0, 1) === '/') {
                                            //link starts with a /, making it absolute (relative to DocumentRoot)
                                            $files_list[] = [$source, 'local', 'abs'];
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $source,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } elseif (strstr($source, '..') === 0) {
                                            //link is relative but going back in the hierarchy
                                            $files_list[] = [$source, 'local', 'rel'];
                                            $dir = '';
                                            if (!empty($abs_path)) {
                                                $dir = dirname($abs_path).'/';
                                            }
                                            $new_abs_path = realpath($dir.$source);
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $new_abs_path,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        } else {
                                            //no starting '/', making it relative to current document's path
                                            if (substr($source, 0, 2) == './') {
                                                $source = substr($source, 2);
                                            }
                                            $files_list[] = [$source, 'local', 'rel'];
                                            $dir = '';
                                            if (!empty($abs_path)) {
                                                $dir = dirname($abs_path).'/';
                                            }
                                            $new_abs_path = realpath($dir.$source);
                                            $in_files_list[] = self::get_resources_from_source_html(
                                                $new_abs_path,
                                                true,
                                                TOOL_DOCUMENT,
                                                $recursivity + 1
                                            );
                                            if (count($in_files_list) > 0) {
                                                $files_list = array_merge($files_list, $in_files_list);
                                            }
                                        }
                                    }
                                }
                                //found some protocol there
                                if (strpos($source, api_get_path(WEB_PATH)) !== false) {
                                    //we found the current portal url
                                    $files_list[] = [$source, 'local', 'url'];
                                    $in_files_list[] = self::get_resources_from_source_html(
                                        $source,
                                        true,
                                        TOOL_DOCUMENT,
                                        $recursivity + 1
                                    );
                                    if (count($in_files_list) > 0) {
                                        $files_list = array_merge($files_list, $in_files_list);
                                    }
                                } else {
                                    //we didn't find any trace of current portal
                                    $files_list[] = [$source, 'remote', 'url'];
                                }
                            } else {
                                //no protocol found, make link local
                                if (substr($source, 0, 1) === '/') {
                                    //link starts with a /, making it absolute (relative to DocumentRoot)
                                    $files_list[] = [$source, 'local', 'abs'];
                                    $in_files_list[] = self::get_resources_from_source_html(
                                        $source,
                                        true,
                                        TOOL_DOCUMENT,
                                        $recursivity + 1
                                    );
                                    if (count($in_files_list) > 0) {
                                        $files_list = array_merge($files_list, $in_files_list);
                                    }
                                } elseif (strpos($source, '..') === 0) {
                                    //link is relative but going back in the hierarchy
                                    $files_list[] = [$source, 'local', 'rel'];
                                    $dir = '';
                                    if (!empty($abs_path)) {
                                        $dir = dirname($abs_path).'/';
                                    }
                                    $new_abs_path = realpath($dir.$source);
                                    $in_files_list[] = self::get_resources_from_source_html(
                                        $new_abs_path,
                                        true,
                                        TOOL_DOCUMENT,
                                        $recursivity + 1
                                    );
                                    if (count($in_files_list) > 0) {
                                        $files_list = array_merge($files_list, $in_files_list);
                                    }
                                } else {
                                    //no starting '/', making it relative to current document's path
                                    if (substr($source, 0, 2) == './') {
                                        $source = substr($source, 2);
                                    }
                                    $files_list[] = [$source, 'local', 'rel'];
                                    $dir = '';
                                    if (!empty($abs_path)) {
                                        $dir = dirname($abs_path).'/';
                                    }
                                    $new_abs_path = realpath($dir.$source);
                                    $in_files_list[] = self::get_resources_from_source_html(
                                        $new_abs_path,
                                        true,
                                        TOOL_DOCUMENT,
                                        $recursivity + 1
                                    );
                                    if (count($in_files_list) > 0) {
                                        $files_list = array_merge($files_list, $in_files_list);
                                    }
                                }
                            }
                        }
                    }
                }
                break;
            default: //ignore
                break;
        }

        $checked_files_list = [];
        $checked_array_list = [];

        if (count($files_list) > 0) {
            foreach ($files_list as $idx => $file) {
                if (!empty($file[0])) {
                    if (!in_array($file[0], $checked_files_list)) {
                        $checked_files_list[] = $files_list[$idx][0];
                        $checked_array_list[] = $files_list[$idx];
                    }
                }
            }
        }

        return $checked_array_list;
    }

    /**
     * Parses the HTML attributes given as string.
     *
     * @param string HTML attribute string
     * @param array List of attributes that we want to get back
     * @param array
     *
     * @return array An associative array of attributes
     *
     * @author Based on a function from the HTML_Common2 PEAR module     *
     */
    public static function parse_HTML_attributes($attrString, $wanted = [], $explode_variables = [])
    {
        $attributes = [];
        $regs = [];
        $reduced = false;
        if (count($wanted) > 0) {
            $reduced = true;
        }
        try {
            //Find all occurences of something that looks like a URL
            // The structure of this regexp is:
            // (find protocol) then
            // (optionally find some kind of space 1 or more times) then
            // find (either an equal sign or a bracket) followed by an optional space
            // followed by some text without quotes (between quotes itself or not)
            // then possible closing brackets if we were in the opening bracket case
            // OR something like @import()
            $res = preg_match_all(
                '/(((([A-Za-z_:])([A-Za-z0-9_:\.-]*))'.
                // '/(((([A-Za-z_:])([A-Za-z0-9_:\.-]|[^\x00-\x7F])*)' . -> seems to be taking too much
                // '/(((([A-Za-z_:])([^\x00-\x7F])*)' . -> takes only last letter of parameter name
                '([ \n\t\r]+)?('.
                // '(=([ \n\t\r]+)?("[^"]+"|\'[^\']+\'|[^ \n\t\r]+))' . -> doesn't restrict close enough to the url itself
                '(=([ \n\t\r]+)?("[^"\)]+"|\'[^\'\)]+\'|[^ \n\t\r\)]+))'.
                '|'.
                // '(\(([ \n\t\r]+)?("[^"]+"|\'[^\']+\'|[^ \n\t\r]+)\))' . -> doesn't restrict close enough to the url itself
                '(\(([ \n\t\r]+)?("[^"\)]+"|\'[^\'\)]+\'|[^ \n\t\r\)]+)\))'.
                '))'.
                '|'.
                // '(@import([ \n\t\r]+)?("[^"]+"|\'[^\']+\'|[^ \n\t\r]+)))?/', -> takes a lot (like 100's of thousands of empty possibilities)
                '(@import([ \n\t\r]+)?("[^"]+"|\'[^\']+\'|[^ \n\t\r]+)))/',
                $attrString,
                $regs
            );
        } catch (Exception $e) {
            error_log('Caught exception: '.$e->getMessage(), 0);
        }
        if ($res) {
            for ($i = 0; $i < count($regs[1]); $i++) {
                $name = trim($regs[3][$i]);
                $check = trim($regs[0][$i]);
                $value = trim($regs[10][$i]);
                if (empty($value) and !empty($regs[13][$i])) {
                    $value = $regs[13][$i];
                }
                if (empty($name) && !empty($regs[16][$i])) {
                    $name = '@import';
                    $value = trim($regs[16][$i]);
                }
                if (!empty($name)) {
                    if (!$reduced || in_array(strtolower($name), $wanted)) {
                        if ($name == $check) {
                            $attributes[strtolower($name)][] = strtolower($name);
                        } else {
                            if (!empty($value) && ($value[0] == '\'' || $value[0] == '"')) {
                                $value = substr($value, 1, -1);
                            }

                            if ($value == 'API.LMSGetValue(name') {
                                $value = 'API.LMSGetValue(name)';
                            }
                            //Gets the xx.flv value from the string flashvars="width=320&height=240&autostart=false&file=xxx.flv&repeat=false"
                            if (isset($explode_variables[$name])) {
                                $value_modified = str_replace('&amp;', '&', $value);
                                $value_array = explode('&', $value_modified);
                                foreach ($value_array as $item) {
                                    $itemParts = explode('=', $item);
                                    $key = $itemParts[0];
                                    $item_value = !empty($itemParts[1]) ? $itemParts[1] : '';
                                    if ($key == $explode_variables[$name]) {
                                        $attributes[strtolower($name)][] = $item_value;
                                    }
                                }
                            }
                            $attributes[strtolower($name)][] = $value;
                        }
                    }
                }
            }
        }

        return $attributes;
    }

    /**
     * Replace urls inside content html from a copy course.
     *
     * @param string $content_html
     * @param string $origin_course_code
     * @param string $destination_course_directory
     * @param string $origin_course_path_from_zip
     * @param string $origin_course_info_path
     *
     * @return string new content html with replaced urls or return false if content is not a string
     */
    public static function replaceUrlWithNewCourseCode(
        $content_html,
        $origin_course_code,
        $destination_course_directory,
        $origin_course_path_from_zip = null,
        $origin_course_info_path = null
    ) {
        if (empty($content_html)) {
            return false;
        }

        $orig_source_html = self::get_resources_from_source_html($content_html);
        $orig_course_info = api_get_course_info($origin_course_code);

        // Course does not exist in the current DB probably this came from a zip file?
        if (empty($orig_course_info)) {
            if (!empty($origin_course_path_from_zip)) {
                $orig_course_path = $origin_course_path_from_zip.'/';
                $orig_course_info_path = $origin_course_info_path;
            }
        } else {
            $orig_course_path = api_get_path(SYS_COURSE_PATH).$orig_course_info['path'].'/';
            $orig_course_info_path = $orig_course_info['path'];
        }

        $destination_course_code = CourseManager::getCourseCodeFromDirectory($destination_course_directory);
        $destination_course_info = api_get_course_info($destination_course_code);
        $dest_course_path = api_get_path(SYS_COURSE_PATH).$destination_course_directory.'/';
        $dest_course_path_rel = api_get_path(REL_COURSE_PATH).$destination_course_directory.'/';

        $user_id = api_get_user_id();

        if (!empty($orig_source_html)) {
            foreach ($orig_source_html as $source) {
                // Get information about source url
                $real_orig_url = $source[0]; // url
                $scope_url = $source[1]; // scope (local, remote)
                $type_url = $source[2]; // type (rel, abs, url)

                // Get path and query from origin url
                $orig_parse_url = parse_url($real_orig_url);
                $real_orig_path = isset($orig_parse_url['path']) ? $orig_parse_url['path'] : null;
                $real_orig_query = isset($orig_parse_url['query']) ? $orig_parse_url['query'] : null;

                // Replace origin course code by destination course code from origin url query
                $dest_url_query = '';

                if (!empty($real_orig_query)) {
                    $dest_url_query = '?'.$real_orig_query;
                    if (strpos($dest_url_query, $origin_course_code) !== false) {
                        $dest_url_query = str_replace($origin_course_code, $destination_course_code, $dest_url_query);
                    }
                }

                if ($scope_url == 'local') {
                    if ($type_url == 'abs' || $type_url == 'rel') {
                        $document_file = strstr($real_orig_path, 'document');

                        if (strpos($real_orig_path, $document_file) !== false) {
                            $origin_filepath = $orig_course_path.$document_file;
                            $destination_filepath = $dest_course_path.$document_file;

                            // copy origin file inside destination course
                            if (file_exists($origin_filepath)) {
                                $filepath_dir = dirname($destination_filepath);

                                if (!is_dir($filepath_dir)) {
                                    $perm = api_get_permissions_for_new_directories();
                                    $result = @mkdir($filepath_dir, $perm, true);
                                    if ($result) {
                                        $filepath_to_add = str_replace(
                                            [$dest_course_path, 'document'],
                                            '',
                                            $filepath_dir
                                        );

                                        //Add to item properties to the new folder
                                        $doc_id = add_document(
                                            $destination_course_info,
                                            $filepath_to_add,
                                            'folder',
                                            0,
                                            basename($filepath_to_add)
                                        );
                                        api_item_property_update(
                                            $destination_course_info,
                                            TOOL_DOCUMENT,
                                            $doc_id,
                                            'FolderCreated',
                                            $user_id,
                                            null,
                                            null,
                                            null,
                                            null
                                        );
                                    }
                                }

                                if (!file_exists($destination_filepath)) {
                                    $result = @copy($origin_filepath, $destination_filepath);
                                    if ($result) {
                                        $filepath_to_add = str_replace(
                                            [$dest_course_path, 'document'],
                                            '',
                                            $destination_filepath
                                        );
                                        $size = filesize($destination_filepath);

                                        // Add to item properties to the file
                                        $doc_id = add_document(
                                            $destination_course_info,
                                            $filepath_to_add,
                                            'file',
                                            $size,
                                            basename($filepath_to_add)
                                        );
                                        api_item_property_update(
                                            $destination_course_info,
                                            TOOL_DOCUMENT,
                                            $doc_id,
                                            'FolderCreated',
                                            $user_id,
                                            null,
                                            null,
                                            null,
                                            null
                                        );
                                    }
                                }
                            }

                            // Replace origin course path by destination course path.
                            if (strpos($content_html, $real_orig_url) !== false) {
                                $url_course_path = str_replace(
                                    $orig_course_info_path.'/'.$document_file,
                                    '',
                                    $real_orig_path
                                );
                                // See BT#7780
                                $destination_url = $dest_course_path_rel.$document_file.$dest_url_query;
                                // If the course code doesn't exist in the path? what we do? Nothing! see BT#1985
                                if (strpos($real_orig_path, $origin_course_code) === false) {
                                    $url_course_path = $real_orig_path;
                                    $destination_url = $real_orig_path;
                                }
                                $content_html = str_replace($real_orig_url, $destination_url, $content_html);
                            }
                        }

                        // replace origin course code by destination course code  from origin url
                        if (strpos($real_orig_url, '?') === 0) {
                            $dest_url = str_replace($origin_course_code, $destination_course_code, $real_orig_url);
                            $content_html = str_replace($real_orig_url, $dest_url, $content_html);
                        }
                    }
                }
            }
        }

        return $content_html;
    }

    /**
     * Export document to PDF.
     *
     * @param int    $document_id
     * @param string $courseCode
     * @param string $orientation
     * @param bool   $showHeaderAndFooter
     */
    public static function export_to_pdf(
        $document_id,
        $courseCode,
        $orientation = 'landscape',
        $showHeaderAndFooter = true
    ) {
        $course_data = api_get_course_info($courseCode);
        $document_data = self::get_document_data_by_id($document_id, $courseCode);
        $file_path = api_get_path(SYS_COURSE_PATH).$course_data['path'].'/document'.$document_data['path'];
        if ($orientation == 'landscape') {
            $pageFormat = 'A4-L';
            $pdfOrientation = 'L';
        } else {
            $pageFormat = 'A4';
            $pdfOrientation = 'P';
        }
        $pdf = new PDF(
            $pageFormat,
            $pdfOrientation,
            $showHeaderAndFooter ? [] : ['top' => 0, 'left' => 0, 'bottom' => 0, 'right' => 0]
        );

        if (api_get_configuration_value('use_alternative_document_pdf_footer')) {
            $view = new Template('', false, false, false, true, false, false);
            $template = $view->get_template('export/alt_pdf_footer.tpl');

            $pdf->set_custom_footer([
                'html' => $view->fetch($template),
            ]);
        }

        $pdf->html_to_pdf(
            $file_path,
            $document_data['title'],
            $courseCode,
            false,
            $showHeaderAndFooter
        );
    }

    /**
     * Uploads a document.
     *
     * @param array  $files                   the $_FILES variable
     * @param string $path
     * @param string $title
     * @param string $comment
     * @param int    $unzip                   unzip or not the file
     * @param string $ifExists                overwrite, rename or warn (default)
     * @param bool   $index_document          index document (search xapian module)
     * @param bool   $show_output             print html messages
     * @param string $fileKey
     * @param bool   $treat_spaces_as_hyphens
     *
     * @return array|bool
     */
    public static function upload_document(
        $files,
        $path,
        $title = '',
        $comment = '',
        $unzip = 0,
        $ifExists = '',
        $index_document = false,
        $show_output = false,
        $fileKey = 'file',
        $treat_spaces_as_hyphens = true
    ) {
        $course_info = api_get_course_info();
        $sessionId = api_get_session_id();
        $course_dir = $course_info['path'].'/document';
        $sys_course_path = api_get_path(SYS_COURSE_PATH);
        $base_work_dir = $sys_course_path.$course_dir;

        if (isset($files[$fileKey])) {
            $uploadOk = process_uploaded_file($files[$fileKey], $show_output);
            if ($uploadOk) {
                $new_path = handle_uploaded_document(
                    $course_info,
                    $files[$fileKey],
                    $base_work_dir,
                    $path,
                    api_get_user_id(),
                    api_get_group_id(),
                    null,
                    $unzip,
                    $ifExists,
                    $show_output,
                    false,
                    null,
                    $sessionId,
                    $treat_spaces_as_hyphens
                );

                // Showing message when sending zip files
                if ($new_path === true && $unzip == 1) {
                    if ($show_output) {
                        echo Display::return_message(
                            get_lang('UplUploadSucceeded').'<br />',
                            'confirm',
                            false
                        );
                    }

                    return [
                        'title' => $files[$fileKey]['name'],
                        'url' => '#',
                    ];
                }

                if ($new_path) {
                    $documentId = self::get_document_id(
                        $course_info,
                        $new_path,
                        $sessionId
                    );

                    if (!empty($documentId)) {
                        $table_document = Database::get_course_table(TABLE_DOCUMENT);
                        $params = [];

