<?php // $Id: question.class.php 20990 2009-05-26 14:20:05Z juliomontoya $
 
/*
==============================================================================
	Dokeos - elearning and course management software

	Copyright (c) 2004-2008 Dokeos SPRL
	Copyright (c) 2003 Ghent University (UGent)
	Copyright (c) 2001 Universite catholique de Louvain (UCL)
	Copyright (c) various contributors

	For a full list of contributors, see "credits.txt".
	The full license can be read in "license.txt".

	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.

	See the GNU General Public License for more details.

	Contact address: Dokeos, rue du Corbeau, 108, B-1030 Brussels, Belgium
	Mail: info@dokeos.com
==============================================================================
*/

/**
*	File containing the Question class.
*	@package dokeos.exercise
* 	@author Olivier Brouckaert
* 	@version $Id: question.class.php 20990 2009-05-26 14:20:05Z juliomontoya $
*/


if(!class_exists('Question')):

// answer types
define('UNIQUE_ANSWER',	1);
define('MULTIPLE_ANSWER',	2);
define('FILL_IN_BLANKS',	3);
define('MATCHING',		4);
define('FREE_ANSWER',     5);
define('HOT_SPOT', 		6);
define('HOT_SPOT_ORDER', 	7);


/**
	CLASS QUESTION
 *
 *	This class allows to instantiate an object of type Question
 *
 *	@author Olivier Brouckaert, original author
 *	@author Patrick Cool, LaTeX support
 *	@package dokeos.exercise
 */
abstract class Question
{
	var $id;
	var $question;
	var $description;
	var $weighting;
	var $position;
	var $type;
	var $level;
	var $picture;
	var $exerciseList;  // array with the list of exercises which this question is in

	static $typePicture = 'new_question.png';
	static $explanationLangVar = '';
	static $questionTypes = array(
							UNIQUE_ANSWER => array('unique_answer.class.php' , 'UniqueAnswer'),
							MULTIPLE_ANSWER => array('multiple_answer.class.php' , 'MultipleAnswer'),
							FILL_IN_BLANKS => array('fill_blanks.class.php' , 'FillBlanks'),
							MATCHING => array('matching.class.php' , 'Matching'),
							FREE_ANSWER => array('freeanswer.class.php' , 'FreeAnswer'),
							HOT_SPOT => array('hotspot.class.php' , 'HotSpot')
							);

	/**
	 * constructor of the class
	 *
	 * @author - Olivier Brouckaert
	 */
	function Question()
	{
		$this->id=0;
		$this->question='';
		$this->description='';
		$this->weighting=0;
		$this->position=1;
		$this->picture='';
		$this->level = 1;
		$this->exerciseList=array();
	}

	/**
	 * reads question informations from the data base
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $id - question ID
	 * @return - boolean - true if question exists, otherwise false
	 */
	static function read($id)
	{
		global $_course;

		$TBL_EXERCICES         = Database::get_course_table(TABLE_QUIZ_TEST);
		$TBL_QUESTIONS         = Database::get_course_table(TABLE_QUIZ_QUESTION);
		$TBL_EXERCICE_QUESTION = Database::get_course_table(TABLE_QUIZ_TEST_QUESTION);
		$sql="SELECT question,description,ponderation,position,type,picture,level FROM $TBL_QUESTIONS WHERE id='".Database::escape_string($id)."'";

		$result=api_sql_query($sql,__FILE__,__LINE__);

		// if the question has been found
		if($object=mysql_fetch_object($result))
		{
			$objQuestion = Question::getInstance($object->type);
			$objQuestion->id=$id;
			$objQuestion->question=$object->question;
			$objQuestion->description=$object->description;
			$objQuestion->weighting=$object->ponderation;
			$objQuestion->position=$object->position;
			$objQuestion->type=$object->type;
			$objQuestion->picture=$object->picture;
			$objQuestion->level=(int) $object->level;

			$sql="SELECT exercice_id FROM $TBL_EXERCICE_QUESTION WHERE question_id='".intval($id)."'";
			$result=api_sql_query($sql,__FILE__,__LINE__);

			// fills the array with the exercises which this question is in
			while($object=mysql_fetch_object($result))
			{
				$objQuestion->exerciseList[]=$object->exercice_id;
			}

			return $objQuestion;
		}

		// question not found
		return false;
	}

	/**
	 * returns the question ID
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - question ID
	 */
	function selectId()
	{
		return $this->id;
	}

	/**
	 * returns the question title
	 *
	 * @author - Olivier Brouckaert
	 * @return - string - question title
	 */
	function selectTitle()
	{
		$this->question=api_parse_tex($this->question);
		return $this->question;
	}

