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testimage.sh

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  • locallib.php 68.78 KiB
    <?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/>.
    /**
     * @package   mod_pdfannotator
     * @copyright 2018 RWTH Aachen (see README)
     * @authors   Rabea de Groot, Anna Heynkes, Friederike Schwager
     * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
     */
    defined('MOODLE_INTERNAL') || die;
    
    require_once("$CFG->libdir/filelib.php");
    require_once("$CFG->libdir/resourcelib.php");
    require_once("$CFG->dirroot/mod/pdfannotator/lib.php");
    
    /**
     * Display embedded pdfannotator file.
     * @param object $pdfannotator
     * @param object $cm
     * @param object $course
     * @param stored_file $file main file
     * @return does not return
     */
    function pdfannotator_display_embed($pdfannotator, $cm, $course, $file, $page = 1, $annoid = null, $commid = null) {
        global $CFG, $PAGE, $OUTPUT, $USER;
        require_once($CFG->dirroot . '/mod/pdfannotator/classes/output/index.php');
    
        // The revision attribute's existance is demanded by moodle for versioning and could be saved in the pdfannotator table in the future.
        // Note, however, that we forbid file replacement in order to prevent a change of meaning in other people's comments.
        $pdfannotator->revision = 1;
    
        $context = context_module::instance($cm->id);
        $path = '/' . $context->id . '/mod_pdfannotator/content/' . $pdfannotator->revision . $file->get_filepath() . $file->get_filename();
        $fullurl = file_encode_url($CFG->wwwroot . '/pluginfile.php', $path, false);
    
        $documentobject = new stdClass();
        $documentobject->annotatorid = $pdfannotator->id;
        $documentobject->fullurl = $fullurl;
    
        $stringman = get_string_manager();
        // With this method you get the strings of the language-Files.
        $strings = $stringman->load_component_strings('pdfannotator', 'en');
        // Method to use the language-strings in javascript.
        $PAGE->requires->strings_for_js(array_keys($strings), 'pdfannotator');
        // Load and execute the javascript files.
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/pdf.js"));
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/pdf_viewer.js"));
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/textclipper.js"));
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/index.js?ver=00011"));
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/locallib.js?ver=00002"));
    
        // Pass parameters from PHP to JavaScript.
    
        // 1. Toolbar settings.
        $toolbarsettings = new stdClass();
        $toolbarsettings->use_studenttextbox = $pdfannotator->use_studenttextbox;
        $toolbarsettings->use_studentdrawing = $pdfannotator->use_studentdrawing;
        $toolbarsettings->useprint = $pdfannotator->useprint;
        $toolbarsettings->useprintcomments = $pdfannotator->useprintcomments;
        // 2. Capabilities.
        $capabilities = new stdClass();
        $capabilities->viewquestions = has_capability('mod/pdfannotator:viewquestions', $context);
        $capabilities->viewanswers = has_capability('mod/pdfannotator:viewanswers', $context);
        $capabilities->viewposts = has_capability('mod/pdfannotator:viewposts', $context);
        $capabilities->viewreports = has_capability('mod/pdfannotator:viewreports', $context);
        $capabilities->deleteany = has_capability('mod/pdfannotator:deleteany', $context);
        $capabilities->hidecomment = has_capability('mod/pdfannotator:hidecomments', $context);
        $capabilities->seehiddencomments = has_capability('mod/pdfannotator:seehiddencomments', $context);
        $capabilities->usetextbox = has_capability('mod/pdfannotator:usetextbox', $context);
        $capabilities->usedrawing = has_capability('mod/pdfannotator:usedrawing', $context);
        $capabilities->useprint = has_capability('mod/pdfannotator:printdocument', $context);
        $capabilities->useprintcomments = has_capability('mod/pdfannotator:printcomments', $context);
    
        $params = [$cm, $documentobject, $USER->id, $capabilities, $toolbarsettings, $page, $annoid, $commid];
        $PAGE->requires->js_init_call('adjustPdfannotatorNavbar', null, true);
        $PAGE->requires->js_init_call('startIndex', $params, true);
        // The renderer renders the original index.php / takes the template and renders it.
        $myrenderer = $PAGE->get_renderer('mod_pdfannotator');
        echo $myrenderer->render_index(new index($pdfannotator, $capabilities, $file));
    
        pdfannotator_print_intro($pdfannotator, $cm, $course);
    
        echo $OUTPUT->footer();
        die;
    }
    
    function pdfannotator_get_instance_name($id) {
    
        global $DB;
        return $DB->get_field('pdfannotator', 'name', array('id' => $id), $strictness = MUST_EXIST);
    }
    
    function pdfannotator_get_course_name_by_id($courseid) {
        global $DB;
        return $DB->get_field('course', 'fullname', array('id' => $courseid), $strictness = MUST_EXIST);
    }
    
    function pdfannotator_get_username($userid) {
        global $DB;
        $user = $DB->get_record('user', array('id' => $userid));
        return fullname($user);
    }
    
    function pdfannotator_get_annotationtype_id($typename) {
        global $DB;
        if ($typename == 'point') {
            $typename = 'pin';
        }
        $result = $DB->get_records('pdfannotator_annotationtypes', array('name' => $typename));
        foreach ($result as $r) {
            return $r->id;
        }
    }
    
    function pdfannotator_get_annotationtype_name($typeid) {
        global $DB;
        $result = $DB->get_records('pdfannotator_annotationtypes', array('id' => $typeid));
        foreach ($result as $r) {
            return $r->name;
        }
    }
    
    function pdfannotator_handle_latex($subject) {
    
        global $CFG;
        require_once($CFG->dirroot . '/mod/pdfannotator/constants.php');
    
        // Look for these formulae: $$ ... $$, \( ... \) and \[ ... \]
        // !!! keep indentation!
        $pattern = <<<'SIGN'
    ~(?:\$\$.*?\$\$)|(?:\\\(.*?\\\))|(?:\\\[.*?\\\])~
    SIGN;
        // Working, but less readable, alternative: $pattern = '~(?:\\$\\$.*?\\$\\$)|(?:\\\\\\(.*?\\\\\\))|(?:\\\\\\[.*?\\\\\\])~';
    
        $matches = array();
        $hits = preg_match_all($pattern, $subject, $matches, PREG_OFFSET_CAPTURE);
    
        if ($hits == 0) {
            return $subject;
        }
    
        $textstart = 0;
        $formulalength = 0;
        $formulaoffset = 0;
        $result = [];
        $matches = $matches[0];
        foreach ($matches as $match) {
            $formulalength = strlen($match[0]);
            $formulaoffset = $match[1];
            $result[] = trim(substr($subject, $textstart, $formulaoffset - $textstart));
            $result[] = pdfannotator_process_latex($match[0]);
            $textstart = $formulaoffset + $formulalength;
        }
        if ($textstart != strlen($subject) - 1) {
            $result[] = trim(substr($subject, $textstart, strlen($subject) - $textstart));
        }
        return $result;
    }
    
    /**
     * Function takes a latex code string, modifies and url encodes it for the Google Api to process,
     * and returns the resulting image along with its height
     *
     * @param type $string
     * @return type
     */
    function pdfannotator_process_latex($string) {
        $string = str_replace('\xrightarrow', '\rightarrow', $string);
        $string = str_replace('\xlefttarrow', '\leftarrow', $string);
    
        $pos = strpos($string, '\\[');
        if ($pos !== false) {
            $string = substr_replace($string, '', $pos, strlen('\\['));
        }
    
        $pos = strpos($string, '\\(');
        if ($pos !== false) {
            $string = substr_replace($string, '', $pos, strlen('\\('));
        }
    
        $string = str_replace('\\]', '', $string);
    
        $string = str_replace('\\)', '', $string);
    
        $string = str_replace('\begin{aligned}', '', $string);
        $string = str_replace('\end{aligned}', '', $string);
    
        $string = str_replace('\begin{align*}', '', $string);
        $string = str_replace('\end{align*}', '', $string);
    
        // Find any backslash preceding a ( or [ and replace it with \backslash
        $pattern = '~\\\\(?=[\\\(\\\[])~';
        $string = preg_replace($pattern, '\\backslash', $string);
    
        $length = strlen($string);
    