                        if (!empty($title)) {
                            $params['title'] = $title;
                        }

                        if (!empty($comment)) {
                            $params['comment'] = trim($comment);
                        }

                        Database::update(
                            $table_document,
                            $params,
                            [
                                'id = ? AND c_id = ? ' => [
                                    $documentId,
                                    $course_info['real_id'],
                                ],
                            ]
                        );
                    }

                    if ($index_document) {
                        self::index_document(
                            $documentId,
                            $course_info['code'],
                            null,
                            $_POST['language'],
                            $_REQUEST,
                            $ifExists
                        );
                    }

                    if (!empty($documentId) && is_numeric($documentId)) {
                        $documentData = self::get_document_data_by_id(
                            $documentId,
                            $course_info['code'],
                            false,
                            $sessionId
                        );

                        return $documentData;
                    }
                }
            }
        }

        return false;
    }

    /**
     * Obtains the text inside the file with the right parser.
     */
    public static function get_text_content($doc_path, $doc_mime)
    {
        // TODO: review w$ compatibility
        // Use usual exec output lines array to store stdout instead of a temp file
        // because we need to store it at RAM anyway before index on ChamiloIndexer object
        $ret_val = null;
        switch ($doc_mime) {
            case 'text/plain':
                $handle = fopen($doc_path, 'r');
                $output = [fread($handle, filesize($doc_path))];
                fclose($handle);
                break;
            case 'application/pdf':
                exec("pdftotext $doc_path -", $output, $ret_val);
                break;
            case 'application/postscript':
                $temp_file = tempnam(sys_get_temp_dir(), 'chamilo');
                exec("ps2pdf $doc_path $temp_file", $output, $ret_val);
                if ($ret_val !== 0) { // shell fail, probably 127 (command not found)
                    return false;
                }
                exec("pdftotext $temp_file -", $output, $ret_val);
                unlink($temp_file);
                break;
            case 'application/msword':
                exec("catdoc $doc_path", $output, $ret_val);
                break;
            case 'text/html':
                exec("html2text $doc_path", $output, $ret_val);
                break;
            case 'text/rtf':
                // Note: correct handling of code pages in unrtf
                // on debian lenny unrtf v0.19.2 can not, but unrtf v0.20.5 can
                exec("unrtf --text $doc_path", $output, $ret_val);
                if ($ret_val == 127) { // command not found
                    return false;
                }
                // Avoid index unrtf comments
                if (is_array($output) && count($output) > 1) {
                    $parsed_output = [];
                    foreach ($output as &$line) {
                        if (!preg_match('/^###/', $line, $matches)) {
                            if (!empty($line)) {
                                $parsed_output[] = $line;
                            }
                        }
                    }
                    $output = $parsed_output;
                }
                break;
            case 'application/vnd.ms-powerpoint':
                exec("catppt $doc_path", $output, $ret_val);
                break;
            case 'application/vnd.ms-excel':
                exec("xls2csv -c\" \" $doc_path", $output, $ret_val);
                break;
        }

        $content = '';
        if (!is_null($ret_val)) {
            if ($ret_val !== 0) { // shell fail, probably 127 (command not found)
                return false;
            }
        }
        if (isset($output)) {
            foreach ($output as &$line) {
                $content .= $line."\n";
            }

            return $content;
        } else {
            return false;
        }
    }

    /**
     * Calculates the total size of all documents in a course.
     *
     * @author Bert vanderkimpen
     *
     * @param int $course_id
     * @param int $group_id   (to calculate group document space)
     * @param int $session_id
     *
     * @return int total size
     */
    public static function documents_total_space($course_id = null, $group_id = null, $session_id = null)
    {
        $TABLE_ITEMPROPERTY = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $TABLE_DOCUMENT = Database::get_course_table(TABLE_DOCUMENT);
        $session_id = intval($session_id);
        $group_id = intval($group_id);
        $course_id = intval($course_id);

        if (!$course_id) {
            $course_id = api_get_course_int_id();
        }

        $group_condition = '';
        if ($group_id) {
            $group_condition = " AND props.to_group_id='".$group_id."' ";
        }

        $session_condition = '';
        if ($session_id) {
            $session_condition = " AND props.session_id='".$session_id."' ";
        }

        $sql = "SELECT SUM(size)
                FROM $TABLE_ITEMPROPERTY AS props
                INNER JOIN $TABLE_DOCUMENT AS docs
                ON (docs.id = props.ref AND props.c_id = docs.c_id)
                WHERE
                    props.c_id 	= $course_id AND
                    docs.c_id 	= $course_id AND
                    props.tool 	= '".TOOL_DOCUMENT."' AND
                    props.visibility <> 2
                    $group_condition
                    $session_condition
                ";
        $result = Database::query($sql);

        if ($result && Database::num_rows($result) != 0) {
            $row = Database::fetch_row($result);

            return $row[0];
        } else {
            return 0;
        }
    }

    /**
     * Display the document quota in a simple way.
     *
     *  Here we count 1 Kilobyte = 1024 Bytes, 1 Megabyte = 1048576 Bytes
     */
    public static function displaySimpleQuota($course_quota, $already_consumed_space)
    {
        $course_quota_m = round($course_quota / 1048576);
        $already_consumed_space_m = round($already_consumed_space / 1048576, 2);
        $percentage = $already_consumed_space / $course_quota * 100;
        $percentage = round($percentage, 1);
        $message = get_lang('YouAreCurrentlyUsingXOfYourX');
        $message = sprintf($message, $already_consumed_space_m, $percentage.'%', $course_quota_m.' ');

        return Display::div($message, ['id' => 'document_quota']);
    }

    /**
     * Checks if there is enough place to add a file on a directory
     * on the base of a maximum directory size allowed.
     *
     * @author Bert Vanderkimpen
     *
     * @param int $file_size     size of the file in byte
     * @param int $max_dir_space maximum size
     *
     * @return bool true if there is enough space, false otherwise
     *
     * @see enough_space() uses  documents_total_space() function
     */
    public static function enough_space($file_size, $max_dir_space)
    {
        if ($max_dir_space) {
            $already_filled_space = self::documents_total_space();
            if (($file_size + $already_filled_space) > $max_dir_space) {
                return false;
            }
        }

        return true;
    }

    /**
     * @param array $params count, url, extension
     *
     * @return string
     */
    public static function generateAudioJavascript($params = [])
    {
        $js = '
            $(\'audio.audio_preview\').mediaelementplayer({
                features: [\'playpause\'],
                audioWidth: 30,
                audioHeight: 30,
                success: function(mediaElement, originalNode, instance) {                
                }
            });';

        return $js;
    }

    /**
     * Shows a play icon next to the document title in the document list.
     *
     * @param string $documentWebPath
     * @param array  $documentInfo
     *
     * @return string
     */
    public static function generateAudioPreview($documentWebPath, $documentInfo)
    {
        $filePath = $documentWebPath.$documentInfo['path'];
        $extension = $documentInfo['file_extension'];
        $html = '<span class="preview"> <audio class="audio_preview skip" src="'.$filePath.'" type="audio/'.$extension.'" > </audio></span>';

        return $html;
    }

    /**
     * @param string $file
     * @param string $extension
     *
     * @return string
     */
    public static function generateVideoPreview($file, $extension)
    {
        $type = '';
        /*if ($extension != 'flv') {

        }*/
        //$type = "video/$extension";
        $html = '<video id="myvideo"  src="'.$file.'" controls '.$type.'">';

        return $html;
    }

    /**
     * @param array  $course_info
     * @param bool   $lp_id
     * @param string $target
     * @param int    $session_id
     * @param bool   $add_move_button
     * @param string $filter_by_folder
     * @param string $overwrite_url
     * @param bool   $showInvisibleFiles
     * @param bool   $showOnlyFolders
     * @param int    $folderId
     *
     * @return string
     */
    public static function get_document_preview(
        $course_info,
        $lp_id = false,
        $target = '',
        $session_id = 0,
        $add_move_button = false,
        $filter_by_folder = null,
        $overwrite_url = '',
        $showInvisibleFiles = false,
        $showOnlyFolders = false,
        $folderId = false
    ) {
        if (empty($course_info['real_id']) || empty($course_info['code']) || !is_array($course_info)) {
            return '';
        }

        $user_id = api_get_user_id();
        $userInfo = api_get_user_info();

        $user_in_course = false;
        if (api_is_platform_admin()) {
            $user_in_course = true;
        }

        if (!$user_in_course) {
            if (CourseManager::is_course_teacher($user_id, $course_info['code'])) {
                $user_in_course = true;
            }
        }

        // Condition for the session
        $session_id = intval($session_id);

        if (!$user_in_course) {
            if (empty($session_id)) {
                if (CourseManager::is_user_subscribed_in_course($user_id, $course_info['code'])) {
                    $user_in_course = true;
                }
                // Check if course is open then we can consider that the student is registered to the course
                if (isset($course_info) && in_array($course_info['visibility'], [2, 3])) {
                    $user_in_course = true;
                }
            } else {
                $user_status = SessionManager::get_user_status_in_course_session(
                    $user_id,
                    $course_info['real_id'],
                    $session_id
                );
                //is true if is an student, course session teacher or coach
                if (in_array($user_status, ['0', '2', '6'])) {
                    $user_in_course = true;
                }
            }
        }

        $tbl_doc = Database::get_course_table(TABLE_DOCUMENT);
        $tbl_item_prop = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $condition_session = " AND (last.session_id = '$session_id' OR last.session_id = '0' OR last.session_id IS NULL)";

        $add_folder_filter = null;
        if (!empty($filter_by_folder)) {
            $add_folder_filter = " AND docs.path LIKE '".Database::escape_string($filter_by_folder)."%'";
        }

        // If we are in LP display hidden folder https://support.chamilo.org/issues/6679
        $lp_visibility_condition = null;
        if ($lp_id) {
            // $lp_visibility_condition = " OR filetype='folder'";
            if ($showInvisibleFiles) {
                $lp_visibility_condition .= ' OR last.visibility = 0';
            }
        }

        $showOnlyFoldersCondition = null;
        if ($showOnlyFolders) {
            //$showOnlyFoldersCondition = " AND docs.filetype = 'folder' ";
        }

        $folderCondition = " AND docs.path LIKE '/%' ";

        if (!api_is_allowed_to_edit()) {
            $protectedFolders = self::getProtectedFolderFromStudent();
            foreach ($protectedFolders as $folder) {
                $folderCondition .= " AND docs.path NOT LIKE '$folder' ";
            }
        }

        $parentData = [];
        if ($folderId !== false) {
            $parentData = self::get_document_data_by_id(
                $folderId,
                $course_info['code'],
                false,
                $session_id
            );
            if (!empty($parentData)) {
                $cleanedPath = $parentData['path'];
                $num = substr_count($cleanedPath, '/');

                $notLikeCondition = '';
                for ($i = 1; $i <= $num; $i++) {
                    $repeat = str_repeat('/%', $i + 1);
                    $notLikeCondition .= " AND docs.path NOT LIKE '".Database::escape_string($cleanedPath.$repeat)."' ";
                }

                $folderId = (int) $folderId;
                $folderCondition = " AND
                    docs.id <> $folderId AND
                    docs.path LIKE '".$cleanedPath."/%'
                    $notLikeCondition
                ";
            } else {
                $folderCondition = " AND docs.filetype = 'file' ";
            }
        }

        $levelCondition = null;
        if ($folderId === false) {
            $levelCondition = " AND docs.path NOT LIKE'/%/%'";
        }

        $sql = "SELECT DISTINCT last.visibility, docs.*
                FROM $tbl_item_prop AS last 
                INNER JOIN $tbl_doc AS docs
                ON (docs.id = last.ref AND docs.c_id = last.c_id)
                WHERE
                    docs.path NOT LIKE '%_DELETED_%' AND
                    last.tool = '".TOOL_DOCUMENT."' $condition_session AND
                    (last.visibility = '1' $lp_visibility_condition) AND
                    last.visibility <> 2 AND
                    docs.c_id = {$course_info['real_id']} AND
                    last.c_id = {$course_info['real_id']}
                    $showOnlyFoldersCondition
                    $folderCondition
                    $levelCondition
                    $add_folder_filter
                ORDER BY docs.filetype DESC, docs.title ASC";

        $res_doc = Database::query($sql);
        $resources = Database::store_result($res_doc, 'ASSOC');

        $return = '';
        if ($lp_id) {
            if ($folderId === false) {
                /*$return .= '<div class="lp_resource_element">';
                $return .= Display::return_icon('new_doc.gif', '', [], ICON_SIZE_SMALL);
                $return .= Display::url(
                    get_lang('CreateTheDocument'),
                    api_get_self().'?'.api_get_cidreq().'&action=add_item&type='.TOOL_DOCUMENT.'&lp_id='.$_SESSION['oLP']->lp_id
                );
                $return .= '</div>';*/
            }
        } else {
            $return .= Display::div(
                Display::url(
                    Display::return_icon('close.png', get_lang('Close'), [], ICON_SIZE_SMALL),
                    ' javascript:void(0);',
                    ['id' => 'close_div_'.$course_info['real_id'].'_'.$session_id, 'class' => 'close_div']
                ),
                ['style' => 'position:absolute;right:10px']
            );
        }

        // If you want to debug it, I advise you to do "echo" on the eval statements.
        $newResources = [];
        if (!empty($resources) && $user_in_course) {
            foreach ($resources as $resource) {
                $is_visible = self::is_visible_by_id(
                    $resource['id'],
                    $course_info,
                    $session_id,
                    api_get_user_id()
                );

                if ($showInvisibleFiles == false) {
                    if (!$is_visible) {
                        continue;
                    }
                }

                $newResources[] = $resource;
            }
        }

        $label = get_lang('Documents');

        $documents = [];
        if ($folderId === false) {
            $documents[$label] = [
                'id' => 0,
                'files' => $newResources,
            ];
        } else {
            if (is_array($parentData)) {
                $documents[$parentData['title']] = [
                    'id' => intval($folderId),
                    'files' => $newResources,
                ];
            }
        }

        $write_result = self::write_resources_tree(
            $userInfo,
            $course_info,
            $session_id,
            $documents,
            $lp_id,
            $target,
            $add_move_button,
            $overwrite_url,
            $folderId
        );

        $return .= $write_result;
        if ($lp_id == false) {
            $url = api_get_path(WEB_AJAX_PATH).'lp.ajax.php?a=get_documents&url='.$overwrite_url.'&lp_id='.$lp_id.'&cidReq='.$course_info['code'];
            $return .= "<script>
            $('.doc_folder').click(function() {
                var realId = this.id;
                var my_id = this.id.split('_')[2];
                var tempId = 'temp_'+my_id;
                $('#res_'+my_id).show();

                var tempDiv = $('#'+realId).find('#'+tempId);
                if (tempDiv.length == 0) {
                    $.ajax({
                        async: false,
                        type: 'GET',
                        url:  '".$url."',
                        data: 'folder_id='+my_id,
                        success: function(data) {
                            $('#'+realId).append('<div id='+tempId+'>'+data+'</div>');
                        }
                    });
                }
            });

            $('.close_div').click(function() {
                var course_id = this.id.split('_')[2];
                var session_id = this.id.split('_')[3];
                $('#document_result_'+course_id+'_'+session_id).hide();
                $('.lp_resource').remove();
                $('.document_preview_container').html('');
            });

