<?php
/* For licensing terms, see /license.txt*/
/**
* This script allows teachers to subscribe existing users
* to their course.
* @package chamilo.user
*/

// name of the language file that needs to be included
$language_file = array('registration','admin');
require_once '../inc/global.inc.php';
$current_course_tool  = TOOL_USER;

// the section (for the tabs)
$this_section = SECTION_COURSES;

// notice for unauthorized people.
api_protect_course_script(true);

if (api_get_setting('allow_user_course_subscription_by_course_admin') == 'false') {
    if (!api_is_platform_admin()) {
        api_not_allowed(true);
    }
}

// Access restriction
if (!api_is_allowed_to_edit()) {
	 api_not_allowed(true);
}

$tool_name = get_lang("SubscribeUserToCourse");
$type = isset($_REQUEST['type']) ? Security::remove_XSS($_REQUEST['type']) : null;
$keyword = isset($_REQUEST['keyword']) ? Security::remove_XSS($_REQUEST['keyword']) : null;

if ($type == 'teacher') {
	$tool_name = get_lang("SubscribeUserToCourseAsTeacher");
}

//extra entries in breadcrumb
$interbreadcrumb[] = array ("url" => "user.php", "name" => get_lang("ToolUser"));
if ($keyword) {
	$interbreadcrumb[] = array ("url" => "subscribe_user.php?type=".$type, "name" => $tool_name);
	$tool_name = get_lang('SearchResults');
}

Display :: display_header($tool_name, "User");

// Build search-form
echo '<div class="actions">';
$actions = null;
if (isset($keyword)) {
    $actions .= '<a href="subscribe_user.php?type='.$type.'">'.Display::return_icon('clean_group.gif').' '.get_lang('ClearSearchResults').'</a>';
}
if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value'])) {
    $actions .= '<a href="subscribe_user.php?type='.$type.'">'.Display::return_icon('clean_group.gif').' '.get_lang('ClearFilterResults').'</a>';
}
if (api_get_setting('ProfilingFilterAddingUsers') == 'true') {
    display_extra_profile_fields_filter();
}

// Build search-form
$form = new FormValidator('search_user', 'get', '', '', null, false);
$renderer = $form->defaultRenderer();
$renderer->setElementTemplate('<span>{element}</span> ');
$form->addText('keyword', '', false);
$form->addElement('hidden', 'type', $type);
$form->addButtonSearch(get_lang('Search'));
$form->addElement('static', 'additionalactions', null, $actions);
$form->display();
echo '</div>';

/*
		MAIN SECTION
*/

$current_session_id = api_get_session_id();
$list_register_user='';
$list_not_register_user='';

if (isset($_REQUEST['register'])) {
	if ($type =='teacher') {
		if (!empty($current_session_id)) {
			$result_simple_sub = SessionManager::set_coach_to_course_session($_REQUEST['user_id'], $current_session_id, $_course['sysCode']);
		} else {
			$result_simple_sub = CourseManager :: subscribe_user($_REQUEST['user_id'], $_course['sysCode'], COURSEMANAGER);
		}
	} else {
		$result_simple_sub=CourseManager :: subscribe_user($_REQUEST['user_id'], $_course['sysCode']);
	}

	$user_id_temp = $_SESSION['session_user_id'];

	if (is_array($user_id_temp)) {
		$counter = count($user_id_temp);
		for ($j=0; $j<$counter;$j++) {
			if 	($user_id_temp[$j]==$_GET['user_id']) {
				if ($result_simple_sub)	{
					Display::display_confirmation_message($_SESSION['session_user_name'][$j].' '.get_lang('AddedToCourse'));
				} else {
					Display::display_error_message($_SESSION['session_user_name'][$j].' '.get_lang('NotAddedToCourse'));