        $im = null;
        if ($length <= 200) { // Google API constraint XXX find better alternative if possible.
            $latexdata = urlencode($string);
            $requesturl = LATEX_TO_PNG_REQUEST . $latexdata;
            $im = @file_get_contents($requesturl); // '@' suppresses warnings so that one failed google request doesn't prevent the pdf from being printed,
            // but just the one formula from being presented as a picture.
        }
        if ($im != null) {
            $array = [];
            try {
                list($width, $height) = getimagesize($requesturl); // XXX alternative: acess height by decoding the string (saving the extra server request)?
                if ($height != null) {
                    $imagedata = IMAGE_PREFIX . base64_encode($im); // Image.
                    $array['image'] = $imagedata;
                    $array['imageheight'] = $height;
                    return $array;
                }
            } catch (Exception $ex) {
                return $string;
            }
        } else {
            return $string;
        }
    }
    
    function pdfannotator_send_forward_message($recipients, $messageparams, $course, $cm, $context) {
        $name = 'forwardedquestion';
        $text = new stdClass();
        $module = get_string('modulename', 'pdfannotator');
        $text->text = pdfannotator_format_notification_message_text($course, $cm, $context, $module, $cm->name, $messageparams, $name);
        $text->html = pdfannotator_format_notification_message_html($course, $cm, $context, $module, $cm->name, $messageparams, $name);
        $text->url = $messageparams->urltoquestion;
    
        foreach ($recipients as $recipient) {
            pdfannotator_notify_manager($recipient, $course, $cm, $name, $text);
        }
    }
    
    function pdfannotator_notify_manager($recipient, $course, $cm, $name, $messagetext, $anonymous = false) {
    
        global $USER;
        $userfrom = $USER;
        if ($anonymous) {
            $userfrom = clone($USER);
            $userfrom->firstname = get_string('pdfannotatorname', 'pdfannotator') . ':';
            $userfrom->lastname = $cm->name;
        }
        $message = new \core\message\message();
        $message->component = 'mod_pdfannotator';
        $message->name = $name;
        $message->courseid = $course->id;
        $message->userfrom = $userfrom;
        $message->userto = $recipient;
        $message->subject = get_string('notificationsubject:' . $name, 'pdfannotator', $cm->name);
        $message->fullmessage = $messagetext->text;
        $message->fullmessageformat = FORMAT_PLAIN;
        $message->fullmessagehtml = $messagetext->html;
        $message->smallmessage = get_string('notificationsubject:' . $name, 'pdfannotator', $cm->name);
        $message->notification = 1; // For personal messages '0'. Important: the 1 without '' and 0 with ''.
        $message->contexturl = $messagetext->url;
        $message->contexturlname = 'Context name';
        $content = array('*' => array('header' => ' test ', 'footer' => ' test ')); // Extra content for specific processor.
    
        $messageid = message_send($message);
    
        return $messageid;
    }
    
    function pdfannotator_format_notification_message_text($course, $cm, $context, $modulename, $pdfannotatorname, $paramsforlanguagestring, $messagetype) {
        global $CFG;
        $formatparams = array('context' => $context->get_course_context());
        $posttext = format_string($course->shortname, true, $formatparams) .
                ' -> ' .
                $modulename .
                ' -> ' .
                format_string($pdfannotatorname, true, $formatparams) . "\n";
        $posttext .= '---------------------------------------------------------------------' . "\n";
        $posttext .= "\n";
        $posttext .= get_string($messagetype . 'text', 'pdfannotator', $paramsforlanguagestring) . "\n---------------------------------------------------------------------\n";
        return $posttext;
    }
    
    /**
     * Format a notification for HTML.
     *
     * @param string $messagetype
     * @param stdClass $info
     * @param stdClass $course
     * @param stdClass $context
     * @param string $modulename
     * @param stdClass $coursemodule
     * @param string $assignmentname
     */
    function pdfannotator_format_notification_message_html($course, $cm, $context, $modulename, $pdfannotatorname, $report, $messagetype) {
        global $CFG, $USER;
        $formatparams = array('context' => $context->get_course_context());
        $posthtml = '<p><font face="sans-serif">' .
                '<a href="' . $CFG->wwwroot . '/course/view.php?id=' . $course->id . '">' .
                format_string($course->shortname, true, $formatparams) .
                '</a> ->' .
                '<a href="' . $CFG->wwwroot . '/mod/pdfannotator/index.php?id=' . $course->id . '">' .
                $modulename .
                '</a> ->' .
                '<a href="' . $CFG->wwwroot . '/mod/pdfannotator/view.php?id=' . $cm->id . '">' .
                format_string($pdfannotatorname, true, $formatparams) .
                '</a></font></p>';
        $posthtml .= '<hr /><font face="sans-serif">';
        $report->urltoreport = $CFG->wwwroot . '/mod/pdfannotator/view.php?id=' . $cm->id . '&action=overviewreports';
        $posthtml .= '<p>' . get_string($messagetype . 'html', 'pdfannotator', $report) . '</p>';
        $linktonotificationsettingspage = new moodle_url('/message/notificationpreferences.php', array('userid' => $USER->id));
        $linktonotificationsettingspage = $linktonotificationsettingspage->__toString();
        $posthtml .= '</font><hr />';
        $posthtml .= '<font face="sans-serif"><p>' . get_string('unsubscribe_notification', 'pdfannotator', $linktonotificationsettingspage) . '</p></font>';
        return $posthtml;
    }
    
    /**
     * Internal function - create click to open text with link.
     */
    function pdfannotator_get_clicktoopen($file, $revision, $extra = '') {
        global $CFG;
    
        $filename = $file->get_filename();
        $path = '/' . $file->get_contextid() . '/mod_pdfannotator/content/' . $revision . $file->get_filepath() . $file->get_filename();
        $fullurl = file_encode_url($CFG->wwwroot . '/pluginfile.php', $path, false);
    
        $string = get_string('clicktoopen2', 'pdfannotator', "<a href=\"$fullurl\" $extra>$filename</a>");
    
        return $string;
    }
    
    /**
     * Internal function - create click to open text with link.
     */
    function pdfannotator_get_clicktodownload($file, $revision) {
        global $CFG;
    
        $filename = $file->get_filename();
        $path = '/' . $file->get_contextid() . '/mod_pdfannotator/content/' . $revision . $file->get_filepath() . $file->get_filename();
        $fullurl = file_encode_url($CFG->wwwroot . '/pluginfile.php', $path, true);
    
        $string = get_string('clicktodownload', 'pdfannotator', "<a href=\"$fullurl\">$filename</a>");
    
        return $string;
    }
    
    /**
     * Print pdfannotator header.
     * @param object $pdfannotator
     * @param object $cm
     * @param object $course
     * @return void
     */
    function pdfannotator_print_header($pdfannotator, $cm, $course) {
        global $PAGE, $OUTPUT;
        $PAGE->set_title($course->shortname . ': ' . $pdfannotator->name);
        $PAGE->set_heading($course->fullname);
        $PAGE->set_activity_record($pdfannotator);
        echo $OUTPUT->header();
    }
    
    /**
     * Gets details of the file to cache in course cache to be displayed using {@link pdfannotator_get_optional_details()}
     *
     * @param object $pdfannotator pdfannotator table row (only property 'displayoptions' is used here)
     * @param object $cm Course-module table row
     * @return string Size and type or empty string if show options are not enabled
     */
    function pdfannotator_get_file_details($pdfannotator, $cm) {
        $filedetails = array();
    
        $context = context_module::instance($cm->id);
        $fs = get_file_storage();
        $files = $fs->get_area_files($context->id, 'mod_pdfannotator', 'content', 0, 'sortorder DESC, id ASC', false);
        // For a typical file pdfannotator, the sortorder is 1 for the main file
        // and 0 for all other files. This sort approach is used just in case
        // there are situations where the file has a different sort order.
        $mainfile = $files ? reset($files) : null;
    
        foreach ($files as $file) {
            // This will also synchronize the file size for external files if needed.
            $filedetails['size'] += $file->get_filesize();
            if ($file->get_repository_id()) {
                // If file is a reference the 'size' attribute can not be cached.
                $filedetails['isref'] = true;
            }
        }
    
        return $filedetails;
    }
    
    /**
     * Print pdfannotator introduction.
     * @param object $pdfannotator
     * @param object $cm
     * @param object $course
     * @param bool $ignoresettings print even if not specified in modedit
     * @return void
     */
    function pdfannotator_print_intro($pdfannotator, $cm, $course, $ignoresettings = false) {
        global $OUTPUT;
        if ($ignoresettings) {
            $gotintro = trim(strip_tags($pdfannotator->intro));
            if ($gotintro || $extraintro) {
                echo $OUTPUT->box_start('mod_introbox', 'pdfannotatorintro');
                if ($gotintro) {
                    echo format_module_intro('pdfannotator', $pdfannotator, $cm->id);
                }
                echo $extraintro;
                echo $OUTPUT->box_end();
            }
        }
    }
    
