<?php    // $Id$ 
// Alton College, Hampshire, UK - Tom Flannaghan, Andrew Walker
// Imports learnwise multiple choice quizzes (single and multiple answers)
// currently ignores the deduct attribute for multiple answer questions
// deductions are currently simply found by dividing the award for the incorrect 
// answer by the total number of options
// Based on format.php, included by ../../import.php
/**
 * @package questionbank
 * @subpackage importexport
 */

class qformat_learnwise extends qformat_default {

    function provide_import() {
      return true;
    }

    function readquestions($lines) {
        $questions = array();
        $currentquestion = array();

        foreach($lines as $line) {
            $line = trim($line);
            $currentquestion[] = $line;

            if ($question = $this->readquestion($currentquestion)) {
                $questions[] = $question;
                $currentquestion = array();
            }
        }
        return $questions;
    }

    function readquestion($lines) {
        $text = implode(' ', $lines);
        $text = str_replace(array('\t','\n','\r','\''), array('','','','\\\''), $text);

        $startpos = strpos($text, '<question type');
        $endpos = strpos($text, '</question>');
        if ($startpos === false || $endpos === false) {
            return false;
        }

        preg_match("/<question type=[\"\']([^\"\']+)[\"\']>/i", $text, $matches);
        $type = strtolower($matches[1]); // multichoice or multianswerchoice

        $questiontext = $this->unhtmlentities($this->stringbetween($text, '<text>', '</text>'));
        $questionhint = $this->unhtmlentities($this->stringbetween($text, '<hint>', '</hint>'));
        $questionaward = $this->stringbetween($text, '<award>', '</award>');
        $optionlist = $this->stringbetween($text, '<answer>', '</answer>');

        $optionlist = explode('<option', $optionlist);

        $n = 0;

        $optionscorrect = array();
        $optionstext = array();

        if ($type == 'multichoice') {
            foreach ($optionlist as $option) {
                $correct = $this->stringbetween($option, ' correct="', '">');
                $answer = $this->stringbetween($option, '">', '</option>');
                $optionscorrect[$n] = $correct; 
                $optionstext[$n] = $this->unhtmlentities($answer);
                ++$n;
            }
        } else if ($type == 'multianswerchoice') {
            $numcorrect = 0;
            $totalaward = 0;

            $optionsaward = array();

            foreach ($optionlist as $option) {
                preg_match("/correct=\"([^\"]*)\"/i", $option, $correctmatch);
                preg_match("/award=\"([^\"]*)\"/i", $option, $awardmatch);

                $correct = $correctmatch[1];
                $award = $awardmatch[1];
                if ($correct == 'yes') {
                    $totalaward += $award;
                    ++$numcorrect;
                }

                $answer = $this->stringbetween($option, '">', '</option>');

                $optionscorrect[$n] = $correct; 
                $optionstext[$n] = $this->unhtmlentities($answer);
                $optionsaward[$n] = $award;
                ++$n;
            }

        } else {
            echo "<p>I don't understand this question type (type = <strong>$type</strong>).</p>\n";
        }

        $question = $this->defaultquestion();
        $question->qtype = MULTICHOICE;
        $question->name = substr($questiontext, 0, 30);
        if (strlen($questiontext) > 30) {
            $question->name .= '...';
        }

        $question->questiontext = $questiontext;
        $question->single = ($type == 'multichoice') ? 1 : 0;
        $question->feedback[] = '';

        $question->fraction = array();
        $question->answer = array();
        for ($n = 0; $n < count($optionstext); ++$n) {
            if ($optionstext[$n]) {
                if (!isset($numcorrect)) { // single answer
                    if ($optionscorrect[$n] == 'yes') {
                        $fraction = (int) $questionaward; 
                    } else {
                        $fraction = 0;
                    } 
                } else { // mulitple answers
                    if ($optionscorrect[$n] == 'yes') {
                        $fraction = $optionsaward[$n] / $totalaward; 
                    } else {
                        $fraction = -$optionsaward[$n] / count($optionstext);
                    }
                }
                $question->fraction[] = $fraction;
                $question->answer[] = $optionstext[$n];
                $question->feedback[] = ''; // no feedback in this type
            }
        }

        return $question;
    }

    function stringbetween($text, $start, $end) {
        $startpos = strpos($text, $start) + strlen($start);
        $endpos = strpos($text, $end);

        if ($startpos <= $endpos) {
            return substr($text, $startpos, $endpos - $startpos);
        }
    }

    function unhtmlentities($string) {
        $transtable = get_html_translation_table(HTML_ENTITIES);
        $transtable = array_flip($transtable);
        return strtr($string, $transtable);
    } 

}

?>