/mod/lesson/locallib.php

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<?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_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");

/** Answer format is HTML */
define("LESSON_ANSWER_HTML", "HTML");

/** Placeholder answer for all other answers. */
define("LESSON_OTHER_ANSWERS", "@#wronganswer#@");

//////////////////////////////////////////////////////////////////////////////////////
/// 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;
    }

    if (!$seenbranches = $lesson->get_content_pages_viewed($retakes, $userid, '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 block';
    $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->timelimit == 0 || has_capability('mod/lesson:manage', $context)) {
        return null;
    }

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

    $clocksettings = array('starttime' => $timer->starttime, 'servertime' => time(), 'testlength' => $lesson->timelimit);
    $page->requires->data_for_js('clocksettings', $clocksettings, true);
    $page->requires->strings_for_js(array('timeisup'), 'lesson');
    $page->requires->js('/mod/lesson/timer.js');
    $page->requires->js_init_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="accesshide">' .
        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,
                'returnto' => $PAGE->url->out_as_local_url(false)
            ));
            $PAGE->set_button($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));

    $mediamanager = core_media_manager::instance($PAGE);
    $embedoptions = array(
        core_media_manager::OPTION_TRUSTED => true,
        core_media_manager::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 ($mediamanager->can_embed_url($url, $embedoptions)) {
        // Media (audio/video) file.
        $code = $mediamanager->embed_url($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;
}

/**
 * Logic to happen when a/some group(s) has/have been deleted in a course.
 *
 * @param int $courseid The course ID.
 * @param int $groupid The group id if it is known
 * @return void
 */
function lesson_process_group_deleted_in_course($courseid, $groupid = null) {
    global $DB;

    $params = array('courseid' => $courseid);
    if ($groupid) {
        $params['groupid'] = $groupid;
        // We just update the group that was deleted.
        $sql = "SELECT o.id, o.lessonid
                  FROM {lesson_overrides} o
                  JOIN {lesson} lesson ON lesson.id = o.lessonid
                 WHERE lesson.course = :courseid
                   AND o.groupid = :groupid";
    } else {
        // No groupid, we update all orphaned group overrides for all lessons in course.
        $sql = "SELECT o.id, o.lessonid
                  FROM {lesson_overrides} o
                  JOIN {lesson} lesson ON lesson.id = o.lessonid
             LEFT JOIN {groups} grp ON grp.id = o.groupid
                 WHERE lesson.course = :courseid
                   AND o.groupid IS NOT NULL
                   AND grp.id IS NULL";
    }
    $records = $DB->get_records_sql_menu($sql, $params);
    if (!$records) {
        return; // Nothing to do.
    }
    $DB->delete_records_list('lesson_overrides', 'id', array_keys($records));
}

/**
 * Return the overview report table and data.
 *
 * @param  lesson $lesson       lesson instance
 * @param  mixed $currentgroup  false if not group used, 0 for all groups, group id (int) to filter by that groups
 * @return mixed false if there is no information otherwise html_table and stdClass with the table and data
 * @since  Moodle 3.3
 */
function lesson_get_overview_report_table_and_data(lesson $lesson, $currentgroup) {
    global $DB, $CFG, $OUTPUT;
    require_once($CFG->dirroot . '/mod/lesson/pagetypes/branchtable.php');

    $context = $lesson->context;
    $cm = $lesson->cm;
    // Count the number of branch and question pages in this lesson.
    $branchcount = $DB->count_records('lesson_pages', array('lessonid' => $lesson->id, 'qtype' => LESSON_PAGE_BRANCHTABLE));
    $questioncount = ($DB->count_records('lesson_pages', array('lessonid' => $lesson->id)) - $branchcount);

    // Only load students if there attempts for this lesson.
    $attempts = $DB->record_exists('lesson_attempts', array('lessonid' => $lesson->id));
    $branches = $DB->record_exists('lesson_branch', array('lessonid' => $lesson->id));
    $timer = $DB->record_exists('lesson_timer', array('lessonid' => $lesson->id));
    if ($attempts or $branches or $timer) {
        list($esql, $params) = get_enrolled_sql($context, '', $currentgroup, true);
        list($sort, $sortparams) = users_order_by_sql('u');

