assessment/classes/class.assQuestion.php

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<?php
 /*
   +----------------------------------------------------------------------------+
   | ILIAS open source                                                          |
   +----------------------------------------------------------------------------+
   | Copyright (c) 1998-2001 ILIAS open source, University of Cologne           |
   |                                                                            |
   | 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.                     |
   |                                                                            |
   | This program is distributed in the hope that it will be useful,            |
   | but WITHOUT ANY WARRANTY; without even the implied warranty of             |
   | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the              |
   | GNU General Public License for more details.                               |
   |                                                                            |
   | You should have received a copy of the GNU General Public License          |
   | along with this program; if not, write to the Free Software                |
   | Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. |
   +----------------------------------------------------------------------------+
*/

require_once "./assessment/classes/class.assClozeTestGUI.php";
require_once "./assessment/classes/class.assImagemapQuestionGUI.php";
require_once "./assessment/classes/class.assJavaAppletGUI.php";
require_once "./assessment/classes/class.assMatchingQuestionGUI.php";
require_once "./assessment/classes/class.assMultipleChoiceGUI.php";
require_once "./assessment/classes/class.assOrderingQuestionGUI.php";
require_once "./assessment/classes/class.assTextQuestionGUI.php";
require_once "./content/classes/Pages/class.ilPageObject.php";

define("LIMIT_NO_LIMIT", 0);
define("LIMIT_TIME_ONLY", 1);

define("OUTPUT_HTML", 0);
define("OUTPUT_JAVASCRIPT", 1);

class ASS_Question
{
        var $id;

        var $title;

        var $comment;

        var $owner;

        var $author;

        var $est_working_time;

        var $shuffle;

        var $test_id;

        var $obj_id;

        var $ilias;

        var $tpl;

        var $lng;

        var $domxml;

        var $outputType;

        var $suggested_solutions;
        function ASS_Question(
                $title = "",
                $comment = "",
                $author = "",
                $owner = -1
        )
        {
                global $ilias;
                global $lng;
                global $tpl;

                $this->ilias =& $ilias;
                $this->lng =& $lng;
                $this->tpl =& $tpl;

                $this->title = $title;
                $this->comment = $comment;
                $this->author = $author;
                if (!$this->author)
                {
                        $this->author = $this->ilias->account->fullname;
                }
                $this->owner = $owner;
                if ($this->owner == -1)
                {
                        $this->owner = $this->ilias->account->id;
                }
                $this->id = -1;
                $this->test_id = -1;
                $this->suggested_solutions = array();
                $this->shuffle = 1;
                $this->setEstimatedWorkingTime(0,1,0);
                $this->outputType = OUTPUT_HTML;
                register_shutdown_function(array(&$this, '_ASS_Question'));
        }

        function _ASS_Question()
        {
                if (!empty($this->domxml))
                {
                        $this->domxml->free();
                }
        }

        function to_xml()
        {
                // to be implemented in the successor classes of ASS_Question
        }

        function isComplete()
        {
                return false;
        }

        function questionTitleExists($title)
        {
                $query = sprintf("SELECT * FROM qpl_questions WHERE title = %s",
                        $this->ilias->db->quote($title)
                        );
                $result = $this->ilias->db->query($query);
                if (strcmp(strtolower(get_class($result)), db_result) == 0)
                {
                        if ($result->numRows() == 1)
                        {
                                return TRUE;
                        }
                }
                return FALSE;
        }

        function setTitle($title = "")
        {
                $this->title = $title;
        }

        function setId($id = -1)
        {
                $this->id = $id;
        }

        function setTestId($id = -1)
        {
                $this->test_id = $id;
        }

        function setComment($comment = "")
        {
                $this->comment = $comment;
        }

        function setOutputType($outputType = OUTPUT_HTML)
        {
                $this->outputType = $outputType;
        }


        function setShuffle($shuffle = true)
        {
                if ($shuffle)
                {
                        $this->shuffle = 1;
                }
                        else
                {
                        $this->shuffle = 0;
                }
        }