    /**
     * Print warning that file can not be found.
     * @param object $pdfannotator
     * @param object $cm
     * @param object $course
     * @return void, does not return
     */
    function pdfannotator_print_filenotfound($pdfannotator, $cm, $course) {
        global $DB, $OUTPUT;
    
        pdfannotator_print_header($pdfannotator, $cm, $course);
        // pdfannotator_print_heading($pdfannotator, $cm, $course);//TODO Method is not defined.
        pdfannotator_print_intro($pdfannotator, $cm, $course);
        echo $OUTPUT->notification(get_string('filenotfound', 'pdfannotator'));
    
        echo $OUTPUT->footer();
        die;
    }
    
    /**
     * Function returns the number of new comments, drawings and textboxes*
     * in this annotator. 'New' is defined here as 'no older than 24h' but
     * can easily be changed to another time span.
     * *Drawings and textboxes cannot be commented. In their case (only),
     * therefore, annotations are counted.
     *
     * @global type $DB
     */
    function pdfannotator_get_number_of_new_activities($annotatorid) {
    
        global $DB;
    
        $parameters = array();
        $parameters[] = $annotatorid;
        $parameters[] = strtotime("-1 day");
    
        $sql = "SELECT c.id FROM {pdfannotator_annotations} a JOIN {pdfannotator_comments} c ON c.annotationid = a.id "
                . "WHERE a.pdfannotatorid = ? AND c.timemodified >= ?";
        $sql2 = "SELECT a.id FROM {pdfannotator_annotations} a JOIN {pdfannotator_annotationtypes} t ON a.annotationtypeid = t.id "
                . "WHERE a.pdfannotatorid = ? AND a.timecreated >= ? AND t.name IN('drawing','textbox')";
    
        return ( count($DB->get_records_sql($sql, $parameters)) + count($DB->get_records_sql($sql2, $parameters)) );
    }
    
    /**
     * Function returns the datetime of the last modification on or in the specified annotator.
     * The modification can be the creation of the annotator, a change of title or description,
     * a new annotation or a new comment. Reports are not considered.
     *
     * @global type $DB
     * @param int $annotatorid
     * @return datetime $timemodified
     * The timestamp can be transformed into a readable string with this moodle method:
     * userdate($timestamp, $format = '', $timezone = 99, $fixday = true, $fixhour = true);
     */
    function pdfannotator_get_datetime_of_last_modification($annotatorid) {
    
        global $DB;
    
        // 1. When was the last time the annotator itself (i.e. its title, description or pdf) was modified?
        $timemodified = $DB->get_record('pdfannotator', array('id' => $annotatorid), 'timemodified', MUST_EXIST);
        $timemodified = $timemodified->timemodified;
    
        // 2. When was the last time an annotation or a comment was added in the specified annotator?
        $sql = "SELECT max(a.timecreated) as 'last_annotation', max(c.timemodified) as 'last_comment' "
                . "FROM {pdfannotator_annotations} a LEFT OUTER JOIN {pdfannotator_comments} c ON a.id = c.annotationid "
                . "WHERE a.pdfannotatorid = ?";
        $newposts = $DB->get_records_sql($sql, array($annotatorid));
    
        if (!empty($newposts)) {
    
            foreach ($newposts as $entry) {
    
                // 2.a) If there is an annotation younger than the creation/modification of the annotator, set timemodified to the annotation time.
                if (!empty($entry->last_annotation) && ($entry->last_annotation > $timemodified)) {
                    $timemodified = $entry->last_annotation;
                }
                // 2.b) If there is a comment younger than the creation/modification of the annotator or its newest annotation, set timemodified to the comment time.
                if (!empty($entry->last_comment) && ($entry->last_comment > $timemodified)) {
                    $timemodified = $entry->last_comment;
                }
                return $timemodified;
            }
        }
    }
    
    /**
     * File browsing support class
     */
    class pdfannotator_content_file_info extends file_info_stored {
    
        public function get_parent() {
            if ($this->lf->get_filepath() === '/' and $this->lf->get_filename() === '.') {
                return $this->browser->get_file_info($this->context);
            }
            return parent::get_parent();
        }
    
        public function get_visible_name() {
            if ($this->lf->get_filepath() === '/' and $this->lf->get_filename() === '.') {
                return $this->topvisiblename;
            }
            return parent::get_visible_name();
        }
    
    }
    
    function pdfannotator_set_mainfile($data) {
        global $DB;
        $fs = get_file_storage();
        $cmid = $data->coursemodule;
        $draftitemid = $data->files; // Name from the filemanger.
    
        $context = context_module::instance($cmid);
        if ($draftitemid) {
            file_save_draft_area_files($draftitemid, $context->id, 'mod_pdfannotator', 'content', 0, array('subdirs' => true));
        }
        $files = $fs->get_area_files($context->id, 'mod_pdfannotator', 'content', 0, 'sortorder', false);
        if (count($files) == 1) {
            // Only one file attached, set it as main file automatically.
            $file = reset($files);
            file_set_sortorder($context->id, 'mod_pdfannotator', 'content', 0, $file->get_filepath(), $file->get_filename(), 1);
        }
    }
    
    function pdfannotator_render_listitem_actions(array $actions = null) {
        $menu = new action_menu();
        $menu->attributes['class'] .= ' course-item-actions item-actions';
        $hasitems = false;
        foreach ($actions as $key => $action) {
            $hasitems = true;
            $menu->add(new action_menu_link(
                    $action['url'], $action['icon'], $action['string'], in_array($key, []), ['data-action' => $key, 'class' => 'action-' . $key]
            ));
        }
        if (!$hasitems) {
            return '';
        }
        return pdfannotator_render_action_menu($menu);
    }
    
    function pdfannotator_render_action_menu($menu) {
        global $OUTPUT;
        return $OUTPUT->render($menu);
    }
    
    function pdfannotator_subscribe_all($annotatorid) {
        global $DB;
        $sql = "SELECT id FROM {pdfannotator_annotations} "
                . "WHERE pdfannotatorid = ? AND annotationtypeid NOT IN "
                . "(SELECT id FROM {pdfannotator_annotationtypes} WHERE name = ? OR name = ?)";
        $params = [$annotatorid, 'drawing', 'textbox'];
        $ids = $DB->get_fieldset_sql($sql, $params);
        foreach ($ids as $annotationid) {
            pdfannotator_comment::insert_subscription($annotationid);
        }
    }
    
    function pdfannotator_unsubscribe_all($annotatorid) {
        global $DB, $USER;
        $sql = "SELECT a.id FROM {pdfannotator_annotations} a JOIN {pdfannotator_subscriptions} s "
                . "ON s.annotationid = a.id AND s.userid = ? WHERE pdfannotatorid = ?";
        $ids = $DB->get_fieldset_sql($sql, [$USER->id, $annotatorid]);
        foreach ($ids as $annotationid) {
            pdfannotator_comment::delete_subscription($annotationid);
        }
    }
    
    /**
     * Checks wether a user has subscribed to all questions in an annotator.
     * Returns 1 if all questions are subscribed, 0 if no questions are subscribed and -1 if at least one but not all questions are subscribed.
     * @global type $DB
     * @global type $USER
     * @param type $annotatorid
     */
    function pdfannotator_subscribed($annotatorid) {
        global $DB, $USER;
        $sql = "SELECT COUNT(*) FROM {pdfannotator_annotations} a JOIN {pdfannotator_subscriptions} s "
                . "ON s.annotationid = a.id AND s.userid = ? WHERE a.pdfannotatorid = ?";
        $subscriptions = $DB->count_records_sql($sql, [$USER->id, $annotatorid]);
        $sql = "SELECT COUNT(*) FROM {pdfannotator_annotations} "
                . "WHERE pdfannotatorid = ? AND annotationtypeid NOT IN "
                . "(SELECT id FROM {pdfannotator_annotationtypes} WHERE name = ? OR name = ?)";
        $params = [$annotatorid, 'drawing', 'textbox'];
        $annotations = $DB->count_records_sql($sql, $params);
    
        if ($subscriptions === 0) {
            return 0;
        } else if ($subscriptions === $annotations) {
            return 1;
        } else {
            return -1;
        }
    }
    
    /**
     *
     * @param type $timestamp
     * @return string Day, D Month Y, Time
     */
    function pdfannotator_get_user_datetime($timestamp) {
        $userdatetime = userdate($timestamp, $format = '', $timezone = 99, $fixday = true, $fixhour = true); // Method in lib/moodlelib.php
        return $userdatetime;
    }
    
