<?php  // $Id: questiontype.php,v 1.12.2.2 2008/01/30 18:18:34 tjhunt Exp $
/**
 * Class for the random question type.
 * 
 * The random question type does not have any options. When the question is 
 * attempted, it picks a question at random from the category it is in (and
 * optionally its subcategories). For details see create_session_and_responses.
 * Then all other method calls as delegated to that other question.
 * 
 * @package questionbank
 * @subpackage questiontypes
 */
class random_qtype extends default_questiontype {

    // Caches questions available as randoms sorted by category
    // This is a 2-d array. The first key is question category, and the
    // second is whether to include subcategories.
    var $catrandoms = array();

    function name() {
        return 'random';
    }

    function menu_name() {
        // Don't include this question type in the 'add new question' menu.
        return false;
    }

    function is_usable_by_random() {
        return false;
    }

    function get_question_options(&$question) {
        // Don't do anything here, because the random question has no options.
        // Everything is handled by the create- or restore_session_and_responses
        // functions.
        return true;
    }

    /**
     * Random questions always get a question name that is Random (cateogryname).
     * This function is a centralised place to calculate that, given the category.
     */
    function question_name($category) {
        return get_string('random', 'quiz') .' ('. $category->name .')';
    }

    function save_question($question, $form, $course) {
        // If the category is changing, set things up as default_questiontype::save_question expects.
        list($formcategory, $unused) = explode(',', $form->category);
        if (isset($question->id) && $formcategory != $question->category) {
            $form->categorymoveto = $form->category;
        }
        $form->name = '';
        $question = parent::save_question($question, $form, $course);
        if (!$category = get_record('question_categories', 'id', $question->category)) {
            error('Could retrieve question category');
        }
        $question->name = $this->question_name($category);
        if (!set_field('question', 'name', $question->name, 'id', $question->id)) {
            error('Could not update random question name');
        }
        return $question;
    }

    function save_question_options($question) {
        // No options, but we set the parent field to the question's own id.
        // Setting the parent field has the effect of hiding this question in
        // various places.
        return (set_field('question', 'parent', $question->id, 'id',
         $question->id) ? true : false);
    }

    function create_session_and_responses(&$question, &$state, $cmoptions, $attempt) {
        global $QTYPE_EXCLUDE_FROM_RANDOM;
        // Choose a random question from the category:
        // We need to make sure that no question is used more than once in the
        // quiz. Therfore the following need to be excluded:
        // 1. All questions that are explicitly assigned to the quiz
        // 2. All random questions
        // 3. All questions that are already chosen by an other random question
        // 4. Deleted questions
        if (!isset($cmoptions->questionsinuse)) {
            $cmoptions->questionsinuse = $attempt->layout;
        }

        if (!isset($this->catrandoms[$question->category][$question->questiontext])) {
            // Need to fetch random questions from category $question->category"
            // (Note: $this refers to the questiontype, not the question.)
            global $CFG;
            if ($question->questiontext == "1") {
                // recurse into subcategories
                $categorylist = question_categorylist($question->category);
            } else {
                $categorylist = $question->category;
            }
            if ($catrandoms = get_records_select('question',
                    "category IN ($categorylist)
                         AND parent = '0'
                         AND hidden = '0'
                         AND id NOT IN ($cmoptions->questionsinuse)
                         AND qtype NOT IN ($QTYPE_EXCLUDE_FROM_RANDOM)", '', 'id')) {
                $this->catrandoms[$question->category][$question->questiontext] =
                        draw_rand_array($catrandoms, count($catrandoms));
            } else {
                $this->catrandoms[$question->category][$question->questiontext] = array();
            }
        }

        while ($wrappedquestion =
                array_pop($this->catrandoms[$question->category][$question->questiontext])) {
            if (!ereg("(^|,)$wrappedquestion->id(,|$)", $cmoptions->questionsinuse)) {
                /// $randomquestion is not in use and will therefore be used
                /// as the randomquestion here...
                $wrappedquestion = get_record('question', 'id', $wrappedquestion->id);
                global $QTYPES;
                $QTYPES[$wrappedquestion->qtype]
                 ->get_question_options($wrappedquestion);
                $QTYPES[$wrappedquestion->qtype]
                 ->create_session_and_responses($wrappedquestion,
                 $state, $cmoptions, $attempt);
                $wrappedquestion->name_prefix = $question->name_prefix;
                $wrappedquestion->maxgrade    = $question->maxgrade;
                $cmoptions->questionsinuse .= ",$wrappedquestion->id";
                $state->options->question = &$wrappedquestion;
                return true;
            }
        }
        $question->questiontext = '<span class="notifyproblem">'.
         get_string('toomanyrandom', 'quiz'). '</span>';
        $question->qtype = 'description';
        $state->responses = array('' => '');
        return true;
    }