        function setEstimatedWorkingTime($hour=0, $min=0, $sec=0)
        {
                $this->est_working_time = array("h" => (int)$hour, "m" => (int)$min, "s" => (int)$sec);
        }

        function keyInArray($searchkey, $array)
        {
                if ($searchKey)
                {
                        foreach ($array as $key => $value)
                        {
                                if (strcmp($key, $searchkey)==0)
                                {
                                        return true;
                                }
                        }
                }
                return false;
        }

        function setAuthor($author = "")
        {
                if (!$author)
                {
                        $author = $this->ilias->account->fullname;
                }
                $this->author = $author;
        }

        function setOwner($owner = "")
        {
                $this->owner = $owner;
        }

        function getTitle()
        {
                return $this->title;
        }

        function getId()
        {
                return $this->id;
        }

        function getShuffle()
        {
                return $this->shuffle;
        }

        function getTestId()
        {
                return $this->test_id;
        }

        function getComment()
        {
                return $this->comment;
        }

        function getOutputType()
        {
                return $this->outputType;
        }

        function getEstimatedWorkingTime()
        {
                if (!$this->est_working_time)
                {
                        $this->est_working_time = array("h" => 0, "m" => 0, "s" => 0);
                }
                return $this->est_working_time;
        }

        function getAuthor()
        {
                return $this->author;
        }

        function getOwner()
        {
                return $this->owner;
        }

        function getObjId()
        {
                return $this->obj_id;
        }

        function setObjId($obj_id = 0)
        {
                $this->obj_id = $obj_id;
        }

        function createPageObject()
        {
//              $qpl_id = ilObject::_lookupObjectId($this->getRefId());
                $qpl_id = $this->getObjId();

                $this->page = new ilPageObject("qpl", 0);
                $this->page->setId($this->getId());
                $this->page->setParentId($qpl_id);
                $this->page->setXMLContent("<PageObject><PageContent>".
                        "<Question QRef=\"il__qst_".$this->getId()."\"/>".
                        "</PageContent></PageObject>");
                $this->page->create();
        }

        function insertIntoTest($test_id)
        {
                // get maximum sequence index in test
                $query = sprintf("SELECT MAX(sequence) AS seq FROM dum_test_question WHERE test_fi=%s",
                        $this->ilias->db->quote($test_id)
                        );
                $result = $this->ilias->db->query($query);
                $sequence = 1;
                if ($result->numRows() == 1)
                {
                        $data = $result->fetchRow(DB_FETCHMODE_OBJECT);
                        $sequence = $data->seq + 1;
                }
                $query = sprintf("INSERT INTO dum_test_question (test_question_id, test_fi, question_fi, sequence, TIMESTAMP) VALUES (NULL, %s, %s, %s, NULL)",
                        $this->ilias->db->quote($test_id),
                        $this->ilias->db->quote($this->getId()),
                        $this->ilias->db->quote($sequence)
                        );
                $result = $this->ilias->db->query($query);
                if ($result != DB_OK)
                {
                // Fehlermeldung
                }
        }

        function _getReachedPoints($user_id, $test_id)
        {
                return 0;
        }

        function getReachedPoints($user_id, $test_id)
        {
                return 0;
        }

        function getMaximumPoints()
        {
                return 0;
        }

        function saveWorkingData($limit_to = LIMIT_NO_LIMIT)
        {
        /*    global $ilias;
                $db =& $ilias->db;

                // Increase the number of tries for that question
                $query = sprintf("SELECT * FROM dum_assessment_solution_order WHERE user_fi = %s AND test_fi = %s AND question_fi = %s",
                $db->quote($this->ilias->account->id),
                $db->quote($_GET["test"]),
                $db->quote($this->getId())
                );
                $result = $db->query($query);
                $data = $result->fetchRow(DB_FETCHMODE_OBJECT);
                $query = sprintf("UPDATE dum_assessment_solution_order SET tries = %s WHERE solution_order_id = %s",
                $db->quote($data->tries + 1),
                $db->quote($data->solution_order_id)
                );
                $result = $db->query($query);
        */
        }

        function getJavaPath() {
                return CLIENT_WEB_DIR . "/assessment/$this->obj_id/$this->id/java/";
        }

