controller.php

<?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.md)
 * @authors   Anna Heynkes, Friederike Schwager
 * @license   http://www.gnu.org/copyleft/gpl.html GNU GPL v3 or later
 */
defined('MOODLE_INTERNAL') || die();

$action = optional_param('action', 'view', PARAM_ALPHA); // The default action is 'view'.

$taburl = new moodle_url('/mod/pdfannotator/view.php', array('id' => $id));

$myrenderer = $PAGE->get_renderer('mod_pdfannotator');

require_course_login($pdfannotator->course, true, $cm);

/* * ********************************************** Display overview page *********************************************** */

if ($action === 'overview') {
    // Go to question-overview by default.
    $action = 'overviewquestions';
}

if ($action === 'forwardquestion') {
    require_sesskey();
    require_capability('mod/pdfannotator:forwardquestions', $context);
    require_once($CFG->dirroot . '/mod/pdfannotator/forward_form.php');
    global $USER;

    $commentid = required_param('commentid', PARAM_INT);
    $fromoverview = optional_param('fromoverview', 0, PARAM_INT);
    $cminfo = pdfannotator_instance::get_cm_info($cm->course);
    // Make sure user is allowed to see cm with the question. (Might happen if user changes commentid in url).
    list($insql, $inparams) = $DB->get_in_or_equal(array_keys($cminfo));
    $sql = "SELECT c.*, a.page, cm.id AS cmid "
            . "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 "
            . "WHERE c.isdeleted = 0 AND c.id = ? AND cm.id $insql";
    $params = array_merge([$commentid], $inparams);
    $comments = $DB->get_records_sql($sql, $params);
    $error = false;
    if (!$comments) {
        $error = true;
    } else {
        $comment = $comments[$commentid];
        if (!$error && $comment->ishidden && !has_capability('mod/pdfannotator:seehiddencomments', $context)) {
            $error = true;
        }
    }

    $possiblerecipients = get_enrolled_users($context, 'mod/pdfannotator:getforwardedquestions');
    $recipientslist = [];