<?php

// This file is part of Moodle - http://moodle.org/
//
// Moodle 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 3 of the License, or
// (at your option) any later version.
//
// Moodle 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 Moodle.  If not, see <http://www.gnu.org/licenses/>.

/**
 * This page is the entry page into the quiz UI. Displays information about the
 * quiz to students and teachers, and lets students see their previous attempts.
 *
 * @package    mod
 * @subpackage quiz
 * @copyright  1999 onwards Martin Dougiamas  {@link http://moodle.com}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */


require_once(dirname(__FILE__) . '/../../config.php');
require_once($CFG->libdir.'/gradelib.php');
require_once($CFG->dirroot.'/mod/quiz/locallib.php');
require_once($CFG->libdir . '/completionlib.php');

$id = optional_param('id', 0, PARAM_INT); // Course Module ID, or
$q = optional_param('q',  0, PARAM_INT);  // quiz ID

if ($id) {
    if (!$cm = get_coursemodule_from_id('quiz', $id)) {
        print_error('invalidcoursemodule');
    }
    if (!$course = $DB->get_record('course', array('id' => $cm->course))) {
        print_error('coursemisconf');
    }
    if (!$quiz = $DB->get_record('quiz', array('id' => $cm->instance))) {
        print_error('invalidcoursemodule');
    }
} else {
    if (!$quiz = $DB->get_record('quiz', array('id' => $q))) {
        print_error('invalidquizid', 'quiz');
    }
    if (!$course = $DB->get_record('course', array('id' => $quiz->course))) {
        print_error('invalidcourseid');
    }
    if (!$cm = get_coursemodule_from_instance("quiz", $quiz->id, $course->id)) {
        print_error('invalidcoursemodule');
    }
}

// Check login and get context.
require_login($course->id, false, $cm);
$context = get_context_instance(CONTEXT_MODULE, $cm->id);
require_capability('mod/quiz:view', $context);

// Cache some other capabilities we use several times.
$canattempt = has_capability('mod/quiz:attempt', $context);
$canreviewmine = has_capability('mod/quiz:reviewmyattempts', $context);
$canpreview = has_capability('mod/quiz:preview', $context);

// Create an object to manage all the other (non-roles) access rules.
$timenow = time();
$accessmanager = new quiz_access_manager(quiz::create($quiz->id, $USER->id), $timenow,
        has_capability('mod/quiz:ignoretimelimits', $context, null, false));

// Log this request.
add_to_log($course->id, 'quiz', 'view', 'view.php?id=' . $cm->id, $quiz->id, $cm->id);

// Initialize $PAGE, compute blocks
$PAGE->set_url('/mod/quiz/view.php', array('id' => $cm->id));

$edit = optional_param('edit', -1, PARAM_BOOL);
if ($edit != -1 && $PAGE->user_allowed_editing()) {
    $USER->editing = $edit;
}

$title = $course->shortname . ': ' . format_string($quiz->name);
$PAGE->set_title($title);
$PAGE->set_heading($course->fullname);
echo $OUTPUT->header();

// Print quiz name and description
echo $OUTPUT->heading(format_string($quiz->name));
if (trim(strip_tags($quiz->intro))) {
    echo $OUTPUT->box(format_module_intro('quiz', $quiz, $cm->id), 'generalbox', 'intro');
}

// Display information about this quiz.
$messages = $accessmanager->describe_rules();
if ($quiz->attempts != 1) {
    $messages[] = get_string('gradingmethod', 'quiz',
            quiz_get_grading_option_name($quiz->grademethod));
}
echo $OUTPUT->box_start('quizinfo');
$accessmanager->print_messages($messages);
echo $OUTPUT->box_end();

// Show number of attempts summary to those who can view reports.
if (has_capability('mod/quiz:viewreports', $context)) {
    if ($strattemptnum = quiz_attempt_summary_link_to_reports($quiz, $cm, $context)) {
        echo '<div class="quizattemptcounts">' . $strattemptnum . "</div>\n";
    }
}

// Guests can't do a quiz, so offer them a choice of logging in or going back.
if (isguestuser()) {
    echo $OUTPUT->confirm('<p>' . get_string('guestsno', 'quiz') . "</p>\n\n<p>" .
            get_string('liketologin') . "</p>\n", get_login_url(), get_referer(false));
    echo $OUTPUT->footer();
    exit;
}

// If they are not enrolled in this course in a good enough role, tell them to enrol.
if (!($canattempt || $canpreview || $canreviewmine)) {
    echo $OUTPUT->box('<p>' . get_string('youneedtoenrol', 'quiz') . "</p>\n\n<p>" .
            $OUTPUT->continue_button($CFG->wwwroot . '/course/view.php?id=' . $course->id) .
            "</p>\n", 'generalbox', 'notice');
    echo $OUTPUT->footer();
    exit;
}

// Update the quiz with overrides for the current user
$quiz = quiz_update_effective_access($quiz, $USER->id);

// Get this user's attempts.
$attempts = quiz_get_user_attempts($quiz->id, $USER->id, 'finished', true);
$lastfinishedattempt = end($attempts);
$unfinished = false;
if ($unfinishedattempt = quiz_get_user_attempt_unfinished($quiz->id, $USER->id)) {
    $attempts[] = $unfinishedattempt;
    $unfinished = true;
}
$numattempts = count($attempts);