        function getImagePath()
        {
                return CLIENT_WEB_DIR . "/assessment/$this->obj_id/$this->id/images/";
        }

        function getJavaPathWeb()
        {
                $webdir = ilUtil::removeTrailingPathSeparators(CLIENT_WEB_DIR) . "/assessment/$this->obj_id/$this->id/java/";
                return str_replace(ilUtil::removeTrailingPathSeparators(ILIAS_ABSOLUTE_PATH), ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH), $webdir);
        }

        function getImagePathWeb()
        {
                $webdir = ilUtil::removeTrailingPathSeparators(CLIENT_WEB_DIR) . "/assessment/$this->obj_id/$this->id/images/";
                return str_replace(ilUtil::removeTrailingPathSeparators(ILIAS_ABSOLUTE_PATH), ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH), $webdir);
        }

        function &getSolutionValues($test_id)
        {
                global $ilDB;
                global $ilUser;

                $db =& $ilDB->db;

                $query = sprintf("SELECT * FROM tst_solutions WHERE user_fi = %s AND test_fi = %s AND question_fi = %s",
                        $db->quote($ilUser->id),
                        $db->quote($test_id),
                        $db->quote($this->getId())
                        );
                $result = $db->query($query);
                $values = array();
                while   ($row = $result->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        array_push($values, $row);
                }

                return $values;
        }

        function isInUse()
        {
                $query = sprintf("SELECT COUNT(question_id) AS question_count FROM qpl_questions WHERE original_id = %s",
                        $this->ilias->db->quote("$this->id")
                        );
                $result = $this->ilias->db->query($query);
                $row = $result->fetchRow(DB_FETCHMODE_OBJECT);
                return $row->question_count;
        }

        function removeAllQuestionReferences($question_id = "")
        {
        /*
                if (!$question_id)
                {
                        $question_id = $this->getId();
                }
                $query = sprintf("SELECT * FROM tst_solutions WHERE question_fi = %s", $this->ilias->db->quote("$question_id"));
                $result = $this->ilias->db->query($query);
                while ($row = $result->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        // Mark all tests containing this question as "not started"
                        $querychange = sprintf("DELETE FROM tst_active WHERE user_fi = %s AND test_fi = %s",
                                $this->ilias->db->quote("$result->user_fi"),
                                $this->ilias->db->quote("$result->test_fi")
                                );
                        $changeresult = $this->ilias->db->query($querychange);
                }
                // delete all resultsets for this question
                $querydelete = sprintf("DELETE FROM tst_solutions WHERE question_fi = %s", $this->ilias->db->quote("$question_id"));
                $deleteresult = $this->ilias->db->query($querydelete);
                */
        }

        function pcArrayShuffle($array)
        {
                mt_srand((double)microtime()*1000000);
                $i = count($array);
                if ($i > 0)
                {
                        while(--$i)
                        {
                                $j = mt_rand(0, $i);
                                if ($i != $j)
                                {
                                        // swap elements
                                        $tmp = $array[$j];
                                        $array[$j] = $array[$i];
                                        $array[$i] = $tmp;
                                }
                        }
                }
                return $array;
        }

        function getQuestionTypeFromDb($question_id)
        {
                global $ilDB;

                $query = sprintf("SELECT qpl_question_type.type_tag FROM qpl_question_type, qpl_questions WHERE qpl_questions.question_id = %s AND qpl_questions.question_type_fi = qpl_question_type.question_type_id",
                        $ilDB->quote($question_id));

                $result = $ilDB->query($query);
                $data = $result->fetchRow(DB_FETCHMODE_OBJECT);

                return $data->type_tag;
        }

        function delete($question_id)
        {
                if ($question_id < 1)
                return;

                $query = sprintf("SELECT obj_fi FROM qpl_questions WHERE question_id = %s",
                        $this->ilias->db->quote($question_id)
                        );
        $result = $this->ilias->db->query($query);
                if ($result->numRows() == 1)
                {
                        $row = $result->fetchRow(DB_FETCHMODE_ASSOC);
                        $obj_id = $row["obj_fi"];
                }
                else
                {
                        return;
                }

