public static function get_forums_by_courses($courseids = array()) {
        global $CFG;

        require_once($CFG->dirroot . "/mod/forum/lib.php");

        $params = self::validate_parameters(self::get_forums_by_courses_parameters(), array('courseids' => $courseids));

        $courses = array();
        if (empty($params['courseids'])) {
            $courses = enrol_get_my_courses();
            $params['courseids'] = array_keys($courses);
        }

        // Array to store the forums to return.
        $arrforums = array();
        $warnings = array();

        // Ensure there are courseids to loop through.
        if (!empty($params['courseids'])) {

            list($courses, $warnings) = external_util::validate_courses($params['courseids'], $courses);

            // Get the forums in this course. This function checks users visibility permissions.
            $forums = get_all_instances_in_courses("forum", $courses);
            foreach ($forums as $forum) {

                $course = $courses[$forum->course];
                $cm = get_coursemodule_from_instance('forum', $forum->id, $course->id);
                $context = context_module::instance($cm->id);

                // Skip forums we are not allowed to see discussions.
                if (!has_capability('mod/forum:viewdiscussion', $context)) {
                    continue;
                }

                $forum->name = external_format_string($forum->name, $context->id);
                // Format the intro before being returning using the format setting.
                list($forum->intro, $forum->introformat) = external_format_text($forum->intro, $forum->introformat,
                                                                                $context->id, 'mod_forum', 'intro', null);
                $forum->introfiles = external_util::get_area_files($context->id, 'mod_forum', 'intro', false, false);
                // Discussions count. This function does static request cache.
                $forum->numdiscussions = forum_count_discussions($forum, $cm, $course);
                $forum->cmid = $forum->coursemodule;
                $forum->cancreatediscussions = forum_user_can_post_discussion($forum, null, -1, $cm, $context);
                $forum->istracked = forum_tp_is_tracked($forum);
                if ($forum->istracked) {
                    $forum->unreadpostscount = forum_tp_count_forum_unread_posts($cm, $course);
                }

                // Add the forum to the array to return.
                $arrforums[$forum->id] = $forum;
            }
        }

        return $arrforums;
    }