	/**
	 * returns the question description
	 *
	 * @author - Olivier Brouckaert
	 * @return - string - question description
	 */
	function selectDescription()
	{
		$this->description=api_parse_tex($this->description);
		return $this->description;
	}

	/**
	 * returns the question weighting
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - question weighting
	 */
	function selectWeighting()
	{
		return $this->weighting;
	}

	/**
	 * returns the question position
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - question position
	 */
	function selectPosition()
	{
		return $this->position;
	}

	/**
	 * returns the answer type
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - answer type
	 */
	function selectType()
	{
		return $this->type;
	}

	/**
	 * returns the level of the question
	 *
	 * @author - Nicolas Raynaud
	 * @return - integer - level of the question, 0 by default.
	 */
	function selectLevel()
	{
		return $this->level;
	}

	/**
	 * returns the picture name
	 *
	 * @author - Olivier Brouckaert
	 * @return - string - picture name
	 */
	function selectPicture()
	{
		return $this->picture;
	}

	/**
	 * returns the array with the exercise ID list
	 *
	 * @author - Olivier Brouckaert
	 * @return - array - list of exercise ID which the question is in
	 */
	function selectExerciseList()
	{
		return $this->exerciseList;
	}

	/**
	 * returns the number of exercises which this question is in
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - number of exercises
	 */
	function selectNbrExercises()
	{
		return sizeof($this->exerciseList);
	}

	/**
	 * changes the question title
	 *
	 * @author - Olivier Brouckaert
	 * @param - string $title - question title
	 */
	function updateTitle($title)
	{
		$this->question=$title;
	}

	/**
	 * changes the question description
	 *
	 * @author - Olivier Brouckaert
	 * @param - string $description - question description
	 */
	function updateDescription($description)
	{
		$this->description=$description;
	}

	/**
	 * changes the question weighting
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $weighting - question weighting
	 */
	function updateWeighting($weighting)
	{
		$this->weighting=$weighting;
	}

	/**
	 * changes the question position
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $position - question position
	 */
	function updatePosition($position)
	{
		$this->position=$position;
	}

	/**
	 * changes the question level
	 *
	 * @author - Nicolas Raynaud
	 * @param - integer $level - question level
	 */
	function updateLevel($level)
	{
		$this->level=$level;
	}

	/**
	 * changes the answer type. If the user changes the type from "unique answer" to "multiple answers"
	 * (or conversely) answers are not deleted, otherwise yes
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $type - answer type
	 */
	function updateType($type)
	{
		global $TBL_REPONSES;

		// if we really change the type
		if($type != $this->type)
		{
			// if we don't change from "unique answer" to "multiple answers" (or conversely)
			if(!in_array($this->type,array(UNIQUE_ANSWER,MULTIPLE_ANSWER)) || !in_array($type,array(UNIQUE_ANSWER,MULTIPLE_ANSWER)))
			{
				// removes old answers
				$sql="DELETE FROM $TBL_REPONSES WHERE question_id='".Database::escape_string($this->id)."'";
				api_sql_query($sql,__FILE__,__LINE__);
			}

			$this->type=$type;
		}
	}

	/**
	 * adds a picture to the question
	 *
	 * @author - Olivier Brouckaert
	 * @param - string $Picture - temporary path of the picture to upload
	 * @param - string $PictureName - Name of the picture
	 * @return - boolean - true if uploaded, otherwise false
	 */
	function uploadPicture($Picture,$PictureName)
	{
		global $picturePath, $_course, $_user;

		// if the question has got an ID
		if($this->id)
		{
			
			$extension = pathinfo($PictureName, PATHINFO_EXTENSION);
			$this->picture='quiz-'.$this->id.'.jpg';
			if($extension == 'gif' || $extension == 'png')
			{
				$o_img = new image($Picture);
				$o_img->send_image('JPG',$picturePath.'/'.$this->picture);
				$document_id = add_document($_course, '/images/'.$this->picture, 'file', filesize($picturePath.'/'.$this->picture),$this->picture);
			}
			else
			{
				move_uploaded_file($Picture,$picturePath.'/'.$this->picture)?true:false;	
			}
			$document_id = add_document($_course, '/images/'.$this->picture, 'file', filesize($picturePath.'/'.$this->picture),$this->picture);
			if($document_id)
			{
				return api_item_property_update($_course, TOOL_DOCUMENT, $document_id, 'DocumentAdded', $_user['user_id']);
			}
		}

		return false;
	}

	/**
	 * Resizes a picture || Warning!: can only be called after uploadPicture, or if picture is already available in object.
	 *
	 * @author - Toon Keppens
	 * @param - string $Dimension - Resizing happens proportional according to given dimension: height|width|any
	 * @param - integer $Max - Maximum size
	 * @return - boolean - true if success, false if failed
	 */
	function resizePicture($Dimension, $Max)
	{
		global $picturePath;