            </script>";
        } else {
            //For LPs
            $url = api_get_path(WEB_AJAX_PATH).'lp.ajax.php?a=get_documents&lp_id='.$lp_id.'&'.api_get_cidreq();
            $return .= "<script>

            function testResources(id, img) {
                var numericId = id.split('_')[1];
                var parentId = 'doc_id_'+numericId;
                var tempId = 'temp_'+numericId;
                var image = $('#'+img);

                if (image.hasClass('open')) {
                    image.removeClass('open');
                    image.attr('src', '".Display::returnIconPath('nolines_plus.gif')."');
                    $('#'+id).show();
                    $('#'+tempId).hide();
                } else {
                    image.addClass('open');
                    image.attr('src', '".Display::returnIconPath('nolines_minus.gif')."');
                    $('#'+id).hide();
                    $('#'+tempId).show();

                    var tempDiv = $('#'+parentId).find('#'+tempId);
                    if (tempDiv.length == 0) {
                        $.ajax({
                            type: 'GET',
                            async: false,
                            url:  '".$url."',
                            data: 'folder_id='+numericId,
                            success: function(data) {
                                tempDiv = $('#doc_id_'+numericId).append('<div id='+tempId+'>'+data+'</div>');
                            }
                        });
                    }
                }
            }
            </script>";
        }

        if (!$user_in_course) {
            $return = '';
        }

        return $return;
    }

    /**
     * Generate and return an HTML list of resources based on a given array.
     * This list is used to show the course creator a list of available resources to choose from
     * when creating a learning path.
     *
     * @param array  $userInfo        current user info
     * @param array  $course_info
     * @param int    $session_id
     * @param array  $documents
     * @param bool   $lp_id
     * @param string $target
     * @param bool   $add_move_button
     * @param string $overwrite_url
     * @param int    $folderId
     *
     * @return string
     */
    public static function write_resources_tree(
        $userInfo,
        $course_info,
        $session_id,
        $documents,
        $lp_id = false,
        $target = '',
        $add_move_button = false,
        $overwrite_url = '',
        $folderId = false
    ) {
        $return = '';
        if (!empty($documents)) {
            foreach ($documents as $key => $resource) {
                if (isset($resource['id']) && is_int($resource['id'])) {
                    $mainFolderResource = [
                        'id' => $resource['id'],
                        'title' => $key,
                    ];

                    if ($folderId === false) {
                        $return .= self::parseFolder($folderId, $mainFolderResource, $lp_id);
                    }

                    if (isset($resource['files'])) {
                        $return .= self::write_resources_tree(
                            $userInfo,
                            $course_info,
                            $session_id,
                            $resource['files'],
                            $lp_id,
                            $target,
                            $add_move_button,
                            $overwrite_url
                        );
                    }
                    $return .= '</div>';
                    $return .= '</ul>';
                } else {
                    if ($resource['filetype'] == 'folder') {
                        $return .= self::parseFolder($folderId, $resource, $lp_id);
                    } else {
                        $return .= self::parseFile(
                            $userInfo,
                            $course_info,
                            $session_id,
                            $resource,
                            $lp_id,
                            $add_move_button,
                            $target,
                            $overwrite_url
                        );
                    }
                }
            }
        }

        return $return;
    }

    /**
     * @param int    $doc_id
     * @param string $course_code
     * @param int    $session_id
     * @param int    $user_id
     * @param int    $groupId     iid
     *
     * @return bool
     */
    public static function check_visibility_tree(
        $doc_id,
        $course_code,
        $session_id,
        $user_id,
        $groupId = 0
    ) {
        $document_data = self::get_document_data_by_id(
            $doc_id,
            $course_code,
            null,
            $session_id
        );
        if ($session_id != 0 && !$document_data) {
            $document_data = self::get_document_data_by_id(
                $doc_id,
                $course_code,
                null,
                0
            );
        }

        if (!empty($document_data)) {
            // If admin or course teacher, allow anyway
            if (api_is_platform_admin() || CourseManager::is_course_teacher($user_id, $course_code)) {
                return true;
            }
            $course_info = api_get_course_info($course_code);
            if ($document_data['parent_id'] == false || empty($document_data['parent_id'])) {
                if (!empty($groupId)) {
                    return true;
                }
                $visible = self::is_visible_by_id($doc_id, $course_info, $session_id, $user_id);

                return $visible;
            } else {
                $visible = self::is_visible_by_id($doc_id, $course_info, $session_id, $user_id);

                if (!$visible) {
                    return false;
                } else {
                    return self::check_visibility_tree(
                        $document_data['parent_id'],
                        $course_code,
                        $session_id,
                        $user_id,
                        $groupId
                    );
                }
            }
        } else {
            return false;
        }
    }

    /**
     * Index a given document.
     *
     * @param   int     Document ID inside its corresponding course
     * @param   string  Course code
     * @param   int     Session ID (not used yet)
     * @param   string  Language of document's content (defaults to course language)
     * @param   array   Array of specific fields (['code'=>'value',...])
     * @param   string  What to do if the file already exists (default or overwrite)
     * @param   bool    When set to true, this runs the indexer without actually saving anything to any database
     *
     * @return bool Returns true on presumed success, false on failure
     */
    public static function index_document(
        $docid,
        $course_code,
        $session_id = 0,
        $lang = 'english',
        $specific_fields_values = [],
        $if_exists = '',
        $simulation = false
    ) {
        if (api_get_setting('search_enabled') !== 'true') {
            return false;
        }
        if (empty($docid) or $docid != intval($docid)) {
            return false;
        }
        if (empty($session_id)) {
            $session_id = api_get_session_id();
        }
        $course_info = api_get_course_info($course_code);
        $course_dir = $course_info['path'].'/document';
        $sys_course_path = api_get_path(SYS_COURSE_PATH);
        $base_work_dir = $sys_course_path.$course_dir;

        $course_id = $course_info['real_id'];
        $table_document = Database::get_course_table(TABLE_DOCUMENT);

        $qry = "SELECT path, title FROM $table_document WHERE c_id = $course_id AND id = '$docid' LIMIT 1";
        $result = Database::query($qry);
        if (Database::num_rows($result) == 1) {
            $row = Database::fetch_array($result);
            $doc_path = api_get_path(SYS_COURSE_PATH).$course_dir.$row['path'];
            //TODO: mime_content_type is deprecated, fileinfo php extension is enabled by default as of PHP 5.3.0
            // now versions of PHP on Debian testing(5.2.6-5) and Ubuntu(5.2.6-2ubuntu) are lower, so wait for a while
            $doc_mime = mime_content_type($doc_path);
            $allowed_mime_types = self::file_get_mime_type(true);

            // mime_content_type does not detect correctly some formats that
            // are going to be supported for index, so an extensions array is used for the moment
            if (empty($doc_mime)) {
                $allowed_extensions = [
                    'doc',
                    'docx',
                    'ppt',
                    'pptx',
                    'pps',
                    'ppsx',
                    'xls',
                    'xlsx',
                    'odt',
                    'odp',
                    'ods',
                    'pdf',
                    'txt',
                    'rtf',
                    'msg',
                    'csv',
                    'html',
                    'htm',
                ];
                $extensions = preg_split("/[\/\\.]/", $doc_path);
                $doc_ext = strtolower($extensions[count($extensions) - 1]);
                if (in_array($doc_ext, $allowed_extensions)) {
                    switch ($doc_ext) {
                        case 'ppt':
                        case 'pps':
                            $doc_mime = 'application/vnd.ms-powerpoint';
                            break;
                        case 'xls':
                            $doc_mime = 'application/vnd.ms-excel';
                            break;
                    }
                }
            }

            //@todo move this nightmare in a search controller or something like that!!! J.M

            if (in_array($doc_mime, $allowed_mime_types)) {
                $file_title = $row['title'];
                $file_content = self::get_text_content($doc_path, $doc_mime);
                $course_code = Database::escape_string($course_code);
                $ic_slide = new IndexableChunk();
                $ic_slide->addValue('title', $file_title);
                $ic_slide->addCourseId($course_code);
                $ic_slide->addToolId(TOOL_DOCUMENT);
                $xapian_data = [
                    SE_COURSE_ID => $course_code,
                    SE_TOOL_ID => TOOL_DOCUMENT,
                    SE_DATA => ['doc_id' => $docid],
                    SE_USER => api_get_user_id(),
                ];

                $ic_slide->xapian_data = serialize($xapian_data);
                $di = new ChamiloIndexer();
                $return = $di->connectDb(null, null, $lang);

                require_once api_get_path(LIBRARY_PATH).'specific_fields_manager.lib.php';
                $specific_fields = get_specific_field_list();

                // process different depending on what to do if file exists
                /**
                 * @TODO Find a way to really verify if the file had been
                 * overwriten. Now all work is done at
                 * handle_uploaded_document() and it's difficult to verify it
                 */
                if (!empty($if_exists) && $if_exists == 'overwrite') {
                    // Overwrite the file on search engine
                    // Actually, it consists on a delete of terms from db,
                    // insert new ones, create a new search engine document,
                    // and remove the old one
                    // Get search_did
                    $tbl_se_ref = Database::get_main_table(TABLE_MAIN_SEARCH_ENGINE_REF);
                    $sql = 'SELECT * FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_high_level=%s LIMIT 1';
                    $sql = sprintf($sql, $tbl_se_ref, $course_code, TOOL_DOCUMENT, $docid);

                    $res = Database::query($sql);

                    if (Database::num_rows($res) > 0) {
                        $se_ref = Database::fetch_array($res);
                        if (!$simulation) {
                            $di->remove_document($se_ref['search_did']);
                        }
                        $all_specific_terms = '';
                        foreach ($specific_fields as $specific_field) {
                            if (!$simulation) {
                                delete_all_specific_field_value($course_code, $specific_field['id'], TOOL_DOCUMENT, $docid);
                            }
                            // Update search engine
                            if (isset($specific_fields_values[$specific_field['code']])) {
                                $sterms = trim($specific_fields_values[$specific_field['code']]);
                            } else { //if the specific field is not defined, force an empty one
                                $sterms = '';
                            }
                            $all_specific_terms .= ' '.$sterms;
                            $sterms = explode(',', $sterms);
                            foreach ($sterms as $sterm) {
                                $sterm = trim($sterm);
                                if (!empty($sterm)) {
                                    $ic_slide->addTerm($sterm, $specific_field['code']);
                                    // updated the last param here from $value to $sterm without being sure - see commit15464
                                    if (!$simulation) {
                                        add_specific_field_value(
                                            $specific_field['id'],
                                            $course_code,
                                            TOOL_DOCUMENT,
                                            $docid,
                                            $sterm
                                        );
                                    }
                                }
                            }
                        }
                        // Add terms also to content to make terms findable by probabilistic search
                        $file_content = $all_specific_terms.' '.$file_content;

                        if (!$simulation) {
                            $ic_slide->addValue('content', $file_content);
                            $di->addChunk($ic_slide);
                            // Index and return a new search engine document id
                            $did = $di->index();

                            if ($did) {
                                // update the search_did on db
                                $tbl_se_ref = Database::get_main_table(TABLE_MAIN_SEARCH_ENGINE_REF);
                                $sql = 'UPDATE %s SET search_did=%d WHERE id=%d LIMIT 1';
                                $sql = sprintf($sql, $tbl_se_ref, (int) $did, (int) $se_ref['id']);
                                Database::query($sql);
                            }
                        }
                    }
                } else {
                    // Add all terms
                    $all_specific_terms = '';
                    foreach ($specific_fields as $specific_field) {
                        if (isset($specific_fields_values[$specific_field['code']])) {
                            $sterms = trim($specific_fields_values[$specific_field['code']]);
                        } else { //if the specific field is not defined, force an empty one
                            $sterms = '';
                        }
                        $all_specific_terms .= ' '.$sterms;
                        if (!empty($sterms)) {
                            $sterms = explode(',', $sterms);
                            foreach ($sterms as $sterm) {
                                if (!$simulation) {
                                    $ic_slide->addTerm(trim($sterm), $specific_field['code']);
                                    add_specific_field_value(
                                        $specific_field['id'],
                                        $course_code,
                                        TOOL_DOCUMENT,
                                        $docid,
                                        $sterm
                                    );
                                }
                            }
                        }
                    }
                    // Add terms also to content to make terms findable by probabilistic search
                    $file_content = $all_specific_terms.' '.$file_content;
                    if (!$simulation) {
                        $ic_slide->addValue('content', $file_content);
                        $di->addChunk($ic_slide);
                        // Index and return search engine document id
                        $did = $di->index();
                        if ($did) {
                            // Save it to db
                            $tbl_se_ref = Database::get_main_table(TABLE_MAIN_SEARCH_ENGINE_REF);
                            $sql = 'INSERT INTO %s (id, course_code, tool_id, ref_id_high_level, search_did)
                            VALUES (NULL , \'%s\', \'%s\', %s, %s)';
                            $sql = sprintf($sql, $tbl_se_ref, $course_code, TOOL_DOCUMENT, $docid, $did);
                            Database::query($sql);
                        } else {
                            return false;
                        }
                    }
                }
            } else {
                return false;
            }
        }

        return true;
    }

    /**
     * @return array
     */
    public static function get_web_odf_extension_list()
    {
        return ['ods', 'odt', 'odp'];
    }

    /**
     * Set of extension allowed to use Jodconverter.
     *
     * @param $mode 'from'
     *              'to'
     *              'all'
     * @param $format   'text'
     *                  'spreadsheet'
     *                  'presentation'
     *                  'drawing'
     *                  'all'
     *
     * @return array
     */
    public static function getJodconverterExtensionList($mode, $format)
    {
        $extensionList = [];
        $extensionListFromText = [
            'odt',
            'sxw',
            'rtf',
            'doc',
            'docx',
            'wpd',
            'txt',
        ];
        $extensionListToText = [
            'pdf',
            'odt',
            'sxw',
            'rtf',
            'doc',
            'docx',
            'txt',
        ];
        $extensionListFromSpreadsheet = [
            'ods',
            'sxc',
            'xls',
            'xlsx',
            'csv',
            'tsv',
        ];
        $extensionListToSpreadsheet = [
            'pdf',
            'ods',
            'sxc',
            'xls',
            'xlsx',
            'csv',
            'tsv',
        ];
        $extensionListFromPresentation = [
            'odp',
            'sxi',
            'ppt',
            'pptx',
        ];
        $extensionListToPresentation = [
            'pdf',
            'swf',
            'odp',
            'sxi',
            'ppt',
            'pptx',
        ];
        $extensionListFromDrawing = ['odg'];
        $extensionListToDrawing = ['svg', 'swf'];

        if ($mode === 'from') {
            if ($format === 'text') {
                $extensionList = array_merge($extensionList, $extensionListFromText);
            } elseif ($format === 'spreadsheet') {
                $extensionList = array_merge($extensionList, $extensionListFromSpreadsheet);
            } elseif ($format === 'presentation') {
                $extensionList = array_merge($extensionList, $extensionListFromPresentation);
            } elseif ($format === 'drawing') {
                $extensionList = array_merge($extensionList, $extensionListFromDrawing);
            } elseif ($format === 'all') {
                $extensionList = array_merge($extensionList, $extensionListFromText);
                $extensionList = array_merge($extensionList, $extensionListFromSpreadsheet);
                $extensionList = array_merge($extensionList, $extensionListFromPresentation);
                $extensionList = array_merge($extensionList, $extensionListFromDrawing);
            }
        } elseif ($mode === 'to') {
            if ($format === 'text') {
                $extensionList = array_merge($extensionList, $extensionListToText);
            } elseif ($format === 'spreadsheet') {
                $extensionList = array_merge($extensionList, $extensionListToSpreadsheet);
            } elseif ($format === 'presentation') {
                $extensionList = array_merge($extensionList, $extensionListToPresentation);
            } elseif ($format === 'drawing') {
                $extensionList = array_merge($extensionList, $extensionListToDrawing);
            } elseif ($format === 'all') {
                $extensionList = array_merge($extensionList, $extensionListToText);
                $extensionList = array_merge($extensionList, $extensionListToSpreadsheet);
                $extensionList = array_merge($extensionList, $extensionListToPresentation);
                $extensionList = array_merge($extensionList, $extensionListToDrawing);
            }
        } elseif ($mode === 'all') {
            if ($format === 'text') {
                $extensionList = array_merge($extensionList, $extensionListFromText);
                $extensionList = array_merge($extensionList, $extensionListToText);
            } elseif ($format === 'spreadsheet') {
                $extensionList = array_merge($extensionList, $extensionListFromSpreadsheet);
                $extensionList = array_merge($extensionList, $extensionListToSpreadsheet);
            } elseif ($format === 'presentation') {
                $extensionList = array_merge($extensionList, $extensionListFromPresentation);
                $extensionList = array_merge($extensionList, $extensionListToPresentation);
            } elseif ($format === 'drawing') {
                $extensionList = array_merge($extensionList, $extensionListFromDrawing);
                $extensionList = array_merge($extensionList, $extensionListToDrawing);
            } elseif ($format === 'all') {
                $extensionList = array_merge($extensionList, $extensionListFromText);
                $extensionList = array_merge($extensionList, $extensionListToText);
                $extensionList = array_merge($extensionList, $extensionListFromSpreadsheet);
                $extensionList = array_merge($extensionList, $extensionListToSpreadsheet);
                $extensionList = array_merge($extensionList, $extensionListFromPresentation);
                $extensionList = array_merge($extensionList, $extensionListToPresentation);
                $extensionList = array_merge($extensionList, $extensionListFromDrawing);
                $extensionList = array_merge($extensionList, $extensionListToDrawing);
            }
        }

        return $extensionList;
    }

    /**
     * Get Format type list by extension and mode.
     *
     * @param string $mode Mode to search format type list
     *
     * @example 'from'
     * @example 'to'
     *
     * @param string $extension file extension to check file type
     *
     * @return array
     */
    public static function getFormatTypeListConvertor($mode = 'from', $extension)
    {
        $formatTypesList = [];
        $formatTypes = ['text', 'spreadsheet', 'presentation', 'drawing'];
        foreach ($formatTypes as $formatType) {
            if (in_array($extension, self::getJodconverterExtensionList($mode, $formatType))) {
                $formatTypesList[] = $formatType;
            }
        }

        return $formatTypesList;
    }

    /**
     * @param string $path
     * @param bool   $is_certificate_mode
     *
     * @return bool
     */
    public static function is_folder_to_avoid($path, $is_certificate_mode = false)
    {
        $foldersToAvoid = [
            '/HotPotatoes_files',
            '/certificates',
        ];
        $systemFolder = api_get_course_setting('show_system_folders');

        if ($systemFolder == 1) {
            $foldersToAvoid = [];
        }

        if (basename($path) == 'css') {
            return true;
        }

        if ($is_certificate_mode == false) {
            //Certificate results
            if (strstr($path, 'certificates')) {
                return true;
            }
        }

