protected function _order($fields)
    {
        $direction = 'ASC';

        $result = [];
        foreach ($fields as $field => $value) {
            if (!is_int($field)) {
                $result[$field] = $value;
                continue;
            }
            if (preg_match('/^(.*?)\s+((?:a|de)sc)$/i', $value, $match)) {
                $value = $match[1];
                $dir = $match[2];
            } else {
                $dir = $direction;
            }
            $result[$value] = $dir;
        }
        return $result;
    }