		// if the question has an ID
		if($this->id)
		{
	  		// Get dimensions from current image.
	  		$current_img = imagecreatefromjpeg($picturePath.'/'.$this->picture);

	  		$current_image_size = getimagesize($picturePath.'/'.$this->picture);
	  		$current_height = imagesy($current_img);
			$current_width = imagesx($current_img);

			if($current_image_size[0] < $Max && $current_image_size[1] <$Max)
				return true;
			elseif($current_height == "")
				return false;

			// Resize according to height.
			if ($Dimension == "height")
			{
				$resize_scale = $current_height / $Max;
				$new_height = $Max;
				$new_width = ceil($current_width / $resize_scale);
			}

			// Resize according to width
			if ($Dimension == "width")
			{
				$resize_scale = $current_width / $Max;
				$new_width = $Max;
				$new_height = ceil($current_height / $resize_scale);
			}

			// Resize according to height or width, both should not be larger than $Max after resizing.
			if ($Dimension == "any")
			{
				if ($current_height > $current_width || $current_height == $current_width)
				{
					$resize_scale = $current_height / $Max;
					$new_height = $Max;
					$new_width = ceil($current_width / $resize_scale);
				}
				if ($current_height < $current_width)
				{
					$resize_scale = $current_width / $Max;
					$new_width = $Max;
					$new_height = ceil($current_height / $resize_scale);
				}
			}

			// Create new image
		    $new_img = imagecreatetruecolor($new_width, $new_height);
			$bgColor = imagecolorallocate($new_img, 255,255,255);
			imagefill($new_img , 0,0 , $bgColor);

			// Resize image
			imagecopyresized($new_img, $current_img, 0, 0, 0, 0, $new_width, $new_height, $current_width, $current_height);

			// Write image to file
		    $result = imagejpeg($new_img, $picturePath.'/'.$this->picture, 100);

		    // Delete temperory images, clear memory
			imagedestroy($current_img);
			imagedestroy($new_img);

			if ($result)
			{
				return true;
			}
			else
			{
				return false;
			}
		}


	}

	/**
	 * deletes the picture
	 *
	 * @author - Olivier Brouckaert
	 * @return - boolean - true if removed, otherwise false
	 */
	function removePicture()
	{
		global $picturePath;

		// if the question has got an ID and if the picture exists
		if($this->id)
		{
			$picture=$this->picture;
			$this->picture='';

			return @unlink($picturePath.'/'.$picture)?true:false;
		}

		return false;
	}

	/**
	 * exports a picture to another question
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $questionId - ID of the target question
	 * @return - boolean - true if copied, otherwise false
	 */
	function exportPicture($questionId)
	{
		global $TBL_QUESTIONS, $picturePath;

		// if the question has got an ID and if the picture exists
		if($this->id && !empty($this->picture))
		{
			$picture=explode('.',$this->picture);
			$Extension=$picture[sizeof($picture)-1];
			$picture='quiz-'.$questionId.'.'.$Extension;

			$sql="UPDATE $TBL_QUESTIONS SET picture='".Database::escape_string($picture)."' WHERE id='".Database::escape_string($questionId)."'";
			api_sql_query($sql,__FILE__,__LINE__);

			return @copy($picturePath.'/'.$this->picture,$picturePath.'/'.$picture)?true:false;
		}

		return false;
	}

	/**
	 * saves the picture coming from POST into a temporary file
	 * Temporary pictures are used when we don't want to save a picture right after a form submission.
	 * For example, if we first show a confirmation box.
	 *
	 * @author - Olivier Brouckaert
	 * @param - string $Picture - temporary path of the picture to move
	 * @param - string $PictureName - Name of the picture
	 */
	function setTmpPicture($Picture,$PictureName)
	{
		global $picturePath;

		$PictureName=explode('.',$PictureName);
		$Extension=$PictureName[sizeof($PictureName)-1];

		// saves the picture into a temporary file
		@move_uploaded_file($Picture,$picturePath.'/tmp.'.$Extension);
	}

	/**
	 * moves the temporary question "tmp" to "quiz-$questionId"
	 * Temporary pictures are used when we don't want to save a picture right after a form submission.
	 * For example, if we first show a confirmation box.
	 *
	 * @author - Olivier Brouckaert
	 * @return - boolean - true if moved, otherwise false
	 */
	function getTmpPicture()
	{
		global $picturePath;

		// if the question has got an ID and if the picture exists
		if($this->id)
		{
			if(file_exists($picturePath.'/tmp.jpg'))
			{
				$Extension='jpg';
			}
			elseif(file_exists($picturePath.'/tmp.gif'))
			{
				$Extension='gif';
			}
			elseif(file_exists($picturePath.'/tmp.png'))
			{
				$Extension='png';
			}