    /**
     *
     * @param type $timestamp
     * @return string
     */
    function pdfannotator_get_user_datetime_shortformat($timestamp) {
        $shortformat = get_string('strftimedatetime', 'pdfannotator'); // Format strings in moodle\lang\en\langconfig.php.
        $userdatetime = userdate($timestamp, $shortformat, $timezone = 99, $fixday = true, $fixhour = true); // Method in lib/moodlelib.php
        return $userdatetime;
    }
    
    /**
     * Function is executed each time one of the overview categories is accessed.
     * It creates the tab navigation and makes javascript accessible.
     *
     * @param type $CFG
     * @param type $PAGE
     * @param type $myrenderer
     * @param type $taburl
     * @param type $action
     * @param type $pdfannotator
     * @param type $context
     */
    function pdfannotator_prepare_overviewpage($cmid, $myrenderer, $taburl, $action, $pdfannotator, $context) {
    
        global $CFG, $PAGE;
    
        $PAGE->set_title("overview");
    
        // 1.1 Display tab navigation.
        echo $myrenderer->pdfannotator_render_tabs($taburl, $action['tab'], $pdfannotator->name, $context);
    
        // 1.2 Give javascript (see below) access to the language string repository.
        $stringman = get_string_manager();
        $strings = $stringman->load_component_strings('pdfannotator', 'en'); // Method gets the strings of the language files.
        $PAGE->requires->strings_for_js(array_keys($strings), 'pdfannotator'); // Method to use the language-strings in javascript.
        // 1.3 Add the javascript file that determines the dynamic behaviour of the page.
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/locallib.js?ver=00002"));
        $PAGE->requires->js(new moodle_url("/mod/pdfannotator/shared/overview.js?ver=00002"));
    
        // 1.4 Check user capabilities to view the different categories.
        // The argument 'false' disregards administrator's magical 'doanything' power.
        $capabilities = new stdClass();
        $capabilities->viewquestions = has_capability('mod/pdfannotator:viewquestions', $context);
        $capabilities->viewanswers = has_capability('mod/pdfannotator:viewanswers', $context);
        $capabilities->viewposts = has_capability('mod/pdfannotator:viewposts', $context);
        $capabilities->viewreports = has_capability('mod/pdfannotator:viewreports', $context);
    
        $params = array($pdfannotator->id, $cmid, $capabilities, $action['action']);
        $PAGE->requires->js_init_call('startOverview', $params, true); // 1. name of JS function, 2. parameters.
    }
    
    /**
     * Function serves as subcontroller that tells the annotator model to collect
     * all or all unsolved/solved questions asked in this course.
     *
     * @global type $OUTPUT
     * @param int $openannotator
     * @param int $courseid
     * @param type $questionfilter
     * @return type
     */
    function pdfannotator_get_questions($courseid, $context, $questionfilter) {
    
        global $DB;
    
        $cminfo = pdfannotator_instance::get_cm_info($courseid);
        list($insql, $inparams) = $DB->get_in_or_equal(array_keys($cminfo));
    
        $sql = "SELECT a.id as annoid, a.page, a.pdfannotatorid, p.name AS pdfannotatorname, p.usevotes, cm.id AS cmid, "
                . "c.id as commentid, c.content, c.userid, c.visibility, c.timecreated, c.isdeleted, c.ishidden, "
                . "SUM(vote) AS votes, COUNT(answ.id)-1 AS answercount, MAX(answ.timecreated) AS lastanswered "
                . "FROM {pdfannotator_annotations} a "
                . "JOIN {pdfannotator_comments} c ON c.annotationid = a.id "
                . "JOIN {pdfannotator} p ON a.pdfannotatorid = p.id "
                . "JOIN {course_modules} cm ON p.id = cm.instance "
                . "LEFT JOIN {pdfannotator_votes} v ON c.id=v.commentid "
                . "LEFT JOIN {pdfannotator_comments} answ ON answ.annotationid = a.id "
                . "WHERE c.isquestion = 1 AND p.course = ? AND cm.id $insql";
        if ($questionfilter == 0) {
            $sql = $sql . ' AND c.solved = 0 ';
        }
        if ($questionfilter == 1) {
            $sql = $sql . ' AND NOT c.solved = 0 ';
        }
        $sql = $sql . "GROUP BY a.id, p.name, p.usevotes, cm.id, c.id";
        $params = array_merge([$courseid], $inparams);
        $questions = $DB->get_records_sql($sql, $params);
    
        $seehidden = has_capability('mod/pdfannotator:seehiddencomments', $context);
        $labelhidden = "<br><span class='tag tag-info'>" . get_string('hiddenfromstudents') . "</span>"; // XXX use moodle method if exists.
        $labelunavailable = "<br><span class='tag tag-info'>" . get_string('restricted') . "</span>";
    
        foreach ($questions as $key => $question) {
    
            if (empty($question->votes)) {
                $question->votes = 0;
            }
            if ($question->usevotes == 0) {
                $question->votes = '-';
            }
            if (empty($question->answercount)) {
                $question->answercount = 0;
            }
            if ($question->lastanswered != $question->timecreated) {
                $conditions = array('annotationid' => $question->annoid, 'timecreated' => $question->lastanswered, 'isquestion' => 0);
                $r = $DB->get_record('pdfannotator_comments', $conditions, 'userid, visibility', IGNORE_MISSING);
                if (!empty($r)) {
                    $question->lastuser = $r->userid;
                    $question->lastuservisibility = $r->visibility;
                }
            } else {
                $question->lastanswered = false;
            }
    
            if ($question->isdeleted == 1) {
                $question->content = "<em>" . get_string('deletedQuestion', 'pdfannotator') . "</em>";
            } else if ($question->ishidden) {
                switch ($seehidden) {
                    case 0:
                        $question->content = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                        break;
                    case 1:
                        $question->content = $question->content . $labelhidden;
                        $question->displayhidden = true;
                        break;
                    default:
                        $question->content = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                }
            }
    
            if (!$cminfo[$question->cmid]['visible']) { // Annotator is not visible for students.
                $question->content = $question->content . $labelhidden;
                $question->displayhidden = true;
            }
            if ($cminfo[$question->cmid]['availableinfo']) { // Annotator is restricted.
                $question->content = $question->content . $labelunavailable . " " . $cminfo[$question->cmid]['availableinfo'];
                $question->displayhidden = true;
            }
    
            $question->content = format_text($question->content);
            $question->link = (new moodle_url('/mod/pdfannotator/view.php', array('id' => $question->cmid,
                'page' => $question->page, 'annoid' => $question->annoid, 'commid' => $question->commentid)))->out();
        }
        return $questions;
    }
    
    /**
     * Function serves as subcontroller that tells the annotator model to collect all
     * questions and answers this user posted in the course.
     *
     * @global type $DB
     * @global type $USER
     * @param int $courseid
     * @return type
     */
    function pdfannotator_get_posts_by_this_user($courseid, $context) {
    
        global $DB, $USER;
    
        $cminfo = pdfannotator_instance::get_cm_info($courseid);
        list($insql, $inparams) = $DB->get_in_or_equal(array_keys($cminfo));
    
        $seehidden = has_capability('mod/pdfannotator:seehiddencomments', $context);
        $labelhidden = "<br><span class='tag tag-info'>" . get_string('hiddenforparticipants', 'pdfannotator') . "</span>";
        $labelunavailable = "<br><span class='tag tag-info'>" . get_string('restricted') . "</span>";
    
        $sql = "SELECT c.id as commid, c.annotationid, c.content, c.timemodified, c.ishidden, a.id AS annoid, "
                . "a.page, a.pdfannotatorid, p.name AS pdfannotatorname, p.usevotes, cm.id AS cmid, "
                . "SUM(v.vote) AS votes "
                . "FROM {pdfannotator_comments} c "
                . "JOIN {pdfannotator_annotations} a ON c.annotationid = a.id "
                . "JOIN {pdfannotator} p ON a.pdfannotatorid = p.id "
                . "JOIN {course_modules} cm ON p.id = cm.instance "
                . "LEFT JOIN {pdfannotator_votes} v ON c.id = v.commentid "
                . "WHERE c.userid = ? AND p.course = ? AND cm.id $insql "
                . "GROUP BY a.id, p.name, p.usevotes, cm.id, c.id";
    
        $params = array_merge([$USER->id, $courseid], $inparams);
    
        $posts = $DB->get_records_sql($sql, $params);
    
        foreach ($posts as $key => $post) {
            if (empty($post->votes)) {
                $post->votes = 0;
            }
            if ($post->usevotes == 0) {
                $post->votes = '-';
            }
    
            if ($post->ishidden) { // Post in annotator is hidden.
                switch ($seehidden) {
                    case 0:
                        $post->content = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                        break;
                    case 1:
                        $post->content = $post->content . $labelhidden;
                        $post->displayhidden = true;
                        break;
                    default:
                        $post->content = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                }
            }
    
            if (!$cminfo[$post->cmid]['visible']) {  // Annotator is hidden.
                $post->content = $post->content . $labelhidden;
                $post->displayhidden = true;
            }
            if ($cminfo[$post->cmid]['availableinfo']) {  // Annotator is restricted.
                $post->content = $post->content . $labelunavailable . " " . $cminfo[$post->cmid]['availableinfo'];
                $post->displayhidden = true;
            }
    
