/mod/lesson/locallib.php

Large files files are truncated, but you can click here to view the full file

<?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/>.

/**
 * Local library file for Lesson.  These are non-standard functions that are used
 * only by Lesson.
 *
 * @package    mod
 * @subpackage lesson
 * @copyright 1999 onwards Martin Dougiamas  {@link http://moodle.com}
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or late
 **/

/** Make sure this isn't being directly accessed */
defined('MOODLE_INTERNAL') || die();

/** Include the files that are required by this module */
require_once($CFG->dirroot.'/course/moodleform_mod.php');
require_once($CFG->dirroot . '/mod/lesson/lib.php');
require_once($CFG->libdir . '/filelib.php');

/** This page */
define('LESSON_THISPAGE', 0);
/** Next page -> any page not seen before */
define("LESSON_UNSEENPAGE", 1);
/** Next page -> any page not answered correctly */
define("LESSON_UNANSWEREDPAGE", 2);
/** Jump to Next Page */
define("LESSON_NEXTPAGE", -1);
/** End of Lesson */
define("LESSON_EOL", -9);
/** Jump to an unseen page within a branch and end of branch or end of lesson */
define("LESSON_UNSEENBRANCHPAGE", -50);
/** Jump to Previous Page */
define("LESSON_PREVIOUSPAGE", -40);
/** Jump to a random page within a branch and end of branch or end of lesson */
define("LESSON_RANDOMPAGE", -60);
/** Jump to a random Branch */
define("LESSON_RANDOMBRANCH", -70);
/** Cluster Jump */
define("LESSON_CLUSTERJUMP", -80);
/** Undefined */
define("LESSON_UNDEFINED", -99);

/** LESSON_MAX_EVENT_LENGTH = 432000 ; 5 days maximum */
define("LESSON_MAX_EVENT_LENGTH", "432000");


//////////////////////////////////////////////////////////////////////////////////////
/// Any other lesson functions go here.  Each of them must have a name that
/// starts with lesson_

/**
 * Checks to see if a LESSON_CLUSTERJUMP or
 * a LESSON_UNSEENBRANCHPAGE is used in a lesson.
 *
 * This function is only executed when a teacher is
 * checking the navigation for a lesson.
 *
 * @param stdClass $lesson Id of the lesson that is to be checked.
 * @return boolean True or false.
 **/
function lesson_display_teacher_warning($lesson) {
    global $DB;

    // get all of the lesson answers
    $params = array ("lessonid" => $lesson->id);
    if (!$lessonanswers = $DB->get_records_select("lesson_answers", "lessonid = :lessonid", $params)) {
        // no answers, then not using cluster or unseen
        return false;
    }
    // just check for the first one that fulfills the requirements
    foreach ($lessonanswers as $lessonanswer) {
        if ($lessonanswer->jumpto == LESSON_CLUSTERJUMP || $lessonanswer->jumpto == LESSON_UNSEENBRANCHPAGE) {
            return true;
        }
    }

    // if no answers use either of the two jumps
    return false;
}

/**
 * Interprets the LESSON_UNSEENBRANCHPAGE jump.
 *
 * will return the pageid of a random unseen page that is within a branch
 *
 * @param lesson $lesson
 * @param int $userid Id of the user.
 * @param int $pageid Id of the page from which we are jumping.
 * @return int Id of the next page.
 **/
function lesson_unseen_question_jump($lesson, $user, $pageid) {
    global $DB;

    // get the number of retakes
    if (!$retakes = $DB->count_records("lesson_grades", array("lessonid"=>$lesson->id, "userid"=>$user))) {
        $retakes = 0;
    }

    // get all the lesson_attempts aka what the user has seen
    if ($viewedpages = $DB->get_records("lesson_attempts", array("lessonid"=>$lesson->id, "userid"=>$user, "retry"=>$retakes), "timeseen DESC")) {
        foreach($viewedpages as $viewed) {
            $seenpages[] = $viewed->pageid;
        }
    } else {
        $seenpages = array();
    }

    // get the lesson pages
    $lessonpages = $lesson->load_all_pages();

    if ($pageid == LESSON_UNSEENBRANCHPAGE) {  // this only happens when a student leaves in the middle of an unseen question within a branch series
        $pageid = $seenpages[0];  // just change the pageid to the last page viewed inside the branch table
    }

    // go up the pages till branch table
    while ($pageid != 0) { // this condition should never be satisfied... only happens if there are no branch tables above this page
        if ($lessonpages[$pageid]->qtype == LESSON_PAGE_BRANCHTABLE) {
            break;
        }
        $pageid = $lessonpages[$pageid]->prevpageid;
    }

    $pagesinbranch = $lesson->get_sub_pages_of($pageid, array(LESSON_PAGE_BRANCHTABLE, LESSON_PAGE_ENDOFBRANCH));

    // this foreach loop stores all the pages that are within the branch table but are not in the $seenpages array
    $unseen = array();
    foreach($pagesinbranch as $page) {
        if (!in_array($page->id, $seenpages)) {
            $unseen[] = $page->id;
        }
    }

    if(count($unseen) == 0) {
        if(isset($pagesinbranch)) {
            $temp = end($pagesinbranch);
            $nextpage = $temp->nextpageid; // they have seen all the pages in the branch, so go to EOB/next branch table/EOL
        } else {
            // there are no pages inside the branch, so return the next page
            $nextpage = $lessonpages[$pageid]->nextpageid;
        }
        if ($nextpage == 0) {
            return LESSON_EOL;
        } else {
            return $nextpage;
        }
    } else {
        return $unseen[rand(0, count($unseen)-1)];  // returns a random page id for the next page
    }
}

