components/sync/driver/resources/sync_log.js

// Copyright (c) 2011 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.

// require: cr.js
// require: cr/event_target.js

/**
 * @fileoverview This creates a log object which listens to and
 * records all sync events.
 */

cr.define('chrome.sync', function() {
  'use strict';

  const eventsByCategory = {
    notifier: [
      'onIncomingNotification',
      'onNotificationStateChange',
    ],

    manager: [
      'onActionableError',
      'onChangesApplied',
      'onChangesComplete',
      'onConnectionStatusChange',
      'onEncryptedTypesChanged',
      'onEncryptionComplete',
      'onInitializationComplete',
      'onPassphraseAccepted',
      'onPassphraseRequired',
      'onStopSyncingPermanently',
      'onSyncCycleCompleted',
    ],

    transaction: [
      'onTransactionWrite',
    ],

    protocol: [
      'onProtocolEvent',
    ]
  };

  /**
   * Creates a new log object which then immediately starts recording
   * sync events.  Recorded entries are available in the 'entries'
   * property and there is an 'append' event which can be listened to.
   */
  class Log extends cr.EventTarget {
    constructor() {
      super();
      const self = this;

      /**
       * The recorded log entries.
       * @type {!Array}
       */
      this.entries =  [];

      /**
       * Creates a callback function to be invoked when an event arrives.
       */
      const makeCallback = function(categoryName, eventName) {
        return function(e) {
          self.log_(categoryName, eventName, e.details);
        };
      };

      for (const categoryName in eventsByCategory) {
        for (let i = 0; i < eventsByCategory[categoryName].length; ++i) {
          const eventName = eventsByCategory[categoryName][i];
          chrome.sync.events.addEventListener(
              eventName,
              makeCallback(categoryName, eventName));
        }
      }
    }

    /**
     * Records a single event with the given parameters and fires the
     * 'append' event with the newly-created event as the 'detail'
     * field of a custom event.
     * @param {string} submodule The sync submodule for the event.
     * @param {string} event The name of the event.
     * @param {!Object} details A dictionary of event-specific details.
     */
    log_(submodule, event, details) {
      const entry = {
        submodule: submodule,
        event: event,
        date: new Date(),
        details: details,
        textDetails: ''
      };
      entry.textDetails = JSON.stringify(entry.details, null, 2);
      this.entries.push(entry);
      // Fire append event.
      const e = document.createEvent('CustomEvent');
      e.initCustomEvent('append', false, false, entry);
      this.dispatchEvent(e);
    }
  }

  return {
    log: new Log()
  };
});