public static function get_wikis_by_courses($courseids = array()) {

        $returnedwikis = array();
        $warnings = array();

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

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

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

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

            // Get the wikis in this course, this function checks users visibility permissions.
            // We can avoid then additional validate_context calls.
            $wikis = get_all_instances_in_courses('wiki', $courses);

            foreach ($wikis as $wiki) {

                $context = context_module::instance($wiki->coursemodule);

                // Entry to return.
                $module = array();

                // First, we return information that any user can see in (or can deduce from) the web interface.
                $module['id'] = $wiki->id;
                $module['coursemodule'] = $wiki->coursemodule;
                $module['course'] = $wiki->course;
                $module['name']  = external_format_string($wiki->name, $context->id);

                $viewablefields = [];
                if (has_capability('mod/wiki:viewpage', $context)) {
                    list($module['intro'], $module['introformat']) =
                        external_format_text($wiki->intro, $wiki->introformat, $context->id, 'mod_wiki', 'intro', null);
                    $module['introfiles'] = external_util::get_area_files($context->id, 'mod_wiki', 'intro', false, false);

                    $viewablefields = array('firstpagetitle', 'wikimode', 'defaultformat', 'forceformat', 'editbegin', 'editend',
                                            'section', 'visible', 'groupmode', 'groupingid');
                }

                // Check additional permissions for returning optional private settings.
                if (has_capability('moodle/course:manageactivities', $context)) {
                    $additionalfields = array('timecreated', 'timemodified');
                    $viewablefields = array_merge($viewablefields, $additionalfields);
                }

                foreach ($viewablefields as $field) {
                    $module[$field] = $wiki->{$field};
                }

                // Check if user can add new pages.
                $module['cancreatepages'] = wiki_can_create_pages($context);

                $returnedwikis[] = $module;
            }
        }

        $result = array();
        $result['wikis'] = $returnedwikis;
        $result['warnings'] = $warnings;
        return $result;
    }