				}
			}
		}
		unset($_SESSION['session_user_id']);
		unset($_SESSION['session_user_name']);
	}
}

if (isset ($_POST['action'])) {
	switch ($_POST['action']) {
		case 'subscribe' :
			if (is_array($_POST['user'])) {
				foreach ($_POST['user'] as $index => $user_id) {
					$user_id=intval($user_id);
					if ($type =='teacher') {
						if (!empty($current_session_id)) {
							$is_suscribe[] = SessionManager::set_coach_to_course_session(
                                $user_id,
                                $current_session_id,
                                $_course['sysCode']
                            );
						} else {
							$is_suscribe[] = CourseManager::subscribe_user($user_id, $_course['sysCode'],COURSEMANAGER);
						}
					} else {
						$is_suscribe[]=CourseManager::subscribe_user($user_id, $_course['sysCode']);
					}
                    $is_suscribe_user_id[]=$user_id;
				}
			}

			$user_id_temp=$_SESSION['session_user_id'];
			$user_name_temp=$_SESSION['session_user_name'];

			unset($_SESSION['session_user_id']);
 			unset($_SESSION['session_user_name']);
			$counter=0;
			$is_suscribe_counter=count($is_suscribe_user_id);

			$list_register_user='';

            for ($i=0; $i<$is_suscribe_counter;$i++) {
                for ($j=0; $j<count($user_id_temp);$j++) {
                    if ($is_suscribe_user_id[$i]==$user_id_temp[$j]) {
                            if ($is_suscribe[$i]) {
                                $list_register_user.=" - ".$user_name_temp[$j].'<br/>';
                                $temp_unique_user=$user_name_temp[$j];
                                $counter++;
                            } else {
                                $list_not_register_user.=" - ".$user_name_temp[$j].'<br/>';
                            }
                    }
                }
            }

			if (!empty($list_register_user)) {
				if ($is_suscribe_counter==1) {
					$register_user_message=$temp_unique_user.' '.get_lang('AddedToCourse');
					Display::display_confirmation_message($register_user_message,false);
				} else {
					$register_user_message='<br />'.get_lang('UsersRegistered').'<br/><br />'.$list_register_user;
					Display::display_confirmation_message($register_user_message,false);
				}
			}

			if (!empty($list_not_register_user)) {
				$not_register_user_message='<br />'.get_lang('UsersNotRegistered').'<br/><br /><br />'.$list_not_register_user;
				Display::display_error_message($not_register_user_message,false);
			}
			break;
	}
}

if (!empty($_SESSION['session_user_id'])) {
	unset($_SESSION['session_user_id']);
}

if (!empty($_SESSION['session_user_name'])) {
	unset($_SESSION['session_user_name']);
}

$is_western_name_order = api_is_western_name_order();
$sort_by_first_name = api_sort_by_first_name();

// Build table
$table = new SortableTable('subscribe_users', 'get_number_of_users', 'get_user_data', ($is_western_name_order xor $sort_by_first_name) ? 3 : 2);
$parameters['keyword'] = $keyword;
$parameters['type'] = $type;
$table->set_additional_parameters($parameters);
$col = 0;
$table->set_header($col ++, '', false);
$table->set_header($col ++, get_lang('OfficialCode'));
if (api_is_western_name_order()) {
    $table->set_header($col ++, get_lang('FirstName'));
    $table->set_header($col ++, get_lang('LastName'));
} else {
    $table->set_header($col ++, get_lang('LastName'));
    $table->set_header($col ++, get_lang('FirstName'));
}

if (api_get_setting('show_email_addresses') == 'true') {
    $table->set_header($col ++, get_lang('Email'));
    $table->set_column_filter($col -1, 'email_filter');
}
$table->set_header($col ++, get_lang('Active'),false);
$table->set_column_filter($col -1, 'active_filter');
$table->set_header($col ++, get_lang('Actions'), false);
$table->set_column_filter($col -1, 'reg_filter');
$table->set_form_actions(array ('subscribe' => get_lang('reg')), 'user');

if (!empty($_POST['keyword'])) {
    $keyword_name = Security::remove_XSS($_POST['keyword']);
    echo '<br/>'.get_lang('SearchResultsFor').' <span style="font-style: italic ;"> '.$keyword_name.' </span><br>';
}

