<?php  // $Id$
/**
 * This page prints a particular instance of quiz
 *
 * @author Martin Dougiamas and many others. This has recently been completely
 *         rewritten by Alex Smith, Julian Sedding and Gustav Delius as part of
 *         the Serving Mathematics project
 *         {@link http://maths.york.ac.uk/serving_maths}
 * @license http://www.gnu.org/copyleft/gpl.html GNU Public License
 * @package quiz
 */

    require_once("../../config.php");
    require_once("locallib.php");

    // remember the current time as the time any responses were submitted
    // (so as to make sure students don't get penalized for slow processing on this page)
    $timestamp = time();

    // Get submitted parameters.
    $id = optional_param('id', 0, PARAM_INT);               // Course Module ID
    $q = optional_param('q', 0, PARAM_INT);                 // or quiz ID
    $page = optional_param('page', 0, PARAM_INT);
    $questionids = optional_param('questionids', '');
    $finishattempt = optional_param('finishattempt', 0, PARAM_BOOL);
    $timeup = optional_param('timeup', 0, PARAM_BOOL); // True if form was submitted by timer.
    $forcenew = optional_param('forcenew', false, PARAM_BOOL); // Teacher has requested new preview

    if ($id) {
        if (! $cm = get_coursemodule_from_id('quiz', $id)) {
            error("There is no coursemodule with id $id");
        }
        if (! $course = get_record("course", "id", $cm->course)) {
            error("Course is misconfigured");
        }
        if (! $quiz = get_record("quiz", "id", $cm->instance)) {
            error("The quiz with id $cm->instance corresponding to this coursemodule $id is missing");
        }
    } else {
        if (! $quiz = get_record("quiz", "id", $q)) {
            error("There is no quiz with id $q");
        }
        if (! $course = get_record("course", "id", $quiz->course)) {
            error("The course with id $quiz->course that the quiz with id $q belongs to is missing");
        }
        if (! $cm = get_coursemodule_from_instance("quiz", $quiz->id, $course->id)) {
            error("The course module for the quiz with id $q is missing");
        }
    }

    // We treat automatically closed attempts just like normally closed attempts
    if ($timeup) {
        $finishattempt = 1;
    }

    require_login($course->id, false, $cm);

    $coursecontext = get_context_instance(CONTEXT_COURSE, $cm->course); // course context
    $context = get_context_instance(CONTEXT_MODULE, $cm->id);
    $ispreviewing = has_capability('mod/quiz:preview', $context);

    // if no questions have been set up yet redirect to edit.php
    if (!$quiz->questions and has_capability('mod/quiz:manage', $context)) {
        redirect($CFG->wwwroot . '/mod/quiz/edit.php?cmid=' . $cm->id);
    }

    if (!$ispreviewing) {
        require_capability('mod/quiz:attempt', $context);
    }

/// Get number for the next or unfinished attempt
    if(!$attemptnumber = (int)get_field_sql('SELECT MAX(attempt)+1 FROM ' .
            "{$CFG->prefix}quiz_attempts WHERE quiz = '{$quiz->id}' AND " .
            "userid = '{$USER->id}' AND timefinish > 0 AND preview != 1")) {
        $attemptnumber = 1;
    }

    $strattemptnum = get_string('attempt', 'quiz', $attemptnumber);
    $strquizzes = get_string("modulenameplural", "quiz");
    $popup = $quiz->popup && !$ispreviewing; // Controls whether this is shown in a javascript-protected window or with a safe browser.

/// We intentionally do not check open and close times here. Instead we do it lower down.
/// This is to deal with what happens when someone submits close to the exact moment when the quiz closes.

/// Check number of attempts
    $numberofpreviousattempts = count_records_select('quiz_attempts', "quiz = '{$quiz->id}' AND " .
        "userid = '{$USER->id}' AND timefinish > 0 AND preview != 1");
    if (!empty($quiz->attempts) and $numberofpreviousattempts >= $quiz->attempts) {
        print_error('nomoreattempts', 'quiz', "view.php?id={$cm->id}");
    }

/// Check safe browser
    if (!$ispreviewing && $quiz->popup == 2 && !quiz_check_safe_browser()) {
        print_error('safebrowsererror', 'quiz', "view.php?id={$cm->id}");
    }

/// Check subnet access
    if (!$ispreviewing && !empty($quiz->subnet) && !address_in_subnet(getremoteaddr(), $quiz->subnet)) {
        print_error("subneterror", "quiz", "view.php?id=$cm->id");
    }