			$this->picture='quiz-'.$this->id.'.'.$Extension;

			return @rename($picturePath.'/tmp.'.$Extension,$picturePath.'/'.$this->picture)?true:false;
		}

		return false;
	}

	/**
	 * updates the question in the data base
	 * if an exercise ID is provided, we add that exercise ID into the exercise list
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $exerciseId - exercise ID if saving in an exercise
	 */
	function save($exerciseId=0) {
		global $_course,$_user;
		
		$TBL_EXERCICE_QUESTION	= Database::get_course_table(TABLE_QUIZ_TEST_QUESTION);		
		$TBL_QUESTIONS			= Database::get_course_table(TABLE_QUIZ_QUESTION);
		
		$id=$this->id;
		$question=$this->question;
		$description=$this->description;
		$weighting=$this->weighting;
		$position=$this->position;
		$type=$this->type;
		$picture=$this->picture;
		$level=$this->level; 

		// question already exists		
		if(!empty($id)) {
			$sql="UPDATE $TBL_QUESTIONS SET 
					question 	='".Database::escape_string(Security::remove_XSS($question))."',
					description	='".Database::escape_string(Security::remove_XSS(api_html_entity_decode($description),COURSEMANAGERLOWSECURITY))."',
					ponderation	='".Database::escape_string($weighting)."',
					position	='".Database::escape_string($position)."',
					type		='".Database::escape_string($type)."',
					picture		='".Database::escape_string($picture)."',
					level		='".Database::escape_string($level)."' 
				WHERE id='".Database::escape_string($id)."'";
			api_sql_query($sql,__FILE__,__LINE__);
			if(!empty($exerciseId)) {
			api_item_property_update($_course, TOOL_QUIZ, $id,'QuizQuestionUpdated',$_user['user_id']);
			}
            if (api_get_setting('search_enabled')=='true') {
                if ($exerciseId != 0) {
                    $this -> search_engine_edit($exerciseId);
                } else {
                    /**
                     * actually there is *not* an user interface for
                     * creating questions without a relation with an exercise
                     */
                }
            }

		} else {// creates a new question
			$sql="SELECT max(position) FROM $TBL_QUESTIONS as question, $TBL_EXERCICE_QUESTION as test_question WHERE question.id=test_question.question_id AND test_question.exercice_id='".Database::escape_string($exerciseId)."'";
			$result=api_sql_query($sql);
			$current_position=Database::result($result,0,0);
			$this -> updatePosition($current_position+1);
			$position = $this -> position;
			
			$sql="INSERT INTO $TBL_QUESTIONS(question,description,ponderation,position,type,picture,level) VALUES(
					'".Database::escape_string(Security::remove_XSS($question))."',
					'".Database::escape_string(Security::remove_XSS(api_html_entity_decode($description),COURSEMANAGERLOWSECURITY))."',
					'".Database::escape_string($weighting)."',
					'".Database::escape_string($position)."',
					'".Database::escape_string($type)."',
					'".Database::escape_string($picture)."',
					'".Database::escape_string($level)."'
					)";
			api_sql_query($sql,__FILE__,__LINE__);

			$this->id=Database::get_last_insert_id();
			
			api_item_property_update($_course, TOOL_QUIZ, $this->id,'QuizQuestionAdded',$_user['user_id']);
			
			// If hotspot, create first answer
			if ($type == HOT_SPOT || $type == HOT_SPOT_ORDER) {
				$TBL_ANSWERS = Database::get_course_table(TABLE_QUIZ_ANSWER);

				$sql="INSERT INTO $TBL_ANSWERS (`id` , `question_id` , `answer` , `correct` , `comment` , `ponderation` , `position` , `hotspot_coordinates` , `hotspot_type` ) VALUES ('1', '".Database::escape_string($this->id)."', '', NULL , '', '10' , '1', '0;0|0|0', 'square')";
				api_sql_query($sql,__FILE__,__LINE__);
				
            }

            if (api_get_setting('search_enabled')=='true') {
                if ($exerciseId != 0) {
                    $this -> search_engine_edit($exerciseId, TRUE);
                } else {
                    /**
                     * actually there is *not* an user interface for
                     * creating questions without a relation with an exercise
                     */
                }
            }
		}