// Display table
$table->display();

Display::display_footer();

/*		SHOW LIST OF USERS  */

/**
 ** Get the users to display on the current page.
 */
function get_number_of_users()
{
	global $_configuration;

	// Database table definition
	$user_table                    = Database::get_main_table(TABLE_MAIN_USER);
	$course_user_table             = Database::get_main_table(TABLE_MAIN_COURSE_USER);
	$tbl_session_rel_course_user   = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
	$table_user_field_values 	   = Database::get_main_table(TABLE_MAIN_USER_FIELD_VALUES);

	if (isset($_REQUEST['type']) && $_REQUEST['type']=='teacher') {

		if (api_get_session_id() != 0) {

			$sql = "SELECT COUNT(u.user_id)
					FROM $user_table u
					LEFT JOIN $tbl_session_rel_course_user cu on u.user_id = cu.id_user and course_code='".api_get_course_id()."' AND id_session ='".api_get_session_id()."'
					WHERE cu.id_user IS NULL AND u.status=1 AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";

			if ($_configuration['multiple_access_urls']) {
				$url_access_id = api_get_current_access_url_id();
				if ($url_access_id !=-1) {
					$tbl_url_rel_user = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USER);
					$sql = "SELECT COUNT(u.user_id) FROM $user_table u
							LEFT JOIN $tbl_session_rel_course_user cu on u.user_id = cu.id_user and course_code='".api_get_course_id()."' AND id_session ='".api_get_session_id()."'
							INNER JOIN  $tbl_url_rel_user as url_rel_user
							ON (url_rel_user.user_id = u.user_id)
							WHERE cu.id_user IS NULL AND access_url_id= $url_access_id AND u.status=1 AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";
				}
			}
		} else {
			$sql = "SELECT COUNT(u.user_id) FROM $user_table u LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".api_get_course_id()."'
				    WHERE cu.user_id IS NULL AND u.status<>".DRH." ";

			if (api_is_multiple_url_enabled()) {
				$url_access_id = api_get_current_access_url_id();
				if ($url_access_id !=-1) {
					$tbl_url_rel_user = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USER);

					$sql = "SELECT COUNT(u.user_id) FROM $user_table u
						LEFT JOIN $course_user_table cu on u.user_id = cu.user_id AND course_code='".api_get_course_id()."'
						INNER JOIN  $tbl_url_rel_user as url_rel_user
						ON (url_rel_user.user_id = u.user_id)
						WHERE cu.user_id IS NULL AND u.status<>".DRH." AND access_url_id= $url_access_id ";
				}
			}
		}

	} else {
		// students
		if (api_get_session_id() != 0) {
			$sql = "SELECT COUNT(u.user_id)
					FROM $user_table u
					LEFT JOIN $tbl_session_rel_course_user cu on u.user_id = cu.id_user and course_code='".api_get_course_id()."' AND id_session ='".api_get_session_id()."'
					WHERE cu.id_user IS NULL AND u.status<>".DRH." AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";
			if ($_configuration['multiple_access_urls']) {
				$url_access_id = api_get_current_access_url_id();
				if ($url_access_id !=-1) {
					$tbl_url_rel_user = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USER);
					$sql = "SELECT COUNT(u.user_id)
							FROM $user_table u
							LEFT JOIN $tbl_session_rel_course_user cu on u.user_id = cu.id_user and course_code='".api_get_course_id()."' AND id_session ='".api_get_session_id()."'
							INNER JOIN  $tbl_url_rel_user as url_rel_user
							ON (url_rel_user.user_id = u.user_id)
							WHERE cu.id_user IS NULL AND u.status<>".DRH." AND access_url_id= $url_access_id AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";
				}
			}
		} else {
			$sql = "SELECT COUNT(u.user_id)
					FROM $user_table u
					LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".$_SESSION['_course']['id']."'";

