/*
  Copyright 2018 Google LLC

  Use of this source code is governed by an MIT-style
  license that can be found in the LICENSE file or at
  https://opensource.org/licenses/MIT.
*/

import '../_version.mjs';

const CDN_PATH = `WORKBOX_CDN_ROOT_URL`;

const MODULE_KEY_TO_NAME_MAPPING = {
  // TODO(philipwalton): add jsdoc tags to associate these with their module.
  // @name backgroundSync
  // @memberof workbox
  // @see module:workbox-background-sync
  backgroundSync: 'background-sync',
  broadcastUpdate: 'broadcast-update',
  cacheableResponse: 'cacheable-response',
  core: 'core',
  expiration: 'expiration',
  googleAnalytics: 'offline-ga',
  navigationPreload: 'navigation-preload',
  precaching: 'precaching',
  rangeRequests: 'range-requests',
  routing: 'routing',
  strategies: 'strategies',
  streams: 'streams',
};

/**
 * This class can be used to make it easy to use the various parts of
 * Workbox.
 *
 * @private
 */
export class WorkboxSW {
  /**
   * Creates a proxy that automatically loads workbox namespaces on demand.
   *
   * @private
   */
  constructor() {
    this.v = {};
    this._options = {
      debug: self.location.hostname === 'localhost',
      modulePathPrefix: null,
      modulePathCb: null,
    };

    this._env = this._options.debug ? 'dev' : 'prod';
    this._modulesLoaded = false;

    return new Proxy(this, {
      get(target, key) {
        if (target[key]) {
          return target[key];
        }

        const moduleName = MODULE_KEY_TO_NAME_MAPPING[key];
        if (moduleName) {
          target.loadModule(`workbox-${moduleName}`);
        }

        return target[key];
      },
    });
  }

  /**
   * Updates the configuration options. You can specify whether to treat as a
   * debug build and whether to use a CDN or a specific path when importing
   * other workbox-modules
   *
   * @param {Object} [options]
   * @param {boolean} [options.debug] If true, `dev` builds are using, otherwise
   * `prod` builds are used. By default, `prod` is used unless on localhost.
   * @param {Function} [options.modulePathPrefix] To avoid using the CDN with
   * `workbox-sw` set the path prefix of where modules should be loaded from.
   * For example `modulePathPrefix: '/third_party/workbox/v3.0.0/'`.
   * @param {workbox~ModulePathCallback} [options.modulePathCb] If defined,
   * this callback will be responsible for determining the path of each
   * workbox module.
   *
   * @alias workbox.setConfig
   */
  setConfig(options = {}) {
    if (!this._modulesLoaded) {
      Object.assign(this._options, options);
      this._env = this._options.debug ? 'dev' : 'prod';
    } else {
      throw new Error('Config must be set before accessing workbox.* modules');
    }
  }

  /**
   * Load a Workbox module by passing in the appropriate module name.
   *
   * This is not generally needed unless you know there are modules that are
   * dynamically used and you want to safe guard use of the module while the
   * user may be offline.
   *
   * @param {string} moduleName
   *
   * @alias workbox.loadModule
   */
  loadModule(moduleName) {
    const modulePath = this._getImportPath(moduleName);
    try {
      importScripts(modulePath);
      this._modulesLoaded = true;
    } catch (err) {
      // TODO Add context of this error if using the CDN vs the local file.

      // We can't rely on workbox-core being loaded so using console
      // eslint-disable-next-line
      console.error(
          `Unable to import module '${moduleName}' from '${modulePath}'.`);
      throw err;
    }
  }

  /**
   * This method will get the path / CDN URL to be used for importScript calls.
   *
   * @param {string} moduleName
   * @return {string} URL to the desired module.
   *
   * @private
   */
  _getImportPath(moduleName) {
    if (this._options.modulePathCb) {
      return this._options.modulePathCb(moduleName, this._options.debug);
    }

    // TODO: This needs to be dynamic some how.
    let pathParts = [CDN_PATH];

    const fileName = `${moduleName}.${this._env}.js`;

    const pathPrefix = this._options.modulePathPrefix;
    if (pathPrefix) {
      // Split to avoid issues with developers ending / not ending with slash
      pathParts = pathPrefix.split('/');

      // We don't need a slash at the end as we will be adding
      // a filename regardless
      if (pathParts[pathParts.length - 1] === '') {
        pathParts.splice(pathParts.length - 1, 1);
      }
    }

    pathParts.push(fileName);

    return pathParts.join('/');
  }
}