/**
 * Handles the unseen branch table jump.
 *
 * @param lesson $lesson
 * @param int $userid User id.
 * @return int Will return the page id of a branch table or end of lesson
 **/
function lesson_unseen_branch_jump($lesson, $userid) {
    global $DB;

    if (!$retakes = $DB->count_records("lesson_grades", array("lessonid"=>$lesson->id, "userid"=>$userid))) {
        $retakes = 0;
    }

    $params = array ("lessonid" => $lesson->id, "userid" => $userid, "retry" => $retakes);
    if (!$seenbranches = $DB->get_records_select("lesson_branch", "lessonid = :lessonid AND userid = :userid AND retry = :retry", $params,
                "timeseen DESC")) {
        print_error('cannotfindrecords', 'lesson');
    }

    // get the lesson pages
    $lessonpages = $lesson->load_all_pages();

    // this loads all the viewed branch tables into $seen until it finds the branch table with the flag
    // which is the branch table that starts the unseenbranch function
    $seen = array();
    foreach ($seenbranches as $seenbranch) {
        if (!$seenbranch->flag) {
            $seen[$seenbranch->pageid] = $seenbranch->pageid;
        } else {
            $start = $seenbranch->pageid;
            break;
        }
    }
    // this function searches through the lesson pages to find all the branch tables
    // that follow the flagged branch table
    $pageid = $lessonpages[$start]->nextpageid; // move down from the flagged branch table
    $branchtables = array();
    while ($pageid != 0) {  // grab all of the branch table till eol
        if ($lessonpages[$pageid]->qtype == LESSON_PAGE_BRANCHTABLE) {
            $branchtables[] = $lessonpages[$pageid]->id;
        }
        $pageid = $lessonpages[$pageid]->nextpageid;
    }
    $unseen = array();
    foreach ($branchtables as $branchtable) {
        // load all of the unseen branch tables into unseen
        if (!array_key_exists($branchtable, $seen)) {
            $unseen[] = $branchtable;
        }
    }
    if (count($unseen) > 0) {
        return $unseen[rand(0, count($unseen)-1)];  // returns a random page id for the next page
    } else {
        return LESSON_EOL;  // has viewed all of the branch tables
    }
}

/**
 * Handles the random jump between a branch table and end of branch or end of lesson (LESSON_RANDOMPAGE).
 *
 * @param lesson $lesson
 * @param int $pageid The id of the page that we are jumping from (?)
 * @return int The pageid of a random page that is within a branch table
 **/
function lesson_random_question_jump($lesson, $pageid) {
    global $DB;

    // get the lesson pages
    $params = array ("lessonid" => $lesson->id);
    if (!$lessonpages = $DB->get_records_select("lesson_pages", "lessonid = :lessonid", $params)) {
        print_error('cannotfindpages', 'lesson');
    }

    // go up the pages till branch table
    while ($pageid != 0) { // this condition should never be satisfied... only happens if there are no branch tables above this page

        if ($lessonpages[$pageid]->qtype == LESSON_PAGE_BRANCHTABLE) {
            break;
        }
        $pageid = $lessonpages[$pageid]->prevpageid;
    }

    // get the pages within the branch
    $pagesinbranch = $lesson->get_sub_pages_of($pageid, array(LESSON_PAGE_BRANCHTABLE, LESSON_PAGE_ENDOFBRANCH));

    if(count($pagesinbranch) == 0) {
        // there are no pages inside the branch, so return the next page
        return $lessonpages[$pageid]->nextpageid;
    } else {
        return $pagesinbranch[rand(0, count($pagesinbranch)-1)]->id;  // returns a random page id for the next page
    }
}

/**
 * Calculates a user's grade for a lesson.
 *
 * @param object $lesson The lesson that the user is taking.
 * @param int $retries The attempt number.
 * @param int $userid Id of the user (optional, default current user).
 * @return object { nquestions => number of questions answered
                    attempts => number of question attempts
                    total => max points possible
                    earned => points earned by student
                    grade => calculated percentage grade
                    nmanual => number of manually graded questions
                    manualpoints => point value for manually graded questions }
 */
function lesson_grade($lesson, $ntries, $userid = 0) {
    global $USER, $DB;

    if (empty($userid)) {
        $userid = $USER->id;
    }

    // Zero out everything
    $ncorrect     = 0;
    $nviewed      = 0;
    $score        = 0;
    $nmanual      = 0;
    $manualpoints = 0;
    $thegrade     = 0;
    $nquestions   = 0;
    $total        = 0;
    $earned       = 0;

    $params = array ("lessonid" => $lesson->id, "userid" => $userid, "retry" => $ntries);
    if ($useranswers = $DB->get_records_select("lesson_attempts",  "lessonid = :lessonid AND
            userid = :userid AND retry = :retry", $params, "timeseen")) {
        // group each try with its page
        $attemptset = array();
        foreach ($useranswers as $useranswer) {
            $attemptset[$useranswer->pageid][] = $useranswer;
        }

        // Drop all attempts that go beyond max attempts for the lesson
        foreach ($attemptset as $key => $set) {
            $attemptset[$key] = array_slice($set, 0, $lesson->maxattempts);
        }

        // get only the pages and their answers that the user answered
        list($usql, $parameters) = $DB->get_in_or_equal(array_keys($attemptset));
        array_unshift($parameters, $lesson->id);
        $pages = $DB->get_records_select("lesson_pages", "lessonid = ? AND id $usql", $parameters);
        $answers = $DB->get_records_select("lesson_answers", "lessonid = ? AND pageid $usql", $parameters);