			// we change the SQL when we have a filter
			if (isset($_GET['subscribe_user_filter_value']) AND
                !empty($_GET['subscribe_user_filter_value']) AND
                api_get_setting('ProfilingFilterAddingUsers') == 'true'
            ){
				$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
				$sql .=	"
					LEFT JOIN $table_user_field_values field_values
						ON field_values.user_id = u.user_id
					WHERE cu.user_id IS NULL AND u.status<>".DRH."
						AND field_values.field_id = '".intval($field_identification[0])."'
						AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
			} else	{
				$sql .=	"WHERE cu.user_id IS NULL AND u.status<>".DRH." ";
			}

			if (isset($_configuration['multiple_access_urls']) && $_configuration['multiple_access_urls']) {
				$url_access_id = api_get_current_access_url_id();

				if ($url_access_id !=-1) {

					$tbl_url_rel_user = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USER);

					$sql = "SELECT COUNT(u.user_id)
							FROM $user_table u
							LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".$_SESSION['_course']['id']."'
							INNER JOIN  $tbl_url_rel_user as url_rel_user
							ON (url_rel_user.user_id = u.user_id)
							WHERE cu.user_id IS NULL AND access_url_id= $url_access_id AND u.status<>".DRH." ";
				}
			}
		}
	}

	// when there is a keyword then we are searching and we have to change the SQL statement
	if (isset($_GET['keyword']) AND !empty($_GET['keyword'])) {
		$keyword = Database::escape_string(trim($_REQUEST['keyword']));
		$sql .= " AND (firstname LIKE '%".$keyword."%' OR lastname LIKE '%".$keyword."%'   OR email LIKE '%".$keyword."%'  OR username LIKE '%".$keyword."%'  OR official_code LIKE '%".$keyword."%')";

		// we also want to search for users who have something in their profile fields that matches the keyword
		if (api_get_setting('ProfilingFilterAddingUsers') == 'true') {
			$additional_users = search_additional_profile_fields($keyword);
		}

		// getting all the users of the course (to make sure that we do not display users that are already in the course)
		if (!empty($_SESSION["id_session"])) {
			$a_course_users = CourseManager :: get_user_list_from_course_code($_SESSION['_course']['id'], $_SESSION['id_session']);
		} else {
			$a_course_users = CourseManager :: get_user_list_from_course_code($_SESSION['_course']['id'], 0);
	    }
		foreach ($a_course_users as $user_id=>$course_user) {
			$users_of_course[] = $course_user['user_id'];
	    }
	}
    $sql .=" AND u.status <> ".ANONYMOUS." ";
	$res = Database::query($sql);
    $count_user = 0;

    if ($res) {
	   $row = Database::fetch_row($res);
	   $count_user = $row[0];
	}
	return $count_user;
}
/**
 * Get the users to display on the current page.
 */
function get_user_data($from, $number_of_items, $column, $direction)
{
	global $_configuration;

    $url_access_id = api_get_current_access_url_id();
    $course_code = api_get_course_id();
    $session_id = api_get_session_id();

	// Database table definitions
	$user_table                    = Database::get_main_table(TABLE_MAIN_USER);
	$course_user_table             = Database::get_main_table(TABLE_MAIN_COURSE_USER);
	$tbl_session_rel_course_user   = Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);
	$table_user_field_values 	   = Database::get_main_table(TABLE_MAIN_USER_FIELD_VALUES);

    $tbl_url_rel_user = Database::get_main_table(TABLE_MAIN_ACCESS_URL_REL_USER);

