item analysis report contributed by Enrique Castro

[moodle.git] / mod / quiz / report / analysis / report.php

<?php  // $Id$

/// Item analysis displays a table of quiz questions and their performance 

    require_once("locallib.php");
    require_once($CFG->libdir.'/tablelib.php');


function stats_sumx($sum, $data){
    $sum[0] += $data[0];
    $sum[1] += $data[1];
    return $sum;
}       

function stats_sumx2($sum, $data){
    $sum[0] += $data[0]*$data[0];
    $sum[1] += $data[1]*$data[1];
    return $sum;
}    

function stats_sumxy($sum, $data){
    $sum[0] += $data[0]*$data[1];
    return $sum;
}    


/// Item analysis displays a table of quiz questions and their performance 

class quiz_report extends quiz_default_report {

    function display($quiz, $cm, $course) {     /// This function just displays the report

        global $CFG, $SESSION, $db, $QUIZ_QTYPES;
        define(QUIZ_ALLATTEMPTS, 0);
        define(QUIZ_HIGHESTATTEMPT, 1);
        define(QUIZ_FIRSTATTEMPT, 2);
        define(QUIZ_LASTATTEMPT, 3);

        $strnoquiz = get_string('noquiz','quiz');
        $strnoattempts = get_string('noattempts','quiz');
        $strtimeformat = get_string('strftimedatetime');
        
        if (!$quiz->questions) {
            print_heading($strnoattempts);
            return true;
        }
        
    /// Check to see if groups are being used in this quiz
        if ($groupmode = groupmode($course, $cm)) {   // Groups are being used
            $currentgroup = setup_and_print_groups($course, $groupmode, "report.php?id=$cm->id&amp;mode=overview");
        } else {
            $currentgroup = false;
        }

    /// Get all users: teachers and students
        if ($currentgroup) {
            $users = get_group_users($currentgroup);
        }
        else {
            $users = get_course_users($course->id);
        }
        
    /// Remove teachers 
        $teachers = get_course_teachers($course->id);
        if(!empty($teachers)) {
            $keys = array_keys($teachers);
        }
        foreach($keys as $key) {
            unset($users[$key]);
        }

        if(empty($users)) {
            print_heading($strnoattempts);
            return true;
        }
        
        // set tTable and Analysis stats options
        if(!isset($SESSION->quiz_analysis_table)) {
            $SESSION->quiz_analysis_table = array('attemptselection' => 0, 'lowmarklimit' => 0);
        }

        foreach($SESSION->quiz_analysis_table as $option => $value) {
            $urlparam = optional_param($option, NULL);
            if($urlparam === NULL) {
                $$option = $value;
            }
            else {
                $$option = $SESSION->quiz_analysis_table[$option] = $urlparam;
            }
        }
      
        $scorelimit = $quiz->grade * $lowmarklimit/ 100;
        
        // ULPGC ecastro DEBUG this is here to allow for differnt SQL to select attempts
        switch ($attemptselection) {
        case QUIZ_ALLATTEMPTS : 
            $limit = '';
            $group = '';
            break;
        case QUIZ_HIGHESTATTEMPT :
            $limit = ', max(qa.sumgrades) ';
            $group = ' GROUP BY qa.userid ';
            break;
        case QUIZ_FIRSTATTEMPT :
            $limit = ', min(qa.timemodified) ';
            $group = ' GROUP BY qa.userid ';            
            break;
        case QUIZ_LASTATTEMPT : 
            $limit = ', max(qa.timemodified) ';
            $group = ' GROUP BY qa.userid ';            
            break;
        }

        $select = 'SELECT  qa.* '.$limit;
        $sql = 'FROM '.$CFG->prefix.'user u '.
               'LEFT JOIN '.$CFG->prefix.'quiz_attempts qa ON u.id = qa.userid '.
               'LEFT JOIN '.$CFG->prefix.'quiz_states qr ON qr.attempt = qa.id '.   // es posible 
               'WHERE u.id IN ('.implode(',', array_keys($users)).') AND ( qa.quiz = '.$quiz->id.') '. // ULPGC ecastro
               ' AND ( qa.sumgrades >= '.$scorelimit.' ) ';