/// Check password access
    if ($ispreviewing && $forcenew) {
        unset($SESSION->passwordcheckedquizzes[$quiz->id]);
    }

    if (!empty($quiz->password) and empty($SESSION->passwordcheckedquizzes[$quiz->id])) {
        $enteredpassword = optional_param('quizpassword', '', PARAM_RAW);
        if (optional_param('cancelpassword', false)) {
            // User clicked cancel in the password form.
            redirect($CFG->wwwroot . '/mod/quiz/view.php?q=' . $quiz->id);
        } else if (strcmp($quiz->password, $enteredpassword) === 0) {
            // User entered the correct password.
            $SESSION->passwordcheckedquizzes[$quiz->id] = true;
        } else {
            // User entered the wrong password, or has not entered one yet.
            $url = $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . $quiz->id;

            print_header('', '', '', 'quizpassword');

            if (trim(strip_tags($quiz->intro))) {
                $formatoptions->noclean = true;
                print_box(format_text($quiz->intro, FORMAT_MOODLE, $formatoptions), 'generalbox', 'intro');
            }
            print_box_start('generalbox', 'passwordbox');
            if (!empty($enteredpassword)) {
                echo '<p class="notifyproblem">', get_string('passworderror', 'quiz'), '</p>';
            }
?>
<p><?php print_string('requirepasswordmessage', 'quiz'); ?></p>
<form id="passwordform" method="post" action="<?php echo $url; ?>" onclick="this.autocomplete='off'">
    <div>
         <label for="quizpassword"><?php print_string('password'); ?></label>
         <input name="quizpassword" id="quizpassword" type="password" value=""/>
         <input type="submit" value="<?php print_string('ok'); ?>" />
         <input type="submit" name="cancelpassword" value="<?php print_string('cancel'); ?>" />
    </div>
</form>
<?php
            print_box_end();
            print_footer('empty');
            exit;
        }
    }

    if (!empty($quiz->delay1) or !empty($quiz->delay2)) {
        //quiz enforced time delay
        if ($attempts = quiz_get_user_attempts($quiz->id, $USER->id)) {
            $numattempts = count($attempts);
        } else {
            $numattempts = 0;
        }
        $timenow = time();
        $lastattempt_obj = get_record_select('quiz_attempts',
                "quiz = $quiz->id AND attempt = $numattempts AND userid = $USER->id",
                'timefinish, timestart');
        if ($lastattempt_obj) {
            $lastattempt = $lastattempt_obj->timefinish;
            if ($quiz->timelimit > 0) {
                $lastattempt = min($lastattempt, $lastattempt_obj->timestart + $quiz->timelimit*60);
            }
        }
        if ($numattempts == 1 && !empty($quiz->delay1)) {
            if ($timenow - $quiz->delay1 < $lastattempt) {
                print_error('timedelay', 'quiz', 'view.php?q='.$quiz->id);
            }
        } else if($numattempts > 1 && !empty($quiz->delay2)) {
            if ($timenow - $quiz->delay2 < $lastattempt) {
                print_error('timedelay', 'quiz', 'view.php?q='.$quiz->id);
            }
        }
    }

/// Load attempt or create a new attempt if there is no unfinished one

    if ($ispreviewing and $forcenew) { // teacher wants a new preview
        // so we set a finish time on the current attempt (if any).
        // It will then automatically be deleted below
        set_field('quiz_attempts', 'timefinish', $timestamp, 'quiz', $quiz->id, 'userid', $USER->id);
    }

    $attempt = quiz_get_user_attempt_unfinished($quiz->id, $USER->id);

    $newattempt = false;
    if (!$attempt) {
        // Delete any previous preview attempts belonging to this user.
        if ($oldattempts = get_records_select('quiz_attempts', "quiz = '$quiz->id'
                AND userid = '$USER->id' AND preview = 1")) {
            foreach ($oldattempts as $oldattempt) {
                quiz_delete_attempt($oldattempt, $quiz);
            }
        }
        $newattempt = true;
        // Start a new attempt and initialize the question sessions
        $attempt = quiz_create_attempt($quiz, $attemptnumber);
        // If this is an attempt by a teacher mark it as a preview
        if ($ispreviewing) {
            $attempt->preview = 1;
        }
        // Save the attempt
        if (!$attempt->id = insert_record('quiz_attempts', $attempt)) {
            error('Could not create new attempt');
        }
        // make log entries
        if ($ispreviewing) {
            add_to_log($course->id, 'quiz', 'preview',
                           "attempt.php?id=$cm->id",
                           "$quiz->id", $cm->id);
        } else {
            add_to_log($course->id, 'quiz', 'attempt',
                           "review.php?attempt=$attempt->id",
                           "$quiz->id", $cm->id);
        }
    } else {
         add_to_log($course->id, 'quiz', 'continue attemp', // this action used to be called 'continue attempt' but the database field has only 15 characters
                       'review.php?attempt=' . $attempt->id, $quiz->id, $cm->id);
    }
    if (!$attempt->timestart) { // shouldn't really happen, just for robustness
        debugging('timestart was not set for this attempt. That should be impossible.', DEBUG_DEVELOPER);
        $attempt->timestart = $timestamp - 1;
    }