        // Admin setting for Hide/Show the folders of all users
        if (api_get_setting('show_users_folders') == 'false') {
            $foldersToAvoid[] = '/shared_folder';

            if (strstr($path, 'shared_folder_session_')) {
                return true;
            }
        }

        // Admin setting for Hide/Show Default folders to all users
        if (api_get_setting('show_default_folders') == 'false') {
            $foldersToAvoid[] = '/images';
            $foldersToAvoid[] = '/flash';
            $foldersToAvoid[] = '/audio';
            $foldersToAvoid[] = '/video';
        }

        // Admin setting for Hide/Show chat history folder
        if (api_get_setting('show_chat_folder') == 'false') {
            $foldersToAvoid[] = '/chat_files';
        }

        if (is_array($foldersToAvoid)) {
            return in_array($path, $foldersToAvoid);
        } else {
            return false;
        }
    }

    /**
     * @return array
     */
    public static function get_system_folders()
    {
        return [
            '/certificates',
            '/HotPotatoes_files',
            '/chat_files',
            '/images',
            '/flash',
            '/audio',
            '/video',
            '/shared_folder',
            '/learning_path',
        ];
    }

    /**
     * @return array
     */
    public static function getProtectedFolderFromStudent()
    {
        return [
            '/certificates',
            '/HotPotatoes_files',
            '/chat_files',
            '/shared_folder',
            '/learning_path',
        ];
    }

    /**
     * @param string $courseCode
     *
     * @return string 'visible' or 'invisible' string
     */
    public static function getDocumentDefaultVisibility($courseCode)
    {
        $settings = api_get_setting('tool_visible_by_default_at_creation');
        $defaultVisibility = 'visible';

        if (isset($settings['documents'])) {
            $portalDefaultVisibility = 'invisible';
            if ($settings['documents'] == 'true') {
                $portalDefaultVisibility = 'visible';
            }

            $defaultVisibility = $portalDefaultVisibility;
        }

        if (api_get_setting('documents_default_visibility_defined_in_course') == 'true') {
            $courseVisibility = api_get_course_setting('documents_default_visibility', $courseCode);
            if (!empty($courseVisibility) && in_array($courseVisibility, ['visible', 'invisible'])) {
                $defaultVisibility = $courseVisibility;
            }
        }

        return $defaultVisibility;
    }

    /**
     * @param array  $courseInfo
     * @param int    $id         doc id
     * @param string $visibility visible/invisible
     * @param int    $userId
     */
    public static function updateVisibilityFromAllSessions($courseInfo, $id, $visibility, $userId)
    {
        $sessionList = SessionManager::get_session_by_course($courseInfo['real_id']);

        if (!empty($sessionList)) {
            foreach ($sessionList as $session) {
                $sessionId = $session['id'];
                api_item_property_update(
                    $courseInfo,
                    TOOL_DOCUMENT,
                    $id,
                    $visibility,
                    $userId,
                    null,
                    null,
                    null,
                    null,
                    $sessionId
                );
            }
        }
    }

    /**
     * @param string $file
     *
     * @return string
     */
    public static function readNanogongFile($file)
    {
        $nanoGongJarFile = api_get_path(WEB_LIBRARY_PATH).'nanogong/nanogong.jar';
        $html = '<applet id="applet" archive="'.$nanoGongJarFile.'" code="gong.NanoGong" width="160" height="95">';
        $html .= '<param name="SoundFileURL" value="'.$file.'" />';
        $html .= '<param name="ShowSaveButton" value="false" />';
        $html .= '<param name="ShowTime" value="true" />';
        $html .= '<param name="ShowRecordButton" value="false" />';
        $html .= '</applet>';

        return $html;
    }

    /**
     * @param string $filePath
     * @param string $path
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param string $whatIfFileExists overwrite|rename
     * @param int    $userId
     * @param int    $groupId
     * @param int    $toUserId
     * @param string $comment
     *
     * @return bool|path
     */
    public static function addFileToDocumentTool(
        $filePath,
        $path,
        $courseInfo,
        $sessionId,
        $userId,
        $whatIfFileExists = 'overwrite',
        $groupId = null,
        $toUserId = null,
        $comment = null
    ) {
        if (!file_exists($filePath)) {
            return false;
        }

        $fileInfo = pathinfo($filePath);

        $file = [
            'name' => $fileInfo['basename'],
            'tmp_name' => $filePath,
            'size' => filesize($filePath),
            'from_file' => true,
        ];

        $course_dir = $courseInfo['path'].'/document';
        $baseWorkDir = api_get_path(SYS_COURSE_PATH).$course_dir;

        $filePath = handle_uploaded_document(
            $courseInfo,
            $file,
            $baseWorkDir,
            $path,
            $userId,
            $groupId,
            $toUserId,
            false,
            $whatIfFileExists,
            false,
            false,
            $comment,
            $sessionId
        );

        if ($filePath) {
            return self::get_document_id(
                $courseInfo,
                $filePath,
                $sessionId
            );
        }

        return false;
    }

    /**
     * Converts wav to mp3 file.
     * Requires the ffmpeg lib. In ubuntu: sudo apt-get install ffmpeg.
     *
     * @param string $wavFile
     * @param bool   $removeWavFileIfSuccess
     *
     * @return bool
     */
    public static function convertWavToMp3($wavFile, $removeWavFileIfSuccess = false)
    {
        if (file_exists($wavFile)) {
            try {
                $ffmpeg = \FFMpeg\FFMpeg::create();
                $video = $ffmpeg->open($wavFile);

                $mp3File = str_replace('wav', 'mp3', $wavFile);
                $result = $video->save(new FFMpeg\Format\Audio\Mp3(), $mp3File);
                if ($result && $removeWavFileIfSuccess) {
                    unlink($wavFile);
                }

                if (file_exists($mp3File)) {
                    return $mp3File;
                }
            } catch (Exception $e) {
                error_log($e->getMessage());
                error_log($e->getPrevious()->getMessage());
            }
        }

        return false;
    }

    /**
     * @param string $documentData     wav document information
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param int    $userId           user that adds the document
     * @param string $whatIfFileExists
     * @param bool   $deleteWavFile
     *
     * @return bool
     */
    public static function addAndConvertWavToMp3(
        $documentData,
        $courseInfo,
        $sessionId,
        $userId,
        $whatIfFileExists = 'overwrite',
        $deleteWavFile = false
    ) {
        if (empty($documentData)) {
            return false;
        }

        if (isset($documentData['absolute_path']) &&
            file_exists($documentData['absolute_path'])
        ) {
            $mp3FilePath = self::convertWavToMp3($documentData['absolute_path']);
            error_log($mp3FilePath);

            if (!empty($mp3FilePath) && file_exists($mp3FilePath)) {
                $documentId = self::addFileToDocumentTool(
                    $mp3FilePath,
                    dirname($documentData['path']),
                    $courseInfo,
                    $sessionId,
                    $userId,
                    $whatIfFileExists,
                    null,
                    null,
                    $documentData['comment']
                );

                if (!empty($documentId)) {
                    if ($deleteWavFile) {
                        $coursePath = $courseInfo['directory'].'/document';
                        $documentPath = api_get_path(SYS_COURSE_PATH).$coursePath;
                        self::delete_document(
                            $courseInfo,
                            null,
                            $documentPath,
                            $sessionId,
                            $documentData['id']
                        );
                    }

                    return $documentId;
                }
            }
        }

        return false;
    }

    /**
     * Sets.
     *
     * @param string $file         ($document_data['path'])
     * @param string $file_url_sys
     *
     * @return string
     */
    public static function generateAudioTempFile($file, $file_url_sys)
    {
        //make temp audio
        $temp_folder = api_get_path(SYS_ARCHIVE_PATH).'temp/audio';
        if (!file_exists($temp_folder)) {
            @mkdir($temp_folder, api_get_permissions_for_new_directories(), true);
        }

        //make htaccess with allow from all, and file index.html into temp/audio
        $htaccess = api_get_path(SYS_ARCHIVE_PATH).'temp/audio/.htaccess';
        if (!file_exists($htaccess)) {
            $htaccess_content = "order deny,allow\r\nallow from all\r\nOptions -Indexes";
            $fp = @fopen(api_get_path(SYS_ARCHIVE_PATH).'temp/audio/.htaccess', 'w');
            if ($fp) {
                fwrite($fp, $htaccess_content);
                fclose($fp);
            }
        }

        //encript temp name file
        $name_crip = sha1(uniqid()); //encript
        $findext = explode(".", $file);
        $extension = $findext[count($findext) - 1];
        $file_crip = $name_crip.'.'.$extension;

        //copy file to temp/audio directory
        $from_sys = $file_url_sys;
        $to_sys = api_get_path(SYS_ARCHIVE_PATH).'temp/audio/'.$file_crip;

        if (file_exists($from_sys)) {
            copy($from_sys, $to_sys);
        }

        // get file from tmp directory
        Session::write('temp_audio_nanogong', $to_sys);

        return api_get_path(WEB_ARCHIVE_PATH).'temp/audio/'.$file_crip;
    }

    /**
     * Erase temp nanogong audio.
     */
    public static function removeGeneratedAudioTempFile()
    {
        $tempAudio = Session::read('temp_audio_nanogong');
        if (!empty(isset($tempAudio)) && is_file($tempAudio)) {
            unlink($tempAudio);
            Session::erase('temp_audio_nanogong');
        }
    }

    /**
     * Check if the past is used in this course.
     *
     * @param array  $courseInfo
     * @param string $path
     *
     * @return array
     */
    public static function getDocumentByPathInCourse($courseInfo, $path)
    {
        $table = Database::get_course_table(TABLE_DOCUMENT);
        $path = Database::escape_string($path);
        $courseId = $courseInfo['real_id'];
        if (empty($courseId)) {
            return false;
        }
        $sql = "SELECT * FROM $table WHERE c_id = $courseId AND path = '$path'";
        $result = Database::query($sql);

        return Database::store_result($result, 'ASSOC');
    }

    /**
     * @param array $_course
     *
     * @return int
     */
    public static function createDefaultAudioFolder($_course)
    {
        if (!isset($_course['path'])) {
            return false;
        }

        $audioId = null;
        $path = api_get_path(SYS_COURSE_PATH).$_course['path'].'/document/';
        if (!is_dir($path.'audio')) {
            mkdir($path.'audio', api_get_permissions_for_new_directories());
            $audioId = add_document($_course, '/audio', 'folder', 0, 'Audio');
            api_item_property_update(
                $_course,
                TOOL_DOCUMENT,
                $audioId,
                'FolderCreated',
                api_get_user_id(),
                null,
                null,
                null,
                null,
                api_get_session_id()
            );
        }

        return $audioId;
    }

    /**
     * Generate a default certificate for a courses.
     *
     * @todo move to certificate lib
     *
     * @global string $css CSS directory
     * @global string $img_dir image directory
     * @global string $default_course_dir Course directory
     * @global string $js JS directory
     *
     * @param array $courseData     The course info
     * @param bool  $fromBaseCourse
     * @param int   $sessionId
     */
    public static function generateDefaultCertificate(
        $courseData,
        $fromBaseCourse = false,
        $sessionId = 0
    ) {
        if (empty($courseData)) {
            return false;
        }

        global $css, $img_dir, $default_course_dir, $js;
        $codePath = api_get_path(REL_CODE_PATH);
        $dir = '/certificates';
        $comment = null;
        $title = get_lang('DefaultCertificate');
        $fileName = api_replace_dangerous_char($title);
        $filePath = api_get_path(SYS_COURSE_PATH)."{$courseData['directory']}/document$dir";

        if (!is_dir($filePath)) {
            mkdir($filePath, api_get_permissions_for_new_directories());
        }

        $fileFullPath = "$filePath/$fileName.html";
        $fileType = 'file';
        $templateContent = file_get_contents(api_get_path(SYS_CODE_PATH).'gradebook/certificate_template/template.html');

        $search = ['{CSS}', '{IMG_DIR}', '{REL_CODE_PATH}', '{COURSE_DIR}'];
        $replace = [$css.$js, $img_dir, $codePath, $default_course_dir];

        $fileContent = str_replace($search, $replace, $templateContent);
        $saveFilePath = "$dir/$fileName.html";

        if ($fromBaseCourse) {
            $defaultCertificateId = self::get_default_certificate_id(
                $courseData['code'],
                0
            );
            if (!empty($defaultCertificateId)) {
                // We have a certificate from the course base
                $documentData = self::get_document_data_by_id(
                    $defaultCertificateId,
                    $courseData['code'],
                    false,
                    0
                );

                if ($documentData) {
                    $fileContent = file_get_contents($documentData['absolute_path']);
                }
            }
        }

        if (file_exists($fileFullPath) === false) {
            $result = file_put_contents($fileFullPath, $fileContent);
            if ($result) {
                $fileSize = filesize($fileFullPath);

                $documentId = add_document(
                    $courseData,
                    $saveFilePath,
                    $fileType,
                    $fileSize,
                    $title,
                    $comment,
                    0, //$readonly = 0,
                    true, //$save_visibility = true,
                    null, //$group_id = null,
                    $sessionId
                );

                api_item_property_update(
                    $courseData,
                    TOOL_DOCUMENT,
                    $documentId,
                    'DocumentAdded',
                    api_get_user_id(),
                    null,
                    null,
                    null,
                    null,
                    $sessionId
                );

                $defaultCertificateId = self::get_default_certificate_id(
                    $courseData['code'],
                    $sessionId
                );

                if (!isset($defaultCertificateId)) {
                    self::attach_gradebook_certificate(
                        $courseData['code'],
                        $documentId,
                        $sessionId
                    );
                }
            }
        }
    }

    /**
     * Update the document name.
     *
     * @param int    $documentId The document id
     * @param string $newName    The new name
     */
    public static function renameDocument($documentId, $newName)
    {
        $documentId = intval($documentId);
        $newName = Database::escape_string($newName);
        $docuentTable = Database::get_course_table(TABLE_DOCUMENT);

        $values = [
            'title' => $newName,
        ];

        $whereConditions = [
            'id = ?' => $documentId,
        ];

        Database::update($docuentTable, $values, $whereConditions);
    }

    /**
     * Get folder/file suffix.
     *
     * @param array $courseInfo
     * @param int   $sessionId
     * @param int   $groupId
     *
     * @return string
     */
    public static function getDocumentSuffix($courseInfo, $sessionId, $groupId)
    {
        // If no session or group, then no suffix.
        if (empty($sessionId) && empty($groupId)) {
            return '';
        }

        return '__'.intval($sessionId).'__'.intval($groupId);
    }

    /**
     * Fix a document name adding session id and group id
     * Turns picture.jpg -> picture__1__2.jpg
     * Where 1 = session id and 2 group id
     * Of session id and group id are empty then the function returns:
     * picture.jpg ->  picture.jpg.
     *
     * @param string $name       folder or file name
     * @param string $type       'folder' or 'file'
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param int    $groupId
     *
     * @return string
     */
    public static function fixDocumentName($name, $type, $courseInfo, $sessionId, $groupId)
    {
        $suffix = self::getDocumentSuffix($courseInfo, $sessionId, $groupId);

        switch ($type) {
            case 'folder':
                $name = $name.$suffix;
                break;
            case 'file':
                $name = self::addSuffixToFileName($name, $suffix);
                break;
        }

        return $name;
    }

    /**
     * Add a suffix to a file Example:
     * /folder/picture.jpg => to /folder/picture_this.jpg
     * where "_this" is the suffix.
     *
     * @param string $name
     * @param string $suffix
     *
     * @return string
     */
    public static function addSuffixToFileName($name, $suffix)
    {
        $extension = pathinfo($name, PATHINFO_EXTENSION);
        $fileName = pathinfo($name, PATHINFO_FILENAME);
        $dir = pathinfo($name, PATHINFO_DIRNAME);

        if ($dir == '.') {
            $dir = null;
        }

        if (!empty($dir) && $dir != '/') {
            $dir = $dir.'/';
        }

        $name = $dir.$fileName.$suffix.'.'.$extension;

        return $name;
    }

    /**
     * Check if folder exist in the course base or in the session course.
     *
     * @param string $folder     Example: /folder/folder2
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param int    $groupId    group.id
     *
     * @return bool
     */
    public static function folderExists(
        $folder,
        $courseInfo,
        $sessionId,
        $groupId
    ) {
        $courseId = $courseInfo['real_id'];

        if (empty($courseId)) {
            return false;
        }

        $sessionId = intval($sessionId);
        $folderWithSuffix = self::fixDocumentName(
            $folder,
            'folder',
            $courseInfo,
            $sessionId,
            $groupId
        );

        $folder = Database::escape_string($folder);
        $folderWithSuffix = Database::escape_string($folderWithSuffix);

        // Check if pathname already exists inside document table
        $tbl_document = Database::get_course_table(TABLE_DOCUMENT);
        $sql = "SELECT id, path FROM $tbl_document
                WHERE
                    filetype = 'folder' AND
                    c_id = $courseId AND
                    (path = '$folder' OR path = '$folderWithSuffix') AND
                    (session_id = 0 OR session_id = $sessionId)
        ";