            $params = array('id' => $post->cmid, 'page' => $post->page, 'annoid' => $post->annotationid, 'commid' => $post->commid);
            $post->link = (new moodle_url('/mod/pdfannotator/view.php', $params))->out();
            $post->content = format_text($post->content);
        }
        return $posts;
    }
    
    /**
     * Function serves as subcontroller that tells the annotator model to collect
     * all answers given to questions that the current user asked or subscribed to
     * in this course.
     *
     * @global type $DB
     * @global type $USER
     * @param int $courseid
     * @param Moodle object? $context
     * @param int $answerfilter
     * @return array of stdClass objects
     */
    function pdfannotator_get_answers_for_this_user($courseid, $context, $answerfilter = 1) {
    
        global $DB, $USER;
    
        $cminfo = pdfannotator_instance::get_cm_info($courseid);
        list($insql, $inparams) = $DB->get_in_or_equal(array_keys($cminfo));
    
        $seehidden = has_capability('mod/pdfannotator:seehiddencomments', $context);
        $labelhidden = "<br><span class='tag tag-info'>" . get_string('hiddenforparticipants', 'pdfannotator') . "</span>";
        $labelunavailable = "<br><span class='tag tag-info'>" . get_string('restricted') . "</span>";
    
        if ($answerfilter == 0) { // Either: get all answers in this annotator.
            $sql = "SELECT c.id AS answerid, c.content AS answer, c.userid AS answeredby, c.visibility, "
                    . "c.timemodified, c.solved AS correct, c.ishidden AS answerhidden, a.id AS annoid, a.page, q.id AS questionid, "
                    . "q.content AS answeredquestion, q.isdeleted AS questiondeleted, q.ishidden AS questionhidden, p.id AS annotatorid, "
                    . "p.name AS pdfannotatorname, cm.id AS cmid, s.id AS issubscribed "
                    . "FROM {pdfannotator_annotations} a "
                    . "LEFT JOIN {pdfannotator_subscriptions} s ON a.id = s.annotationid AND s.userid = ? "
                    . "JOIN {pdfannotator_comments} q ON q.annotationid = a.id " // Question comment.
                    . "JOIN {pdfannotator_comments} c ON c.annotationid = a.id " // Answer comment.
                    . "JOIN {pdfannotator} p ON a.pdfannotatorid = p.id "
                    . "JOIN {course_modules} cm ON p.id = cm.instance "
                    . "WHERE p.course = ? AND q.isquestion = 1 AND NOT c.isquestion = 1 AND NOT c.isdeleted = 1 AND cm.id $insql "
                    . "ORDER BY annoid ASC";
        } else { // Or: get answers to those questions the user subscribed to.
            $sql = "SELECT c.id AS answerid, c.content AS answer, c.userid AS answeredby, c.visibility, "
                    . "c.timemodified, c.solved AS correct, c.ishidden AS answerhidden, a.id AS annoid, a.page, q.id AS questionid, "
                    . "q.content AS answeredquestion, q.isdeleted AS questiondeleted, q.ishidden AS questionhidden, p.id AS annotatorid, "
                    . "p.name AS pdfannotatorname, cm.id AS cmid "
                    . "FROM {pdfannotator_subscriptions} s "
                    . "JOIN {pdfannotator_annotations} a ON a.id = s.annotationid "
                    . "JOIN {pdfannotator_comments} q ON q.annotationid = a.id " // Question comment.
                    . "JOIN {pdfannotator_comments} c ON c.annotationid = a.id " // Answer comment.
                    . "JOIN {pdfannotator} p ON a.pdfannotatorid = p.id "
                    . "JOIN {course_modules} cm ON p.id = cm.instance "
                    . "WHERE s.userid = ? AND p.course = ? AND q.isquestion = 1 AND NOT c.isquestion = 1 AND NOT c.isdeleted = 1 AND cm.id $insql "
                    . "ORDER BY annoid ASC";
        }
    
        $params = array_merge([$USER->id, $courseid], $inparams);
    
        $entries = $DB->get_records_sql($sql, $params);
    
        foreach ($entries as $key => $entry) {
            $entry->link = (new moodle_url('/mod/pdfannotator/view.php',
                        array('id' => $entry->cmid, 'page' => $entry->page, 'annoid' => $entry->annoid, 'commid' => $entry->answerid)))->out();
            $entry->questionlink = (new moodle_url('/mod/pdfannotator/view.php',
                        array('id' => $entry->cmid, 'page' => $entry->page, 'annoid' => $entry->annoid, 'commid' => $entry->questionid)))->out();
    
            if ($entry->questiondeleted == 1) {
                $entry->answeredquestion = get_string('deletedComment', 'pdfannotator');
            } else if ($entry->questionhidden) {
                switch ($seehidden) {
                    case 0:
                        $entry->answeredquestion = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                        break;
                    case 1:
                        $entry->displayquestionhidden = true;
                        $entry->answeredquestion = $entry->answeredquestion . $labelhidden;
                        break;
                    default:
                        $entry->answeredquestion = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                }
            }
    
            if ($entry->answerhidden) {
                switch ($seehidden) {
                    case 0:
                        $entry->answer = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                        break;
                    case 1:
                        $entry->answer = $entry->answer . $labelhidden;
                        $entry->displayhidden = true;
                        break;
                    default:
                        $entry->answer = "<em>" . get_string('hiddenComment', 'pdfannotator') . "</em>";
                }
            }
    
            if (!$cminfo[$entry->cmid]['visible']) {  // Annotator is hidden.
                $entry->answeredquestion = $entry->answeredquestion . $labelhidden;
                $entry->answer = $entry->answer . $labelhidden;
                $entry->displayhidden = true;
            }
            if ($cminfo[$entry->cmid]['availableinfo']) {  // Annotator is restricted.
                 $entry->answeredquestion = $entry->answeredquestion . $labelunavailable . " ". $cminfo[$entry->cmid]['availableinfo'];;
                $entry->answer = $entry->answer . $labelunavailable . " ". $cminfo[$entry->cmid]['availableinfo'];
                $entry->displayhidden = true;
            }
    
            $entry->answeredquestion = format_text($entry->answeredquestion);
            $entry->answer = format_text($entry->answer);
        }
    
        return $entries;
    }
    
    /**
     * Function retrieves reports and their respective reported comments from db.
     * Depending on the reportfilter, only read/unread reports or all reports are retrieved.
     *
     * @global type $DB
     * @param int $courseid
     * @param int $reportfilter: 0 for unread, 1 for read, 2 for all
     * @return array of report objects
     */
    function pdfannotator_get_reports($courseid, $reportfilter = 0) {
    
        global $DB;
    
        $cminfo = pdfannotator_instance::get_cm_info($courseid);
        list($insql, $inparams) = $DB->get_in_or_equal(array_keys($cminfo));
    
        // Retrieve reports from db as an array of stdClass objects, representing a report record each.
        $sql = "SELECT r.id as reportid, r.commentid, r.message as report, r.userid AS reportinguser, r.timecreated, r.seen, "
                . "a.page, c.id AS commentid, c.annotationid, c.userid AS commentauthor, c.content AS reportedcomment, c.timecreated AS commenttime, c.visibility, "
                . "p.id AS annotatorid, p.name AS pdfannotatorname, cm.id AS cmid, cm.visible AS cmvisible "
                . "FROM {pdfannotator_reports} r "
                . "JOIN {pdfannotator_comments} c ON r.commentid = c.id "
                . "JOIN {pdfannotator_annotations} a ON c.annotationid = a.id "
                . "JOIN {pdfannotator} p ON a.pdfannotatorid = p.id "
                . "JOIN {course_modules} cm ON p.id = cm.instance "
                . "WHERE cm.id $insql AND r.courseid = ?"; // Be careful with order of parameters!
    
        if ($reportfilter != 2) {
            $sql = $sql . ' AND r.seen = ?';
            $params = array($courseid, $reportfilter);
        } else {
            $params = array($courseid);
        }
        $params = array_merge($inparams, $params); // Be careful with order of parameters!
        $reports = $DB->get_records_sql($sql, $params);
    
        foreach ($reports as $report) {
                $report->link = (new moodle_url('/mod/pdfannotator/view.php',
                            array('id' => $report->cmid, 'page' => $report->page, 'annoid' => $report->annotationid, 'commid' => $report->commentid)))->out();
            $report->reportedcomment = format_text($report->reportedcomment);
            $report->report = format_text($report->report);
        }
        return $reports;
    }
    