                $query = sprintf("DELETE FROM qpl_questions WHERE question_id = %s",
                        $this->ilias->db->quote($question_id)
                        );
                $result = $this->ilias->db->query($query);
                $query = sprintf("DELETE FROM qpl_answers WHERE question_fi = %s",
                        $this->ilias->db->quote($question_id)
                        );
                $result = $this->ilias->db->query($query);

                $this->removeAllQuestionReferences($question_id);

                // delete page object
                $page = new ilPageObject("qpl", $question_id);
                $page->delete();

                // delete the question in the tst_test_question table (list of test questions)
                $querydelete = sprintf("DELETE FROM tst_test_question WHERE question_fi = %s", $this->ilias->db->quote($question_id));
                $deleteresult = $this->ilias->db->query($querydelete);

                // delete suggested solutions contained in the question
                $querydelete = sprintf("DELETE FROM qpl_suggested_solutions WHERE question_fi = %s", $this->ilias->db->quote($question_id));
                $deleteresult = $this->ilias->db->query($querydelete);
                                
                $directory = CLIENT_WEB_DIR . "/assessment/" . $obj_id . "/$question_id";
                if (preg_match("/\d+/", $obj_id) and preg_match("/\d+/", $question_id) and is_dir($directory))
                {
                        $directory = escapeshellarg($directory);
                        exec("rm -rf $directory");
                }
        }

        function getTotalAnswers()
        {
                return $this->_getTotalAnswers($this->id);
        }

        function _getTotalAnswers($a_q_id)
        {
                global $ilDB;

                $query = sprintf("SELECT question_id FROM qpl_questions WHERE original_id = %s",
                        $ilDB->quote($a_q_id));

                $result = $ilDB->query($query);

                if ($result->numRows() == 0)
                {
                        return 0;
                }
                $found_id = array();
                while ($row = $result->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        array_push($found_id, $row->question_id);
                }

                $query = sprintf("SELECT * FROM tst_solutions WHERE question_fi IN (%s) GROUP BY CONCAT(user_fi,test_fi)",
                        join($found_id, ","));

                $result = $ilDB->query($query);

                return $result->numRows();
        }


        function _getTotalRightAnswers($a_q_id)
        {
                global $ilDB;
                $query = sprintf("SELECT question_id FROM qpl_questions WHERE original_id = %s",
                        $ilDB->quote($a_q_id)
                );
                $result = $ilDB->query($query);
                if ($result->numRows() == 0)
                {
                        return 0;
                }
                $found_id = array();
                while ($row = $result->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        array_push($found_id, $row->question_id);
                }
                $query = sprintf("SELECT * FROM tst_solutions WHERE question_fi IN (%s) GROUP BY CONCAT(user_fi,test_fi)",
                        join($found_id, ",")
                );
                $result = $ilDB->query($query);
                $answers = array();
                while ($row = $result->fetchRow(DB_FETCHMODE_OBJECT))
                {
                        $question =& ASS_Question::_instanciateQuestion($row->question_fi);
                        $reached = $question->getReachedPoints($row->user_fi, $row->test_fi);
                        $max = $question->getMaximumPoints();
                        array_push($answers, array("reached" => $reached, "max" => $max));
                }
                $max = 0.0;
                $reached = 0.0;
                foreach ($answers as $key => $value)
                {
                        $max += $value["max"];
                        $reached += $value["reached"];
                }
                if ($max > 0)
                {
                        return $reached / $max;
                }
                else
                {
                        return 0;
                }
        }

        function copyPageOfQuestion($a_q_id)
        {
                if ($a_q_id > 0)
                {
                        $page = new ilPageObject("qpl", $a_q_id);

                        $xml = str_replace("il__qst_".$a_q_id, "il__qst_".$this->id,
                                $page->getXMLContent());

                        $this->page->setXMLContent($xml);
                        $this->page->updateFromXML();
                }
        }

        function getPageOfQuestion()
        {
                $page = new ilPageObject("qpl", $this->id);
                return $page->getXMLContent();
        }

  function _getQuestionType($question_id) {
                global $ilDB;

    if ($question_id < 1)
      return "";

