/*
 * Copyright 2021 The Backstage Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import { relative, isAbsolute } from 'path';

/**
 * Checks if path is the same as or a child path of base.
 *
 * @public
 */
export function isChildPath(base: string, path: string): boolean {
  const relativePath = relative(base, path);
  if (relativePath === '') {
    // The same directory
    return true;
  }

  const outsideBase = relativePath.startsWith('..'); // not outside base
  const differentDrive = isAbsolute(relativePath); // on Windows, this means dir is on a different drive from base.

  return !outsideBase && !differentDrive;
}