        // Number of pages answered
        $nquestions = count($pages);

        foreach ($attemptset as $attempts) {
            $page = lesson_page::load($pages[end($attempts)->pageid], $lesson);
            if ($lesson->custom) {
                $attempt = end($attempts);
                // If essay question, handle it, otherwise add to score
                if ($page->requires_manual_grading()) {
                    $useranswerobj = unserialize($attempt->useranswer);
                    if (isset($useranswerobj->score)) {
                        $earned += $useranswerobj->score;
                    }
                    $nmanual++;
                    $manualpoints += $answers[$attempt->answerid]->score;
                } else if (!empty($attempt->answerid)) {
                    $earned += $page->earned_score($answers, $attempt);
                }
            } else {
                foreach ($attempts as $attempt) {
                    $earned += $attempt->correct;
                }
                $attempt = end($attempts); // doesn't matter which one
                // If essay question, increase numbers
                if ($page->requires_manual_grading()) {
                    $nmanual++;
                    $manualpoints++;
                }
            }
            // Number of times answered
            $nviewed += count($attempts);
        }

        if ($lesson->custom) {
            $bestscores = array();
            // Find the highest possible score per page to get our total
            foreach ($answers as $answer) {
                if(!isset($bestscores[$answer->pageid])) {
                    $bestscores[$answer->pageid] = $answer->score;
                } else if ($bestscores[$answer->pageid] < $answer->score) {
                    $bestscores[$answer->pageid] = $answer->score;
                }
            }
            $total = array_sum($bestscores);
        } else {
            // Check to make sure the student has answered the minimum questions
            if ($lesson->minquestions and $nquestions < $lesson->minquestions) {
                // Nope, increase number viewed by the amount of unanswered questions
                $total =  $nviewed + ($lesson->minquestions - $nquestions);
            } else {
                $total = $nviewed;
            }
        }
    }

    if ($total) { // not zero
        $thegrade = round(100 * $earned / $total, 5);
    }

    // Build the grade information object
    $gradeinfo               = new stdClass;
    $gradeinfo->nquestions   = $nquestions;
    $gradeinfo->attempts     = $nviewed;
    $gradeinfo->total        = $total;
    $gradeinfo->earned       = $earned;
    $gradeinfo->grade        = $thegrade;
    $gradeinfo->nmanual      = $nmanual;
    $gradeinfo->manualpoints = $manualpoints;

    return $gradeinfo;
}

/**
 * Determines if a user can view the left menu.  The determining factor
 * is whether a user has a grade greater than or equal to the lesson setting
 * of displayleftif
 *
 * @param object $lesson Lesson object of the current lesson
 * @return boolean 0 if the user cannot see, or $lesson->displayleft to keep displayleft unchanged
 **/
function lesson_displayleftif($lesson) {
    global $CFG, $USER, $DB;

    if (!empty($lesson->displayleftif)) {
        // get the current user's max grade for this lesson
        $params = array ("userid" => $USER->id, "lessonid" => $lesson->id);
        if ($maxgrade = $DB->get_record_sql('SELECT userid, MAX(grade) AS maxgrade FROM {lesson_grades} WHERE userid = :userid AND lessonid = :lessonid GROUP BY userid', $params)) {
            if ($maxgrade->maxgrade < $lesson->displayleftif) {
                return 0;  // turn off the displayleft
            }
        } else {
            return 0; // no grades
        }
    }

    // if we get to here, keep the original state of displayleft lesson setting
    return $lesson->displayleft;
}

/**
 *
 * @param $cm
 * @param $lesson
 * @param $page
 * @return unknown_type
 */
function lesson_add_fake_blocks($page, $cm, $lesson, $timer = null) {
    $bc = lesson_menu_block_contents($cm->id, $lesson);
    if (!empty($bc)) {
        $regions = $page->blocks->get_regions();
        $firstregion = reset($regions);
        $page->blocks->add_fake_block($bc, $firstregion);
    }

    $bc = lesson_mediafile_block_contents($cm->id, $lesson);
    if (!empty($bc)) {
        $page->blocks->add_fake_block($bc, $page->blocks->get_default_region());
    }

    if (!empty($timer)) {
        $bc = lesson_clock_block_contents($cm->id, $lesson, $timer, $page);
        if (!empty($bc)) {
            $page->blocks->add_fake_block($bc, $page->blocks->get_default_region());
        }
    }
}

/**
 * If there is a media file associated with this
 * lesson, return a block_contents that displays it.
 *
 * @param int $cmid Course Module ID for this lesson
 * @param object $lesson Full lesson record object
 * @return block_contents
 **/
function lesson_mediafile_block_contents($cmid, $lesson) {
    global $OUTPUT;
    if (empty($lesson->mediafile)) {
        return null;
    }

    $options = array();
    $options['menubar'] = 0;
    $options['location'] = 0;
    $options['left'] = 5;
    $options['top'] = 5;
    $options['scrollbars'] = 1;
    $options['resizable'] = 1;
    $options['width'] = $lesson->mediawidth;
    $options['height'] = $lesson->mediaheight;

    $link = new moodle_url('/mod/lesson/mediafile.php?id='.$cmid);
    $action = new popup_action('click', $link, 'lessonmediafile', $options);
    $content = $OUTPUT->action_link($link, get_string('mediafilepopup', 'lesson'), $action, array('title'=>get_string('mediafilepopup', 'lesson')));

    $bc = new block_contents();
    $bc->title = get_string('linkedmedia', 'lesson');
    $bc->attributes['class'] = 'mediafile';
    $bc->content = $content;

    return $bc;
}

/**
 * If a timed lesson and not a teacher, then
 * return a block_contents containing the clock.
 *
 * @param int $cmid Course Module ID for this lesson
 * @param object $lesson Full lesson record object
 * @param object $timer Full timer record object
 * @return block_contents
 **/
function lesson_clock_block_contents($cmid, $lesson, $timer, $page) {
    // Display for timed lessons and for students only
    $context = context_module::instance($cmid);
    if(!$lesson->timed || has_capability('mod/lesson:manage', $context)) {
        return null;
    }