/// Load all the questions and states needed by this script

    // list of questions needed by page
    $pagelist = quiz_questions_on_page($attempt->layout, $page);

    if ($newattempt) {
        $questionlist = quiz_questions_in_quiz($attempt->layout);
    } else {
        $questionlist = $pagelist;
    }

    // add all questions that are on the submitted form
    if ($questionids) {
        $questionlist .= ','.$questionids;
    }

    if (!$questionlist) {
        print_error('noquestionsfound', 'quiz', 'view.php?q='.$quiz->id);
    }

    $sql = "SELECT q.*, i.grade AS maxgrade, i.id AS instance".
           "  FROM {$CFG->prefix}question q,".
           "       {$CFG->prefix}quiz_question_instances i".
           " WHERE i.quiz = '$quiz->id' AND q.id = i.question".
           "   AND q.id IN ($questionlist)";

    // Load the questions
    if (!$questions = get_records_sql($sql)) {
        print_error('noquestionsfound', 'quiz', 'view.php?q='.$quiz->id);
    }

    // Load the question type specific information
    if (!get_question_options($questions)) {
        error('Could not load question options');
    }

    // If the new attempt is to be based on a previous attempt find its id
    $lastattemptid = false;
    if ($newattempt and $attempt->attempt > 1 and $quiz->attemptonlast and !$attempt->preview) {
        // Find the previous attempt
        if (!$lastattemptid = get_field('quiz_attempts', 'uniqueid', 'quiz', $attempt->quiz, 'userid', $attempt->userid, 'attempt', $attempt->attempt-1)) {
            error('Could not find previous attempt to build on');
        }
    }

    // Restore the question sessions to their most recent states
    // creating new sessions where required
    if (!$states = get_question_states($questions, $quiz, $attempt, $lastattemptid)) {
        error('Could not restore question sessions');
    }

    // Save all the newly created states
    if ($newattempt) {
        foreach ($questions as $i => $question) {
            save_question_session($questions[$i], $states[$i]);
        }
    }

/// Process form data /////////////////////////////////////////////////

    if ($responses = data_submitted() and empty($responses->quizpassword)) {

        // set the default event. This can be overruled by individual buttons.
        $event = (array_key_exists('markall', $responses)) ? QUESTION_EVENTSUBMIT :
         ($finishattempt ? QUESTION_EVENTCLOSE : QUESTION_EVENTSAVE);

        // Unset any variables we know are not responses
        unset($responses->id);
        unset($responses->q);
        unset($responses->oldpage);
        unset($responses->newpage);
        unset($responses->review);
        unset($responses->questionids);
        unset($responses->saveattempt); // responses get saved anway
        unset($responses->finishattempt); // same as $finishattempt
        unset($responses->markall);
        unset($responses->forcenewattempt);

        // extract responses
        // $actions is an array indexed by the questions ids
        $actions = question_extract_responses($questions, $responses, $event);

        // Process each question in turn

        $questionidarray = explode(',', $questionids);
        $success = true;
        foreach($questionidarray as $i) {
            if (!isset($actions[$i])) {
                $actions[$i]->responses = array('' => '');
                $actions[$i]->event = QUESTION_EVENTOPEN;
            }
            $actions[$i]->timestamp = $timestamp;
            if (question_process_responses($questions[$i], $states[$i], $actions[$i], $quiz, $attempt)) {
                save_question_session($questions[$i], $states[$i]);
            } else {
                $success = false;
            }
        }

        if (!$success) {
            $pagebit = '';
            if ($page) {
                $pagebit = '&amp;page=' . $page;
            }
            print_error('errorprocessingresponses', 'question',
                    $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . $quiz->id . $pagebit);
        }

        $attempt->timemodified = $timestamp;

    // We have now finished processing form data
    }

/// Finish attempt if requested
    if ($finishattempt) {

        // Set the attempt to be finished
        $attempt->timefinish = $timestamp;