    // adding teachers
	$is_western_name_order = api_is_western_name_order();

    if (api_get_setting('show_email_addresses') == 'true') {

        $select_fields = "u.user_id              AS col0,
                u.official_code        AS col1,
                ".($is_western_name_order
                ? "u.firstname         AS col2,
                u.lastname             AS col3,"
                : "u.lastname          AS col2,
                u.firstname            AS col3,")."
                u.email 	           AS col4,
                u.active               AS col5,
                u.user_id              AS col6";
    } else {
        $select_fields = "u.user_id              AS col0,
                u.official_code        AS col1,
                ".($is_western_name_order
                ? "u.firstname         AS col2,
                u.lastname             AS col3,"
                : "u.lastname          AS col2,
                u.firstname            AS col3,")."
                u.active               AS col4,
                u.user_id              AS col5";
    }

	if (isset($_REQUEST['type']) && $_REQUEST['type'] == 'teacher') {
		// adding a teacher through a session
		if (!empty($session_id)) {
			$sql = "SELECT $select_fields
					FROM $user_table u
					LEFT JOIN $tbl_session_rel_course_user cu on u.user_id = cu.id_user AND course_code='".$course_code."' AND id_session ='".$session_id."'
                    INNER JOIN  $tbl_url_rel_user as url_rel_user ON (url_rel_user.user_id = u.user_id) ";

			// applying the filter of the additional user profile fields
			if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value']) AND api_get_setting('ProfilingFilterAddingUsers') == 'true') {
				$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
				$sql .=	"
					LEFT JOIN $table_user_field_values field_values
						ON field_values.user_id = u.user_id
					WHERE cu.id_user IS NULL AND u.status=1 AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL)
						AND field_values.field_id = '".intval($field_identification[0])."'
						AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
			} else {
				$sql .=	"WHERE cu.id_user IS NULL AND u.status=1 AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";
			}

            $sql .=	" AND access_url_id= $url_access_id";

		} else {
		     // adding a teacher NOT through a session
			$sql = "SELECT $select_fields
                    FROM $user_table u
                    LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code = '".$course_code."'";

				// applying the filter of the additional user profile fields
				if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value']) AND api_get_setting('ProfilingFilterAddingUsers') == 'true'){
					$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
					$sql .=	"
						LEFT JOIN $table_user_field_values field_values
							ON field_values.user_id = u.user_id
						WHERE cu.user_id IS NULL AND u.status<>".DRH."
							AND field_values.field_id = '".intval($field_identification[0])."'
							AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
				} else	{
					$sql .=	"WHERE cu.user_id IS NULL AND u.status<>".DRH." ";
				}

				// adding a teacher NOT trough a session on a portal with multiple URLs
				if (api_is_multiple_url_enabled()) {
					if ($url_access_id !=-1) {
						$sql = "SELECT $select_fields
						FROM $user_table u
						LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".$course_code."'
						INNER JOIN  $tbl_url_rel_user as url_rel_user ON (url_rel_user.user_id = u.user_id) ";

					// applying the filter of the additional user profile fields
					if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value']) AND api_get_setting('ProfilingFilterAddingUsers') == 'true'){
						$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
						$sql .=	"
							LEFT JOIN $table_user_field_values field_values
								ON field_values.user_id = u.user_id
							WHERE cu.user_id IS NULL AND u.status<>".DRH."
								AND field_values.field_id = '".intval($field_identification[0])."'
								AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
					} else	{
						$sql .=	"WHERE cu.user_id IS NULL AND u.status<>".DRH." AND access_url_id= $url_access_id ";
					}
				}
			}
		}
	} else {
		// adding a student
		if (!empty($session_id)) {
			$sql = "SELECT $select_fields
                    FROM $user_table u
                    LEFT JOIN $tbl_session_rel_course_user cu ON u.user_id = cu.id_user AND course_code='".$course_code."' AND id_session ='".$session_id."' ";

            if (isset($_configuration['multiple_access_urls']) && $_configuration['multiple_access_urls']) {
                $sql .= " INNER JOIN  $tbl_url_rel_user as url_rel_user ON (url_rel_user.user_id = u.user_id) ";
            }