		// if the question is created in an exercise
		if($exerciseId) {
			/*
			$sql = 'UPDATE '.Database::get_course_table(TABLE_LP_ITEM).' 
					SET max_score = '.intval($weighting).'
					WHERE item_type = "'.TOOL_QUIZ.'"
					AND path='.intval($exerciseId);
			api_sql_query($sql,__FILE__,__LINE__);
			*/
			// adds the exercise into the exercise list of this question
			$this->addToList($exerciseId, TRUE);
		}
	}

    function search_engine_edit($exerciseId, $addQs=FALSE, $rmQs=FALSE) {
        // update search engine and its values table if enabled
        if (api_get_setting('search_enabled')=='true') {
            $course_id = api_get_course_id();
            // get search_did
            $tbl_se_ref = Database::get_main_table(TABLE_MAIN_SEARCH_ENGINE_REF);
            if ($addQs || $rmQs) {
                //there's only one row per question on normal db and one document per question on search engine db
                $sql = 'SELECT * FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_second_level=%s LIMIT 1';
                $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, $this->id);
            } else {
              $sql = 'SELECT * FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_high_level=%s AND ref_id_second_level=%s LIMIT 1';
              $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, $exerciseId, $this->id);
            }
            $res = api_sql_query($sql, __FILE__, __LINE__);

            if (Database::num_rows($res) > 0 || $addQs) {
                require_once(api_get_path(LIBRARY_PATH) . 'search/DokeosIndexer.class.php');
                require_once(api_get_path(LIBRARY_PATH) . 'search/IndexableChunk.class.php');

                $di = new DokeosIndexer();
                if ($addQs) {
                	$question_exercises = array((int)$exerciseId);
                } else {
                    $question_exercises = array();
                }
                isset($_POST['language'])? $lang=Database::escape_string($_POST['language']): $lang = 'english';
                $di->connectDb(NULL, NULL, $lang);

                // retrieve others exercise ids
                $se_ref = Database::fetch_array($res);
                $se_doc = $di->get_document((int)$se_ref['search_did']);
                if ($se_doc !== FALSE) {
	                if ( ($se_doc_data=$di->get_document_data($se_doc)) !== FALSE ) {
		                $se_doc_data = unserialize($se_doc_data);
		                if (isset($se_doc_data[SE_DATA]['type']) && $se_doc_data[SE_DATA]['type'] == SE_DOCTYPE_EXERCISE_QUESTION) {
			                if (isset($se_doc_data[SE_DATA]['exercise_ids']) && is_array($se_doc_data[SE_DATA]['exercise_ids'])) {
                                foreach ($se_doc_data[SE_DATA]['exercise_ids'] as $old_value) {
                                    if (!in_array($old_value, $question_exercises)) {
                                    	$question_exercises[] = $old_value;
                                    }
                                }
			                }
		                } 
	                }
                }
                if ($rmQs) {
                	while ( ($key=array_search($exerciseId, $question_exercises)) !== FALSE) {
                		unset($question_exercises[$key]);
                	}
                }

                // build the chunk to index
                $ic_slide = new IndexableChunk();
                $ic_slide->addValue("title", $this->question);
                $ic_slide->addCourseId($course_id);
                $ic_slide->addToolId(TOOL_QUIZ);
                $xapian_data = array(
                    SE_COURSE_ID => $course_id,
                    SE_TOOL_ID => TOOL_QUIZ,
                    SE_DATA => array('type' => SE_DOCTYPE_EXERCISE_QUESTION, 'exercise_ids' => $question_exercises, 'question_id' => (int)$this->id),
                    SE_USER => (int)api_get_user_id(),
                );
                $ic_slide->xapian_data = serialize($xapian_data);
                $ic_slide->addValue("content", $this->description);

                //TODO: index answers, see also form validation on question_admin.inc.php

                $di->remove_document((int)$se_ref['search_did']);
                $di->addChunk($ic_slide);

                //index and return search engine document id
                if (!empty($question_exercises)) { // if empty there is nothing to index
                	$did = $di->index();
                    unset($di);
                }
                if ($did || $rmQs) {
                    // save it to db
                    if ($addQs || $rmQs) {
                    	$sql = 'DELETE FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_second_level=\'%s\'';
                        $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, $this->id);
                    } else {
                        $sql = 'DELETE FROM %s WHERE course_code=\'%s\' AND tool_id=\'%s\' AND ref_id_high_level=\'%s\' AND ref_id_second_level=\'%s\'';
                        $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, $exerciseId, $this->id);
                    }
                    api_sql_query($sql,__FILE__,__LINE__);
                    if ($rmQs) {
                        if (!empty($question_exercises)) {
                          $sql = 'INSERT INTO %s (id, course_code, tool_id, ref_id_high_level, ref_id_second_level, search_did)
                              VALUES (NULL , \'%s\', \'%s\', %s, %s, %s)';
                          $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, array_shift($question_exercises), $this->id, $did);
                          api_sql_query($sql,__FILE__,__LINE__);
                        }
                    } else {
                        $sql = 'INSERT INTO %s (id, course_code, tool_id, ref_id_high_level, ref_id_second_level, search_did)
                            VALUES (NULL , \'%s\', \'%s\', %s, %s, %s)';
                        $sql = sprintf($sql, $tbl_se_ref, $course_id, TOOL_QUIZ, $exerciseId, $this->id, $did);
                        api_sql_query($sql,__FILE__,__LINE__);
                    }
                }