        $rs = Database::query($sql);
        if (Database::num_rows($rs)) {
            return true;
        }

        return false;
    }

    /**
     * Check if file exist in the course base or in the session course.
     *
     * @param string $fileName   Example: /folder/picture.jpg
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param int    $groupId
     *
     * @return bool
     */
    public static function documentExists(
        $fileName,
        $courseInfo,
        $sessionId,
        $groupId
    ) {
        $courseId = $courseInfo['real_id'];

        if (empty($courseId)) {
            return false;
        }

        $sessionId = intval($sessionId);
        $fileNameEscape = Database::escape_string($fileName);

        $fileNameWithSuffix = self::fixDocumentName(
            $fileName,
            'file',
            $courseInfo,
            $sessionId,
            $groupId
        );

        $fileNameWithSuffix = Database::escape_string($fileNameWithSuffix);

        // Check if pathname already exists inside document table
        $table = Database::get_course_table(TABLE_DOCUMENT);
        $sql = "SELECT id, path FROM $table
                WHERE
                    filetype = 'file' AND
                    c_id = $courseId AND
                    (
                        path = '".$fileNameEscape."' OR
                        path = '$fileNameWithSuffix'
                    ) AND
                    (session_id = 0 OR session_id = $sessionId)
        ";
        $rs = Database::query($sql);
        if (Database::num_rows($rs)) {
            return true;
        }

        return false;
    }

    /**
     * Undo the suffix applied to a file example:
     * turns picture__1__1.jpg to picture.jpg.
     *
     * @param string $name
     * @param int    $courseId
     * @param int    $sessionId
     * @param int    $groupId
     *
     * @return string
     */
    public static function undoFixDocumentName(
        $name,
        $courseId,
        $sessionId,
        $groupId
    ) {
        if (empty($sessionId) && empty($groupId)) {
            return $name;
        }

        $suffix = self::getDocumentSuffix(
            ['real_id' => $courseId],
            $sessionId,
            $groupId
        );

        $name = str_replace($suffix, '', $name);

        return $name;
    }

    /**
     * @param string $path
     * @param string $name
     * @param array  $courseInfo
     * @param int    $sessionId
     * @param int    $groupId
     *
     * @return string
     */
    public static function getUniqueFileName($path, $name, $courseInfo, $sessionId, $groupId)
    {
        $counter = 1;
        $filePath = $path.$name;
        $uniqueName = $name;
        while ($documentExists = self::documentExists(
            $filePath,
            $courseInfo,
            $sessionId,
            $groupId
        )) {
            $uniqueName = self::addSuffixToFileName($name, '_'.$counter);
            $filePath = $path.$uniqueName;
            $counter++;
        }

        return $uniqueName;
    }

    /**
     * Builds the form that enables the user to
     * select a directory to browse/upload in.
     *
     * @param array    An array containing the folders we want to be able to select
     * @param string    The current folder (path inside of the "document" directory, including the prefix "/")
     * @param string    Group directory, if empty, prevents documents to be uploaded
     * (because group documents cannot be uploaded in root)
     * @param bool    Whether to change the renderer (this will add a template <span>
     * to the QuickForm object displaying the form)
     *
     * @return string html form
     */
    public static function build_directory_selector(
        $folders,
        $document_id,
        $group_dir = '',
        $change_renderer = false,
        &$form = null,
        $selectName = 'id'
    ) {
        $doc_table = Database::get_course_table(TABLE_DOCUMENT);
        $course_id = api_get_course_int_id();
        $folder_titles = [];

        if (is_array($folders)) {
            $escaped_folders = [];
            foreach ($folders as $key => &$val) {
                $escaped_folders[$key] = Database::escape_string($val);
            }
            $folder_sql = implode("','", $escaped_folders);

            $sql = "SELECT path, title 
                    FROM $doc_table
                    WHERE 
                        filetype = 'folder' AND 
                        c_id = $course_id AND 
                        path IN ('".$folder_sql."')";
            $res = Database::query($sql);
            $folder_titles = [];
            while ($obj = Database::fetch_object($res)) {
                $folder_titles[$obj->path] = $obj->title;
            }
        }

        $attributes = [];
        if (empty($form)) {
            $form = new FormValidator('selector', 'GET', api_get_self().'?'.api_get_cidreq());
            $attributes = ['onchange' => 'javascript: document.selector.submit();'];
        }
        $form->addElement('hidden', 'cidReq', api_get_course_id());
        $parent_select = $form->addSelect(
            $selectName,
            get_lang('CurrentDirectory'),
            '',
            $attributes
        );

        // Group documents cannot be uploaded in the root
        if (empty($group_dir)) {
            $parent_select->addOption(get_lang('Documents'), '/');

            if (is_array($folders)) {
                foreach ($folders as $folder_id => &$folder) {
                    $selected = ($document_id == $folder_id) ? ' selected="selected"' : '';
                    $path_parts = explode('/', $folder);
                    $folder_titles[$folder] = cut($folder_titles[$folder], 80);
                    $counter = count($path_parts) - 2;
                    if ($counter > 0) {
                        $label = str_repeat('&nbsp;&nbsp;&nbsp;', $counter).' &mdash; '.$folder_titles[$folder];
                    } else {
                        $label = ' &mdash; '.$folder_titles[$folder];
                    }
                    $parent_select->addOption($label, $folder_id);
                    if ($selected != '') {
                        $parent_select->setSelected($folder_id);
                    }
                }
            }
        } else {
            if (!empty($folders)) {
                foreach ($folders as $folder_id => &$folder) {
                    $selected = ($document_id == $folder_id) ? ' selected="selected"' : '';
                    $label = $folder_titles[$folder];
                    if ($folder == $group_dir) {
                        $label = get_lang('Documents');
                    } else {
                        $path_parts = explode('/', str_replace($group_dir, '', $folder));
                        $label = cut($label, 80);
                        $label = str_repeat('&nbsp;&nbsp;&nbsp;', count($path_parts) - 2).' &mdash; '.$label;
                    }
                    $parent_select->addOption($label, $folder_id);
                    if ($selected != '') {
                        $parent_select->setSelected($folder_id);
                    }
                }
            }
        }

        $html = $form->toHtml();

        return $html;
    }

    /**
     * Create a html hyperlink depending on if it's a folder or a file.
     *
     * @param string $documentWebPath
     * @param array  $document_data
     * @param bool   $show_as_icon      - if it is true, only a clickable icon will be shown
     * @param int    $visibility        (1/0)
     * @param int    $counter
     * @param int    $size
     * @param bool   $isAllowedToEdit
     * @param bool   $isCertificateMode
     *
     * @return string url
     */
    public static function create_document_link(
        $documentWebPath,
        $document_data,
        $show_as_icon = false,
        $counter = null,
        $visibility,
        $size = 0,
        $isAllowedToEdit = false,
        $isCertificateMode = false
    ) {
        global $dbl_click_id;
        $www = $documentWebPath;

        $sessionId = api_get_session_id();
        $courseParams = api_get_cidreq();
        $webODFList = self::get_web_odf_extension_list();

        // Get the title or the basename depending on what we're using
        if ($document_data['title'] != '') {
            $title = $document_data['title'];
        } else {
            $title = basename($document_data['path']);
        }

        $filetype = $document_data['filetype'];
        $path = $document_data['path'];
        $url_path = urlencode($document_data['path']);

        // Add class="invisible" on invisible files
        $visibility_class = $visibility == false ? ' class="muted"' : '';
        $forcedownload_link = '';
        $forcedownload_icon = '';
        $prevent_multiple_click = '';
        $force_download_html = '';

        if (!$show_as_icon) {
            // Build download link (icon)
            $forcedownload_link = $filetype == 'folder' ? api_get_self().'?'.$courseParams.'&action=downloadfolder&id='.$document_data['id'] : api_get_self().'?'.$courseParams.'&amp;action=download&amp;id='.$document_data['id'];
            // Folder download or file download?
            $forcedownload_icon = $filetype == 'folder' ? 'save_pack.png' : 'save.png';
            // Prevent multiple clicks on zipped folder download
            $prevent_multiple_click = $filetype == 'folder' ? " onclick=\"javascript: if(typeof clic_$dbl_click_id == 'undefined' || !clic_$dbl_click_id) { clic_$dbl_click_id=true; window.setTimeout('clic_".($dbl_click_id++)."=false;',10000); } else { return false; }\"" : '';
        }

        $target = '_self';
        $is_browser_viewable_file = false;

        if ($filetype == 'file') {
            // Check the extension
            $ext = explode('.', $path);
            $ext = strtolower($ext[sizeof($ext) - 1]);

            // HTML-files an some other types are shown in a frameset by default.
            $is_browser_viewable_file = self::isBrowserViewable($ext);
            if ($is_browser_viewable_file) {
                if ($ext == 'pdf' || in_array($ext, $webODFList)) {
                    $url = api_get_self().'?'.$courseParams.'&amp;action=download&amp;id='.$document_data['id'];
                } else {
                    $url = 'showinframes.php?'.$courseParams.'&id='.$document_data['id'];
                }
            } else {
                // url-encode for problematic characters (we may not call them dangerous characters...)
                //$path = str_replace('%2F', '/', $url_path).'?'.$courseParams;
                $url = $www.str_replace('%2F', '/', $url_path).'?'.$courseParams;
            }
        } else {
            $url = api_get_self().'?'.$courseParams.'&id='.$document_data['id'];
        }

        if ($isCertificateMode) {
            $url .= '&certificate=true&selectcat='.(isset($_GET['selectcat']) ? $_GET['selectcat'] : '');
        }

        // The little download icon
        $tooltip_title = $title;
        $tooltip_title_alt = $tooltip_title;

        if ($filetype == 'link') {
            $tooltip_title_alt = $title;
            $url = $document_data['comment'].'" target="_blank';
        }

        if ($path == '/shared_folder') {
            $tooltip_title_alt = get_lang('UserFolders');
        } elseif (strstr($path, 'shared_folder_session_')) {
            $tooltip_title_alt = get_lang('UserFolders').' ('.api_get_session_name(api_get_session_id()).')';
        } elseif (strstr($tooltip_title, 'sf_user_')) {
            $userinfo = api_get_user_info(substr($tooltip_title, 8));
            $tooltip_title_alt = get_lang('UserFolder').' '.$userinfo['complete_name'];
        } elseif ($path == '/chat_files') {
            $tooltip_title_alt = get_lang('ChatFiles');
        } elseif ($path == '/learning_path') {
            $tooltip_title_alt = get_lang('LearningPaths');
        } elseif ($path == '/video') {
            $tooltip_title_alt = get_lang('Video');
        } elseif ($path == '/audio') {
            $tooltip_title_alt = get_lang('Audio');
        } elseif ($path == '/flash') {
            $tooltip_title_alt = get_lang('Flash');
        } elseif ($path == '/images') {
            $tooltip_title_alt = get_lang('Images');
        } elseif ($path == '/images/gallery') {
            $tooltip_title_alt = get_lang('DefaultCourseImages');
        }

        $copyToMyFiles = $open_in_new_window_link = '';
        $curdirpath = isset($_GET['curdirpath']) ? Security::remove_XSS($_GET['curdirpath']) : null;
        $send_to = null;
        $checkExtension = $path;
        $extension = pathinfo($path, PATHINFO_EXTENSION);
        $document_data['file_extension'] = $extension;

        if (!$show_as_icon) {
            if ($filetype == 'folder') {
                if ($isAllowedToEdit ||
                    api_is_platform_admin() ||
                    api_get_setting('students_download_folders') == 'true'
                ) {
                    // filter: when I am into a shared folder, I can only show "my shared folder" for donwload
                    if (self::is_shared_folder($curdirpath, $sessionId)) {
                        if (preg_match('/shared_folder\/sf_user_'.api_get_user_id().'$/', urldecode($forcedownload_link)) ||
                            preg_match('/shared_folder_session_'.$sessionId.'\/sf_user_'.api_get_user_id().'$/', urldecode($forcedownload_link)) ||
                            $isAllowedToEdit || api_is_platform_admin()
                        ) {
                            $force_download_html = ($size == 0) ? '' : '<a href="'.$forcedownload_link.'" style="float:right"'.$prevent_multiple_click.'>'.
                                Display::return_icon($forcedownload_icon, get_lang('Download'), [], ICON_SIZE_SMALL).'</a>';
                        }
                    } elseif (!preg_match('/shared_folder/', urldecode($forcedownload_link)) ||
                        $isAllowedToEdit ||
                        api_is_platform_admin()
                    ) {
                        $force_download_html = ($size == 0) ? '' : '<a href="'.$forcedownload_link.'" style="float:right"'.$prevent_multiple_click.'>'.
                            Display::return_icon($forcedownload_icon, get_lang('Download'), [], ICON_SIZE_SMALL).'</a>';
                    }
                }
            } else {
                $force_download_html = ($size == 0) ? '' : '<a href="'.$forcedownload_link.'" style="float:right"'.$prevent_multiple_click.' download="'.$document_data['basename'].'">'.
                    Display::return_icon($forcedownload_icon, get_lang('Download'), [], ICON_SIZE_SMALL).'</a>';
            }

            // Copy files to user's myfiles
            if (api_get_setting('allow_my_files') === 'true' &&
                api_get_setting('users_copy_files') === 'true' && api_is_anonymous() === false
            ) {
                $copy_myfiles_link = $filetype == 'file' ? api_get_self().'?'.$courseParams.'&action=copytomyfiles&id='.$document_data['id'] : api_get_self().'?'.$courseParams;
                if ($filetype == 'file') {
                    $copyToMyFiles = '<a href="'.$copy_myfiles_link.'" style="float:right"'.$prevent_multiple_click.'>'.
                        Display::return_icon('briefcase.png', get_lang('CopyToMyFiles'), [], ICON_SIZE_SMALL).'&nbsp;&nbsp;</a>';

                    if (api_get_setting('allow_my_files') === 'false') {
                        $copyToMyFiles = '';
                    }
                }
            }

            $pdf_icon = '';
            if (!$isAllowedToEdit &&
                api_get_setting('students_export2pdf') == 'true' &&
                $filetype == 'file' &&
                in_array($extension, ['html', 'htm'])
            ) {
                $pdf_icon = ' <a style="float:right".'.$prevent_multiple_click.' href="'.api_get_self().'?'.$courseParams.'&action=export_to_pdf&id='.$document_data['id'].'&curdirpath='.$curdirpath.'">'.
                    Display::return_icon('pdf.png', get_lang('Export2PDF'), [], ICON_SIZE_SMALL).'</a> ';
            }

            if ($is_browser_viewable_file) {
                $open_in_new_window_link = '<a href="'.$www.str_replace('%2F', '/', $url_path).'?'.$courseParams.'" style="float:right"'.$prevent_multiple_click.' target="_blank">'.
                    Display::return_icon('open_in_new_window.png', get_lang('OpenInANewWindow'), [], ICON_SIZE_SMALL).'&nbsp;&nbsp;</a>';
            }

            if ($filetype == 'file') {
                // Sound preview
                if (preg_match('/mp3$/i', urldecode($checkExtension)) ||
                    (preg_match('/wav$/i', urldecode($checkExtension))) ||
                    preg_match('/ogg$/i', urldecode($checkExtension))
                ) {
                    return '<span style="float:left" '.$visibility_class.'>'.
                    $title.
                    '</span>'.$force_download_html.$send_to.$copyToMyFiles.$open_in_new_window_link.$pdf_icon;
                } elseif (
                    // Show preview
                    preg_match('/swf$/i', urldecode($checkExtension)) ||
                    preg_match('/png$/i', urldecode($checkExtension)) ||
                    preg_match('/gif$/i', urldecode($checkExtension)) ||
                    preg_match('/jpg$/i', urldecode($checkExtension)) ||
                    preg_match('/jpeg$/i', urldecode($checkExtension)) ||
                    preg_match('/bmp$/i', urldecode($checkExtension)) ||
                    preg_match('/svg$/i', urldecode($checkExtension))
                ) {
                    // Simpler version of showinframesmin.php with no headers
                    $url = 'show_content.php?'.$courseParams.'&id='.$document_data['id'];
                    $class = 'ajax';
                    if ($visibility == false) {
                        $class = "ajax text-muted";
                    }

                    return Display::url(
                        $title,
                        $url,
                        [
                            'class' => $class,
                            'title' => $tooltip_title_alt,
                            'data-title' => $title,
                            'style' => 'float:left;',
                        ]
                    )
                    .$force_download_html.$send_to.$copyToMyFiles
                    .$open_in_new_window_link.$pdf_icon;
                } else {
                    // For a "PDF Download" of the file.
                    $pdfPreview = null;
                    if ($ext != 'pdf' && !in_array($ext, $webODFList)) {
                        $url = 'showinframes.php?'.$courseParams.'&id='.$document_data['id'];
                    } else {
                        $pdfPreview = Display::url(
                            Display::return_icon('preview.png', get_lang('Preview'), null, ICON_SIZE_SMALL),
                            api_get_path(WEB_CODE_PATH).'document/showinframes.php?'.$courseParams.'&id='.$document_data['id'],
                            ['style' => 'float:right']
                        );
                    }
                    // No plugin just the old and good showinframes.php page
                    return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" style="float:left" '.$visibility_class.' >'.$title.'</a>'.
                    $pdfPreview.$force_download_html.$send_to.$copyToMyFiles.$open_in_new_window_link.$pdf_icon;
                }
            } else {
                return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" '.$visibility_class.' style="float:left">'.$title.'</a>'.
                $force_download_html.$send_to.$copyToMyFiles.$open_in_new_window_link.$pdf_icon;
            }
            // end copy files to users myfiles
        } else {
            // Icon column
            if (preg_match('/shared_folder/', urldecode($checkExtension)) &&
                preg_match('/shared_folder$/', urldecode($checkExtension)) == false &&
                preg_match('/shared_folder_session_'.$sessionId.'$/', urldecode($url)) == false
            ) {
                if ($filetype == 'file') {
                    //Sound preview
                    if (preg_match('/mp3$/i', urldecode($checkExtension)) ||
                        (preg_match('/wav$/i', urldecode($checkExtension))) ||
                        preg_match('/ogg$/i', urldecode($checkExtension))) {
                        $soundPreview = self::generateAudioPreview($documentWebPath, $document_data);