            // applying the filter of the additional user profile fields
            if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value'])){
                $field_identification = explode('*',$_GET['subscribe_user_filter_value']);
                $sql .=	"
                    LEFT JOIN $table_user_field_values field_values
                        ON field_values.user_id = u.user_id
                    WHERE cu.id_user IS NULL AND u.status<>".DRH." AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL)
                        AND field_values.field_id = '".intval($field_identification[0])."'
                        AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
            } else	{
                $sql .=	"WHERE cu.id_user IS NULL AND u.status<>".DRH." AND (u.official_code <> 'ADMIN' OR u.official_code IS NULL) ";
            }

            if (isset($_configuration['multiple_access_urls']) && $_configuration['multiple_access_urls']) {
                $sql .=  "AND access_url_id = $url_access_id";
            }

		} else {
            $sql = "SELECT $select_fields
                    FROM $user_table u
                    LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".$course_code."'";

			// applying the filter of the additional user profile fields
			if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value'])){
				$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
				$sql .=	"
					LEFT JOIN $table_user_field_values field_values
						ON field_values.user_id = u.user_id
					WHERE cu.user_id IS NULL AND u.status<>".DRH."
						AND field_values.field_id = '".intval($field_identification[0])."'
						AND field_values.field_value = '".Database::escape_string($field_identification[1])."'";
			} else	{
				$sql .=	"WHERE cu.user_id IS NULL AND u.status<>".DRH." ";
			}

			//showing only the courses of the current Chamilo access_url_id

			if (isset($_configuration['multiple_access_urls']) && $_configuration['multiple_access_urls']) {

				if ($url_access_id !=-1) {

					$sql = "SELECT $select_fields
						FROM $user_table u
						LEFT JOIN $course_user_table cu on u.user_id = cu.user_id and course_code='".$course_code."'
						INNER JOIN  $tbl_url_rel_user as url_rel_user
						ON (url_rel_user.user_id = u.user_id) ";


					// applying the filter of the additional user profile fields
					if (isset($_GET['subscribe_user_filter_value']) AND !empty($_GET['subscribe_user_filter_value']) AND api_get_setting('ProfilingFilterAddingUsers') == 'true'){
						$field_identification = explode('*',$_GET['subscribe_user_filter_value']);
						$sql .=	"
							LEFT JOIN $table_user_field_values field_values
								ON field_values.user_id = u.user_id
							WHERE cu.user_id IS NULL AND u.status<>".DRH."
								AND field_values.field_id = '".intval($field_identification[0])."'
								AND field_values.field_value = '".Database::escape_string($field_identification[1])."' AND access_url_id= $url_access_id  ";
					} else	{
						$sql .=	"WHERE  cu.user_id IS NULL AND u.status<>".DRH." AND access_url_id= $url_access_id ";
					}
				}
			}
		}
	}

	// adding additional WHERE statements to the SQL for the search functionality
    $additional_users = null;
	if (isset($_REQUEST['keyword'])) {
		$keyword = Database::escape_string(trim($_REQUEST['keyword']));
		$sql .= " AND (firstname LIKE '%".$keyword."%' OR lastname LIKE '%".$keyword."%'   OR email LIKE '%".$keyword."%'  OR username LIKE '%".$keyword."%'  OR official_code LIKE '%".$keyword."%')";

		if (api_get_setting('ProfilingFilterAddingUsers') == 'true') {
			// we also want to search for users who have something in their profile fields that matches the keyword
			$additional_users = search_additional_profile_fields($keyword);
		}

		// getting all the users of the course (to make sure that we do not display users that are already in the course)
		if (!empty($session_id)) {
			$a_course_users = CourseManager :: get_user_list_from_course_code($course_code, $session_id);
		} else {
			$a_course_users = CourseManager :: get_user_list_from_course_code($course_code, 0);
	    }
		foreach ($a_course_users as $user_id=>$course_user) {
			$users_of_course[] = $course_user['user_id'];
		}
	}