    $query = sprintf("SELECT type_tag FROM qpl_questions, qpl_question_type WHERE qpl_questions.question_id = %s AND qpl_questions.question_type_fi = qpl_question_type.question_type_id",
      $ilDB->quote($question_id)
    );
    $result = $ilDB->query($query);
    if ($result->numRows() == 1) {
      $data = $result->fetchRow(DB_FETCHMODE_OBJECT);
      return $data->type_tag;
    } else {
      return "";
    }
  }

  function _getQuestionTitle($question_id) {
                global $ilDB;

    if ($question_id < 1)
      return "";

    $query = sprintf("SELECT title FROM qpl_questions WHERE qpl_questions.question_id = %s",
      $ilDB->quote($question_id)
    );
    $result = $ilDB->query($query);
    if ($result->numRows() == 1) {
      $data = $result->fetchRow(DB_FETCHMODE_ASSOC);
      return $data["title"];
    } else {
      return "";
    }
  }

        function loadFromDb($question_id)
        {
                $query = sprintf("SELECT * FROM qpl_suggested_solutions WHERE question_fi = %s",
                        $this->ilias->db->quote($this->getId() . "")
                );
                $result = $this->ilias->db->query($query);
                $this->suggested_solutions = array();
                if ($result->numRows())
                {
                        while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC))
                        {
                                $this->suggested_solutions[$row["subquestion_index"]] = array(
                                        "internal_link" => $row["internal_link"],
                                        "import_id" => $row["import_id"]
                                );
                        }
                }
        }

        function saveToDb($original_id = "")
        {
                require_once "./content/classes/Pages/class.ilInternalLink.php";
                $query = sprintf("DELETE FROM qpl_suggested_solutions WHERE question_fi = %s",
                        $this->ilias->db->quote($this->getId() . "")
                );
                $result = $this->ilias->db->query($query);
                ilInternalLink::_deleteAllLinksOfSource("qst", $this->getId());
                foreach ($this->suggested_solutions as $index => $solution)
                {
                        $query = sprintf("INSERT INTO qpl_suggested_solutions (suggested_solution_id, question_fi, internal_link, import_id, subquestion_index, TIMESTAMP) VALUES (NULL, %s, %s, %s, %s, NULL)",
                                $this->ilias->db->quote($this->getId() . ""),
                                $this->ilias->db->quote($solution["internal_link"] . ""),
                                $this->ilias->db->quote($solution["import_id"] . ""),
                                $this->ilias->db->quote($index . "")
                        );
                        $this->ilias->db->query($query);
                        if (preg_match("/il_(\d*?)_(\w+)_(\d+)/", $solution["internal_link"], $matches))
                        {
                                ilInternalLink::_saveLink("qst", $this->getId(), $matches[2], $matches[3], $matches[1]);
                        }
                }
        }
        
        function deleteSuggestedSolutions()
        {
                // delete the links in the qpl_suggested_solutions table
                $query = sprintf("DELETE FROM qpl_suggested_solutions WHERE question_fi = %s",
                        $this->ilias->db->quote($this->getId() . "")
                );
                $result = $this->ilias->db->query($query);
                // delete the links in the int_link table
                require_once "./content/classes/Pages/class.ilInternalLink.php";
                ilInternalLink::_deleteAllLinksOfSource("qst", $this->getId());
        }
        
        function getSuggestedSolution($subquestion_index = 0)
        {
                if (array_key_exists($subquestion_index, $this->suggested_solutions))
                {
                        return $this->suggested_solutions[$subquestion_index];
                }
                else
                {
                        return array();
                }
        }

        function getSuggestedSolutionTitle($subquestion_index = 0)
        {
                if (array_key_exists($subquestion_index, $this->suggested_solutions))
                {
                        $title = $this->suggested_solutions[$subquestion_index]["internal_link"];
                        // TO DO: resolve internal link an get link type and title
                }
                else
                {
                        $title = "";
                }
                return $title;
        }