        $extrafields = get_extra_user_fields($context);

        $params['a1lessonid'] = $lesson->id;
        $params['b1lessonid'] = $lesson->id;
        $params['c1lessonid'] = $lesson->id;
        $ufields = user_picture::fields('u', $extrafields);
        $sql = "SELECT DISTINCT $ufields
                FROM {user} u
                JOIN (
                    SELECT userid, lessonid FROM {lesson_attempts} a1
                    WHERE a1.lessonid = :a1lessonid
                        UNION
                    SELECT userid, lessonid FROM {lesson_branch} b1
                    WHERE b1.lessonid = :b1lessonid
                        UNION
                    SELECT userid, lessonid FROM {lesson_timer} c1
                    WHERE c1.lessonid = :c1lessonid
                    ) a ON u.id = a.userid
                JOIN ($esql) ue ON ue.id = a.userid
                ORDER BY $sort";

        $students = $DB->get_recordset_sql($sql, $params);
        if (!$students->valid()) {
            $students->close();
            return array(false, false);
        }
    } else {
        return array(false, false);
    }

    if (! $grades = $DB->get_records('lesson_grades', array('lessonid' => $lesson->id), 'completed')) {
        $grades = array();
    }

    if (! $times = $DB->get_records('lesson_timer', array('lessonid' => $lesson->id), 'starttime')) {
        $times = array();
    }

    // Build an array for output.
    $studentdata = array();

    $attempts = $DB->get_recordset('lesson_attempts', array('lessonid' => $lesson->id), 'timeseen');
    foreach ($attempts as $attempt) {
        // if the user is not in the array or if the retry number is not in the sub array, add the data for that try.
        if (empty($studentdata[$attempt->userid]) || empty($studentdata[$attempt->userid][$attempt->retry])) {
            // restore/setup defaults
            $n = 0;
            $timestart = 0;
            $timeend = 0;
            $usergrade = null;
            $eol = 0;

            // search for the grade record for this try. if not there, the nulls defined above will be used.
            foreach($grades as $grade) {
                // check to see if the grade matches the correct user
                if ($grade->userid == $attempt->userid) {
                    // see if n is = to the retry
                    if ($n == $attempt->retry) {
                        // get grade info
                        $usergrade = round($grade->grade, 2); // round it here so we only have to do it once
                        break;
                    }
                    $n++; // if not equal, then increment n
                }
            }
            $n = 0;
            // search for the time record for this try. if not there, the nulls defined above will be used.
            foreach($times as $time) {
                // check to see if the grade matches the correct user
                if ($time->userid == $attempt->userid) {
                    // see if n is = to the retry
                    if ($n == $attempt->retry) {
                        // get grade info
                        $timeend = $time->lessontime;
                        $timestart = $time->starttime;
                        $eol = $time->completed;
                        break;
                    }
                    $n++; // if not equal, then increment n
                }
            }

            // build up the array.
            // this array represents each student and all of their tries at the lesson
            $studentdata[$attempt->userid][$attempt->retry] = array( "timestart" => $timestart,
                                                                    "timeend" => $timeend,
                                                                    "grade" => $usergrade,
                                                                    "end" => $eol,
                                                                    "try" => $attempt->retry,
                                                                    "userid" => $attempt->userid);
        }
    }
    $attempts->close();