    /**
     * Comparison functions (for sorting tables on overview tab).
     */
    class pdfannotator_compare {
    
        public static function compare_votes_ascending($a, $b) {
            if ($a->usevotes == 0 && $b->usevotes == 0 && $a->votes == $b->votes) {
                return 0;
            }
            return ($a->usevotes != 1 || ($a->votes < $b->votes)) ? -1 : 1;
        }
    
        public static function compare_votes_descending($a, $b) {
            if ($a->usevotes == 0 && $b->usevotes == 0 && $a->votes == $b->votes) {
                return 0;
            }
            return ($b->usevotes != 1 || ($a->votes > $b->votes)) ? -1 : 1;
        }
    
        public static function compare_answers_ascending($a, $b) {
            if ($a->answercount == $b->answercount) {
                return 0;
            }
            return ($a->answercount < $b->answercount) ? -1 : 1;
        }
    
        public static function compare_answers_descending($a, $b) {
            if ($a->answercount == $b->answercount) {
                return 0;
            }
            return ($a->answercount > $b->answercount) ? -1 : 1;
        }
    
        public static function compare_time_ascending($a, $b) {
            if ($a->timemodified == $b->timemodified) {
                return 0;
            }
            return ($a->timemodified < $b->timemodified) ? -1 : 1;
        }
    
        public static function compare_time_descending($a, $b) {
            if ($a->timemodified == $b->timemodified) {
                return 0;
            }
            return ($a->timemodified > $b->timemodified) ? -1 : 1;
        }
    
        public static function compare_lastanswertime_ascending($a, $b) {
            if ($a->lastanswered == $b->lastanswered) {
                return 0;
            }
            return ($a->lastanswered < $b->lastanswered) ? -1 : 1;
        }
    
        public static function compare_lastanswertime_descending($a, $b) {
            if ($a->lastanswered == $b->lastanswered) {
                return 0;
            }
            return ($a->lastanswered > $b->lastanswered) ? -1 : 1;
        }
    
        public static function compare_commenttime_ascending($a, $b) {
            if ($a->commenttime == $b->commenttime) {
                return 0;
            }
            return ($a->commenttime < $b->commenttime) ? -1 : 1;
        }
    
        public static function compare_commenttime_descending($a, $b) {
            if ($a->commenttime == $b->commenttime) {
                return 0;
            }
            return ($a->commenttime > $b->commenttime) ? -1 : 1;
        }
    
        public static function compare_creationtime_ascending($a, $b) {
            if ($a->timecreated == $b->timecreated) {
                return 0;
            }
            return ($a->timecreated < $b->timecreated) ? -1 : 1;
        }
    
        public static function compare_creationtime_descending($a, $b) {
            if ($a->timecreated == $b->timecreated) {
                return 0;
            }
            return ($a->timecreated > $b->timecreated) ? -1 : 1;
        }
    
        public static function compare_alphabetically_ascending($a, $b) {
            if ($a->pdfannotatorname == $b->pdfannotatorname) {
                return 0;
            }
            if (strcasecmp($a->pdfannotatorname, $b->pdfannotatorname) < 0) {
                return -1;
            } else {
                return 1;
            }
        }
    
        public static function compare_alphabetically_descending($a, $b) {
            if ($a->pdfannotatorname == $b->pdfannotatorname) {
                return 0;
            }
            if (strcasecmp($a->pdfannotatorname, $b->pdfannotatorname) > 0) {
                return -1;
            } else {
                return 1;
            }
        }
    
        public static function compare_question_ascending($a, $b) {
            if ($a->answeredquestion == $b->answeredquestion) {
                return 0;
            }
            if (strcasecmp($a->answeredquestion, $b->answeredquestion) < 0) {
                return -1;
            } else {
                return 1;
            }
        }
    
        public static function compare_question_descending($a, $b) {
            if ($a->answeredquestion == $b->answeredquestion) {
                return 0;
            }
            if (strcasecmp($a->answeredquestion, $b->answeredquestion) > 0) {
                return -1;
            } else {
                return 1;
            }
        }
    
    }
    
    /**
     * Function sorts entries in a table according to time, number of votes or annotator.
     * Function is applicable to 'unsolved questions' and 'my posts' category on overview page.
     *
     * @param array $questions
     * @param string $sortcriterium The column according to which the table should be sorted
     * @param int $sortorder 3 for descending, 4 for ascending
     */
    function pdfannotator_sort_entries($questions, $sortcriterium, $sortorder) {
        switch ($sortcriterium) {
            case 'col1':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_time_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_time_descending');
                }
                break;
            case 'col2':
                if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_votes_ascending');
                } else if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_votes_descending');
                }
                break;
            case 'col3':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_alphabetically_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_alphabetically_descending');
                }
                break;
            default:
        }
        return $questions;
    }
    
    function pdfannotator_sort_questions($questions, $sortcriterium, $sortorder) {
        switch ($sortcriterium) {
            case 'col1':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_creationtime_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_creationtime_descending');
                }
                break;
            case 'col2':
                if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_votes_ascending');
                } else if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_votes_descending');
                }
                break;
            case 'col3':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_answers_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_answers_descending');
                }
                break;
            case 'col4':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_lastanswertime_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_lastanswertime_descending');
                }
                break;
            case 'col5':
                if ($sortorder === 4) {
                    usort($questions, 'pdfannotator_compare::compare_alphabetically_ascending');
                } else if ($sortorder === 3) {
                    usort($questions, 'pdfannotator_compare::compare_alphabetically_descending');
                }
                break;
            default:
        }
        return $questions;
    }
    
    /**
     * Function sorts entries in a table according to annotator or time.
     * Applicable for overview answers category.
     *
     * XXX Maybe rename 'colx' into something like 'time', so as to avoid code redundancy.
     *
     * @param array $answers
     * @param int $sortcriterium
     * @param int $sortorder
     * @return array $answers
     */
    function pdfannotator_sort_answers($answers, $sortcriterium, $sortorder) {
        switch ($sortcriterium) {
            case 'col4':
                if ($sortorder === 4) {
                    usort($answers, 'pdfannotator_compare::compare_alphabetically_ascending');
                } else if ($sortorder === 3) {
                    usort($answers, 'pdfannotator_compare::compare_alphabetically_descending');
                }
                break;
            case 'col2':
                if ($sortorder === 4) {
                    usort($answers, 'pdfannotator_compare::compare_time_ascending');
                } else if ($sortorder === 3) {
                    usort($answers, 'pdfannotator_compare::compare_time_descending');
                }
                break;
            case 'col3':
                if ($sortorder === 4) {
                    usort($answers, 'pdfannotator_compare::compare_question_ascending');
                } else if ($sortorder === 3) {
                    usort($answers, 'pdfannotator_compare::compare_question_descending');
                }
                break;
            default:
        }
        return $answers;
    }
    
    /**
     *
     * @param array $reports
     * @param string $sortcriterium
     * @param int $sortorder
     * @return array $reports (sorted)
     */
    function pdfannotator_sort_reports($reports, $sortcriterium, $sortorder) {
        switch ($sortcriterium) {
            case 'col1':
                if ($sortorder === 4) {
                    usort($reports, 'pdfannotator_compare::compare_creationtime_ascending');
                } else if ($sortorder === 3) {
                    usort($reports, 'pdfannotator_compare::compare_creationtime_descending');
                }
                break;
            case 'col3':
                if ($sortorder === 4) {
                    usort($reports, 'pdfannotator_compare::compare_commenttime_ascending');
                } else if ($sortorder === 3) {
                    usort($reports, 'pdfannotator_compare::compare_commenttime_descending');
                }
                break;
            default:
        }
        return $reports;
    }
    
    /**
     * Function takes an array and returns its first key.
     *
     * @param array $array
     * @return mixed
     */
    function pdfannotator_get_first_key_in_array($array) {
    
        if (!function_exists('array_key_first')) { // Function exists in PHP version 7.3 and later.
            /**
             * Gets the first key of an array
             *
             * @param array $array
             * @return mixed
             */
    
            function array_key_first(array $array) {
                if (count($array)) {
                    reset($array);
                    return key($array);
                }
                return null;
            }
    