            }
        }

    }

	/**
	 * adds an exercise into the exercise list
	 *
	 * @author - Olivier Brouckaert
     * @param - integer $exerciseId - exercise ID
     * @param - boolean $fromSave - comming from $this->save() or not
	 */
	function addToList($exerciseId, $fromSave=FALSE) {
		global $TBL_EXERCICE_QUESTION;
		$id=$this->id;
		// checks if the exercise ID is not in the list		
		if(!in_array($exerciseId,$this->exerciseList)) {
			$this->exerciseList[]=$exerciseId;
			$sql="INSERT INTO $TBL_EXERCICE_QUESTION (question_id, exercice_id) VALUES('".Database::escape_string($id)."','".Database::escape_string($exerciseId)."')";
			api_sql_query($sql,__FILE__,__LINE__);
            // we do not want to reindex if we had just saved adnd indexed the question
            if (!$fromSave) {
            	$this->search_engine_edit($exerciseId, TRUE);
            }
		}
	}

	/**
	 * removes an exercise from the exercise list
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $exerciseId - exercise ID
	 * @return - boolean - true if removed, otherwise false
	 */
	function removeFromList($exerciseId) {
		global $TBL_EXERCICE_QUESTION;

		$id=$this->id;

		// searches the position of the exercise ID in the list
		$pos=array_search($exerciseId,$this->exerciseList);

		// exercise not found
		if($pos === false) {
			return false;
		} else {
			// deletes the position in the array containing the wanted exercise ID
			unset($this->exerciseList[$pos]);
            //update order of other elements
            $sql = "SELECT question_order FROM $TBL_EXERCICE_QUESTION WHERE question_id='".Database::escape_string($id)."' AND exercice_id='".Database::escape_string($exerciseId)."'";
            $res = api_sql_query($sql,__FILE__,__LINE__);
            if (Database::num_rows($res)>0) {
                $row = Database::fetch_array($res);
                if (!empty($row['question_order'])) {
                    $sql = "UPDATE $TBL_EXERCICE_QUESTION SET question_order = question_order-1 WHERE exercice_id='".Database::escape_string($exerciseId)."' AND question_order > ".$row['question_order'];
                    $res = api_sql_query($sql,__FILE__,__LINE__);
                }
            }

			$sql="DELETE FROM $TBL_EXERCICE_QUESTION WHERE question_id='".Database::escape_string($id)."' AND exercice_id='".Database::escape_string($exerciseId)."'";
			api_sql_query($sql,__FILE__,__LINE__);

			return true;
		}
	}

	/**
	 * deletes a question from the database
	 * the parameter tells if the question is removed from all exercises (value = 0),
	 * or just from one exercise (value = exercise ID)
	 *
	 * @author - Olivier Brouckaert
	 * @param - integer $deleteFromEx - exercise ID if the question is only removed from one exercise
	 */
	function delete($deleteFromEx=0) {
		global $_course,$_user;
		
		$TBL_EXERCICE_QUESTION	= Database::get_course_table(TABLE_QUIZ_TEST_QUESTION);		
		$TBL_QUESTIONS			= Database::get_course_table(TABLE_QUIZ_QUESTION);
		$TBL_REPONSES          = Database::get_course_table(TABLE_QUIZ_ANSWER);
		
		$id=$this->id;

		// if the question must be removed from all exercises
		if(!$deleteFromEx)
		{
            //update the question_order of each question to avoid inconsistencies
            $sql = "SELECT exercice_id, question_order FROM $TBL_EXERCICE_QUESTION WHERE question_id='".Database::escape_string($id)."'";
            $res = api_sql_query($sql,__FILE__,__LINE__);
            if (Database::num_rows($res)>0) {
                while ($row = Database::fetch_array($res)) {
                    if (!empty($row['question_order'])) {
                        $sql = "UPDATE $TBL_EXERCICE_QUESTION SET question_order = question_order-1 WHERE exercice_id='".Database::escape_string($row['exercice_id'])."' AND question_order > ".$row['question_order'];
                        $res = api_sql_query($sql,__FILE__,__LINE__);
                    }
                }
            }
			$sql="DELETE FROM $TBL_EXERCICE_QUESTION WHERE question_id='".Database::escape_string($id)."'";
			api_sql_query($sql,__FILE__,__LINE__);

			$sql="DELETE FROM $TBL_QUESTIONS WHERE id='".Database::escape_string($id)."'";
			api_sql_query($sql,__FILE__,__LINE__);