// Work out the final grade, checking whether it was overridden in the gradebook.
$mygrade = quiz_get_best_grade($quiz, $USER->id);
$mygradeoverridden = false;
$gradebookfeedback = '';

$grading_info = grade_get_grades($course->id, 'mod', 'quiz', $quiz->id, $USER->id);
if (!empty($grading_info->items)) {
    $item = $grading_info->items[0];
    if (isset($item->grades[$USER->id])) {
        $grade = $item->grades[$USER->id];

        if ($grade->overridden) {
            $mygrade = $grade->grade + 0; // Convert to number.
            $mygradeoverridden = true;
        }
        if (!empty($grade->str_feedback)) {
            $gradebookfeedback = $grade->str_feedback;
        }
    }
}

// Print table with existing attempts
if ($attempts) {

    echo $OUTPUT->heading(get_string('summaryofattempts', 'quiz'));

    // Work out which columns we need, taking account what data is available in each attempt.
    list($someoptions, $alloptions) = quiz_get_combined_reviewoptions($quiz, $attempts, $context);

    $attemptcolumn = $quiz->attempts != 1;

    $gradecolumn = $someoptions->marks >= question_display_options::MARK_AND_MAX &&
            quiz_has_grades($quiz);
    $markcolumn = $gradecolumn && ($quiz->grade != $quiz->sumgrades);
    $overallstats = $alloptions->marks >= question_display_options::MARK_AND_MAX;

    $feedbackcolumn = quiz_has_feedback($quiz) && $alloptions->overallfeedback;

    // Prepare table header
    $table = new html_table();
    $table->attributes['class'] = 'generaltable quizattemptsummary';
    $table->head = array();
    $table->align = array();
    $table->size = array();
    if ($attemptcolumn) {
        $table->head[] = get_string('attemptnumber', 'quiz');
        $table->align[] = 'center';
        $table->size[] = '';
    }
    $table->head[] = get_string('timecompleted', 'quiz');
    $table->align[] = 'left';
    $table->size[] = '';
    if ($markcolumn) {
        $table->head[] = get_string('marks', 'quiz') . ' / ' .
                quiz_format_grade($quiz, $quiz->sumgrades);
        $table->align[] = 'center';
        $table->size[] = '';
    }
    if ($gradecolumn) {
        $table->head[] = get_string('grade') . ' / ' .
                quiz_format_grade($quiz, $quiz->grade);
        $table->align[] = 'center';
        $table->size[] = '';
    }
    if ($canreviewmine) {
        $table->head[] = get_string('review', 'quiz');
        $table->align[] = 'center';
        $table->size[] = '';
    }
    if ($feedbackcolumn) {
        $table->head[] = get_string('feedback', 'quiz');
        $table->align[] = 'left';
        $table->size[] = '';
    }
    if (isset($quiz->showtimetaken)) {
        $table->head[] = get_string('timetaken', 'quiz');
        $table->align[] = 'left';
        $table->size[] = '';
    }

    // One row for each attempt
    foreach ($attempts as $attempt) {
        $attemptoptions = quiz_get_review_options($quiz, $attempt, $context);
        $row = array();

        // Add the attempt number, making it a link, if appropriate.
        if ($attemptcolumn) {
            if ($attempt->preview) {
                $row[] = get_string('preview', 'quiz');
            } else {
                $row[] = $attempt->attempt;
            }
        }

        // prepare strings for time taken and date completed
        $timetaken = '';
        $datecompleted = '';
        if ($attempt->timefinish > 0) {
            // attempt has finished
            $timetaken = format_time($attempt->timefinish - $attempt->timestart);
            $datecompleted = userdate($attempt->timefinish);
        } else if (!$quiz->timeclose || $timenow < $quiz->timeclose) {
            // The attempt is still in progress.
            $timetaken = format_time($timenow - $attempt->timestart);
            $datecompleted = get_string('inprogress', 'quiz');
        } else {
            $timetaken = format_time($quiz->timeclose - $attempt->timestart);
            $datecompleted = userdate($quiz->timeclose);
        }
        $row[] = $datecompleted;

        if ($markcolumn && $attempt->timefinish > 0) {
            if ($attemptoptions->marks >= question_display_options::MARK_AND_MAX) {
                $row[] = quiz_format_grade($quiz, $attempt->sumgrades);
            } else {
                $row[] = '';
            }
        }

        // Ouside the if because we may be showing feedback but not grades.
        $attemptgrade = quiz_rescale_grade($attempt->sumgrades, $quiz, false);

        if ($gradecolumn) {
            if ($attemptoptions->marks >= question_display_options::MARK_AND_MAX &&
                    $attempt->timefinish > 0) {
                $formattedgrade = quiz_format_grade($quiz, $attemptgrade);
                // highlight the highest grade if appropriate
                if ($overallstats && !$attempt->preview && $numattempts > 1 && !is_null($mygrade) &&
                        $attemptgrade == $mygrade && $quiz->grademethod == QUIZ_GRADEHIGHEST) {
                    $table->rowclasses[$attempt->attempt] = 'bestrow';
                }