    function restore_session_and_responses(&$question, &$state) {
        /// The raw response records for random questions come in two flavours:
        /// ---- 1 ----
        /// For responses stored by Moodle version 1.5 and later the answer
        /// field has the pattern random#-* where the # part is the numeric
        /// question id of the actual question shown in the quiz attempt
        /// and * represents the student response to that actual question.
        /// ---- 2 ----
        /// For responses stored by older Moodle versions - the answer field is
        /// simply the question id of the actual question. The student response
        /// to the actual question is stored in a separate response record.
        /// -----------------------
        /// This means that prior to Moodle version 1.5, random questions needed
        /// two response records for storing the response to a single question.
        /// From version 1.5 and later the question type random works like all
        /// the other question types in that it now only needs one response
        /// record per question.
        global $QTYPES;
        if (!ereg('^random([0-9]+)-(.*)$', $state->responses[''], $answerregs)) {
            if (empty($state->responses[''])) {
                // This is the case if there weren't enough questions available in the category.
                $question->questiontext = '<span class="notifyproblem">'.
                 get_string('toomanyrandom', 'quiz'). '</span>';
                $question->qtype = 'description';
                return true;
            }
            // this must be an old-style state which stores only the id for the wrapped question
            if (!$wrappedquestion = get_record('question', 'id', $state->responses[''])) {
                notify("Can not find wrapped question {$state->responses['']}");
            }
            // In the old model the actual response was stored in a separate entry in
            // the state table and fortunately there was only a single state per question
            if (!$state->responses[''] = get_field('question_states', 'answer', 'attempt', $state->attempt, 'question', $wrappedquestion->id)) {
                notify("Wrapped state missing");
            }
        } else {
            if (!$wrappedquestion = get_record('question', 'id', $answerregs[1])) {
                // The teacher must have deleted this question by mistake
                // Convert it into a description type question with an explanation to the student
                $wrappedquestion = clone($question);
                $wrappedquestion->id = $answerregs[1];
                $wrappedquestion->questiontext = get_string('questiondeleted', 'quiz');
                $wrappedquestion->qtype = 'missingtype';
            }
            $state->responses[''] = (false === $answerregs[2]) ? '' : $answerregs[2];
        }

        if (!$QTYPES[$wrappedquestion->qtype]
         ->get_question_options($wrappedquestion)) {
            return false;
        }

        if (!$QTYPES[$wrappedquestion->qtype]
         ->restore_session_and_responses($wrappedquestion, $state)) {
            return false;
        }
        $wrappedquestion->name_prefix = $question->name_prefix;
        $wrappedquestion->maxgrade    = $question->maxgrade;
        $state->options->question = &$wrappedquestion;
        return true;
    }

    function save_session_and_responses(&$question, &$state) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;

        // Trick the wrapped question into pretending to be the random one.
        $realqid = $wrappedquestion->id;
        $wrappedquestion->id = $question->id;
        $QTYPES[$wrappedquestion->qtype]
         ->save_session_and_responses($wrappedquestion, $state);

        // Read what the wrapped question has just set the answer field to
        // (if anything)
        $response = get_field('question_states', 'answer', 'id', $state->id);
        if(false === $response) {
            return false;
        }

        // Prefix the answer field...
        $response = "random$realqid-$response";

        // ... and save it again.
        if (!set_field('question_states', 'answer', addslashes($response), 'id', $state->id)) {
            return false;
        }

        // Restore the real id
        $wrappedquestion->id = $realqid;
        return true;
    }

    function get_correct_responses(&$question, &$state) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->get_correct_responses($wrappedquestion, $state);
    }

    // ULPGC ecastro
    function get_all_responses(&$question, &$state){
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->get_all_responses($wrappedquestion, $state);
    }

    // ULPGC ecastro
    function get_actual_response(&$question, &$state){
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->get_actual_response($wrappedquestion, $state);
    }

    function get_html_head_contributions(&$question, &$state) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
                ->get_html_head_contributions($wrappedquestion, $state);
    }

    function print_question(&$question, &$state, &$number, $cmoptions, $options) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        $wrappedquestion->randomquestionid = $question->id;
        $QTYPES[$wrappedquestion->qtype]
         ->print_question($wrappedquestion, $state, $number, $cmoptions, $options);
    }

    function grade_responses(&$question, &$state, $cmoptions) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->grade_responses($wrappedquestion, $state, $cmoptions);
    }

    function get_texsource(&$question, &$state, $cmoptions, $type) {
        global $QTYPES;
        $wrappedquestion = &$state->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->get_texsource($wrappedquestion, $state, $cmoptions, $type);
    }

    function compare_responses(&$question, $state, $teststate) {
        global $QTYPES;
        $wrappedquestion = &$teststate->options->question;
        return $QTYPES[$wrappedquestion->qtype]
         ->compare_responses($wrappedquestion, $state, $teststate);
    }

}
//// END OF CLASS ////

//////////////////////////////////////////////////////////////////////////
//// INITIATION - Without this line the question type is not in use... ///
//////////////////////////////////////////////////////////////////////////
question_register_questiontype(new random_qtype());

?>