        // load all the questions
        $closequestionlist = quiz_questions_in_quiz($attempt->layout);
        $sql = "SELECT q.*, i.grade AS maxgrade, i.id AS instance".
               "  FROM {$CFG->prefix}question q,".
               "       {$CFG->prefix}quiz_question_instances i".
               " WHERE i.quiz = '$quiz->id' AND q.id = i.question".
               "   AND q.id IN ($closequestionlist)";
        if (!$closequestions = get_records_sql($sql)) {
            error('Questions missing');
        }

        // Load the question type specific information
        if (!get_question_options($closequestions)) {
            error('Could not load question options');
        }

        // Restore the question sessions
        if (!$closestates = get_question_states($closequestions, $quiz, $attempt)) {
            error('Could not restore question sessions');
        }

        $success = true;
        foreach($closequestions as $key => $question) {
            $action->event = QUESTION_EVENTCLOSE;
            $action->responses = $closestates[$key]->responses;
            $action->timestamp = $closestates[$key]->timestamp;
            
            if (question_process_responses($question, $closestates[$key], $action, $quiz, $attempt)) {
                save_question_session($question, $closestates[$key]);
            } else {
                $success = false;
            }
        }

        if (!$success) {
            $pagebit = '';
            if ($page) {
                $pagebit = '&amp;page=' . $page;
            }
            print_error('errorprocessingresponses', 'question',
                    $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . $quiz->id . $pagebit);
        }

        add_to_log($course->id, 'quiz', 'close attempt', 'review.php?attempt=' . $attempt->id, $quiz->id, $cm->id);
    }

/// Update the quiz attempt and the overall grade for the quiz
    if ($responses || $finishattempt) {
        if (!update_record('quiz_attempts', $attempt)) {
            error('Failed to save the current quiz attempt!');
        }
        if (($attempt->attempt > 1 || $attempt->timefinish > 0) and !$attempt->preview) {
            quiz_save_best_grade($quiz);
        }
    }

/// Send emails to those who have the capability set
    if ($finishattempt && !$attempt->preview) {
        quiz_send_notification_emails($course, $quiz, $attempt, $context, $cm);
    }

    if ($finishattempt) {
        if (!empty($SESSION->passwordcheckedquizzes[$quiz->id])) {
            unset($SESSION->passwordcheckedquizzes[$quiz->id]);
        }
        redirect($CFG->wwwroot . '/mod/quiz/review.php?attempt='.$attempt->id, 0);
    }

// Now is the right time to check the open and close times.
    if (!$ispreviewing && ($timestamp < $quiz->timeopen || ($quiz->timeclose && $timestamp > $quiz->timeclose))) {
        print_error('notavailable', 'quiz', "view.php?id={$cm->id}");
    }

/// Print the quiz page ////////////////////////////////////////////////////////

    // Print the page header
    require_js($CFG->wwwroot . '/mod/quiz/quiz.js');
    $pagequestions = explode(',', $pagelist);
    $headtags = get_html_head_contributions($pagequestions, $questions, $states);
    if (!$ispreviewing && $quiz->popup) {
        define('MESSAGE_WINDOW', true);  // This prevents the message window coming up
        print_header($course->shortname.': '.format_string($quiz->name), '', '', '', $headtags, false, '', '', false, ' class="securewindow"');
        if ($quiz->popup == 1) {
            include('protect_js.php');
        }
    } else {
        $strupdatemodule = has_capability('moodle/course:manageactivities', $coursecontext)
                    ? update_module_button($cm->id, $course->id, get_string('modulename', 'quiz'))
                    : "";
        $navigation = build_navigation($strattemptnum, $cm);
        print_header_simple(format_string($quiz->name), "", $navigation, "", $headtags, true, $strupdatemodule);
    }

    echo '<div id="overDiv" style="position:absolute; visibility:hidden; z-index:1000;"></div>'; // for overlib