	$sql .=" AND u.status != ".ANONYMOUS." ";

	// Sorting and pagination (used by the sortable table)
	$sql .= " ORDER BY col$column $direction ";
	$sql .= " LIMIT $from,$number_of_items";

	$res = Database::query($sql);
	$users = array ();
	while ($user = Database::fetch_row($res)) {
		$users[] = $user;
		$_SESSION['session_user_id'][] = $user[0];
		if ($is_western_name_order) {
			$_SESSION['session_user_name'][] = api_get_person_name($user[2], $user[3]);
		} else {
			$_SESSION['session_user_name'][] = api_get_person_name($user[3], $user[2]);
		}
	}
	// adding additional users based on the search on the additional profile fields
	if (isset($_REQUEST['keyword'])){
		if (is_array($additional_users)) {
			foreach($additional_users as $additional_user_key=>$additional_user_value){
				if (!in_array($additional_user_key, $_SESSION['session_user_id']) AND !in_array($additional_user_key,$users_of_course)){
					$users[]= array($additional_user_value['col0'],$additional_user_value['col1'],$additional_user_value['col2'].'*',$additional_user_value['col3'].'*',$additional_user_value['col4'],$additional_user_value['col5'], $additional_user_value['col6']);
				}
			}
		}
	}
	return $users;
}
/**
* Returns a mailto-link
* @param string $email An email-address
* @return string HTML-code with a mailto-link
*/
function email_filter($email) {
	return Display :: encrypted_mailto_link($email, $email);
}
/**
 * Build the reg-column of the table
 * @param int $user_id The user id
 * @return string Some HTML-code
 */
function reg_filter($user_id) {
	if(isset($_REQUEST['type']) && $_REQUEST['type']=='teacher') $type='teacher'; else $type='student';
	$result = '<a class="btn btn-small btn-primary" href="'.api_get_self().'?register=yes&type='.$type.'&user_id='.$user_id.'">'.get_lang("reg").'</a>';
	return $result;
}

/**
 * Build the active-column of the table to lock or unlock a certain user
 * lock = the user can no longer use this account
 * @author Patrick Cool <patrick.cool@UGent.be>, Ghent University
 * @param int $active the current state of the account
 * @param int $user_id The user id
 * @param string $url_params
 * @return string Some HTML-code with the lock/unlock button
 */

function active_filter($active, $url_params, $row) {
	global $_user;
	if ($active=='1') {
		$action='AccountActive';
		$image='accept';
	}

	if ($active=='0') {
		$action='AccountInactive';
		$image='error';
	}
    $result = null;
	if ($row['0']<>$_user['user_id']) { // you cannot lock yourself out otherwise you could disable all the accounts including your own => everybody is locked out and nobody can change it anymore.
		$result = Display::return_icon($image.'.png',  get_lang(ucfirst($action)), array() , ICON_SIZE_TINY);
	}
	return $result;
}

/**
 * Search the additional user profile fields defined by the platform administrator in
 * platform administration > profiling for a given keyword.
 * We not only search in the predefined options but also in the input fields wherer
 * the user can enter some text.
 *
 * For this we get the additional profile field options that match the (search) keyword,
 * then we find all the users who have entered the (search)keyword in a input field of the
 * additional profile fields or have chosen one of the matching predefined options
 *
 * @param string $keyword a keyword we are looking for in the additional profile fields
 * @return array $additional_users an array with the users who have an additional profile field that matches the keyword
 */
function search_additional_profile_fields($keyword)
{
	// database table definitions
	$table_user_field_options 	= Database :: get_main_table(TABLE_MAIN_USER_FIELD_OPTIONS);
	$table_user_field_values 	= Database::get_main_table(TABLE_MAIN_USER_FIELD_VALUES);
	$table_user 				= Database::get_main_table(TABLE_MAIN_USER);
	$table_course_user		 	= Database :: get_main_table(TABLE_MAIN_COURSE_USER);
	$table_session_course_user 	= Database::get_main_table(TABLE_MAIN_SESSION_COURSE_USER);