    $branches = $DB->get_recordset('lesson_branch', array('lessonid' => $lesson->id), 'timeseen');
    foreach ($branches as $branch) {
        // If the user is not in the array or if the retry number is not in the sub array, add the data for that try.
        if (empty($studentdata[$branch->userid]) || empty($studentdata[$branch->userid][$branch->retry])) {
            // Restore/setup defaults.
            $n = 0;
            $timestart = 0;
            $timeend = 0;
            $usergrade = null;
            $eol = 0;
            // Search for the time record for this try. if not there, the nulls defined above will be used.
            foreach ($times as $time) {
                // Check to see if the grade matches the correct user.
                if ($time->userid == $branch->userid) {
                    // See if n is = to the retry.
                    if ($n == $branch->retry) {
                        // Get grade info.
                        $timeend = $time->lessontime;
                        $timestart = $time->starttime;
                        $eol = $time->completed;
                        break;
                    }
                    $n++; // If not equal, then increment n.
                }
            }

            // Build up the array.
            // This array represents each student and all of their tries at the lesson.
            $studentdata[$branch->userid][$branch->retry] = array( "timestart" => $timestart,
                                                                    "timeend" => $timeend,
                                                                    "grade" => $usergrade,
                                                                    "end" => $eol,
                                                                    "try" => $branch->retry,
                                                                    "userid" => $branch->userid);
        }
    }
    $branches->close();

    // Need the same thing for timed entries that were not completed.
    foreach ($times as $time) {
        $endoflesson = $time->completed;
        // If the time start is the same with another record then we shouldn't be adding another item to this array.
        if (isset($studentdata[$time->userid])) {
            $foundmatch = false;
            $n = 0;
            foreach ($studentdata[$time->userid] as $key => $value) {
                if ($value['timestart'] == $time->starttime) {
                    // Don't add this to the array.
                    $foundmatch = true;
                    break;
                }
            }
            $n = count($studentdata[$time->userid]) + 1;
            if (!$foundmatch) {
                // Add a record.
                $studentdata[$time->userid][] = array(
                                "timestart" => $time->starttime,
                                "timeend" => $time->lessontime,
                                "grade" => null,
                                "end" => $endoflesson,
                                "try" => $n,
                                "userid" => $time->userid
                            );
            }
        } else {
            $studentdata[$time->userid][] = array(
                                "timestart" => $time->starttime,
                                "timeend" => $time->lessontime,
                                "grade" => null,
                                "end" => $endoflesson,
                                "try" => 0,
                                "userid" => $time->userid
                            );
        }
    }

    // To store all the data to be returned by the function.
    $data = new stdClass();

    // Determine if lesson should have a score.
    if ($branchcount > 0 AND $questioncount == 0) {
        // This lesson only contains content pages and is not graded.
        $data->lessonscored = false;
    } else {
        // This lesson is graded.
        $data->lessonscored = true;
    }
    // set all the stats variables
    $data->numofattempts = 0;
    $data->avescore      = 0;
    $data->avetime       = 0;
    $data->highscore     = null;
    $data->lowscore      = null;
    $data->hightime      = null;
    $data->lowtime       = null;
    $data->students      = array();

    $table = new html_table();

    $headers = [get_string('name')];

    foreach ($extrafields as $field) {
        $headers[] = get_user_field_name($field);
    }

    $caneditlesson = has_capability('mod/lesson:edit', $context);
    $attemptsheader = get_string('attempts', 'lesson');
    if ($caneditlesson) {
        $selectall = get_string('selectallattempts', 'lesson');
        $deselectall = get_string('deselectallattempts', 'lesson');
        // Build the select/deselect all control.
        $selectallid = 'selectall-attempts';
        $mastercheckbox = new \core\output\checkbox_toggleall('lesson-attempts', true, [
            'id' => $selectallid,
            'name' => $selectallid,
            'value' => 1,
            'label' => $selectall,
            'selectall' => $selectall,
            'deselectall' => $deselectall,
            'labelclasses' => 'form-check-label'
        ]);
        $attemptsheader = $OUTPUT->render($mastercheckbox);
    }
    $headers [] = $attemptsheader;

    // Set up the table object.
    if ($data->lessonscored) {
        $headers [] = get_string('highscore', 'lesson');
    }

    $colcount = count($headers);

    $table->head = $headers;