        }
        return array_key_first($array);
    }
    
    /**
     * This function renders the table of unsolved questions on the overview page.
     *
     * @global type $CFG
     * @param array $questions
     * @param int $thiscourse
     * @param Moodle url object $url
     * @param int $currentpage
     */
    function pdfannotator_print_questions($questions, $thiscourse, $urlparams, $currentpage, $itemsperpage, $context) {
    
        global $CFG, $OUTPUT;
        require_once("$CFG->dirroot/mod/pdfannotator/model/overviewtable.php");
    
        $showdropdown = has_capability('mod/pdfannotator:forwardquestions', $context);
        $questioncount = count($questions);
        $usepagination = !($itemsperpage == -1 || $itemsperpage >= $questioncount);
        $offset = $currentpage * $itemsperpage;
    
        if ($usepagination == 1 && ($offset >= $questioncount)) {
            $offset = 0;
            $urlparams['page'] = 0;
        }
        $url = new moodle_url($CFG->wwwroot . '/mod/pdfannotator/view.php', $urlparams);
    
        // Define flexible table.
        $table = new questionstable($url, $showdropdown);
        $table->setup();
        // $table->pageable(false);
        // Sort the entries of the table according to time or number of votes.
        if (!empty($sortinfo = $table->get_sort_columns())) {
            $sortcriterium = pdfannotator_get_first_key_in_array($sortinfo); // Returns the name (e.g. col2) of the column which was clicked for sorting.
            $sortorder = $sortinfo[$sortcriterium]; // 3 for descending, 4 for ascending.
            $questions = pdfannotator_sort_questions($questions, $sortcriterium, $sortorder);
        }
    
        // Add data to the table and print the requested table (page).
        if (pdfannotator_is_phone() || $itemsperpage == -1 || $itemsperpage >= $questioncount) { // No pagination.
            foreach ($questions as $question) {
                pdfannotator_questionstable_add_row($thiscourse, $table, $question, $urlparams, $showdropdown);
            }
        } else {
            $table->pagesize($itemsperpage, $questioncount);
            for ($i = $offset; $i < $questioncount; $i++) {
                $question = $questions[$i];
                if ($itemsperpage === 0) {
                    break;
                }
                pdfannotator_questionstable_add_row($thiscourse, $table, $question, $urlparams, $showdropdown);
                $itemsperpage--;
            }
        }
        $table->finish_html();
    }
    
    /**
     * Function prints a table view of all answers to questions the current
     * user asked or subscribed to.
     *
     * @global type $CFG
     * @global type $OUTPUT
     * @param int $annotator
     * @param Moodle url object $url
     * @param int $thiscourse
     */
    function pdfannotator_print_answers($data, $thiscourse, $url, $currentpage, $itemsperpage, $cmid, $answerfilter) {
    
        global $CFG, $OUTPUT;
        require_once("$CFG->dirroot/mod/pdfannotator/model/overviewtable.php");
    
        $table = new answerstable($url);
        $table->setup();
    
        // Sort the entries of the table according to time or number of votes.
        if (!empty($sortinfo = $table->get_sort_columns())) {
            $sortcriterium = pdfannotator_get_first_key_in_array($sortinfo); // Returns the name (e.g. col2) of the column which was clicked for sorting.
            $sortorder = $sortinfo[$sortcriterium]; // 3 for descending, 4 for ascending.
            $data = pdfannotator_sort_answers($data, $sortcriterium, $sortorder);
        }
    
        // Add data to the table and print the requested table page.
        if ($itemsperpage == -1) { // No pagination.
            foreach ($data as $answer) {
                pdfannotator_answerstable_add_row($thiscourse, $table, $answer, $cmid, $currentpage, $itemsperpage, $answerfilter);
            }
        } else {
            $answercount = count($data);
            $table->pagesize($itemsperpage, $answercount);
            $offset = $currentpage * $itemsperpage;
            $rowstoprint = $itemsperpage;
            for ($i = $offset; $i < $answercount; $i++) {
                $answer = $data[$i];
                if ($rowstoprint === 0) {
                    break;
                }
                pdfannotator_answerstable_add_row($thiscourse, $table, $answer, $cmid, $currentpage, $itemsperpage, $answerfilter);
                $rowstoprint--;
            }
        }
        $table->finish_html();
    }
    
    /**
     *
     * @global type $CFG
     * @global type $DB
     * @global type $USER
     * @param type $posts
     * @param type $url
     * @param type $thiscourse
     */
    function pdfannotator_print_this_users_posts($posts, $thiscourse, $url, $currentpage, $itemsperpage) {
    
        global $CFG;
        require_once("$CFG->dirroot/mod/pdfannotator/model/overviewtable.php");
    
        $table = new userspoststable($url);
        $table->setup();
    
        // Sort the entries of the table according to time or number of votes.
        if (!empty($sortinfo = $table->get_sort_columns())) {
            $sortcriterium = pdfannotator_get_first_key_in_array($sortinfo); // Returns the name (e.g. col2) of the column which was clicked for sorting.
            $sortorder = $sortinfo[$sortcriterium]; // 3 for descending, 4 for ascending.
            $posts = pdfannotator_sort_entries($posts, $sortcriterium, $sortorder);
        }
    
        // Add data to the table and print the requested table page.
        if ($itemsperpage == -1) {
            foreach ($posts as $post) {
                pdfannotator_userspoststable_add_row($table, $post);
            }
        } else {
            $postcount = count($posts);
            $table->pagesize($itemsperpage, $postcount);
            $offset = $currentpage * $itemsperpage;
            for ($i = $offset; $i < $postcount; $i++) {
                $post = $posts[$i];
                if ($itemsperpage === 0) {
                    break;
                }
                pdfannotator_userspoststable_add_row($table, $post);
                $itemsperpage--;
            }
        }
        $table->finish_html();
    }
    
    /**
     * Function prints a table view of all comments that were reported as inappropriate.
     *
     * @global type $CFG
     * @param array of objects $reports
     * @param int $thiscourse
     * @param Moodle url object $url
     * @param int $currentpage
     */
    function pdfannotator_print_reports($reports, $thiscourse, $url, $currentpage, $itemsperpage, $cmid, $reportfilter) {
    
        global $CFG, $OUTPUT;
        require_once("$CFG->dirroot/mod/pdfannotator/model/overviewtable.php");
    
        $table = new reportstable($url);
        $table->setup();
        // Sort the entries of the table according to time or number of votes.
        if (!empty($sortinfo = $table->get_sort_columns())) {
            $sortcriterium = pdfannotator_get_first_key_in_array($sortinfo); // Returns the name (e.g. col2) of the column which was clicked for sorting.
            $sortorder = $sortinfo[$sortcriterium]; // 3 for descending, 4 for ascending.
            $reports = pdfannotator_sort_reports($reports, $sortcriterium, $sortorder);
        }
        // Add data to the table and print the requested table page.
        if ($itemsperpage == -1) {
            foreach ($reports as $report) {
                pdfannotator_reportstable_add_row($thiscourse, $table, $report, $cmid, $itemsperpage, $reportfilter, $currentpage);
            }
        } else {
            $reportcount = count($reports);
            $table->pagesize($itemsperpage, $reportcount);
            $offset = $currentpage * $itemsperpage;
            $rowstoprint = $itemsperpage;
            for ($i = $offset; $i < $reportcount; $i++) {
                $report = $reports[$i];
                if ($rowstoprint === 0) {
                    break;
                }
                pdfannotator_reportstable_add_row($thiscourse, $table, $report, $cmid, $itemsperpage, $reportfilter, $currentpage);
                $rowstoprint--;
            }
        }
        $table->finish_html();
    }
    
    /**
     * This function adds a row of data to the overview table that displays all
     * unsolved questions in the course.
     *
     * @param int $thiscourse
     * @param questionstable $table
     * @param object $question
     */
    function pdfannotator_questionstable_add_row($thiscourse, $table, $question, $urlparams, $showdropdown) {
    
        global $CFG, $PAGE;
        if ($question->visibility != 'public') {
            $author = get_string('anonymous', 'pdfannotator');
        } else {
            $author = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$question->userid&course=$thiscourse>" . pdfannotator_get_username($question->userid) . "</a>";
        }
        $time = pdfannotator_get_user_datetime_shortformat($question->timecreated);
        if (!empty($question->lastanswered)) { // ! ($question->lastanswered != $question->timecreated) {
            if ($question->lastuservisibility != 'public') {
                $lastresponder = get_string('anonymous', 'pdfannotator');
            } else {
                $lastresponder = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$question->lastuser&course=$thiscourse>" . pdfannotator_get_username($question->lastuser) . "</a>";
            }
            $answertime = pdfannotator_timeago($question->lastanswered);
            $lastanswered = $lastresponder . "<br>" . $answertime;
        } else {
            $lastanswered = '-';
        }
        $classname = '';
        if (isset($question->displayhidden)) {
            $classname = 'dimmed_text';
        }
        $content = "<a href=$question->link class='more'>$question->content</a>";
        $pdfannotatorname = $question->pdfannotatorname;
    
