<?php
defined('MOODLE_INTERNAL') || die();

require_once $CFG->dirroot . '/lib/externallib.php';

class local_lara_get_children extends external_api
{
    /**
     * Parameter description for get_roles().
     *
     * @return external_function_parameters.
     */
    public static function get_children_parameters()
    {
        return new external_function_parameters([
            'param' => new external_single_structure([
                'roleid' => new external_value(PARAM_INT, 'id of the parent role'),
                'parentid' => new external_value(PARAM_INT, 'parent id'),
            ]),
        ]);
    }

    /**
     * Return roleinformation.
     *
     * This function returns roleid, rolename and roleshortname for all roles or for given roles.
     *
     * @param array $param
     * @return array Array of arrays with role informations.
     */
    public static function get_children($param)
    {
        global $CFG, $DB;
        require_once "$CFG->dirroot/group/lib.php";

        $params = self::validate_parameters(self::get_children_parameters(), ['param' => $param]);

        $roleid = $params['param']['roleid'];
        $parentid = $params['param']['parentid'];

        $children = [];

        $parents = $DB->get_records('role_assignments', ['roleid' => (string) $roleid, 'userid' => (string) $parentid]);
        foreach ($parents as $parent) {
            $ctxid = (string)$parent->contextid;
            $dbChildren = $DB->get_records('context', ['id' => $ctxid, 'contextlevel' => '30']);
            foreach ($dbChildren as $child) {
                $cl = new stdClass;
                $cl->id = ($child->instanceid);
                array_push($children, $cl);
            }
        }
        return $children;
    }

    /**
     * Parameter description for create_sections().
     *
     * @return external_description
     */
    public static function get_children_returns()
    {
        return new external_multiple_structure(
            new external_single_structure([
                'id' => new external_value(PARAM_INT, 'role id'),
            ]));
    }
}