    $table->align = [];
    $table->align = array_pad($table->align, $colcount, 'center');
    $table->align[$colcount - 1] = 'left';

    if ($data->lessonscored) {
        $table->align[$colcount - 2] = 'left';
    }

    $table->wrap = [];
    $table->wrap = array_pad($table->wrap, $colcount, 'nowrap');

    $table->attributes['class'] = 'table table-striped';

    // print out the $studentdata array
    // going through each student that has attempted the lesson, so, each student should have something to be displayed
    foreach ($students as $student) {
        // check to see if the student has attempts to print out
        if (array_key_exists($student->id, $studentdata)) {
            // set/reset some variables
            $attempts = array();
            $dataforstudent = new stdClass;
            $dataforstudent->attempts = array();
            // gather the data for each user attempt
            $bestgrade = 0;

            // $tries holds all the tries/retries a student has done
            $tries = $studentdata[$student->id];
            $studentname = fullname($student, true);

            foreach ($tries as $try) {
                $dataforstudent->attempts[] = $try;

                // Start to build up the checkbox and link.
                $attempturlparams = [
                    'id' => $cm->id,
                    'action' => 'reportdetail',
                    'userid' => $try['userid'],
                    'try' => $try['try'],
                ];

                if ($try["grade"] !== null) { // if null then not done yet
                    // this is what the link does when the user has completed the try
                    $timetotake = $try["timeend"] - $try["timestart"];

                    if ($try["grade"] > $bestgrade) {
                        $bestgrade = $try["grade"];
                    }

                    $attemptdata = (object)[
                        'grade' => $try["grade"],
                        'timestart' => userdate($try["timestart"]),
                        'duration' => format_time($timetotake),
                    ];
                    $attemptlinkcontents = get_string('attemptinfowithgrade', 'lesson', $attemptdata);

                } else {
                    if ($try["end"]) {
                        // User finished the lesson but has no grade. (Happens when there are only content pages).
                        $timetotake = $try["timeend"] - $try["timestart"];
                        $attemptdata = (object)[
                            'timestart' => userdate($try["timestart"]),
                            'duration' => format_time($timetotake),
                        ];
                        $attemptlinkcontents = get_string('attemptinfonograde', 'lesson', $attemptdata);
                    } else {
                        // This is what the link does/looks like when the user has not completed the attempt.
                        if ($try['timestart'] !== 0) {
                            // Teacher previews do not track time spent.
                            $attemptlinkcontents = get_string("notcompletedwithdate", "lesson", userdate($try["timestart"]));
                        } else {
                            $attemptlinkcontents = get_string("notcompleted", "lesson");
                        }
                        $timetotake = null;
                    }
                }
                $attempturl = new moodle_url('/mod/lesson/report.php', $attempturlparams);
                $attemptlink = html_writer::link($attempturl, $attemptlinkcontents, ['class' => 'lesson-attempt-link']);

                if ($caneditlesson) {
                    $attemptid = 'attempt-' . $try['userid'] . '-' . $try['try'];
                    $attemptname = 'attempts[' . $try['userid'] . '][' . $try['try'] . ']';

                    $checkbox = new \core\output\checkbox_toggleall('lesson-attempts', false, [
                        'id' => $attemptid,
                        'name' => $attemptname,
                        'label' => $attemptlink
                    ]);
                    $attemptlink = $OUTPUT->render($checkbox);
                }

                // build up the attempts array
                $attempts[] = $attemptlink;

                // Run these lines for the stats only if the user finnished the lesson.
                if ($try["end"]) {
                    // User has completed the lesson.
                    $data->numofattempts++;
                    $data->avetime += $timetotake;
                    if ($timetotake > $data->hightime || $data->hightime == null) {
                        $data->hightime = $timetotake;
                    }
                    if ($timetotake < $data->lowtime || $data->lowtime == null) {
                        $data->lowtime = $timetotake;
                    }
                    if ($try["grade"] !== null) {
                        // The lesson was scored.
                        $data->avescore += $try["grade"];
                        if ($try["grade"] > $data->highscore || $data->highscore === null) {
                            $data->highscore = $try["grade"];
                        }
                        if ($try["grade"] < $data->lowscore || $data->lowscore === null) {
                            $data->lowscore = $try["grade"];
                        }