        $data = array($content, $author . '<br>' . $time, $question->votes, $question->answercount, $lastanswered, $pdfannotatorname);
    
        if ($showdropdown) {
            require_once($CFG->dirroot . '/mod/pdfannotator/classes/output/questionmenu.php');
            $myrenderer = $PAGE->get_renderer('mod_pdfannotator');
            $dropdown = $myrenderer->render_dropdownmenu(new questionmenu($question->commentid, $urlparams));
            $data[] = $dropdown;
        }
        $table->add_data($data, $classname);
    }
    
    /**
     * This function adds a row of data to the overview table that displays
     * answers to any question the user subscribed to.
     *
     * @global type $CFG
     * @param int $thiscourse
     * @param answerstable $table
     * @param object $answer
     */
    function pdfannotator_answerstable_add_row($thiscourse, $table, $answer, $cmid, $currentpage, $itemsperpage, $answerfilter) {
        global $CFG, $PAGE;
    
        if (isset($answer->displayquestionhidden)) {
            $question = "<a class='" . $answer->annoid . " more dimmed' href=$answer->questionlink>$answer->answeredquestion</a>";
        } else {
            $question = "<a class='" . $answer->annoid . " more' href=$answer->questionlink>$answer->answeredquestion</a>";
        }
        $pdfannotatorname = $answer->pdfannotatorname;
        if ($answer->correct) {
            $checked = "<i class='icon fa fa-check fa-fw' style='color:green;'></i>";
        } else {
            $checked = "";
        }
        $answerid = 'answer_' . $answer->answerid;
        $answerlink = "<a id=$answerid data-question=$answer->questionid href=$answer->link class='more'>$answer->answer</a>";
    
        if ($answer->visibility != 'public') {
            $answeredby = get_string('anonymous', 'pdfannotator');
        } else {
            $answeredby = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$answer->answeredby&course=$thiscourse>" . pdfannotator_get_username($answer->answeredby) . "</a>";
        }
        $answertime = pdfannotator_get_user_datetime_shortformat($answer->timemodified);
    
        if (empty($answer->issubscribed)) {
            $issubscribed = null;
        } else {
            $issubscribed = $answer->issubscribed;
        }
    
        $classname = '';
        if (isset($answer->displayhidden)) {
            $classname = 'dimmed_text';
        }
    
        require_once($CFG->dirroot . '/mod/pdfannotator/classes/output/answermenu.php');
        $myrenderer = $PAGE->get_renderer('mod_pdfannotator');
        $dropdown = $myrenderer->render_dropdownmenu(new answermenu($answer->annoid, $issubscribed, $cmid, $currentpage, $itemsperpage, $answerfilter));
    
        $table->add_data(array($answerlink, $checked, $answeredby . '<br>' . $answertime, $question, $pdfannotatorname, $dropdown), $classname);
    }
    
    /**
     * This function adds a row of data to the overview table that displays all
     * comments the current user posted in this course.
     *
     * @param userspoststable $table
     * @param object $post
     */
    function pdfannotator_userspoststable_add_row($table, $post) {
        $time = pdfannotator_get_user_datetime_shortformat($post->timemodified);
        $content = "<a href=$post->link class='more'>$post->content</a>";
    
        $classname = '';
        if (isset($post->displayhidden)) {
            $classname = 'dimmed_text';
        }
        $pdfannotatorname = $post->pdfannotatorname;
        $table->add_data(array($content, $time, $post->votes, $pdfannotatorname), $classname);
    }
    
    /**
     * This function adds a row of data to the overview table that displays all
     * comments reported in this course.
     *
     * @global type $CFG
     * @param int $thiscourse
     * @param reportstable $table
     * @param object $report
     * @param int $cmid
     * @param int $itemsperpage
     * @param int $reportfilter
     * @param int $currentpage
     */
    function pdfannotator_reportstable_add_row($thiscourse, $table, $report, $cmid, $itemsperpage, $reportfilter, $currentpage) {
        global $CFG, $PAGE;
    
        // Prepare report data for display.
        $reportid = 'report_' . $report->reportid;
        $reportedcommmentlink = "<a id=$reportid href=$report->link class='more'>$report->reportedcomment</a>";
        $writtenby = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$report->commentauthor&course=$thiscourse>" . pdfannotator_get_username($report->commentauthor) . "</a>";
        $commenttime = pdfannotator_get_user_datetime_shortformat($report->commenttime);
        $reportedby = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$report->reportinguser&course=$thiscourse>" . pdfannotator_get_username($report->reportinguser) . "</a>";
        $reporttime = pdfannotator_get_user_datetime_shortformat($report->timecreated);
        $report->report = "<div class='more'>$report->report</div>";
    
        $classname = '';
        if (!($report->cmvisible)) {
            $classname = 'dimmed_text';
        }
    
        // Create action dropdown menu.
        require_once($CFG->dirroot . '/mod/pdfannotator/classes/output/reportmenu.php');
        $myrenderer = $PAGE->get_renderer('mod_pdfannotator');
        $dropdown = $myrenderer->render_dropdownmenu(new reportmenu($report, $cmid, $currentpage, $itemsperpage, $reportfilter));
    
        // Add a new row to the reports table.
        $table->add_data(array($report->report, $reportedby . '<br>' . $reporttime, $reportedcommmentlink, $writtenby . '<br>' . $commenttime, $dropdown), $classname);
    }
    
    
    /**
     * Function takes a moodle timestamp, calculates how much time has since elapsed
     * and returns this information as a string (e.g.: '3 days ago').
     *
     * @param int $timestamp
     * @return string
     */
    function pdfannotator_timeago($timestamp) {
        $strtime = array(get_string('second', 'pdfannotator'), get_string('minute', 'pdfannotator'), get_string('hour', 'pdfannotator'));
        $strtime[] = get_string('day', 'pdfannotator');
        $strtime[] = get_string('month', 'pdfannotator');
        $strtime[] = get_string('year', 'pdfannotator');
        $strtimeplural = array(get_string('seconds', 'pdfannotator'), get_string('minutes', 'pdfannotator'));
        $strtimeplural[] = get_string('hours', 'pdfannotator');
        $strtimeplural[] = get_string('days', 'pdfannotator');
        $strtimeplural[] = get_string('months', 'pdfannotator');
        $strtimeplural[] = get_string('years', 'pdfannotator');
        $length = array("60", "60", "24", "30", "12", "10");
        $currenttime = time();
        if ($currenttime >= $timestamp) {
            $diff = time() - $timestamp;
            if ($diff < 60) {
                return get_string('justnow', 'pdfannotator');
            }
            for ($i = 0; $diff >= $length[$i] && $i < count($length) - 1; $i++) {
                $diff = $diff / $length[$i];
            }
            $diff = intval(round($diff));
            if ($diff === 1) {
                $diff = $diff . ' ' . $strtime[$i];
            } else {
                $diff = $diff . ' ' . $strtimeplural[$i];
            }
            return get_string('ago', 'pdfannotator', $diff);
        }
    }
    
    /**
     * Function takes a moodle timestamp, calculates how much time has since elapsed
     * and returns this information as a string. If the timestamp is older than 2 days,
     * the ecaxt datetime is returned. Otherwise, the string looks like '3 days ago'.
     *
     * @param type $timestamp
     * @return string
     */
    function pdfannotator_optional_timeago($timestamp) {
        $currenttime = time();
        // For entries older than 2 days, display the exact time.
        if ($currenttime - $timestamp > 172799) {
            return pdfannotator_get_user_datetime_shortformat($timestamp);
        } else {
            return pdfannotator_timeago($timestamp);
        }
    }
    
    function pdfannotator_is_mobile_device() {
        $param = filter_input(INPUT_SERVER, 'HTTP_USER_AGENT', FILTER_DEFAULT); // XXX How to filter, here?
        return preg_match("/(android|avantgo|blackberry|bolt|boost|cricket|docomo|fone|hiptop|mini|mobi|palm|phone|pie|tablet|up\.browser|up\.link|webos|wos)/i", $param);
    }
    
    function pdfannotator_is_phone() {
        $param = filter_input(INPUT_SERVER, 'HTTP_USER_AGENT', FILTER_DEFAULT); // XXX How to filter, here?
        return preg_match("/(android|avantgo|blackberry|bolt|boost|cricket|docomo|fone|hiptop|mini|mobi|palm|phone|pie|tablet|up\.browser|up\.link|webos|wos)/i", $param);
    }