        function setSuggestedSolution($solution_id = "", $subquestion_index = 0, $is_import = false)
        {
                if (strcmp($solution_id, "") != 0)
                {
                        $import_id = "";
                        if ($is_import)
                        {
                                $import_id = $solution_id;
                                $solution_id = $this->_resolveInternalLink($import_id);
                        }
                        $this->suggested_solutions[$subquestion_index] = array(
                                "internal_link" => $solution_id,
                                "import_id" => $import_id
                        );
                }
        }
        
        function _resolveInternalLink($internal_link)
        {
                if (preg_match("/il_(\d+)_(\w+)_(\d+)/", $internal_link, $matches))
                {
                        require_once "./content/classes/Pages/class.ilInternalLink.php";
                        require_once "./content/classes/class.ilLMObject.php";
                        require_once "./content/classes/class.ilGlossaryTerm.php";
                        switch ($matches[2])
                        {
                                case "lm":
                                        $resolved_link = ilLMObject::_getIdForImportId($internal_link);
                                        break;
                                case "pg":
                                        $resolved_link = ilInternalLink::_getIdForImportId("PageObject", $internal_link);
                                        break;
                                case "st":
                                        $resolved_link = ilInternalLink::_getIdForImportId("StructureObject", $internal_link);
                                        break;
                                case "git":
                                        $resolved_link = ilInternalLink::_getIdForImportId("GlossaryItem", $internal_link);
                                        break;
                                case "mob":
                                        $resolved_link = ilInternalLink::_getIdForImportId("MediaObject", $internal_link);
                                        break;
                        }
                        if (strcmp($resolved_link, "") == 0)
                        {
                                $resolved_link = $internal_link;
                        }
                }
                else
                {
                        $resolved_link = $internal_link;
                }
                return $resolved_link;
        }
        
        function _resolveIntLinks($question_id)
        {
                global $ilDB;
                $resolvedlinks = 0;
                $query = sprintf("SELECT * FROM qpl_suggested_solutions WHERE question_fi = %s",
                        $ilDB->quote($question_id . "")
                );
                $result = $ilDB->query($query);
                if ($result->numRows())
                {
                        while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC))
                        {
                                $internal_link = $row["internal_link"];
                                $resolved_link = ASS_Question::_resolveInternalLink($internal_link);
                                if (strcmp($internal_link, $resolved_link) != 0)
                                {
                                        // internal link was resolved successfully
                                        $queryupdate = sprintf("UPDATE qpl_suggested_solutions SET internal_link = %s WHERE suggested_solution_id = %s",
                                                $ilDB->quote($resolved_link),
                                                $ilDB->quote($row["suggested_solution_id"] . "")
                                        );
                                        $updateresult = $ilDB->query($queryupdate);
                                        $resolvedlinks++;
                                }
                        }
                }
                if ($resolvedlinks)
                {
                        // there are resolved links -> reenter theses links to the database

                        // delete all internal links from the database
                        require_once "./content/classes/Pages/class.ilInternalLink.php";
                        ilInternalLink::_deleteAllLinksOfSource("qst", $question_id);

                        $query = sprintf("SELECT * FROM qpl_suggested_solutions WHERE question_fi = %s",
                                $ilDB->quote($question_id . "")
                        );
                        $result = $ilDB->query($query);
                        if ($result->numRows())
                        {
                                while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC))
                                {
                                        if (preg_match("/il_(\d*?)_(\w+)_(\d+)/", $row["internal_link"], $matches))
                                        {
                                                ilInternalLink::_saveLink("qst", $question_id, $matches[2], $matches[3], $matches[1]);
                                        }
                                }
                        }
                }
        }
        