                    }
                }
            }
            // get line breaks in after each attempt
            $attempts = implode("<br />\n", $attempts);
            $row = [$studentname];

            foreach ($extrafields as $field) {
                $row[] = $student->$field;
            }

            $row[] = $attempts;

            if ($data->lessonscored) {
                // Add the grade if the lesson is graded.
                $row[] = $bestgrade."%";
            }

            $table->data[] = $row;

            // Add the student data.
            $dataforstudent->id = $student->id;
            $dataforstudent->fullname = $studentname;
            $dataforstudent->bestgrade = $bestgrade;
            $data->students[] = $dataforstudent;
        }
    }
    $students->close();
    if ($data->numofattempts > 0) {
        $data->avescore = $data->avescore / $data->numofattempts;
    }

    return array($table, $data);
}

/**
 * Return information about one user attempt (including answers)
 * @param  lesson $lesson  lesson instance
 * @param  int $userid     the user id
 * @param  int $attempt    the attempt number
 * @return array the user answers (array) and user data stats (object)
 * @since  Moodle 3.3
 */
function lesson_get_user_detailed_report_data(lesson $lesson, $userid, $attempt) {
    global $DB;

    $context = $lesson->context;
    if (!empty($userid)) {
        // Apply overrides.
        $lesson->update_effective_access($userid);
    }

    $pageid = 0;
    $lessonpages = $lesson->load_all_pages();
    foreach ($lessonpages as $lessonpage) {
        if ($lessonpage->prevpageid == 0) {
            $pageid = $lessonpage->id;
        }
    }

    // now gather the stats into an object
    $firstpageid = $pageid;
    $pagestats = array();
    while ($pageid != 0) { // EOL
        $page = $lessonpages[$pageid];
        $params = array ("lessonid" => $lesson->id, "pageid" => $page->id);
        if ($allanswers = $DB->get_records_select("lesson_attempts", "lessonid = :lessonid AND pageid = :pageid", $params, "timeseen")) {
            // get them ready for processing
            $orderedanswers = array();
            foreach ($allanswers as $singleanswer) {
                // ordering them like this, will help to find the single attempt record that we want to keep.
                $orderedanswers[$singleanswer->userid][$singleanswer->retry][] = $singleanswer;
            }
            // this is foreach user and for each try for that user, keep one attempt record
            foreach ($orderedanswers as $orderedanswer) {
                foreach($orderedanswer as $tries) {
                    $page->stats($pagestats, $tries);
                }
            }
        } else {
            // no one answered yet...
        }
        //unset($orderedanswers);  initialized above now
        $pageid = $page->nextpageid;
    }

    $manager = lesson_page_type_manager::get($lesson);
    $qtypes = $manager->get_page_type_strings();

    $answerpages = array();
    $answerpage = "";
    $pageid = $firstpageid;
    // cycle through all the pages
    //  foreach page, add to the $answerpages[] array all the data that is needed
    //  from the question, the users attempt, and the statistics
    // grayout pages that the user did not answer and Branch, end of branch, cluster
    // and end of cluster pages
    while ($pageid != 0) { // EOL
        $page = $lessonpages[$pageid];
        $answerpage = new stdClass;
        // Keep the original page object.
        $answerpage->page = $page;
        $data ='';

        $answerdata = new stdClass;
        // Set some defaults for the answer data.
        $answerdata->score = null;
        $answerdata->response = null;
        $answerdata->responseformat = FORMAT_PLAIN;

        $answerpage->title = format_string($page->title);

        $options = new stdClass;
        $options->noclean = true;
        $options->overflowdiv = true;
        $options->context = $context;
        $answerpage->contents = format_text($page->contents, $page->contentsformat, $options);