			$sql="DELETE FROM $TBL_REPONSES WHERE question_id='".Database::escape_string($id)."'";
			api_sql_query($sql,__FILE__,__LINE__);
			
			api_item_property_update($_course, TOOL_QUIZ, $id,'QuizQuestionDeleted',$_user['user_id']);
			$this->removePicture();

			// resets the object
			$this->Question();
		}
		// just removes the exercise from the list
		else
		{
			$this->removeFromList($deleteFromEx);
            if (api_get_setting('search_enabled')=='true') {
                // disassociate question with this exercise
                $this -> search_engine_edit($deleteFromEx, FALSE, TRUE);
            }
            api_item_property_update($_course, TOOL_QUIZ, $id,'QuizQuestionDeleted',$_user['user_id']);
		}
	}

	/**
	 * duplicates the question
	 *
	 * @author - Olivier Brouckaert
	 * @return - integer - ID of the new question
	 */
	function duplicate() {
		global $TBL_QUESTIONS, $picturePath;

		$question=$this->question;
		$description=$this->description;
		$weighting=$this->weighting;
		$position=$this->position;
		$type=$this->type;

		$sql="INSERT INTO $TBL_QUESTIONS(question,description,ponderation,position,type) VALUES('".Database::escape_string($question)."','".Database::escape_string($description)."','".Database::escape_string($weighting)."','".Database::escape_string($position)."','".Database::escape_string($type)."')";
		api_sql_query($sql,__FILE__,__LINE__);

		$id=Database::get_last_insert_id();
		// duplicates the picture
		$this->exportPicture($id);

		return $id;
	}

	/**
	 * Returns an instance of the class corresponding to the type
	 * @param integer $type the type of the question
	 * @return an instance of a Question subclass (or of Questionc class by default)
	 */
	static function getInstance ($type) {
		if (!is_null($type)) {
			list($file_name,$class_name) = self::$questionTypes[$type];
			include_once($file_name);
			if (class_exists($class_name)) {
				return new $class_name();
			} else {
				echo 'Can\'t instanciate class '.$class_name.' of type '.$type;
				return null;
			}	
		}
	}

	/**
	 * Creates the form to create / edit a question
	 * A subclass can redifine this function to add fields...
	 * @param FormValidator $form the formvalidator instance (by reference)
	 */
	function createForm (&$form,$fck_config=0)
	{
		echo '	<style>
					div.row div.label{ width: 10%; }
					div.row div.formw{ width: 89%; }
				</style>';
				
		echo '<script>
			function show_media()
			{
			if(document.getElementById(\'media\').style.display == \'none\') {
				document.getElementById(\'media\').style.display = \'block\';
				document.getElementById(\'media_icon\').innerHTML=\'&nbsp;<img style="vertical-align: middle;" src="../img/looknfeelna.png" alt="" />&nbsp;'.get_lang('EnrichQuestion').'\';
			} else {			
				document.getElementById(\'media\').style.display = \'none\';
				document.getElementById(\'media_icon\').innerHTML=\'&nbsp;<img style="vertical-align: middle;" src="../img/looknfeel.png" alt="" />&nbsp;'.get_lang('EnrichQuestion').'\';				
			}	
		}	
			</script>';		
			

		$renderer = $form->defaultRenderer();
		$form->addElement('html','<div class="form">');
		// question name
		$form->addElement('text','questionName','<span class="form_required">*</span> '.get_lang('Question'),'size="60"');
		//$form->applyFilter('questionName','html_filter');
		
		//$radios_results_enabled[] = $form->createElement('static', null, null, null);
		//$test=FormValidator :: createElement ('text', 'questionName');

		//$radios_results_enabled[]=$test;
		// question level
		
		$select_level = array (1,2,3,4,5); 
		//$radios_results_enabled[] = 	
		foreach($select_level as $val) {
			$radios_results_enabled[] = FormValidator :: createElement ('radio', null, null,$val,$val);
		}
		$form->addGroup($radios_results_enabled,'questionLevel',get_lang('Difficulty'));
					
		$renderer->setElementTemplate('<div class="row"><div class="label">{label}</div><div class="formw" >{element}</div></div>','questionName');
		$renderer->setElementTemplate('<div class="row"><div class="label">{label}</div><div class="formw">{element}</div></div>','questionLevel');
		$form->addRule('questionName', get_lang('GiveQuestion'), 'required');

		// question type
		$answerType= intval($_REQUEST['answerType']);
		$form->addElement('hidden','answerType',$_REQUEST['answerType']);
		
		
		// html editor
		global $fck_attribute;
		$fck_attribute = array();
		$fck_attribute['Width'] = '100%';
		$fck_attribute['Height'] = '150px';
		$fck_attribute['ToolbarSet'] = 'QuestionDescription';
		
		if(is_array($fck_config)){
			$fck_attribute = array_merge($fck_attribute,$fck_config);
		}		
		
		if(!api_is_allowed_to_edit()) $fck_attribute['Config']['UserStatus'] = 'student';