    $content = '<div class="jshidewhenenabled">';
    $content .=  $lesson->time_remaining($timer->starttime);
    $content .= '</div>';

    $clocksettings = array('starttime'=>$timer->starttime, 'servertime'=>time(),'testlength'=>($lesson->maxtime * 60));
    $page->requires->data_for_js('clocksettings', $clocksettings);
    $page->requires->js('/mod/lesson/timer.js');
    $page->requires->js_function_call('show_clock');

    $bc = new block_contents();
    $bc->title = get_string('timeremaining', 'lesson');
    $bc->attributes['class'] = 'clock block';
    $bc->content = $content;

    return $bc;
}

/**
 * If left menu is turned on, then this will
 * print the menu in a block
 *
 * @param int $cmid Course Module ID for this lesson
 * @param lesson $lesson Full lesson record object
 * @return void
 **/
function lesson_menu_block_contents($cmid, $lesson) {
    global $CFG, $DB;

    if (!$lesson->displayleft) {
        return null;
    }

    $pages = $lesson->load_all_pages();
    foreach ($pages as $page) {
        if ((int)$page->prevpageid === 0) {
            $pageid = $page->id;
            break;
        }
    }
    $currentpageid = optional_param('pageid', $pageid, PARAM_INT);

    if (!$pageid || !$pages) {
        return null;
    }

    $content = '<a href="#maincontent" class="skip">'.get_string('skip', 'lesson')."</a>\n<div class=\"menuwrapper\">\n<ul>\n";

    while ($pageid != 0) {
        $page = $pages[$pageid];

        // Only process branch tables with display turned on
        if ($page->displayinmenublock && $page->display) {
            if ($page->id == $currentpageid) {
                $content .= '<li class="selected">'.format_string($page->title,true)."</li>\n";
            } else {
                $content .= "<li class=\"notselected\"><a href=\"$CFG->wwwroot/mod/lesson/view.php?id=$cmid&amp;pageid=$page->id\">".format_string($page->title,true)."</a></li>\n";
            }

        }
        $pageid = $page->nextpageid;
    }
    $content .= "</ul>\n</div>\n";

    $bc = new block_contents();
    $bc->title = get_string('lessonmenu', 'lesson');
    $bc->attributes['class'] = 'menu block';
    $bc->content = $content;

    return $bc;
}

/**
 * Adds header buttons to the page for the lesson
 *
 * @param object $cm
 * @param object $context
 * @param bool $extraeditbuttons
 * @param int $lessonpageid
 */
function lesson_add_header_buttons($cm, $context, $extraeditbuttons=false, $lessonpageid=null) {
    global $CFG, $PAGE, $OUTPUT;
    if (has_capability('mod/lesson:edit', $context) && $extraeditbuttons) {
        if ($lessonpageid === null) {
            print_error('invalidpageid', 'lesson');
        }
        if (!empty($lessonpageid) && $lessonpageid != LESSON_EOL) {
            $url = new moodle_url('/mod/lesson/editpage.php', array('id'=>$cm->id, 'pageid'=>$lessonpageid, 'edit'=>1));
            $PAGE->set_button($OUTPUT->single_button($url, get_string('editpagecontent', 'lesson')));
        }
    }
}

/**
 * This is a function used to detect media types and generate html code.
 *
 * @global object $CFG
 * @global object $PAGE
 * @param object $lesson
 * @param object $context
 * @return string $code the html code of media
 */
function lesson_get_media_html($lesson, $context) {
    global $CFG, $PAGE, $OUTPUT;
    require_once("$CFG->libdir/resourcelib.php");

    // get the media file link
    if (strpos($lesson->mediafile, '://') !== false) {
        $url = new moodle_url($lesson->mediafile);
    } else {
        // the timemodified is used to prevent caching problems, instead of '/' we should better read from files table and use sortorder
        $url = moodle_url::make_pluginfile_url($context->id, 'mod_lesson', 'mediafile', $lesson->timemodified, '/', ltrim($lesson->mediafile, '/'));
    }
    $title = $lesson->mediafile;

    $clicktoopen = html_writer::link($url, get_string('download'));

    $mimetype = resourcelib_guess_url_mimetype($url);

    $extension = resourcelib_get_extension($url->out(false));

    $mediarenderer = $PAGE->get_renderer('core', 'media');
    $embedoptions = array(
        core_media::OPTION_TRUSTED => true,
        core_media::OPTION_BLOCK => true
    );

    // find the correct type and print it out
    if (in_array($mimetype, array('image/gif','image/jpeg','image/png'))) {  // It's an image
        $code = resourcelib_embed_image($url, $title);

    } else if ($mediarenderer->can_embed_url($url, $embedoptions)) {
        // Media (audio/video) file.
        $code = $mediarenderer->embed_url($url, $title, 0, 0, $embedoptions);

    } else {
        // anything else - just try object tag enlarged as much as possible
        $code = resourcelib_embed_general($url, $title, $clicktoopen, $mimetype);
    }

    return $code;
}


/**
 * Abstract class that page type's MUST inherit from.
 *
 * This is the abstract class that ALL add page type forms must extend.
 * You will notice that all but two of the methods this class contains are final.
 * Essentially the only thing that extending classes can do is extend custom_definition.
 * OR if it has a special requirement on creation it can extend construction_override
 *
 * @abstract
 * @copyright  2009 Sam Hemelryk
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
abstract class lesson_add_page_form_base extends moodleform {