                $row[] = $formattedgrade;
            } else {
                $row[] = '';
            }
        }

        if ($canreviewmine) {
            $row[] = $accessmanager->make_review_link($attempt, $canpreview, $attemptoptions);
        }

        if ($feedbackcolumn && $attempt->timefinish > 0) {
            if ($attemptoptions->overallfeedback) {
                $row[] = quiz_feedback_for_grade($attemptgrade, $quiz, $context, $cm);
            } else {
                $row[] = '';
            }
        }

        if (isset($quiz->showtimetaken)) {
            $row[] = $timetaken;
        }

        if ($attempt->preview) {
            $table->data['preview'] = $row;
        } else {
            $table->data[$attempt->attempt] = $row;
        }
    } // End of loop over attempts.
    echo html_writer::table($table);
}

// Print information about the student's best score for this quiz if possible.
$moreattempts = $unfinished || !$accessmanager->is_finished($numattempts, $lastfinishedattempt);
if (!$moreattempts) {
    echo $OUTPUT->heading(get_string('nomoreattempts', 'quiz'));
}

if ($numattempts && $gradecolumn && !is_null($mygrade)) {
    $resultinfo = '';

    if ($overallstats) {
        if ($moreattempts) {
            $a = new stdClass();
            $a->method = quiz_get_grading_option_name($quiz->grademethod);
            $a->mygrade = quiz_format_grade($quiz, $mygrade);
            $a->quizgrade = quiz_format_grade($quiz, $quiz->grade);
            $resultinfo .= $OUTPUT->heading(get_string('gradesofar', 'quiz', $a), 2, 'main');
        } else {
            $a = new stdClass();
            $a->grade = quiz_format_grade($quiz, $mygrade);
            $a->maxgrade = quiz_format_grade($quiz, $quiz->grade);
            $a = get_string('outofshort', 'quiz', $a);
            $resultinfo .= $OUTPUT->heading(get_string('yourfinalgradeis', 'quiz', $a), 2, 'main');
        }
    }

    if ($mygradeoverridden) {
        $resultinfo .= '<p class="overriddennotice">' .
                get_string('overriddennotice', 'grades') . "</p>\n";
    }
    if ($gradebookfeedback) {
        $resultinfo .= $OUTPUT->heading(get_string('comment', 'quiz'), 3, 'main');
        $resultinfo .= '<p class="quizteacherfeedback">'.$gradebookfeedback."</p>\n";
    }
    if ($feedbackcolumn) {
        $resultinfo .= $OUTPUT->heading(get_string('overallfeedback', 'quiz'), 3, 'main');
        $resultinfo .= '<p class="quizgradefeedback">' .
                quiz_feedback_for_grade($mygrade, $quiz, $context, $cm) . "</p>\n";
    }

    if ($resultinfo) {
        echo $OUTPUT->box($resultinfo, 'generalbox', 'feedback');
    }
}

// Determine if we should be showing a start/continue attempt button,
// or a button to go back to the course page.
echo $OUTPUT->box_start('quizattempt');
$buttontext = ''; // This will be set something if as start/continue attempt button should appear.
if (!quiz_clean_layout($quiz->questions, true)) {
    echo quiz_no_questions_message($quiz, $cm, $context);
    $buttontext = '';

} else {
    if ($unfinished) {
        if ($canattempt) {
            $buttontext = get_string('continueattemptquiz', 'quiz');
        } else if ($canpreview) {
            $buttontext = get_string('continuepreview', 'quiz');
        }

    } else {
        if ($canattempt) {
            $messages = $accessmanager->prevent_new_attempt($numattempts, $lastfinishedattempt);
            if ($messages) {
                $accessmanager->print_messages($messages);
            } else if ($numattempts == 0) {
                $buttontext = get_string('attemptquiznow', 'quiz');
            } else {
                $buttontext = get_string('reattemptquiz', 'quiz');
            }

        } else if ($canpreview) {
            $buttontext = get_string('previewquiznow', 'quiz');
        }
    }

    // If, so far, we think a button should be printed, so check if they will be
    // allowed to access it.
    if ($buttontext) {
        if (!$moreattempts) {
            $buttontext = '';
        } else if ($canattempt && $messages = $accessmanager->prevent_access()) {
            $accessmanager->print_messages($messages);
            $buttontext = '';
        }
    }
}

// Now actually print the appropriate button.
if ($buttontext) {
    $accessmanager->print_start_attempt_button($canpreview, $buttontext, $unfinished);
} else if ($buttontext === '') {
    echo $OUTPUT->single_button(new moodle_url('/course/view.php', array('id' => $course->id)),
            get_string('backtocourse', 'quiz'), 'get', array('class' => 'continuebutton'));
}
echo $OUTPUT->box_end();

// Mark module as viewed (note, we do this here and not in finish_page,
// otherwise the 'not enrolled' error conditions would result in marking
// 'viewed', I think it's better if they don't.)
$completion = new completion_info($course);
$completion->set_module_viewed($cm);

echo $OUTPUT->footer();