Hangouts remote desktop part III - It2MeService

remoting/webapp/background/it2me_helper_channel.js

+// Copyright 2014 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
+ *
+ * It2MeHelperChannel relays messages between Hangouts and Chrome Remote Desktop
+ * (webapp) for the helper (the Hangouts participant who is giving remote
+ * assistance).
+ *
+ * It runs in the background page and contains two chrome.runtime.Port objects,
+ * respresenting connections to the webapp and hangout, respectively.
+ *
+ * Connection is always initiated from Hangouts.
+ *
+ *   Hangout                     It2MeHelperChannel        Chrome Remote Desktop
+ *      |-----runtime.connect() ------>|                                |
+ *      |------connect message-------->|                                |
+ *      |                              |-------appLauncher.launch()---->|
+ *      |                              |<------runtime.connect()------- |
+ *      |                              |<-----sessionStateChanged------ |
+ *      |<----sessionStateChanged------|                                |
+ *
+ * Disconnection can be initiated from either side:
+ * 1. In the normal flow initiated from hangout
+ *    Hangout                    It2MeHelperChannel        Chrome Remote Desktop
+ *       |-----disconnect message------>|                               |
+ *       |<-sessionStateChanged(CLOSED)-|                               |
+ *       |                              |-----appLauncher.close()------>|
+ *
+ * 2. In the normal flow initiated from webapp
+ *    Hangout                    It2MeHelperChannel        Chrome Remote Desktop
+ *       |                              |<-sessionStateChanged(CLOSED)--|
+ *       |                              |<--------port.disconnect()-----|
+ *       |<--------port.disconnect()----|                               |
+ *
+ * 2. If hangout crashes
+ *    Hangout                    It2MeHelperChannel        Chrome Remote Desktop
+ *       |---------port.disconnect()--->|                               |
+ *       |                              |--------port.disconnect()----->|
+ *       |                              |------appLauncher.close()----->|
+ *
+ * 3. If webapp crashes
+ *    Hangout                    It2MeHelperChannel        Chrome Remote Desktop
+ *       |                              |<-------port.disconnect()------|
+ *       |<-sessionStateChanged(FAILED)-|                               |
+ *       |<--------port.disconnect()----|                               |
+ */
+
+'use strict';
+
+/** @suppress {duplicate} */
+var remoting = remoting || {};
+
+/**
+ * @param {remoting.AppLauncher} appLauncher
+ * @param {chrome.runtime.Port} hangoutPort Represents an active connection to
+ *     Hangouts.
+ * @param {function(remoting.It2MeHelperChannel)} onDisconnectCallback Callback
+ *     to notify when the connection is torn down.  IT2MeService uses this
+ *     callback to dispose of the channel object.
+ * @constructor
+ */
+remoting.It2MeHelperChannel =
+    function(appLauncher, hangoutPort, onDisconnectCallback) {
+
+  /**
+   * @type {remoting.AppLauncher}
+   * @private
+   */
+  this.appLauncher_ = appLauncher;
+
+  /**
+   * @type {chrome.runtime.Port}
+   * @private
+   */
+  this.hangoutPort_ = hangoutPort;
+
+  /**
+   * @type {chrome.runtime.Port}
+   * @private
+   */
+  this.webappPort_ = null;
+
+  /**
+   * @type {string}
+   * @private
+   */
+  this.instanceId_ = '';
+
+  /**
+   * @type {remoting.ClientSession.State}
+   * @private
+   */
+  this.sessionState_ = remoting.ClientSession.State.CONNECTING;
+
+  /**
+   * @type {?function(remoting.It2MeHelperChannel)}
+   * @private
+   */
+  this.onDisconnectCallback_ = onDisconnectCallback;
+
+  this.onWebappMessageRef_ = this.onWebappMessage_.bind(this);
+  this.onWebappDisconnectRef_ = this.onWebappDisconnect_.bind(this);
+  this.onHangoutMessageRef_ = this.onHangoutMessage_.bind(this);
+  this.onHangoutDisconnectRef_ = this.onHangoutDisconnect_.bind(this);
+};
+
+/** @enum {string} */
+remoting.It2MeHelperChannel.HangoutMessageTypes = {
+  CONNECT: 'connect',
+  DISCONNECT: 'disconnect'
+};
+
+/** @enum {string} */
+remoting.It2MeHelperChannel.WebappMessageTypes = {
+  SESSION_STATE_CHANGED: 'sessionStateChanged'
+};
+
+remoting.It2MeHelperChannel.prototype.init = function() {
+  this.hangoutPort_.onMessage.addListener(this.onHangoutMessageRef_);
+  this.hangoutPort_.onDisconnect.addListener(this.onHangoutDisconnectRef_);
+};
+
+/** @return {string} */
+remoting.It2MeHelperChannel.prototype.instanceId = function() {
+  return this.instanceId_;
+};
+
+/**
+ * @param {{method:string, data:Object.<string,*>}} message
+ * @return {boolean} whether the message is handled or not.