    /**
     * This is the classic define that is used to identify this pagetype.
     * Will be one of LESSON_*
     * @var int
     */
    public $qtype;

    /**
     * The simple string that describes the page type e.g. truefalse, multichoice
     * @var string
     */
    public $qtypestring;

    /**
     * An array of options used in the htmleditor
     * @var array
     */
    protected $editoroptions = array();

    /**
     * True if this is a standard page of false if it does something special.
     * Questions are standard pages, branch tables are not
     * @var bool
     */
    protected $standard = true;

    /**
     * Each page type can and should override this to add any custom elements to
     * the basic form that they want
     */
    public function custom_definition() {}

    /**
     * Used to determine if this is a standard page or a special page
     * @return bool
     */
    public final function is_standard() {
        return (bool)$this->standard;
    }

    /**
     * Add the required basic elements to the form.
     *
     * This method adds the basic elements to the form including title and contents
     * and then calls custom_definition();
     */
    public final function definition() {
        $mform = $this->_form;
        $editoroptions = $this->_customdata['editoroptions'];

        $mform->addElement('header', 'qtypeheading', get_string('createaquestionpage', 'lesson', get_string($this->qtypestring, 'lesson')));

        $mform->addElement('hidden', 'id');
        $mform->setType('id', PARAM_INT);

        $mform->addElement('hidden', 'pageid');
        $mform->setType('pageid', PARAM_INT);

        if ($this->standard === true) {
            $mform->addElement('hidden', 'qtype');
            $mform->setType('qtype', PARAM_INT);

            $mform->addElement('text', 'title', get_string('pagetitle', 'lesson'), array('size'=>70));
            $mform->setType('title', PARAM_TEXT);
            $mform->addRule('title', get_string('required'), 'required', null, 'client');

            $this->editoroptions = array('noclean'=>true, 'maxfiles'=>EDITOR_UNLIMITED_FILES, 'maxbytes'=>$this->_customdata['maxbytes']);
            $mform->addElement('editor', 'contents_editor', get_string('pagecontents', 'lesson'), null, $this->editoroptions);
            $mform->setType('contents_editor', PARAM_RAW);
            $mform->addRule('contents_editor', get_string('required'), 'required', null, 'client');
        }

        $this->custom_definition();

        if ($this->_customdata['edit'] === true) {
            $mform->addElement('hidden', 'edit', 1);
            $mform->setType('edit', PARAM_BOOL);
            $this->add_action_buttons(get_string('cancel'), get_string('savepage', 'lesson'));
        } else if ($this->qtype === 'questiontype') {
            $this->add_action_buttons(get_string('cancel'), get_string('addaquestionpage', 'lesson'));
        } else {
            $this->add_action_buttons(get_string('cancel'), get_string('savepage', 'lesson'));
        }
    }

    /**
     * Convenience function: Adds a jumpto select element
     *
     * @param string $name
     * @param string|null $label
     * @param int $selected The page to select by default
     */
    protected final function add_jumpto($name, $label=null, $selected=LESSON_NEXTPAGE) {
        $title = get_string("jump", "lesson");
        if ($label === null) {
            $label = $title;
        }
        if (is_int($name)) {
            $name = "jumpto[$name]";
        }
        $this->_form->addElement('select', $name, $label, $this->_customdata['jumpto']);
        $this->_form->setDefault($name, $selected);
        $this->_form->addHelpButton($name, 'jumps', 'lesson');
    }

    /**
     * Convenience function: Adds a score input element
     *
     * @param string $name
     * @param string|null $label
     * @param mixed $value The default value
     */
    protected final function add_score($name, $label=null, $value=null) {
        if ($label === null) {
            $label = get_string("score", "lesson");
        }

        if (is_int($name)) {
            $name = "score[$name]";
        }
        $this->_form->addElement('text', $name, $label, array('size'=>5));
        $this->_form->setType($name, PARAM_INT);
        if ($value !== null) {
            $this->_form->setDefault($name, $value);
        }
        $this->_form->addHelpButton($name, 'score', 'lesson');

        // Score is only used for custom scoring. Disable the element when not in use to stop some confusion.
        if (!$this->_customdata['lesson']->custom) {
            $this->_form->freeze($name);
        }
    }

    /**
     * Convenience function: Adds an answer editor
     *
     * @param int $count The count of the element to add
     * @param string $label, null means default
     * @param bool $required
     * @return void
     */
    protected final function add_answer($count, $label = null, $required = false) {
        if ($label === null) {
            $label = get_string('answer', 'lesson');
        }
        $this->_form->addElement('editor', 'answer_editor['.$count.']', $label, array('rows'=>'4', 'columns'=>'80'), array('noclean'=>true));
        $this->_form->setDefault('answer_editor['.$count.']', array('text'=>'', 'format'=>FORMAT_MOODLE));
        if ($required) {
            $this->_form->addRule('answer_editor['.$count.']', get_string('required'), 'required', null, 'client');
        }
    }
    /**
     * Convenience function: Adds an response editor
     *
     * @param int $count The count of the element to add
     * @param string $label, null means default
     * @param bool $required
     * @return void
     */
    protected final function add_response($count, $label = null, $required = false) {
        if ($label === null) {
            $label = get_string('response', 'lesson');
        }
        $this->_form->addElement('editor', 'response_editor['.$count.']', $label, array('rows'=>'4', 'columns'=>'80'), array('noclean'=>true));
        $this->_form->setDefault('response_editor['.$count.']', array('text'=>'', 'format'=>FORMAT_MOODLE));
        if ($required) {
            $this->_form->addRule('response_editor['.$count.']', get_string('required'), 'required', null, 'client');
        }
    }