                        return $soundPreview;
                    } elseif (
                        // Show preview
                        preg_match('/swf$/i', urldecode($checkExtension)) ||
                        preg_match('/png$/i', urldecode($checkExtension)) ||
                        preg_match('/gif$/i', urldecode($checkExtension)) ||
                        preg_match('/jpg$/i', urldecode($checkExtension)) ||
                        preg_match('/jpeg$/i', urldecode($checkExtension)) ||
                        preg_match('/bmp$/i', urldecode($checkExtension)) ||
                        preg_match('/svg$/i', urldecode($checkExtension))
                    ) {
                        $url = 'showinframes.php?'.$courseParams.'&id='.$document_data['id'];

                        return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" '.$visibility_class.' style="float:left">'.
                            self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                            Display::return_icon('shared.png', get_lang('ResourceShared'), []).
                        '</a>';
                    } else {
                        return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" '.$visibility_class.' style="float:left">'.
                            self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                            Display::return_icon('shared.png', get_lang('ResourceShared'), []).
                        '</a>';
                    }
                } else {
                    return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" target="'.$target.'"'.$visibility_class.' style="float:left">'.
                        self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                        Display::return_icon('shared.png', get_lang('ResourceShared'), []).
                    '</a>';
                }
            } else {
                if ($filetype == 'file') {
                    // Sound preview with jplayer
                    if (preg_match('/mp3$/i', urldecode($checkExtension)) ||
                        (preg_match('/wav$/i', urldecode($checkExtension))) ||
                        preg_match('/ogg$/i', urldecode($checkExtension))) {
                        $soundPreview = self::generateAudioPreview($documentWebPath, $document_data);

                        return $soundPreview;
                    } elseif (
                        //Show preview
                        preg_match('/html$/i', urldecode($checkExtension)) ||
                        preg_match('/htm$/i', urldecode($checkExtension)) ||
                        preg_match('/swf$/i', urldecode($checkExtension)) ||
                        preg_match('/png$/i', urldecode($checkExtension)) ||
                        preg_match('/gif$/i', urldecode($checkExtension)) ||
                        preg_match('/jpg$/i', urldecode($checkExtension)) ||
                        preg_match('/jpeg$/i', urldecode($checkExtension)) ||
                        preg_match('/bmp$/i', urldecode($checkExtension)) ||
                        preg_match('/svg$/i', urldecode($checkExtension))
                    ) {
                        $url = 'showinframes.php?'.$courseParams.'&id='.$document_data['id']; //without preview
                        return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" '.$visibility_class.' style="float:left">'.
                            self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                        '</a>';
                    } else {
                        return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" '.$visibility_class.' style="float:left">'.
                            self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                        '</a>';
                    }
                } else {
                    return '<a href="'.$url.'" title="'.$tooltip_title_alt.'" target="'.$target.'"'.$visibility_class.' style="float:left">'.
                        self::build_document_icon_tag($filetype, $path, $isAllowedToEdit).
                    '</a>';
                }
            }
        }
    }

    /**
     * Builds an img html tag for the file type.
     *
     * @param string $type            (file/folder)
     * @param string $path
     * @param bool   $isAllowedToEdit
     *
     * @return string img html tag
     */
    public static function build_document_icon_tag($type, $path, $isAllowedToEdit = null)
    {
        $basename = basename($path);
        $sessionId = api_get_session_id();
        if (is_null($isAllowedToEdit)) {
            $isAllowedToEdit = api_is_allowed_to_edit(null, true);
        }
        $user_image = false;
        if ($type == 'file') {
            $icon = choose_image($basename);
            $basename = substr(strrchr($basename, '.'), 1);
        } elseif ($type == 'link') {
            $icon = 'clouddoc.png';
            $basename = get_lang('CloudFileLink');
        } else {
            if ($path == '/shared_folder') {
                $icon = 'folder_users.png';
                if ($isAllowedToEdit) {
                    $basename = get_lang('HelpUsersFolder');
                } else {
                    $basename = get_lang('UserFolders');
                }
            } elseif (strstr($basename, 'sf_user_')) {
                $userInfo = api_get_user_info(substr($basename, 8));
                $icon = $userInfo['avatar_small'];
                $basename = get_lang('UserFolder').' '.$userInfo['complete_name'];
                $user_image = true;
            } elseif (strstr($path, 'shared_folder_session_')) {
                $sessionName = api_get_session_name($sessionId);
                if ($isAllowedToEdit) {
                    $basename = '***('.$sessionName.')*** '.get_lang('HelpUsersFolder');
                } else {
                    $basename = get_lang('UserFolders').' ('.$sessionName.')';
                }
                $icon = 'folder_users.png';
            } else {
                $icon = 'folder_document.png';

                if ($path == '/audio') {
                    $icon = 'folder_audio.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpDefaultDirDocuments');
                    } else {
                        $basename = get_lang('Audio');
                    }
                } elseif ($path == '/flash') {
                    $icon = 'folder_flash.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpDefaultDirDocuments');
                    } else {
                        $basename = get_lang('Flash');
                    }
                } elseif ($path == '/images') {
                    $icon = 'folder_images.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpDefaultDirDocuments');
                    } else {
                        $basename = get_lang('Images');
                    }
                } elseif ($path == '/video') {
                    $icon = 'folder_video.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpDefaultDirDocuments');
                    } else {
                        $basename = get_lang('Video');
                    }
                } elseif ($path == '/images/gallery') {
                    $icon = 'folder_gallery.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpDefaultDirDocuments');
                    } else {
                        $basename = get_lang('Gallery');
                    }
                } elseif ($path == '/chat_files') {
                    $icon = 'folder_chat.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpFolderChat');
                    } else {
                        $basename = get_lang('ChatFiles');
                    }
                } elseif ($path == '/learning_path') {
                    $icon = 'folder_learningpath.png';
                    if ($isAllowedToEdit) {
                        $basename = get_lang('HelpFolderLearningPaths');
                    } else {
                        $basename = get_lang('LearningPaths');
                    }
                }
            }
        }

        if ($user_image) {
            return Display::img($icon, $basename, [], false);
        }

        return Display::return_icon($icon, $basename, [], ICON_SIZE_SMALL);
    }

    /**
     * Creates the row of edit icons for a file/folder.
     *
     * @param array $document_data
     * @param int   $id
     * @param bool  $is_template
     * @param int   $is_read_only
     * @param int   $visibility    (1/0)
     *
     * @return string html img tags with hyperlinks
     */
    public static function build_edit_icons($document_data, $id, $is_template, $is_read_only = 0, $visibility)
    {
        $sessionId = api_get_session_id();
        $courseParams = api_get_cidreq();
        $document_id = $document_data['id'];
        $type = $document_data['filetype'];
        $is_read_only = $document_data['readonly'];
        $path = $document_data['path'];

        if ($type == 'link') {
            $parent_id = self::get_document_id(
                api_get_course_info(),
                rtrim($path, '/'),
                0
            );
        } else {
            $parent_id = self::get_document_id(
                api_get_course_info(),
                dirname($path),
                0
            );
        }

        if (empty($parent_id) && !empty($sessionId)) {
            $parent_id = self::get_document_id(
                api_get_course_info(),
                dirname($path),
                $sessionId
            );
        }

        $curdirpath = dirname($document_data['path']);
        $is_certificate_mode = self::is_certificate_mode($path);
        $curdirpath = urlencode($curdirpath);
        $extension = pathinfo($path, PATHINFO_EXTENSION);
        //@todo Implement remote support for converter
        $usePpt2lp = api_get_setting('service_ppt2lp', 'active') == 'true' && api_get_setting('service_ppt2lp', 'host') == 'localhost';
        $formatTypeList = self::getFormatTypeListConvertor('from', $extension);
        $formatType = current($formatTypeList);

        // If document is read only *or* we're in a session and the document
        // is from a non-session context, hide the edition capabilities
        $modify_icons = [];
        $modify_icons[] = self::getButtonEdit($is_read_only, $document_data, $extension, $is_certificate_mode);
        $modify_icons[] = self::getButtonMove($is_read_only, $document_data, $is_certificate_mode, $parent_id);
        $modify_icons[] = self::getButtonVisibility(
            $is_read_only,
            $visibility,
            $document_data,
            $is_certificate_mode,
            $parent_id
        );
        $modify_icons[] = self::getButtonDelete(
            $is_read_only,
            $document_data,
            $is_certificate_mode,
            $curdirpath,
            $parent_id
        );

        if (!$is_read_only /* or ($session_id!=api_get_session_id()) */) {
            // Add action to covert to PDF, will create a new document whit same filename but .pdf extension
            // @TODO: add prompt to select a format target
            if (!in_array($path, self::get_system_folders())) {
                if ($usePpt2lp && $formatType) {
                    $modify_icons[] = Display::url(
                        Display::return_icon('convert.png', get_lang('Convert')),
                        '#',
                        ['class' => 'convertAction', 'data-documentId' => $document_id, 'data-formatType' => $formatType]
                    );
                }
            }
        }

        if ($type == 'file' && ($extension == 'html' || $extension == 'htm')) {
            if ($is_template == 0) {
                if ((isset($_GET['curdirpath']) && $_GET['curdirpath'] != '/certificates') || !isset($_GET['curdirpath'])) {
                    $modify_icons[] = Display::url(
                        Display::return_icon('wizard.png', get_lang('AddAsTemplate')),
                        api_get_self()."?$courseParams&curdirpath=$curdirpath&add_as_template=$id"
                    );
                }
                if ((isset($_GET['curdirpath']) && $_GET['curdirpath'] == '/certificates') || $is_certificate_mode) {//allow attach certificate to course
                    $visibility_icon_certificate = 'nocertificate';
                    if (self::get_default_certificate_id(api_get_course_id()) == $id) {
                        $visibility_icon_certificate = 'certificate';
                        $certificate = get_lang('DefaultCertificate');
                        $preview = get_lang('PreviewCertificate');
                        $is_preview = true;
                    } else {
                        $is_preview = false;
                        $certificate = get_lang('NoDefaultCertificate');
                    }
                    if (isset($_GET['selectcat'])) {
                        $modify_icons[] = Display::url(
                            Display::return_icon($visibility_icon_certificate.'.png', $certificate),
                            api_get_self()."?$courseParams&curdirpath=$curdirpath&selectcat=".intval($_GET['selectcat'])."&set_certificate=$id"
                        );
                        if ($is_preview) {
                            $modify_icons[] = Display::url(
                                Display::return_icon('preview_view.png', $preview),
                                api_get_self()."?$courseParams&curdirpath=$curdirpath&set_preview=$id"
                            );
                        }
                    }
                }
            } else {
                $modify_icons[] = Display::url(
                    Display::return_icon('wizard_na.png', get_lang('RemoveAsTemplate')),
                    api_get_self()."?$courseParams&curdirpath=$curdirpath&remove_as_template=$id"
                );
            }

            $modify_icons[] = Display::url(
                Display::return_icon('pdf.png', get_lang('Export2PDF')),
                api_get_self()."?$courseParams&action=export_to_pdf&id=$id&curdirpath=$curdirpath"
            );
        }

        return implode(PHP_EOL, $modify_icons);
    }

    /**
     * @param $folders
     * @param $curdirpath
     * @param $move_file
     * @param string $group_dir
     *
     * @return string
     */
    public static function build_move_to_selector($folders, $curdirpath, $move_file, $group_dir = '')
    {
        $form = new FormValidator('move_to', 'post', api_get_self().'?'.api_get_cidreq());

        // Form title
        $form->addHidden('move_file', $move_file);

        $options = [];

        // Group documents cannot be uploaded in the root
        if ($group_dir == '') {
            if ($curdirpath != '/') {
                $options['/'] = get_lang('Documents');
            }

            if (is_array($folders)) {
                foreach ($folders as &$folder) {
                    // Hide some folders
                    if ($folder == '/HotPotatoes_files' ||
                        $folder == '/certificates' ||
                        basename($folder) == 'css'
                    ) {
                        continue;
                    }
                    // Admin setting for Hide/Show the folders of all users
                    if (api_get_setting('show_users_folders') == 'false' &&
                        (strstr($folder, '/shared_folder') || strstr($folder, 'shared_folder_session_'))
                    ) {
                        continue;
                    }

                    // Admin setting for Hide/Show Default folders to all users
                    if (api_get_setting('show_default_folders') == 'false' &&
                        (
                            $folder == '/images' ||
                            $folder == '/flash' ||
                            $folder == '/audio' ||
                            $folder == '/video' ||
                            strstr($folder, '/images/gallery') ||
                            $folder == '/video/flv'
                        )
                    ) {
                        continue;
                    }

                    // Admin setting for Hide/Show chat history folder
                    if (api_get_setting('show_chat_folder') == 'false' &&
                        $folder == '/chat_files') {
                        continue;
                    }

                    // You cannot move a file to:
                    // 1. current directory
                    // 2. inside the folder you want to move
                    // 3. inside a subfolder of the folder you want to move
                    if (($curdirpath != $folder) &&
                        ($folder != $move_file) &&
                        (substr($folder, 0, strlen($move_file) + 1) != $move_file.'/')
                    ) {
                        $path_displayed = $folder;
                        // If document title is used, we have to display titles instead of real paths...
                        $path_displayed = self::get_titles_of_path($folder);

                        if (empty($path_displayed)) {
                            $path_displayed = get_lang('Untitled');
                        }
                        $options[$folder] = $path_displayed;
                    }
                }
            }
        } else {
            foreach ($folders as $folder) {
                if (($curdirpath != $folder) &&
                    ($folder != $move_file) &&
                    (substr($folder, 0, strlen($move_file) + 1) != $move_file.'/')
                ) {
                    // Cannot copy dir into his own subdir
                    $path_displayed = self::get_titles_of_path($folder);
                    $display_folder = substr($path_displayed, strlen($group_dir));
                    $display_folder = ($display_folder == '') ? get_lang('Documents') : $display_folder;
                    //$form .= '<option value="'.$folder.'">'.$display_folder.'</option>';
                    $options[$folder] = $display_folder;
                }
            }
        }
        $form->addElement('select', 'move_to', get_lang('MoveTo'), $options);
        $form->addButtonNext(get_lang('MoveElement'), 'move_file_submit');

        return $form->returnForm();
    }

    /**
     * Gets the path translated with title of docs and folders.
     *
     * @param string $path the real path
     *
     * @return the path which should be displayed
     */
    public static function get_titles_of_path($path)
    {
        global $tmp_folders_titles;
        $course_id = api_get_course_int_id();
        $nb_slashes = substr_count($path, '/');
        $current_slash_pos = 0;
        $path_displayed = '';
        for ($i = 0; $i < $nb_slashes; $i++) {
            // For each folder of the path, retrieve title.
            $current_slash_pos = strpos($path, '/', $current_slash_pos + 1);
            $tmp_path = substr($path, strpos($path, '/', 0), $current_slash_pos);

            if (empty($tmp_path)) {
                // If empty, then we are in the final part of the path
                $tmp_path = $path;
            }

            if (!empty($tmp_folders_titles[$tmp_path])) {
                // If this path has soon been stored here we don't need a new query
                $path_displayed .= $tmp_folders_titles[$tmp_path];
            } else {
                $sql = 'SELECT title FROM '.Database::get_course_table(TABLE_DOCUMENT).'
                        WHERE c_id = '.$course_id.' AND path LIKE BINARY "'.$tmp_path.'"';
                $rs = Database::query($sql);
                $tmp_title = '/'.Database::result($rs, 0, 0);
                $path_displayed .= $tmp_title;
                $tmp_folders_titles[$tmp_path] = $tmp_title;
            }
        }

        return $path_displayed;
    }

    /**
     * Creates form that asks for the directory name.
     *
     * @return string html-output text for the form
     */
    public static function create_dir_form($dirId)
    {
        global $document_id;
        $form = new FormValidator('create_dir_form', 'post', api_get_self().'?'.api_get_cidreq());
        $form->addElement('hidden', 'create_dir', 1);
        $form->addElement('hidden', 'dir_id', intval($document_id));
        $form->addElement('hidden', 'id', intval($dirId));
        $form->addElement('header', get_lang('CreateDir'));
        $form->addText('dirname', get_lang('NewDir'), ['autofocus' => 'autofocus']);
        $form->addButtonCreate(get_lang('CreateFolder'));