    // Print the quiz name heading and tabs for teacher, etc.
    if ($ispreviewing) {
        $currenttab = 'preview';
        include('tabs.php');

        print_heading(get_string('previewquiz', 'quiz', format_string($quiz->name)));
        unset($buttonoptions);
        $buttonoptions['q'] = $quiz->id;
        $buttonoptions['forcenew'] = true;
        echo '<div class="controls">';
        print_single_button($CFG->wwwroot.'/mod/quiz/attempt.php', $buttonoptions, get_string('startagain', 'quiz'));
        echo '</div>';
    /// Notices about restrictions that would affect students.
        if ($quiz->popup == 1) {
            notify(get_string('popupnotice', 'quiz'));
        } else if ($quiz->popup == 2) {
            notify(get_string('safebrowsernotice', 'quiz'));
        }
        if ($timestamp < $quiz->timeopen || ($quiz->timeclose && $timestamp > $quiz->timeclose)) {
            notify(get_string('notavailabletostudents', 'quiz'));
        }
        if ($quiz->subnet && !address_in_subnet(getremoteaddr(), $quiz->subnet)) {
            notify(get_string('subnetnotice', 'quiz'));
        }
    } else {
        if ($quiz->attempts != 1) {
            print_heading(format_string($quiz->name).' - '.$strattemptnum);
        } else {
            print_heading(format_string($quiz->name));
        }
    }

    // Start the form
    $quiz->thispageurl = $CFG->wwwroot . '/mod/quiz/attempt.php?q=' . s($quiz->id) . '&amp;page=' . s($page);
    $quiz->cmid = $cm->id;
    echo '<form id="responseform" method="post" action="', $quiz->thispageurl . '" enctype="multipart/form-data"' .
            ' onkeypress="return check_enter(event);" accept-charset="utf-8">', "\n";
    echo '<script type="text/javascript">', "\n",
            'document.getElementById("responseform").setAttribute("autocomplete", "off")', "\n",
            "</script>\n";
    if ($quiz->timelimit > 0) {
        // Make sure javascript is enabled for time limited quizzes
        ?>
        <script type="text/javascript">
            // Do nothing, but you have to have a script tag before a noscript tag.
        </script>
        <noscript>
        <div>
        <?php print_heading(get_string('noscript', 'quiz')); ?>
        </div>
        </noscript>
        <?php
    }
    echo '<div>';

/// Print the navigation panel if required
    $numpages = quiz_number_of_pages($attempt->layout);
    if ($numpages > 1) {
        quiz_print_navigation_panel($page, $numpages);
    }

/// Print all the questions
    $number = quiz_first_questionnumber($attempt->layout, $pagelist);
    foreach ($pagequestions as $i) {
        $options = quiz_get_renderoptions($quiz->review, $states[$i]);
        // Print the question
        print_question($questions[$i], $states[$i], $number, $quiz, $options);
        save_question_session($questions[$i], $states[$i]);
        $number += $questions[$i]->length;
    }

/// Print the submit buttons
    $strconfirmattempt = addslashes(get_string("confirmclose", "quiz"));
    $onclick = "return confirm('$strconfirmattempt')";
    echo "<div class=\"submitbtns mdl-align\">\n";

    echo "<input type=\"submit\" name=\"saveattempt\" value=\"".get_string("savenosubmit", "quiz")."\" />\n";
    if ($quiz->optionflags & QUESTION_ADAPTIVE) {
        echo "<input type=\"submit\" name=\"markall\" value=\"".get_string("markall", "quiz")."\" />\n";
    }
    echo "<input type=\"submit\" name=\"finishattempt\" value=\"".get_string("finishattempt", "quiz")."\" onclick=\"$onclick\" />\n";

    echo "</div>";

    // Print the navigation panel if required
    if ($numpages > 1) {
        quiz_print_navigation_panel($page, $numpages);
    }

    // Finish the form
    echo '</div>';
    echo '<input type="hidden" name="timeup" id="timeup" value="0" />';

    // Add a hidden field with questionids. Do this at the end of the form, so 
    // if you navigate before the form has finished loading, it does not wipe all
    // the student's answers.
    echo '<input type="hidden" name="questionids" value="'.$pagelist."\" />\n";

    echo "</form>\n";

    // If the quiz has a time limit, or if we are close to the close time, include a floating timer.
    $showtimer = false;
    $timerstartvalue = 999999999999;
    if ($quiz->timeclose) {
        $timerstartvalue = min($timerstartvalue, $quiz->timeclose - time());
        $showtimer = $timerstartvalue < 60*60; // Show the timer if we are less than 60 mins from the deadline.
    }
    if ($quiz->timelimit > 0 && !has_capability('mod/quiz:ignoretimelimits', $context, NULL, false)) {
        $timerstartvalue = min($timerstartvalue, $attempt->timestart + $quiz->timelimit*60- time());
        $showtimer = true;
    }
    if ($showtimer && (!$ispreviewing || $timerstartvalue > 0)) {
        $timerstartvalue = max($timerstartvalue, 1); // Make sure it starts just above zero.
        require('jstimer.php');
    }

    // Finish the page
    if (empty($popup)) {
        print_footer($course);
    }
?>