		$form -> addElement('html','<div class="row">
		<div class="label"></div>
		<div class="formw" style="height:50px">
			<a href="javascript://" onclick=" return show_media()"> <span id="media_icon"> <img style="vertical-align: middle;" src="../img/looknfeel.png" alt="" />&nbsp;'.get_lang('EnrichQuestion').'</span></a>
		</div>
		</div>');
		
		$form -> addElement ('html','<div id="media" style="display:none;">');
				
		$form->add_html_editor('questionDescription', get_lang('langQuestionDescription'), false);
		$form -> addElement ('html','</div>');
		
		$renderer->setElementTemplate('<div class="row"><div class="label">{label}</div><div class="formw">{element}</div></div>','questionDescription');

		// hidden values
		$form->addElement('hidden','myid',$_REQUEST['myid']);

		switch($answerType) {
			case 1:	$this->question = get_lang('langDefaultUniqueQuestion'); break;
			case 2:	$this->question = get_lang('langDefaultMultipleQuestion'); break;
			case 3:	$this->question = get_lang('langDefaultFillBlankQuestion'); break;
			case 4:	$this->question = get_lang('langDefaultMathingQuestion'); break;			
			case 5:	$this->question = get_lang('langDefaultOpenQuestion');	break;
		}
		$form->addElement('html','</div>');	 
		// default values
		$defaults = array();
		$defaults['questionName'] = $this -> question;
		$defaults['questionDescription'] = $this -> description;
		$defaults['questionLevel'] = $this -> level;
		$form -> setDefaults($defaults);
	}

	/**
	 * function which process the creation of questions
	 * @param FormValidator $form the formvalidator instance
	 * @param Exercise $objExercise the Exercise instance
	 */
	function processCreation ($form, $objExercise) {

		$this -> updateTitle($form->getSubmitValue('questionName'));
	    $this -> updateDescription($form->getSubmitValue('questionDescription'));
	    $this -> updateLevel($form->getSubmitValue('questionLevel'));
	    $this -> save($objExercise -> id);

	    // modify the exercise
	    $objExercise->addToList($this -> id);
        $objExercise->update_question_positions();

	}

	/**
	 * abstract function which creates the form to create / edit the answers of the question
	 * @param the formvalidator instance
	 */
	abstract function createAnswersForm ($form);

	/**
	 * abstract function which process the creation of answers
	 * @param the formvalidator instance
	 */
	abstract function processAnswersCreation ($form);


	/**
	 * Displays the menu of question types
	 */
	static function display_type_menu ($feedbacktype = 0)
	{
		global $exerciseId;
		// 1. by default we show all the question types
		$question_type_custom_list = self::$questionTypes;
				
		if (!isset($feedbacktype)) $feedbacktype=0;
		if ($feedbacktype==1) {
			//2. but if it is a feedback DIRECT we only show the UNIQUE_ANSWER type that is currently available
			$question_type_custom_list = array ( UNIQUE_ANSWER => self::$questionTypes[UNIQUE_ANSWER]); 
		}
		echo '<ul class="question_menu" style="padding:0px; margin:-2px;">';
		foreach ($question_type_custom_list as $i=>$a_type) {			
			// include the class of the type
			include_once($a_type[0]);			
			 // get the picture of the type and the langvar which describes it
			eval('$img = '.$a_type[1].'::$typePicture;');			
			eval('$explanation = get_lang('.$a_type[1].'::$explanationLangVar);');			
			echo '<li>';		
			echo '<div class="icon_image_content">';	
			echo '<a href="admin.php?newQuestion=yes&answerType='.$i.'">'.Display::return_icon($img, $explanation).'</a>';
			echo '<br>';
			echo '<a href="admin.php?newQuestion=yes&answerType='.$i.'">'.$explanation.'</a>';
			echo '</div>';
			echo '</li>';
		}
		echo '<li>';
		echo '<div class="icon_image_content">';
		if ($feedbacktype==1) { 
			echo $url = '<a href="question_pool.php?type=1&fromExercise='.$exerciseId.'">';
		} else {
			echo $url = '<a href="question_pool.php?fromExercise='.$exerciseId.'">';	
		}
		echo Display::return_icon('database.png', get_lang('GetExistingQuestion'), '');		
		echo '</a><br>';
		echo $url;
		echo get_lang('GetExistingQuestion');
		echo '</a>';
		echo '</div></li>';
		echo '</ul>';
	}
	
	static function get_types_information()
	{
		return self::$questionTypes;
	}
}
endif;
?>