        return $form->returnForm();
    }

    /**
     * Checks whether the user is in shared folder.
     *
     * @param string $curdirpath
     * @param int    $sessionId
     *
     * @return bool Return true when user is into shared folder
     */
    public static function is_shared_folder($curdirpath, $sessionId)
    {
        $clean_curdirpath = Security::remove_XSS($curdirpath);
        if ($clean_curdirpath == '/shared_folder') {
            return true;
        } elseif ($clean_curdirpath == '/shared_folder_session_'.$sessionId) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Checks whether the user is into any user shared folder.
     *
     * @param string $path
     * @param int    $sessionId
     *
     * @return bool Return true when user is in any user shared folder
     */
    public static function is_any_user_shared_folder($path, $sessionId)
    {
        $clean_path = Security::remove_XSS($path);
        if (strpos($clean_path, 'shared_folder/sf_user_')) {
            return true;
        } elseif (strpos($clean_path, 'shared_folder_session_'.$sessionId.'/sf_user_')) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Create users shared folder for course.
     *
     * @param int   $userId
     * @param array $courseInfo
     * @param int   $sessionId
     */
    public static function createUserSharedFolder($userId, array $courseInfo, $sessionId = 0)
    {
        $documentDirectory = api_get_path(SYS_COURSE_PATH).$courseInfo['directory'].'/document';
        $userInfo = api_get_user_info($userId);

        if (!$sessionId) {
            //Create shared folder. Necessary for recycled courses.
            if (!file_exists($documentDirectory.'/shared_folder')) {
                create_unexisting_directory(
                    $courseInfo,
                    $userId,
                    0,
                    0,
                    0,
                    $documentDirectory,
                    '/shared_folder',
                    get_lang('UserFolders'),
                    0,
                    false,
                    false
                );
            }
            // Create dynamic user shared folder
            if (!file_exists($documentDirectory.'/shared_folder/sf_user_'.$userId)) {
                create_unexisting_directory(
                    $courseInfo,
                    $userId,
                    0,
                    0,
                    0,
                    $documentDirectory,
                    '/shared_folder/sf_user_'.$userId,
                    $userInfo['complete_name'],
                    1,
                    false,
                    false
                );
            }

            return;
        }

        // Create shared folder session.
        if (!file_exists($documentDirectory.'/shared_folder_session_'.$sessionId)) {
            create_unexisting_directory(
                $courseInfo,
                api_get_user_id(),
                $sessionId,
                0,
                0,
                $documentDirectory,
                '/shared_folder_session_'.$sessionId,
                get_lang('UserFolders').' ('.api_get_session_name($sessionId).')',
                0,
                false,
                false
            );
        }
        //Create dynamic user shared folder into a shared folder session
        if (!file_exists($documentDirectory.'/shared_folder_session_'.$sessionId.'/sf_user_'.$userId)) {
            create_unexisting_directory(
                $courseInfo,
                $userId,
                $sessionId,
                0,
                0,
                $documentDirectory,
                '/shared_folder_session_'.$sessionId.'/sf_user_'.$userId,
                $userInfo['complete_name'].'('.api_get_session_name($sessionId).')',
                1,
                false,
                false
            );
        }
    }

    /**
     * Checks whether the user is into his shared folder or into a subfolder.
     *
     * @param int    $user_id
     * @param string $path
     * @param int    $sessionId
     *
     * @return bool Return true when user is in his user shared folder or into a subfolder
     */
    public static function is_my_shared_folder($user_id, $path, $sessionId)
    {
        $clean_path = Security::remove_XSS($path).'/';
        //for security does not remove the last slash
        $main_user_shared_folder = '/shared_folder\/sf_user_'.$user_id.'\//';
        //for security does not remove the last slash
        $main_user_shared_folder_session = '/shared_folder_session_'.$sessionId.'\/sf_user_'.$user_id.'\//';

        if (preg_match($main_user_shared_folder, $clean_path)) {
            return true;
        } elseif (preg_match($main_user_shared_folder_session, $clean_path)) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Check if the file name or folder searched exist.
     *
     * @return bool Return true when exist
     */
    public static function search_keyword($document_name, $keyword)
    {
        if (api_strripos($document_name, $keyword) !== false) {
            return true;
        } else {
            return false;
        }
    }

    /**
     * Checks whether a document can be previewed by using the browser.
     *
     * @param string $file_extension the filename extension of the document (it must be in lower case)
     *
     * @return bool returns TRUE or FALSE
     */
    public static function isBrowserViewable($file_extension)
    {
        static $allowed_extensions = [
            'htm', 'html', 'xhtml',
            'gif', 'jpg', 'jpeg', 'png', 'tif', 'tiff',
            'pdf', 'svg', 'swf',
            'txt', 'log',
            'mp4', 'ogg', 'ogv', 'ogx', 'mpg', 'mpeg', 'mov', 'avi', 'webm', 'wmv',
            'mp3', 'oga', 'wav', 'au', 'wma', 'mid', 'kar',
        ];

        /*
          //TODO: make a admin switch to strict mode
          1. global default $allowed_extensions
          if (in_array($file_extension, $allowed_extensions)) { // Assignment + a logical check.
          return true;
          }
          2. check native support
          3. check plugins: quicktime, mediaplayer, vlc, acrobat, flash, java
         */

        if (!($result = in_array($file_extension, $allowed_extensions))) {
            // Assignment + a logical check.
            return false;
        }

        //check native support (Explorer, Opera, Firefox, Chrome, Safari)
        if ($file_extension == "pdf") {
            return api_browser_support('pdf');
        } elseif ($file_extension == "mp3") {
            return api_browser_support('mp3');
        } elseif ($file_extension == "mp4") {
            return api_browser_support('mp4');
        } elseif ($file_extension == "ogg" || $file_extension == "ogx" || $file_extension == "ogv" || $file_extension == "oga") {
            return api_browser_support('ogg');
        } elseif ($file_extension == "svg") {
            return api_browser_support('svg');
        } elseif ($file_extension == "mpg" || $file_extension == "mpeg") {
            return api_browser_support('mpg');
        } elseif ($file_extension == "mov") {
            return api_browser_support('mov');
        } elseif ($file_extension == "wav") {
            return api_browser_support('wav');
        } elseif ($file_extension == "mid" || $file_extension == "kar") {
            return api_browser_support('mid');
        } elseif ($file_extension == "avi") {
            return api_browser_support('avi');
        } elseif ($file_extension == "wma") {
            return api_browser_support('wma');
        } elseif ($file_extension == "wmv") {
            return api_browser_support('wmv');
        } elseif ($file_extension == "tif" || $file_extension == "tiff") {
            return api_browser_support('tif');
        } elseif ($file_extension == "mov") {
            return api_browser_support('mov');
        } elseif ($file_extension == "au") {
            return api_browser_support('au');
        } elseif ($file_extension == "webm") {
            return api_browser_support('webm');
        }

        return $result;
    }

    /**
     * @param array $courseInfo
     * @param int   $sessionId
     *
     * @return array
     */
    public static function getDeletedDocuments($courseInfo, $sessionId = 0)
    {
        $table = Database::get_course_table(TABLE_DOCUMENT);
        $courseId = $courseInfo['real_id'];
        $sessionCondition = api_get_session_condition($sessionId);
        $sql = "SELECT * FROM $table
                WHERE
                  path LIKE '%DELETED%' AND
                  c_id = $courseId
                  $sessionCondition
                ORDER BY path
        ";

        $result = Database::query($sql);
        $files = [];
        while ($document = Database::fetch_array($result, 'ASSOC')) {
            $files[] = $document;
        }

        return $files;
    }

    /**
     * @param int   $id
     * @param array $courseInfo
     * @param int   $sessionId
     *
     * @return array
     */
    public static function getDeletedDocument($id, $courseInfo, $sessionId = 0)
    {
        if (empty($courseInfo)) {
            return false;
        }

        $table = Database::get_course_table(TABLE_DOCUMENT);
        $courseId = $courseInfo['real_id'];
        $sessionCondition = api_get_session_condition($sessionId);
        $sql = "SELECT * FROM $table
                WHERE
                  path LIKE '%DELETED%' AND
                  id = $id AND
                  c_id = $courseId
                  $sessionCondition
                LIMIT 1
        ";
        $result = Database::query($sql);
        if (Database::num_rows($result)) {
            $result = Database::fetch_array($result, 'ASSOC');

            return $result;
        }

        return [];
    }

    /**
     * @param int   $id
     * @param array $courseInfo
     * @param int   $sessionId
     *
     * @return bool
     */
    public static function purgeDocument($id, $courseInfo, $sessionId = 0)
    {
        $document = self::getDeletedDocument($id, $courseInfo, $sessionId);
        if (!empty($document)) {
            $path = $document['path'];
            $coursePath = api_get_path(SYS_COURSE_PATH).$courseInfo['path'].'/document/';
            my_delete($coursePath.$path);
            // Hard delete.
            self::deleteDocumentFromDb($id, $courseInfo, $sessionId, true);

            return true;
        }

        return false;
    }

    /**
     * @param array $courseInfo
     * @param int   $sessionId
     */
    public static function purgeDocuments($courseInfo, $sessionId)
    {
        $files = self::getDeletedDocuments($courseInfo, $sessionId);
        foreach ($files as $file) {
            self::purgeDocument($file['id'], $courseInfo, $sessionId);
        }
    }

    /**
     * @param int   $id
     * @param array $courseInfo
     * @param int   $sessionId
     */
    public static function downloadDeletedDocument($id, $courseInfo, $sessionId)
    {
        $document = self::getDeletedDocument($id, $courseInfo, $sessionId);
        if (!empty($document)) {
            $coursePath = api_get_path(SYS_COURSE_PATH).$courseInfo['path'].'/document/';

            if (Security::check_abs_path($coursePath.$document['path'], $coursePath)) {
                self::file_send_for_download($coursePath.$document['path']);
                exit;
            }
        }
    }

    /**
     * @param array $courseInfo
     * @param int   $sessionId
     *
     * @return bool
     */
    public static function downloadAllDeletedDocument($courseInfo, $sessionId)
    {
        $files = self::getDeletedDocuments($courseInfo, $sessionId);

        if (empty($files)) {
            return false;
        }

        $coursePath = api_get_path(SYS_COURSE_PATH).$courseInfo['path'].'/document';

        // Creating a ZIP file.
        $tempZipFile = api_get_path(SYS_ARCHIVE_PATH).api_get_unique_id().".zip";
        $zip = new PclZip($tempZipFile);
        foreach ($files as $file) {
            $zip->add(
                $coursePath.$file['path'],
                PCLZIP_OPT_REMOVE_PATH,
                $coursePath
            );
        }

        if (Security::check_abs_path($tempZipFile, api_get_path(SYS_ARCHIVE_PATH))) {
            self::file_send_for_download($tempZipFile, true);
            @unlink($tempZipFile);
            exit;
        }
    }

    /**
     * Delete documents from a session in a course.
     *
     * @param array $courseInfo
     * @param int   $sessionId
     *
     * @return bool
     */
    public static function deleteDocumentsFromSession($courseInfo, $sessionId)
    {
        if (empty($courseInfo)) {
            return false;
        }

        if (empty($sessionId)) {
            return false;
        }

        $itemPropertyTable = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $documentTable = Database::get_course_table(TABLE_DOCUMENT);

        $conditionSession = api_get_session_condition($sessionId, true, false, 'd.session_id');
        $courseId = $courseInfo['real_id'];

        // get invisible folders
        $sql = "SELECT DISTINCT d.id, path
                FROM $itemPropertyTable i
                INNER JOIN $documentTable d
                ON (i.c_id = d.c_id)
                WHERE
                    d.id = i.ref AND
                    i.tool = '".TOOL_DOCUMENT."'
                    $conditionSession AND
                    i.c_id = $courseId AND
                    d.c_id = $courseId ";

        $result = Database::query($sql);
        $documents = Database::store_result($result, 'ASSOC');
        if ($documents) {
            $course_dir = $courseInfo['directory'].'/document';
            $sys_course_path = api_get_path(SYS_COURSE_PATH);
            $base_work_dir = $sys_course_path.$course_dir;

            foreach ($documents as $document) {
                $documentId = $document['id'];
                self::delete_document(
                    $courseInfo,
                    null,
                    $base_work_dir,
                    $sessionId,
                    $documentId
                );
            }
        }

        $sql = "DELETE FROM $documentTable
                WHERE c_id = $courseId AND session_id = $sessionId";
        Database::query($sql);

        $sql = "DELETE FROM $itemPropertyTable
                WHERE c_id = $courseId AND session_id = $sessionId AND tool = '".TOOL_DOCUMENT."'";
        Database::query($sql);
    }

    /**
     * Update the file or directory path in the document db document table.
     *
     * @author - Hugues Peeters <peeters@ipm.ucl.ac.be>
     *
     * @param string $action   - action type require : 'delete' or 'update'
     * @param string $old_path - old path info stored to change
     * @param string $new_path - new path info to substitute
     *
     * @desc Update the file or directory path in the document db document table
     */
    public static function updateDbInfo($action, $old_path, $new_path = '')
    {
        $dbTable = Database::get_course_table(TABLE_DOCUMENT);
        $course_id = api_get_course_int_id();
        $old_path = Database::escape_string($old_path);
        switch ($action) {
            case 'delete':
                $query = "DELETE FROM $dbTable
                          WHERE
                            c_id = $course_id AND
                            (
                                path LIKE BINARY '".$old_path."' OR
                                path LIKE BINARY '".$old_path."/%'
                            )";
                Database::query($query);
                break;
            case 'update':
                if ($new_path[0] == '.') {
                    $new_path = substr($new_path, 1);
                }
                $new_path = str_replace('//', '/', $new_path);

                // Attempt to update	- tested & working for root	dir
                $new_path = Database::escape_string($new_path);
                $query = "UPDATE $dbTable SET
                            path = CONCAT('".$new_path."', SUBSTRING(path, LENGTH('".$old_path."')+1) )
                          WHERE 
                                c_id = $course_id AND 
                                (path LIKE BINARY '".$old_path."' OR path LIKE BINARY '".$old_path."/%')";
                Database::query($query);
                break;
        }
    }

    /**
     * This function calculates the resized width and resized heigt
     * according to the source and target widths
     * and heights, height so that no distortions occur
     * parameters.
     *
     * @param $image = the absolute path to the image
     * @param $target_width = how large do you want your resized image
     * @param $target_height = how large do you want your resized image
     * @param $slideshow (default=0) =
     *      indicates weither we are generating images for a slideshow or not,
     *		this overrides the $_SESSION["image_resizing"] a bit so that a thumbnail
     *	    view is also possible when you choose not to resize the source images
     *
     * @return array
     */
    public static function resizeImageSlideShow(
        $image,
        $target_width,
        $target_height,
        $slideshow = 0
    ) {
        // Modifications by Ivan Tcholakov, 04-MAY-2009.
        $result = [];
        $imageResize = Session::read('image_resizing');
        if ($imageResize == 'resizing' || $slideshow == 1) {
            $new_sizes = api_resize_image($image, $target_width, $target_height);
            $result[] = $new_sizes['height'];
            $result[] = $new_sizes['width'];
        } else {
            $size = api_getimagesize($image);
            $result[] = $size['height'];
            $result[] = $size['width'];
        }

        return $result;
    }

    /**
     * Calculates the total size of a directory by adding the sizes (that
     * are stored in the database) of all files & folders in this directory.
     *
     * @param string $path
     * @param bool   $can_see_invisible
     *
     * @return int Total size
     */
    public static function getTotalFolderSize($path, $can_see_invisible = false)
    {
        $table_itemproperty = Database::get_course_table(TABLE_ITEM_PROPERTY);
        $table_document = Database::get_course_table(TABLE_DOCUMENT);
        $tool_document = TOOL_DOCUMENT;

        $course_id = api_get_course_int_id();
        $session_id = api_get_session_id();
        $session_condition = api_get_session_condition(
            $session_id,
            true,
            true,
            'props.session_id'
        );

        if (empty($course_id)) {
            return 0;
        }

        $path = Database::escape_string($path);
        $visibility_rule = ' props.visibility '.($can_see_invisible ? '<> 2' : '= 1');

        $sql = "SELECT SUM(table1.size) FROM (
                SELECT props.ref, size
                FROM $table_itemproperty AS props 
                INNER JOIN $table_document AS docs
                ON (docs.id = props.ref AND docs.c_id = props.c_id)
                WHERE
                    docs.c_id = $course_id AND                    
                    docs.path LIKE '$path/%' AND
                    props.c_id = $course_id AND
                    props.tool = '$tool_document' AND
                    $visibility_rule
                    $session_condition
                GROUP BY ref
            ) as table1";

        $result = Database::query($sql);
        if ($result && Database::num_rows($result) != 0) {
            $row = Database::fetch_row($result);

            return $row[0] == null ? 0 : $row[0];
        } else {
            return 0;
        }
    }

    /**
     * Adds a cloud link to the database.
     *
     * @author - Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @param array  $_course
     * @param string $path
     * @param string $url
     * @param string $name
     *
     * @return int id of document or 0 if already exists or there was a problem creating it
     */
    public static function addCloudLink($_course, $path, $url, $name)
    {
        $file_path = $path;
        if (!self::cloudLinkExists($_course, $path, $url)) {
            $doc_id = add_document($_course, $file_path, 'link', 0, $name, $url);
            if ($doc_id) {
                // Update document item_property
                api_item_property_update(
                    $_course,
                    TOOL_DOCUMENT,
                    $doc_id,
                    'DocumentAdded',
                    api_get_user_id(),
                    api_get_group_id(),
                    api_get_user_id(),
                    null,
                    null,
                    api_get_session_id()
                );
            }

