locallib.php

    $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.
 *
 * @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.isquestion, "
        . "c.id as commentid, c.content, c.userid, c.visibility, c.timecreated, c.isdeleted, c.ishidden, "
        . "SUM(vote) AS votes, 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, a.page, a.pdfannotatorid, c.content, c.userid, c.visibility,"
        . "c.timecreated, c.isdeleted, c.ishidden, c.isquestion";
    $params = array_merge([$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>";

    $res = [];
    foreach ($questions as $key => $question) {

        if (!pdfannotator_can_see_comment($question, $context)) {
            continue;
        }

        if (empty($question->votes)) {
            $question->votes = 0;
        }
        if ($question->usevotes == 0) {
            $question->votes = '-';
        }
        $question->answercount = pdfannotator_count_answers($question->annoid, $context);

        $lastanswer = pdfannotator_get_last_answer($question->annoid, $context);
        if ($lastanswer) {
            $question->lastuser = $lastanswer->userid;
            $question->lastuservisibility = $lastanswer->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;
        }

        $question->content = pdfannotator_get_relativelink($question->content, $question->commentid, $context);
        $question->content = format_text($question->content, $options = ['filter' => true]);
        $question->link = (new moodle_url('/mod/pdfannotator/view.php', array('id' => $question->cmid,
            'page' => $question->page, 'annoid' => $question->annoid, 'commid' => $question->commentid)))->out();

        $res[] = $question;

    }
    return $res;
}

/**
 * Function serves as subcontroller that tells the annotator model to collect all
 * questions and answers this user posted in the course.
 *
 * @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, c.annotationid, c.content, c.timemodified, c.ishidden, a.page, a.pdfannotatorid";

    $params = array_merge([$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();
        $post->content = pdfannotator_get_relativelink($post->content, $post->commid, $context);
        $post->content = format_text($post->content, $options = ['filter' => true]);
    }
    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.
 *
 * @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 userid, c.visibility, "
            . "c.timemodified, c.solved AS correct, c.ishidden AS answerhidden, a.id AS annoid, a.page, q.id AS questionid,"
            . "q.userid AS questionuserid, c.isquestion, c.annotationid, "
            . "q.visibility AS questionvisibility, "
            . "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 userid, c.visibility, "
            . "c.timemodified, c.solved AS correct, c.ishidden AS answerhidden, a.id AS annoid, a.page, q.id AS questionid, "
            . "q.userid AS questionuserid, c.isquestion, c.annotationid, "
            . "q.visibility AS questionvisibility, "
            . "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);

    $res = [];
    foreach ($entries as $key => $entry) {
        if (!pdfannotator_can_see_comment($entry, $context)) {
            continue;
        }
        $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;
        }

        $res[] = $entry;
    }

    return $res;
}

/**
 * Function retrieves reports and their respective reported comments from db.
 * Depending on the reportfilter, only read/unread reports or all reports are retrieved.
 *
 * @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, $context, $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();
        $report->reportedcomment = pdfannotator_get_relativelink($report->reportedcomment, $report->commentid, $context);
        $report->reportedcomment = format_text($report->reportedcomment, $options = ['filter' => true]);
        $questionid = $DB->get_record('pdfannotator_comments', ['annotationid' => $report->annotationid, 'isquestion' => 1], 'id');
        $report->report = pdfannotator_get_relativelink($report->report, $questionid, $context);
        $report->report = format_text($report->report, $options = ['filter' => true]);
    }
    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.
 *
 * @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.
 *
 * @param int $annotator
 * @param Moodle url object $url
 * @param int $thiscourse
 */
function pdfannotator_print_answers($data, $thiscourse, $url, $currentpage, $itemsperpage, $cmid, $answerfilter, $context) {

    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, $context);
        }
    } 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, $context);
            $rowstoprint--;
        }
    }
    $table->finish_html();
}

/**
 *
 * @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.
 *
 * @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, $context) {

    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, $context);
        }
    } 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, $context);
            $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 == 'anonymous') {
        $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 == 'anonymous') {
            $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) {
        $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.
 *
 * @param int $thiscourse
 * @param answerstable $table
 * @param object $answer
 */
function pdfannotator_answerstable_add_row($thiscourse, $table, $answer, $cmid, $currentpage, $itemsperpage, $answerfilter, $context) {
    global $CFG, $PAGE;

    $answer->answer = pdfannotator_get_relativelink($answer->answer, $answer->answerid, $context);
    $answer->answer = format_text($answer->answer, $options = ['filter' => true]);
    $answer->answeredquestion = pdfannotator_get_relativelink($answer->answeredquestion, $answer->questionid, $context);
    $answer->answeredquestion = format_text($answer->answeredquestion, $options = ['filter' => true]);


    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 == 'anonymous') {
        $answeredby = get_string('anonymous', 'pdfannotator');
    } else {
        $answeredby = "<a href=" . $CFG->wwwroot . "/user/view.php?id=$answer->userid&course=$thiscourse>" . pdfannotator_get_username($answer->userid) . "</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';
    }

    $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.
 *
 * @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, $context) {
    global $CFG, $PAGE, $DB;
    
    $questionid = $DB->get_record('pdfannotator_comments', ['annotationid' => $report->annotationid, 'isquestion' => 1], 'id');
    $report->report = pdfannotator_get_relativelink($report->report, $questionid, $context);
    $report->reportedcomment = pdfannotator_get_relativelink($report->reportedcomment, $report->commentid, $context);

    // 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.
    $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
 */