    /**
     * A function that gets called upon init of this object by the calling script.
     *
     * This can be used to process an immediate action if required. Currently it
     * is only used in special cases by non-standard page types.
     *
     * @return bool
     */
    public function construction_override($pageid, lesson $lesson) {
        return true;
    }
}



/**
 * Class representation of a lesson
 *
 * This class is used the interact with, and manage a lesson once instantiated.
 * If you need to fetch a lesson object you can do so by calling
 *
 * <code>
 * lesson::load($lessonid);
 * // or
 * $lessonrecord = $DB->get_record('lesson', $lessonid);
 * $lesson = new lesson($lessonrecord);
 * </code>
 *
 * The class itself extends lesson_base as all classes within the lesson module should
 *
 * These properties are from the database
 * @property int $id The id of this lesson
 * @property int $course The ID of the course this lesson belongs to
 * @property string $name The name of this lesson
 * @property int $practice Flag to toggle this as a practice lesson
 * @property int $modattempts Toggle to allow the user to go back and review answers
 * @property int $usepassword Toggle the use of a password for entry
 * @property string $password The password to require users to enter
 * @property int $dependency ID of another lesson this lesson is dependent on
 * @property string $conditions Conditions of the lesson dependency
 * @property int $grade The maximum grade a user can achieve (%)
 * @property int $custom Toggle custom scoring on or off
 * @property int $ongoing Toggle display of an ongoing score
 * @property int $usemaxgrade How retakes are handled (max=1, mean=0)
 * @property int $maxanswers The max number of answers or branches
 * @property int $maxattempts The maximum number of attempts a user can record
 * @property int $review Toggle use or wrong answer review button
 * @property int $nextpagedefault Override the default next page
 * @property int $feedback Toggles display of default feedback
 * @property int $minquestions Sets a minimum value of pages seen when calculating grades
 * @property int $maxpages Maximum number of pages this lesson can contain
 * @property int $retake Flag to allow users to retake a lesson
 * @property int $activitylink Relate this lesson to another lesson
 * @property string $mediafile File to pop up to or webpage to display
 * @property int $mediaheight Sets the height of the media file popup
 * @property int $mediawidth Sets the width of the media file popup
 * @property int $mediaclose Toggle display of a media close button
 * @property int $slideshow Flag for whether branch pages should be shown as slideshows
 * @property int $width Width of slideshow
 * @property int $height Height of slideshow
 * @property string $bgcolor Background colour of slideshow
 * @property int $displayleft Display a left menu
 * @property int $displayleftif Sets the condition on which the left menu is displayed
 * @property int $progressbar Flag to toggle display of a lesson progress bar
 * @property int $highscores Flag to toggle collection of high scores
 * @property int $maxhighscores Number of high scores to limit to
 * @property int $available Timestamp of when this lesson becomes available
 * @property int $deadline Timestamp of when this lesson is no longer available
 * @property int $timemodified Timestamp when lesson was last modified
 *
 * These properties are calculated
 * @property int $firstpageid Id of the first page of this lesson (prevpageid=0)
 * @property int $lastpageid Id of the last page of this lesson (nextpageid=0)
 *
 * @copyright  2009 Sam Hemelryk
 * @license    http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
class lesson extends lesson_base {

    /**
     * The id of the first page (where prevpageid = 0) gets set and retrieved by
     * {@see get_firstpageid()} by directly calling <code>$lesson->firstpageid;</code>
     * @var int
     */
    protected $firstpageid = null;
    /**
     * The id of the last page (where nextpageid = 0) gets set and retrieved by
     * {@see get_lastpageid()} by directly calling <code>$lesson->lastpageid;</code>
     * @var int
     */
    protected $lastpageid = null;
    /**
     * An array used to cache the pages associated with this lesson after the first
     * time they have been loaded.
     * A note to developers: If you are going to be working with MORE than one or
     * two pages from a lesson you should probably call {@see $lesson->load_all_pages()}
     * in order to save excess database queries.
     * @var array An array of lesson_page objects
     */
    protected $pages = array();
    /**
     * Flag that gets set to true once all of the pages associated with the lesson
     * have been loaded.
     * @var bool
     */
    protected $loadedallpages = false;

    /**
     * Simply generates a lesson object given an array/object of properties
     * Overrides {@see lesson_base->create()}
     * @static
     * @param object|array $properties
     * @return lesson
     */
    public static function create($properties) {
        return new lesson($properties);
    }

    /**
     * Generates a lesson object from the database given its id
     * @static
     * @param int $lessonid
     * @return lesson
     */
    public static function load($lessonid) {
        global $DB;

        if (!$lesson = $DB->get_record('lesson', array('id' => $lessonid))) {
            print_error('invalidcoursemodule');
        }
        return new lesson($lesson);
    }

    /**
     * Deletes this lesson from the database
     */
    public function delete() {
        global $CFG, $DB;
        require_once($CFG->libdir.'/gradelib.php');
        require_once($CFG->dirroot.'/calendar/lib.php');

        $cm = get_coursemodule_from_instance('lesson', $this->properties->id, $this->properties->course);
        $context = context_module::instance($cm->id);

        $DB->delete_records("lesson", array("id"=>$this->properties->id));
        $DB->delete_records("lesson_pages", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_answers", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_attempts", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_grades", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_timer", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_branch", array("lessonid"=>$this->properties->id));
        $DB->delete_records("lesson_high_scores", array("lessonid"=>$this->properties->id));
        if ($events = $DB->get_records('event', array("modulename"=>'lesson', "instance"=>$this->properties->id))) {
            foreach($events as $event) {
                $event = calendar_event::load($event);
                $event->delete();
            }
        }

        // Delete files associated with this module.
        $fs = get_file_storage();
        $fs->delete_area_files($context->id);

        grade_update('mod/lesson', $this->properties->course, 'mod', 'lesson', $this->properties->id, 0, null, array('deleted'=>1));
        return true;
    }