+ * @private
+ */
+remoting.It2MeHelperChannel.prototype.onHangoutMessage_ = function(message) {
+  try {
+    var MessageTypes = remoting.It2MeHelperChannel.HangoutMessageTypes;
+    switch (message.method) {
+      case MessageTypes.CONNECT:
+        this.launchWebapp_(message);
+        return true;
+      case MessageTypes.DISCONNECT:
+        this.closeWebapp_(message);
+        return true;
+    }
+  } catch(e) {
+    var error = /** @type {Error} */ e;
+    console.error(error);
+    this.hangoutPort_.postMessage({
+      method: message.method + 'Response',
+      error: error.message
+    });
+  }
+  return false;
+};
+
+/**
+ * Disconnect the existing connection to the helpee.
+ *
+ * @param {{method:string, data:Object.<string,*>}} message
+ * @private
+ */
+remoting.It2MeHelperChannel.prototype.closeWebapp_ =
+    function(message) {
+  // TODO(kelvinp): Closing the v2 app currently doesn't disconnect the IT2me
+  // session (crbug.com/402137), so send an explicit notification to Hangouts.
+  this.sessionState_ = remoting.ClientSession.State.CLOSED;
+  this.hangoutPort_.postMessage({
+    method: 'sessionStateChanged',
+    state: this.sessionState_
+  });
+  this.appLauncher_.close(this.instanceId_);
+};
+
+/**
+ * Launches the web app.
+ *
+ * @param {{method:string, data:Object.<string,*>}} message
+ * @private
+ */
+remoting.It2MeHelperChannel.prototype.launchWebapp_ =
+    function(message) {
+  var accessCode = getStringAttr(message, 'accessCode');
+  if (!accessCode) {
+    throw new Error('Access code is missing');
+  }
+
+  // Launch the webapp.
+  this.appLauncher_.launch({
+    mode: 'hangout',
+    accessCode: accessCode
+  }).then(
+    /**
+     * @this {remoting.It2MeHelperChannel}
+     * @param {string} instanceId
+     */
+    function(instanceId){
+      this.instanceId_ = instanceId;
+    }.bind(this));
+};
+
+/**
+ * @private
+ */
+remoting.It2MeHelperChannel.prototype.onHangoutDisconnect_ = function() {
+  this.appLauncher_.close(this.instanceId_);
+  this.unhookPorts_();
+};
+
+/**
+ * @param {chrome.runtime.Port} port The port represents a connection to the
+ *     webapp.
+ * @param {string} id The id of the tab or window that is hosting the webapp.
+ */
+remoting.It2MeHelperChannel.prototype.onWebappConnect = function(port, id) {
+  base.debug.assert(id === this.instanceId_);
+  base.debug.assert(this.hangoutPort_ !== null);
+
+  // Hook listeners.
+  port.onMessage.addListener(this.onWebappMessageRef_);
+  port.onDisconnect.addListener(this.onWebappDisconnectRef_);
+  this.webappPort_ = port;
+};
+
+/** @param {chrome.runtime.Port} port The webapp port. */
+remoting.It2MeHelperChannel.prototype.onWebappDisconnect_ = function(port) {
+  // If the webapp port got disconnected while the session is still connected,
+  // treat it as an error.
+  var States = remoting.ClientSession.State;
+  if (this.sessionState_ === States.CONNECTING ||
+      this.sessionState_ === States.CONNECTED) {
+    this.sessionState_ = States.FAILED;
+    this.hangoutPort_.postMessage({
+      method: 'sessionStateChanged',
+      state: this.sessionState_
+    });
+  }
+  this.unhookPorts_();
+};
+
+/**
+ * @param {{method:string, data:Object.<string,*>}} message
+ * @private
+ */
+remoting.It2MeHelperChannel.prototype.onWebappMessage_ = function(message) {
+  try {
+    console.log('It2MeHelperChannel id=' + this.instanceId_ +
+                ' incoming message method=' + message.method);
+    var MessageTypes = remoting.It2MeHelperChannel.WebappMessageTypes;
+    switch (message.method) {
+      case MessageTypes.SESSION_STATE_CHANGED:
+        var state = getNumberAttr(message, 'state');
+        this.sessionState_ =
+            /** @type {remoting.ClientSession.State} */ state;
+        this.hangoutPort_.postMessage(message);
+        return true;
+    }
+    throw new Error('Unknown message method=' + message.method);
+  } catch(e) {
+    var error = /** @type {Error} */ e;
+    console.error(error);
+    this.webappPort_.postMessage({
+      method: message.method + 'Response',
+      error: error.message
+    });
+  }
+  return false;
+};
+
+remoting.It2MeHelperChannel.prototype.unhookPorts_ = function() {
+  if (this.webappPort_) {
+    this.webappPort_.onMessage.removeListener(this.onWebappMessageRef_);
+    this.webappPort_.onDisconnect.removeListener(this.onWebappDisconnectRef_);
+    this.webappPort_.disconnect();
+    this.webappPort_ = null;
+  }
+
+  if (this.hangoutPort_) {
+    this.hangoutPort_.onMessage.removeListener(this.onHangoutMessageRef_);
+    this.hangoutPort_.onDisconnect.removeListener(this.onHangoutDisconnectRef_);
+    this.hangoutPort_.disconnect();
+    this.hangoutPort_ = null;
+  }
+
+  if (this.onDisconnectCallback_) {
+    this.onDisconnectCallback_(this);
+    this.onDisconnectCallback_  = null;
+  }
+};