chrome/browser/resources/app_management/reducers.js

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

/**
 * @fileoverview Module of functions which produce a new page state in response
 * to an action. Reducers (in the same sense as Array.prototype.reduce) must be
 * pure functions: they must not modify existing state objects, or make any API
 * calls.
 */

cr.define('app_management', function() {
  const AppState = {};

  /**
   * @param {AppMap} apps
   * @param {Object} action
   * @return {AppMap}
   */
  AppState.addApps = function(apps, action) {
    const newAppEntries = {};
    for (const app of action.apps) {
      newAppEntries[app.id] = app;
    }
    return Object.assign({}, apps, newAppEntries);
  };

  /**
   * @param {AppMap} apps
   * @param {Object} action
   * @return {AppMap}
   */
  AppState.updateApps = function(apps, action) {
    switch (action.name) {
      case 'add-apps':
        return AppState.addApps(apps, action);
      default:
        return apps;
    }
  };

  /**
   * Root reducer for the App Management page. This is called by the store in
   * response to an action, and the return value is used to update the UI.
   * @param {!AppManagementPageState} state
   * @param {Object} action
   * @return {!AppManagementPageState}
   */
  function reduceAction(state, action) {
    return {
      apps: AppState.updateApps(state.apps, action),
    };
  }

  return {
    reduceAction: reduceAction,
    AppState: AppState,
  };
});