    /**
     * Fetches messages from the session that may have been set in previous page
     * actions.
     *
     * <code>
     * // Do not call this method directly instead use
     * $lesson->messages;
     * </code>
     *
     * @return array
     */
    protected function get_messages() {
        global $SESSION;

        $messages = array();
        if (!empty($SESSION->lesson_messages) && is_array($SESSION->lesson_messages) && array_key_exists($this->properties->id, $SESSION->lesson_messages)) {
            $messages = $SESSION->lesson_messages[$this->properties->id];
            unset($SESSION->lesson_messages[$this->properties->id]);
        }

        return $messages;
    }

    /**
     * Get all of the attempts for the current user.
     *
     * @param int $retries
     * @param bool $correct Optional: only fetch correct attempts
     * @param int $pageid Optional: only fetch attempts at the given page
     * @param int $userid Optional: defaults to the current user if not set
     * @return array|false
     */
    public function get_attempts($retries, $correct=false, $pageid=null, $userid=null) {
        global $USER, $DB;
        $params = array("lessonid"=>$this->properties->id, "userid"=>$userid, "retry"=>$retries);
        if ($correct) {
            $params['correct'] = 1;
        }
        if ($pageid !== null) {
            $params['pageid'] = $pageid;
        }
        if ($userid === null) {
            $params['userid'] = $USER->id;
        }
        return $DB->get_records('lesson_attempts', $params, 'timeseen ASC');
    }

    /**
     * Returns the first page for the lesson or false if there isn't one.
     *
     * This method should be called via the magic method __get();
     * <code>
     * $firstpage = $lesson->firstpage;
     * </code>
     *
     * @return lesson_page|bool Returns the lesson_page specialised object or false
     */
    protected function get_firstpage() {
        $pages = $this->load_all_pages();
        if (count($pages) > 0) {
            foreach ($pages as $page) {
                if ((int)$page->prevpageid === 0) {
                    return $page;
                }
            }
        }
        return false;
    }

    /**
     * Returns the last page for the lesson or false if there isn't one.
     *
     * This method should be called via the magic method __get();
     * <code>
     * $lastpage = $lesson->lastpage;
     * </code>
     *
     * @return lesson_page|bool Returns the lesson_page specialised object or false
     */
    protected function get_lastpage() {
        $pages = $this->load_all_pages();
        if (count($pages) > 0) {
            foreach ($pages as $page) {
                if ((int)$page->nextpageid === 0) {
                    return $page;
                }
            }
        }
        return false;
    }

    /**
     * Returns the id of the first page of this lesson. (prevpageid = 0)
     * @return int
     */
    protected function get_firstpageid() {
        global $DB;
        if ($this->firstpageid == null) {
            if (!$this->loadedallpages) {
                $firstpageid = $DB->get_field('lesson_pages', 'id', array('lessonid'=>$this->properties->id, 'prevpageid'=>0));
                if (!$firstpageid) {
                    print_error('cannotfindfirstpage', 'lesson');
                }
                $this->firstpageid = $firstpageid;
            } else {
                $firstpage = $this->get_firstpage();
                $this->firstpageid = $firstpage->id;
            }
        }
        return $this->firstpageid;
    }

    /**
     * Returns the id of the last page of this lesson. (nextpageid = 0)
     * @return int
     */
    public function get_lastpageid() {
        global $DB;
        if ($this->lastpageid == null) {
            if (!$this->loadedallpages) {
                $lastpageid = $DB->get_field('lesson_pages', 'id', array('lessonid'=>$this->properties->id, 'nextpageid'=>0));
                if (!$lastpageid) {
                    print_error('cannotfindlastpage', 'lesson');
                }
                $this->lastpageid = $lastpageid;
            } else {
                $lastpageid = $this->get_lastpage();
                $this->lastpageid = $lastpageid->id;
            }
        }

        return $this->lastpageid;
    }

     /**
     * Gets the next page id to display after the one that is provided.
     * @param int $nextpageid
     * @return bool
     */
    public function get_next_page($nextpageid) {
        global $USER, $DB;
        $allpages = $this->load_all_pages();
        if ($this->properties->nextpagedefault) {
            // in Flash Card mode...first get number of retakes
            $nretakes = $DB->count_records("lesson_grades", array("lessonid" => $this->properties->id, "userid" => $USER->id));
            shuffle($allpages);
            $found = false;
            if ($this->properties->nextpagedefault == LESSON_UNSEENPAGE) {
                foreach ($allpages as $nextpage) {
                    if (!$DB->count_records("lesson_attempts", array("pageid" => $nextpage->id, "userid" => $USER->id, "retry" => $nretakes))) {
                        $found = true;
                        break;
                    }
                }
            } elseif ($this->properties->nextpagedefault == LESSON_UNANSWEREDPAGE) {
                foreach ($allpages as $nextpage) {
                    if (!$DB->count_records("lesson_attempts", array('pageid' => $nextpage->id, 'userid' => $USER->id, 'correct' => 1, 'retry' => $nretakes))) {
                        $found = true;
                        break;
                    }
                }
            }
            if ($found) {
                if ($this->properties->maxpages) {
                    // check number of pages viewed (in the lesson)
                    if ($DB->count_records("lesson_attempts", array("lessonid" => $this->properties->id, "userid" => $USER->id, "retry" => $nretakes)) >= $this->properties->maxpages) {
                        return LESSON_EOL;
                    }
                }
                return $nextpage->id;
            }
        }
        // In a normal lesson mode
        foreach ($allpages as $nextpage) {
            if ((int)$nextpage->id === (int)$nextpageid) {
                return $nextpage->id;
            }
        }
        return LESSON_EOL;
    }