        function _getInternalLinkHref($target = "")
        {
                global $ilDB;
                $linktypes = array(
                        "lm" => "LearningModule",
                        "pg" => "PageObject",
                        "st" => "StructureObject",
                        "git" => "GlossaryItem",
                        "mob" => "MediaObject"
                );
                $href = "";
                if (preg_match("/il__(\w+)_(\d+)/", $target, $matches))
                {
                        $type = $matches[1];
                        $target_id = $matches[2];
                        switch($linktypes[$matches[1]])
                        {
                                case "LearningModule":
                                        $href = ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH) ."/goto.php?target=" . $type . "_" . $target_id;
                                        break;
                                case "PageObject":
                                case "StructureObject":
                                        $href = ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH) ."/goto.php?target=" . $type . "_" . $target_id;
                                        break;
                                case "GlossaryItem":
                                        $href = ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH) ."/goto.php?target=" . $type . "_" . $target_id;
                                        break;
                                case "MediaObject":
                                        $href = ilUtil::removeTrailingPathSeparators(ILIAS_HTTP_PATH) . "/content/lm_presentation.php?obj_type=" . $linktypes[$type] . "&cmd=media&ref_id=".$_GET["ref_id"]."&mob_id=".$target_id;
                                        break;
                        }
                }
                return $href;
        }
        
        function _getOriginalId($question_id)
        {
                global $ilDB;
                $query = sprintf("SELECT * FROM qpl_questions WHERE question_id = %s",
                        $ilDB->quote($question_id . "")
                );
                $result = $ilDB->query($query);
                if ($result->numRows() > 0)
                {
                        $row = $result->fetchRow(DB_FETCHMODE_ASSOC);
                        if ($row["original_id"] > 0)
                        {
                                return $row["original_id"];
                        }
                        else
                        {
                                return $row["question_id"];
                        }
                }
                else
                {
                        return "";
                }
        }

        function syncWithOriginal()
        {
                require_once "./content/classes/Pages/class.ilInternalLink.php";
                $query = sprintf("DELETE FROM qpl_suggested_solutions WHERE question_fi = %s",
                        $this->ilias->db->quote($this->original_id . "")
                );
                $result = $this->ilias->db->query($query);
                ilInternalLink::_deleteAllLinksOfSource("qst", $this->original_id);
                foreach ($this->suggested_solutions as $index => $solution)
                {
                        $query = sprintf("INSERT INTO qpl_suggested_solutions (suggested_solution_id, question_fi, internal_link, import_id, subquestion_index, TIMESTAMP) VALUES (NULL, %s, %s, %s, %s, NULL)",
                                $this->ilias->db->quote($this->original_id . ""),
                                $this->ilias->db->quote($solution["internal_link"] . ""),
                                $this->ilias->db->quote($solution["import_id"] . ""),
                                $this->ilias->db->quote($index . "")
                        );
                        $this->ilias->db->query($query);
                        if (preg_match("/il_(\d*?)_(\w+)_(\d+)/", $solution["internal_link"], $matches))
                        {
                                ilInternalLink::_saveLink("qst", $this->original_id, $matches[2], $matches[3], $matches[1]);
                        }
                }
        }

        function createRandomSolution($test_id, $user_id)
        {
        }

        function _questionExists($question_id)
        {
                global $ilDB;

                if ($question_id < 1)
                {
                        return false;
                }
                
                $query = sprintf("SELECT question_id FROM qpl_questions WHERE question_id = %s",
                        $ilDB->quote($question_id)
                );
    $result = $ilDB->query($query);
                if ($result->numRows() == 1)
                {
                        return true;
                }
                else
                {
                        return false;
                }
        }

  function &_instanciateQuestion($question_id) 
        {
                if (strcmp($question_id, "") != 0)
                {
                        $question_type = ASS_Question::_getQuestionType($question_id);
                        switch ($question_type) {
                                case "qt_cloze":
                                        $question = new ASS_ClozeTest();
                                        break;
                                case "qt_matching":
                                        $question = new ASS_MatchingQuestion();
                                        break;
                                case "qt_ordering":
                                        $question = new ASS_OrderingQuestion();
                                        break;
                                case "qt_imagemap":
                                        $question = new ASS_ImagemapQuestion();
                                        break;
                                case "qt_multiple_choice_sr":
                                case "qt_multiple_choice_mr":
                                        $question = new ASS_MultipleChoice();
                                        break;
                                case "qt_javaapplet":
                                        $question = new ASS_JavaApplet();
                                        break;
                                case "qt_text":
                                        $question = new ASS_TextQuestion();
                                        break;
                        }
                        $question->loadFromDb($question_id);
                        return $question;
                }
  }

}

?>