	// getting the field option text that match this keyword (for radio buttons and checkboxes)
	$sql = "SELECT * FROM $table_user_field_options WHERE option_display_text LIKE '%".$keyword."%'";
	$result_profiling = Database::query($sql);
	while ($profiling_field_options = Database::fetch_array($result_profiling)) {
		$profiling_field_options_exact_values[] = $profiling_field_options;
	}

	foreach ($profiling_field_options_exact_values as $profilingkey=>$profilingvalue){
		$profiling_field_options_exact_values_sql .= "OR (field_id = '".$profilingvalue['field_id']."' AND field_value='".$profilingvalue['option_value']."') ";
	}

	// getting all the user ids of the users who have chosen on of the predefined fields that contain the keyword
	// or all the users who have entered the keyword in a free-form field
	$sql_profiling_values = "SELECT user.user_id as col0, user.official_code as col1, user.lastname as col2, user.firstname as col3, user.email as col4, user.active as col5, user.user_id as col6
							FROM $table_user user, $table_user_field_values user_values
							WHERE user.user_id = user_values.user_id
							AND ( field_value LIKE '%".$keyword."%'
							".$profiling_field_options_exact_values_sql.")";
	$result_profiling_values = Database::query($sql_profiling_values);
    $additional_users = array();
	while ($profiled_users = Database::fetch_array($result_profiling_values)) {
		$additional_users[$profiled_users['col0']] = $profiled_users;
	}

	return $additional_users;
}
/**
 * This function displays a dropdown list with all the additional user profile fields defined by the platform administrator in
 * platform administration > profiling. Only the fields that have predefined fields are usefull for such a filter.
 *
 */
function display_extra_profile_fields_filter() {
	// getting all the additional user profile fields
	$extra = UserManager::get_extra_fields(0,50,5,'ASC');

	$return='<option value="">'.get_lang('SelectFilter').'</option>';

	// looping through the additional user profile fields
	foreach($extra as $id => $field_details) {
		// $field_details[2] contains the type of the additional user profile field
		switch($field_details[2]) {
			// text fields cannot be used as a filter
			case UserManager::USER_FIELD_TYPE_TEXT:
				break;
			// text area fields cannot be used as a filter
			case UserManager::USER_FIELD_TYPE_TEXTAREA:
				break;
			case UserManager::USER_FIELD_TYPE_RADIO:
			case UserManager::USER_FIELD_TYPE_SELECT:
			case UserManager::USER_FIELD_TYPE_SELECT_MULTIPLE:
				$return .= '<optgroup label="'.$field_details[3].'">';
				foreach($field_details[9] as $option_id => $option_details) {
					if ($_GET['subscribe_user_filter_value'] == $field_details[0].'*'.$option_details[1]) {
						$selected = 'selected="selected"';
					} else {
						$selected = false;
					}
					$return .= '<option value="'.$field_details[0].'*'.$option_details[1].'" '.$selected.'>'.$option_details[2].'</option>';
				}
				$return .= '</optgroup>';
				break;
		}
	}

	echo '<form id="subscribe_user_filter" name="subscribe_user_filter" method="get" action="'.api_get_self().'?api_get_cidreq" style="float:left;">';
	echo '	<input type="hidden" name="type" id="type" value="'.Security::remove_XSS($_REQUEST['type']).'" />';
	echo   '<select name="subscribe_user_filter_value" id="subscribe_user_filter_value">'.$return.'</select>';
	echo   '<button type="submit" name="submit_filter" id="submit_filter" value="" class="search">'.get_lang('Filter').'</button>';
	echo '</form>';
}