    /**
     * Sets a message against the session for this lesson that will displayed next
     * time the lesson processes messages
     *
     * @param string $message
     * @param string $class
     * @param string $align
     * @return bool
     */
    public function add_message($message, $class="notifyproblem", $align='center') {
        global $SESSION;

        if (empty($SESSION->lesson_messages) || !is_array($SESSION->lesson_messages)) {
            $SESSION->lesson_messages = array();
            $SESSION->lesson_messages[$this->properties->id] = array();
        } else if (!array_key_exists($this->properties->id, $SESSION->lesson_messages)) {
            $SESSION->lesson_messages[$this->properties->id] = array();
        }

        $SESSION->lesson_messages[$this->properties->id][] = array($message, $class, $align);

        return true;
    }

    /**
     * Check if the lesson is accessible at the present time
     * @return bool True if the lesson is accessible, false otherwise
     */
    public function is_accessible() {
        $available = $this->properties->available;
        $deadline = $this->properties->deadline;
        return (($available == 0 || time() >= $available) && ($deadline == 0 || time() < $deadline));
    }

    /**
     * Starts the lesson time for the current user
     * @return bool Returns true
     */
    public function start_timer() {
        global $USER, $DB;
        $USER->startlesson[$this->properties->id] = true;
        $startlesson = new stdClass;
        $startlesson->lessonid = $this->properties->id;
        $startlesson->userid = $USER->id;
        $startlesson->starttime = time();
        $startlesson->lessontime = time();
        $DB->insert_record('lesson_timer', $startlesson);
        if ($this->properties->timed) {
            $this->add_message(get_string('maxtimewarning', 'lesson', $this->properties->maxtime), 'center');
        }
        return true;
    }

    /**
     * Updates the timer to the current time and returns the new timer object
     * @param bool $restart If set to true the timer is restarted
     * @param bool $continue If set to true AND $restart=true then the timer
     *                        will continue from a previous attempt
     * @return stdClass The new timer
     */
    public function update_timer($restart=false, $continue=false) {
        global $USER, $DB;
        // clock code
        // get time information for this user
        if (!$timer = $DB->get_records('lesson_timer', array ("lessonid" => $this->properties->id, "userid" => $USER->id), 'starttime DESC', '*', 0, 1)) {
            print_error('cannotfindtimer', 'lesson');
        } else {
            $timer = current($timer); // this will get the latest start time record
        }

        if ($restart) {
            if ($continue) {
                // continue a previous test, need to update the clock  (think this option is disabled atm)
                $timer->starttime = time() - ($timer->lessontime - $timer->starttime);
            } else {
                // starting over, so reset the clock
                $timer->starttime = time();
            }
        }

        $timer->lessontime = time();
        $DB->update_record('lesson_timer', $timer);
        return $timer;
    }

    /**
     * Updates the timer to the current time then stops it by unsetting the user var
     * @return bool Returns true
     */
    public function stop_timer() {
        global $USER, $DB;
        unset($USER->startlesson[$this->properties->id]);
        return $this->update_timer(false, false);
    }

    /**
     * Checks to see if the lesson has pages
     */
    public function has_pages() {
        global $DB;
        $pagecount = $DB->count_records('lesson_pages', array('lessonid'=>$this->properties->id));
        return ($pagecount>0);
    }

    /**
     * Returns the link for the related activity
     * @return array|false
     */
    public function link_for_activitylink() {
        global $DB;
        $module = $DB->get_record('course_modules', array('id' => $this->properties->activitylink));
        if ($module) {
            $modname = $DB->get_field('modules', 'name', array('id' => $module->module));
            if ($modname) {
                $instancename = $DB->get_field($modname, 'name', array('id' => $module->instance));
                if ($instancename) {
                    return html_writer::link(new moodle_url('/mod/'.$modname.'/view.php', array('id'=>$this->properties->activitylink)),
                        get_string('activitylinkname', 'lesson', $instancename),
                        array('class'=>'centerpadded lessonbutton standardbutton'));
                }
            }
        }
        return '';
    }

    /**
     * Loads the requested page.
     *
     * This function will return the requested page id as either a specialised
     * lesson_page object OR as a generic lesson_page.
     * If the page has been loaded previously it will be returned from the pages
     * array, otherwise it will be loaded from the database first
     *
     * @param int $pageid
     * @return lesson_page A lesson_page object or an object that extends it
     */
    public function load_page($pageid) {
        if (!array_key_exists($pageid, $this->pages)) {
            $manager = lesson_page_type_manager::get($this);
            $this->pages[$pageid] = $manager->load_page($pageid, $this);
        }
        return $this->pages[$pageid];
    }

    /**
     * Loads ALL of the pages for this lesson
     *
     * @return array An array containing all pages from this lesson
     */
    public function load_all_pages() {
        if (!$this->loadedallpages) {
            $manager = lesson_page_type_manager::get($this);
            $this->pages = $manager->load_all_pages($this);
            $this->loadedallpages = true;
        }
        return $this->pages;
    }

    /**
     * Determines if a jumpto value is correct or not.
     *
     * returns true if jumpto page is (logically) after the pageid page or
     * if the jumpto value is a special value.  Returns false in all other cases.
     *
     * @param int $pageid Id of the page from which you are jumping from.
     * @param int $jumpto The jumpto number.
     * @return boolean True or false after a series of tests.
     **/
    public function jumpto_is_correct($pageid, $jumpto) {
        global $DB;

        // first test the special values
        if (!$jumpto) {
            // same page
            return false;
        } elseif ($jumpto == LESSON_NEXTPAGE) {
            return true;
        } elseif ($jumpto == LE…