        $answerpage->qtype = $qtypes[$page->qtype].$page->option_description_string();
        $answerpage->grayout = $page->grayout;
        $answerpage->context = $context;

        if (empty($userid)) {
            // there is no userid, so set these vars and display stats.
            $answerpage->grayout = 0;
            $useranswer = null;
        } elseif ($useranswers = $DB->get_records("lesson_attempts",array("lessonid"=>$lesson->id, "userid"=>$userid, "retry"=>$attempt,"pageid"=>$page->id), "timeseen")) {
            // get the user's answer for this page
            // need to find the right one
            $i = 0;
            foreach ($useranswers as $userattempt) {
                $useranswer = $userattempt;
                $i++;
                if ($lesson->maxattempts == $i) {
                    break; // reached maxattempts, break out
                }
            }
        } else {
            // user did not answer this page, gray it out and set some nulls
            $answerpage->grayout = 1;
            $useranswer = null;
        }
        $i = 0;
        $n = 0;
        $answerpages[] = $page->report_answers(clone($answerpage), clone($answerdata), $useranswer, $pagestats, $i, $n);
        $pageid = $page->nextpageid;
    }

    $userstats = new stdClass;
    if (!empty($userid)) {
        $params = array("lessonid"=>$lesson->id, "userid"=>$userid);

        $alreadycompleted = true;

        if (!$grades = $DB->get_records_select("lesson_grades", "lessonid = :lessonid and userid = :userid", $params, "completed", "*", $attempt, 1)) {
            $userstats->grade = -1;
            $userstats->completed = -1;
            $alreadycompleted = false;
        } else {
            $userstats->grade = current($grades);
            $userstats->completed = $userstats->grade->completed;
            $userstats->grade = round($userstats->grade->grade, 2);
        }

        if (!$times = $lesson->get_user_timers($userid, 'starttime', '*', $attempt, 1)) {
            $userstats->timetotake = -1;
            $alreadycompleted = false;
        } else {
            $userstats->timetotake = current($times);
            $userstats->timetotake = $userstats->timetotake->lessontime - $userstats->timetotake->starttime;
        }

        if ($alreadycompleted) {
            $userstats->gradeinfo = lesson_grade($lesson, $attempt, $userid);
        }
    }

    return array($answerpages, $userstats);
}

/**
 * Return user's deadline for all lessons in a course, hereby taking into account group and user overrides.
 *
 * @param int $courseid the course id.
 * @return object An object with of all lessonsids and close unixdates in this course,
 * taking into account the most lenient overrides, if existing and 0 if no close date is set.
 */
function lesson_get_user_deadline($courseid) {
    global $DB, $USER;

    // For teacher and manager/admins return lesson's deadline.
    if (has_capability('moodle/course:update', context_course::instance($courseid))) {
        $sql = "SELECT lesson.id, lesson.deadline AS userdeadline
                  FROM {lesson} lesson
                 WHERE lesson.course = :courseid";

        $results = $DB->get_records_sql($sql, array('courseid' => $courseid));
        return $results;
    }

    $sql = "SELECT a.id,
                   COALESCE(v.userclose, v.groupclose, a.deadline, 0) AS userdeadline
              FROM (
                      SELECT lesson.id as lessonid,
                             MAX(leo.deadline) AS userclose, MAX(qgo.deadline) AS groupclose
                        FROM {lesson} lesson
                   LEFT JOIN {lesson_overrides} leo on lesson.id = leo.lessonid AND leo.userid = :userid
                   LEFT JOIN {groups_members} gm ON gm.userid = :useringroupid
                   LEFT JOIN {lesson_overrides} qgo on lesson.id = qgo.lessonid AND qgo.groupid = gm.groupid
                       WHERE lesson.course = :courseid
                    GROUP BY lesson.id
                   ) v
              JOIN {lesson} a ON a.id = v.lessonid";

    $results = $DB->get_records_sql($sql, array('userid' => $USER->id, 'useringroupid' => $USER->id, 'courseid' => $courseid));
    return $results;

}

/**
 * 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
     */
    …