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.

import {addWebUIListener} from 'chrome://resources/js/cr.m.js';
import {NativeEventTarget as EventTarget} from 'chrome://resources/js/cr/event_target.m.js';

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

  manager: [
    'onActionableError',
    'onChangesApplied',
    'onChangesComplete',
    'onConnectionStatusChange',
    'onEncryptedTypesChanged',
    '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 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(response) {
        self.log_(categoryName, eventName, response);
      };
    };

    for (const categoryName in eventsByCategory) {
      for (let i = 0; i < eventsByCategory[categoryName].length; ++i) {
        const eventName = eventsByCategory[categoryName][i];
        addWebUIListener(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);
  }
}

export const log = new Log();