            // If the file is in a folder, we need to update all parent folders
            item_property_update_on_folder($_course, $file_path, api_get_user_id());

            return $doc_id;
        } else {
            return 0;
        }
    }

    /**
     * Deletes a cloud link from the database.
     *
     * @author - Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @param array  $courseInfo
     * @param string $documentId
     *
     * @return bool true if success / false if an error occurred
     */
    public static function deleteCloudLink($courseInfo, $documentId)
    {
        if (empty($documentId) || empty($courseInfo)) {
            return false;
        }

        $documentId = (int) $documentId;
        $fileDeletedFromDb = false;
        if (!empty($documentId)) {
            self::deleteDocumentFromDb($documentId, $courseInfo, 0, true);
            // checking
            $table = Database::get_course_table(TABLE_DOCUMENT);
            $courseId = $courseInfo['real_id'];
            echo $sql = "SELECT * FROM $table WHERE id = $documentId AND c_id = $courseId";
            $result = Database::query($sql);
            $exists = Database::num_rows($result) > 0;
            $fileDeletedFromDb = !$exists;
        }

        return $fileDeletedFromDb;
    }

    /**
     * Gets the id of a cloud link with a given path.
     *
     * @author - Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @param array  $courseInfo
     * @param string $path
     * @param string $url
     *
     * @return int link's id / false if no link found
     */
    public static function getCloudLinkId($courseInfo, $path, $url)
    {
        $table = Database::get_course_table(TABLE_DOCUMENT);

        if (empty($courseInfo)) {
            return false;
        }

        $courseId = (int) $courseInfo['real_id'];
        $path = Database::escape_string($path);

        if (substr($path, -1) != '/') {
            // Add final slash to path if not present
            $path .= '/';
        }

        if (!empty($courseId) && !empty($path)) {
            $sql = "SELECT id FROM $table 
                    WHERE 
                        c_id = $courseId AND 
                        path LIKE BINARY '$path' AND 
                        comment = '$url' AND 
                        filetype = 'link' 
                    LIMIT 1";
            $result = Database::query($sql);
            if ($result && Database::num_rows($result)) {
                $row = Database::fetch_array($result);

                return intval($row[0]);
            }
        }

        return false;
    }

    /**
     * Checks if a cloud link exists.
     *
     * @author - Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @param array  $courseInfo
     * @param string $path
     * @param string $url
     *
     * @return bool true if it exists false in other case
     */
    public static function cloudLinkExists($courseInfo, $path, $url)
    {
        $exists = self::getCloudLinkId($courseInfo, $path, $url);

        return $exists;
    }

    /**
     * Gets the wellformed URLs regular expression in order to use it on forms' verifications.
     *
     * @author Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @return string the well formed URLs regular expressions string
     */
    public static function getWellFormedUrlRegex()
    {
        return '/\(?((http|https|ftp):\/\/)(?:((?:[^\W\s]|\.|-|[:]{1})+)@{1})?((?:www.)?(?:[^\W\s]|\.|-)+[\.][^\W\s]{2,4}|localhost(?=\/)|\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})(?::(\d*))?([\/]?[^\s\?]*[\/]{1})*(?:\/?([^\s\n\?\[\]\{\}\#]*(?:(?=\.)){1}|[^\s\n\?\[\]\{\}\.\#]*)?([\.]{1}[^\s\?\#]*)?)?(?:\?{1}([^\s\n\#\[\]]*))?([\#][^\s\n]*)?\)?/i';
    }

    /**
     * Gets the files hosting sites' whitelist.
     *
     * @author Aquilino Blanco Cores <aqblanco@gmail.com>
     *
     * @return array the sites list
     */
    public static function getFileHostingWhiteList()
    {
        return [
            'asuswebstorage.com',
            'dropbox.com',
            'dropboxusercontent.com',
            'fileserve.com',
            'drive.google.com',
            'icloud.com',
            'mediafire.com',
            'mega.nz',
            'onedrive.live.com',
            'slideshare.net',
            'scribd.com',
            'wetransfer.com',
            'box.com',
            'livefilestore.com', // OneDrive
        ];
    }

    /**
     * Parse file information into a link.
     *
     * @param array  $userInfo        Current user info
     * @param array  $course_info
     * @param int    $session_id
     * @param array  $resource
     * @param int    $lp_id
     * @param bool   $add_move_button
     * @param string $target
     * @param string $overwrite_url
     *
     * @return null|string
     */
    private static function parseFile(
        $userInfo,
        $course_info,
        $session_id,
        $resource,
        $lp_id,
        $add_move_button,
        $target,
        $overwrite_url
    ) {
        $img_sys_path = api_get_path(SYS_CODE_PATH).'img/';
        $web_code_path = api_get_path(WEB_CODE_PATH);

        $documentId = $resource['id'];
        $path = $resource['path'];

        if (empty($path)) {
            $num = 0;
        } else {
            $num = substr_count($path, '/') - 1;
        }

        // It's a file.
        $icon = choose_image($path);
        $position = strrpos($icon, '.');
        $icon = substr($icon, 0, $position).'_small.gif';
        $my_file_title = $resource['title'];
        $visibility = $resource['visibility'];

        // If title is empty we try to use the path
        if (empty($my_file_title)) {
            $my_file_title = basename($path);
        }

        // Show the "image name" not the filename of the image.
        if ($lp_id) {
            // LP URL
            $url = api_get_path(WEB_CODE_PATH).'lp/lp_controller.php?'.api_get_cidreq().'&action=add_item&type='.TOOL_DOCUMENT.'&file='.$documentId.'&lp_id='.$lp_id;
            if (!empty($overwrite_url)) {
                $url = $overwrite_url.'&cidReq='.$course_info['code'].'&id_session='.$session_id.'&document_id='.$documentId.'';
            }
        } else {
            // Direct document URL
            $url = $web_code_path.'document/document.php?cidReq='.$course_info['code'].'&id_session='.$session_id.'&id='.$documentId;
            if (!empty($overwrite_url)) {
                $url = $overwrite_url.'&cidReq='.$course_info['code'].'&id_session='.$session_id.'&document_id='.$documentId;
            }
        }

        $img = Display::returnIconPath($icon);
        if (!file_exists($img_sys_path.$icon)) {
            $img = Display::returnIconPath('default_small.gif');
        }

        $link = Display::url(
            '<img alt="" src="'.$img.'" title="" />&nbsp;'.$my_file_title,
            $url,
            ['target' => $target, 'class' => 'moved']
        );

        $directUrl = $web_code_path.'document/document.php?cidReq='.$course_info['code'].'&id_session='.$session_id.'&id='.$documentId;
        $link .= '&nbsp;'.Display::url(
            Display::return_icon('preview_view.png', get_lang('Preview')),
            $directUrl,
            ['target' => '_blank']
        );

        $visibilityClass = null;
        if ($visibility == 0) {
            $visibilityClass = ' text-muted ';
        }
        $return = null;

        if ($lp_id == false) {
            $return .= '<li class="doc_resource '.$visibilityClass.' " data_id="'.$documentId.'" data_type="document" title="'.$my_file_title.'" >';
        } else {
            $return .= '<li class="doc_resource lp_resource_element '.$visibilityClass.' " data_id="'.$documentId.'" data_type="document" title="'.$my_file_title.'" >';
        }

        $return .= '<div class="item_data" style="margin-left:'.($num * 5).'px;margin-right:5px;">';
        if ($add_move_button) {
            $return .= '<a class="moved" href="#">';
            $return .= Display::return_icon('move_everywhere.png', get_lang('Move'), [], ICON_SIZE_TINY);
            $return .= '</a> ';
        }
        $return .= $link;
        $sessionStar = api_get_session_image($resource['session_id'], $userInfo['status']);
        $return .= $sessionStar;

        $return .= '</div></li>';

        return $return;
    }

    /**
     * @param int   $folderId
     * @param array $resource
     * @param int   $lp_id
     *
     * @return null|string
     */
    private static function parseFolder($folderId, $resource, $lp_id)
    {
        $title = isset($resource['title']) ? $resource['title'] : null;
        $path = isset($resource['path']) ? $resource['path'] : null;

        if (empty($path)) {
            $num = 0;
        } else {
            $num = substr_count($path, '/');
        }

        // It's a folder.
        //hide some folders
        if (in_array(
            $path,
            ['shared_folder', 'chat_files', 'HotPotatoes_files', 'css', 'certificates']
        )) {
            return null;
        } elseif (preg_match('/_groupdocs/', $path)) {
            return null;
        } elseif (preg_match('/sf_user_/', $path)) {
            return null;
        } elseif (preg_match('/shared_folder_session_/', $path)) {
            return null;
        }

        $onclick = '';
        // if in LP, hidden folder are displayed in grey
        $folder_class_hidden = '';
        if ($lp_id) {
            if (isset($resource['visible']) && $resource['visible'] == 0) {
                $folder_class_hidden = "doc_folder_hidden"; // in base.css
            }
            $onclick = 'onclick="javascript: testResources(\'res_'.$resource['id'].'\',\'img_'.$resource['id'].'\')"';
        }
        $return = null;

        if (empty($path)) {
            $return = '<ul class="lp_resource">';
        }

        $return .= '<li class="doc_folder '.$folder_class_hidden.'" id="doc_id_'.$resource['id'].'"  style="margin-left:'.($num * 18).'px; ">';

        $image = Display::returnIconPath('nolines_plus.gif');
        if (empty($path)) {
            $image = Display::returnIconPath('nolines_minus.gif');
        }
        $return .= '<img style="cursor: pointer;" src="'.$image.'" align="absmiddle" id="img_'.$resource['id'].'" '.$onclick.'>';
        $return .= Display::return_icon('lp_folder.gif').'&nbsp;';
        $return .= '<span '.$onclick.' style="cursor: pointer;" >'.$title.'</span>';
        $return .= '</li>';

        if (empty($path)) {
            if ($folderId == false) {
                $return .= '<div id="res_'.$resource['id'].'" >';
            } else {
                $return .= '<div id="res_'.$resource['id'].'" style="display: none;" >';
            }
        }

        return $return;
    }

    /**
     * Get the button to edit document.
     *
     * @param bool   $isReadOnly
     * @param array  $documentData
     * @param string $extension
     * @param bool   $isCertificateMode
     *
     * @return string
     */
    private static function getButtonEdit($isReadOnly, array $documentData, $extension, $isCertificateMode)
    {
        $extension = strtolower($extension);
        $iconEn = Display::return_icon('edit.png', get_lang('Modify'));
        $iconDis = Display::return_icon('edit_na.png', get_lang('Modify'));
        $courseParams = api_get_cidreq();
        $webOdfExtensionList = self::get_web_odf_extension_list();
        $path = $documentData['path'];
        $document_id = $documentData['id'];

        if ($isReadOnly) {
            if (!api_is_course_admin() && !api_is_platform_admin()) {
                return $iconDis;
            }

            if (
                $extension == 'svg' && api_browser_support('svg') &&
                api_get_setting('enabled_support_svg') == 'true'
            ) {
                return Display::url($iconEn, "edit_draw.php?$courseParams&id=$document_id");
            }

            if (
                in_array($extension, $webOdfExtensionList) &&
                api_get_configuration_value('enabled_support_odf') === true
            ) {
                return Display::url($iconEn, "edit_odf.php?$courseParams&id=$document_id");
            }

            if (
                in_array($extension, ['png', 'jpg', 'jpeg', 'bmp', 'gif', 'pxd']) &&
                    api_get_setting('enabled_support_pixlr') == 'true'
            ) {
                return Display::url($iconEn, "edit_paint.php?$courseParams&id=$document_id");
            }

            return Display::url($iconEn, "edit_document.php?$courseParams&id=$document_id");
        }

        if (in_array($path, self::get_system_folders())) {
            return $iconDis;
        }

        if ($isCertificateMode) {
            return Display::url($iconEn, "edit_document.php?$courseParams&id=$document_id&curdirpath=/certificates");
        }

        $sessionId = api_get_session_id();

        if ($sessionId && $documentData['session_id'] != $sessionId) {
            return $iconDis;
        }

        if (
            $extension == 'svg' && api_browser_support('svg') &&
            api_get_setting('enabled_support_svg') == 'true'
        ) {
            return Display::url($iconEn, "edit_draw.php?$courseParams&id=$document_id");
        }

        if (
            in_array($extension, $webOdfExtensionList) &&
            api_get_configuration_value('enabled_support_odf') === true
        ) {
            return Display::url($iconEn, "edit_odf.php?$courseParams&id=$document_id");
        }

        if (
            in_array($extension, ['png', 'jpg', 'jpeg', 'bmp', 'gif', 'pxd']) &&
                api_get_setting('enabled_support_pixlr') == 'true'
        ) {
            return Display::url($iconEn, "edit_paint.php?$courseParams&id=$document_id");
        }

        return Display::url($iconEn, "edit_document.php?$courseParams&id=$document_id");
    }

    /**
     * Get the button to move document.
     *
     * @param bool  $isReadOnly
     * @param array $documentData
     * @param bool  $isCertificateMode
     * @param int   $parentId
     *
     * @return string
     */
    private static function getButtonMove($isReadOnly, array $documentData, $isCertificateMode, $parentId)
    {
        $iconEn = Display::return_icon('move.png', get_lang('Move'));
        $iconDis = Display::return_icon('move_na.png', get_lang('Move'));

        if ($isReadOnly) {
            return $iconDis;
        }

        $path = $documentData['path'];
        $document_id = $documentData['id'];
        $sessionId = api_get_session_id();
        $courseParams = api_get_cidreq();

        if ($isCertificateMode || in_array($path, self::get_system_folders())) {
            return $iconDis;
        }

        if ($sessionId) {
            if ($documentData['session_id'] != $sessionId) {
                return $iconDis;
            }
        }

        $urlMoveParams = http_build_query(['id' => $parentId, 'move' => $document_id]);

        return Display::url(
            $iconEn,
            api_get_self()."?$courseParams&$urlMoveParams"
        );
    }

    /**
     * Get the button to set visibility to document.
     *
     * @param bool  $isReadOnly
     * @param int   $visibility
     * @param array $documentData
     * @param bool  $isCertificateMode
     * @param int   $parentId
     *
     * @return null|string
     */
    private static function getButtonVisibility(
        $isReadOnly,
        $visibility,
        array $documentData,
        $isCertificateMode,
        $parentId
    ) {
        $visibility_icon = $visibility == 0 ? 'invisible' : 'visible';
        $visibility_command = $visibility == 0 ? 'set_visible' : 'set_invisible';
        $courseParams = api_get_cidreq();

        if ($isReadOnly) {
            if (api_is_allowed_to_edit() || api_is_platform_admin()) {
                return Display::return_icon($visibility_icon.'.png', get_lang('VisibilityCannotBeChanged'));
            }

            return null;
        }

        if ($isCertificateMode) {
            return Display::return_icon($visibility_icon.'.png', get_lang('VisibilityCannotBeChanged'));
        }

        if (api_is_allowed_to_edit() || api_is_platform_admin()) {
            $tip_visibility = $visibility_icon == 'invisible' ? get_lang('Show') : get_lang('Hide');

            return Display::url(
                Display::return_icon($visibility_icon.'.png', $tip_visibility),
                api_get_self()."?$courseParams&id=$parentId&$visibility_command={$documentData['id']}"
            );
        }

        return null;
    }

    /**
     * GEt the button to delete a document.
     *
     * @param bool   $isReadOnly
     * @param array  $documentData
     * @param bool   $isCertificateMode
     * @param string $curDirPath
     * @param int    $parentId
     *
     * @return string
     */
    private static function getButtonDelete(
        $isReadOnly,
        array $documentData,
        $isCertificateMode,
        $curDirPath,
        $parentId
    ) {
        $iconEn = Display::return_icon('delete.png', get_lang('Delete'));
        $iconDis = Display::return_icon('delete_na.png', get_lang('ThisFolderCannotBeDeleted'));
        $path = $documentData['path'];
        $id = $documentData['id'];
        $courseParams = api_get_cidreq();

        if ($isReadOnly) {
            return $iconDis;
        }

        if (in_array($path, self::get_system_folders())) {
            return $iconDis;
        }

        $titleToShow = addslashes(basename($documentData['title']));
        $urlDeleteParams = http_build_query([
            'curdirpath' => $curDirPath,
            'action' => 'delete_item',
            'id' => $parentId,
            'deleteid' => $documentData['id'],
        ]);
        $btn = Display::url(
            $iconEn,
            api_get_self()."?$courseParams&$urlDeleteParams",
            ['onclick' => "return confirmation('$titleToShow');"]
        );

        if (
            isset($_GET['curdirpath']) &&
            $_GET['curdirpath'] == '/certificates' &&
            self::get_default_certificate_id(api_get_course_id()) == $id
        ) {
            return $btn;
        }

        if ($isCertificateMode) {
            return $btn;
        }

        $sessionId = api_get_session_id();

        if ($sessionId) {
            if ($documentData['session_id'] != $sessionId) {
                return $iconDis;
            }
        }

        return $btn;
    }
}