remoting/webapp/wcs_loader.js

   1 /* Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2  * Use of this source code is governed by a BSD-style license that can be
   3  * found in the LICENSE file.
   4  */
   5
   6 /**
   7  * @fileoverview
   8  * A class that loads a WCS IQ client and constructs remoting.wcs as a
   9  * wrapper for it.
  10  */
  11
  12 'use strict';
  13
  14 /** @suppress {duplicate} */
  15 var remoting = remoting || {};
  16
  17 /** @type {remoting.WcsLoader} */
  18 remoting.wcsLoader = null;
  19
  20 /**
  21  * @constructor
  22  */
  23 remoting.WcsLoader = function() {
  24   /**
  25    * The WCS client that will be downloaded. This variable is initialized (via
  26    * remoting.wcsLoader) by the downloaded Javascript.
  27    * @type {remoting.WcsIqClient}
  28    */
  29   this.wcsIqClient = null;
  30 };
  31
  32 /**
  33  * Load WCS if necessary, then invoke the callback with an access token.
  34  *
  35  * @param {function(string): void} onReady The callback function, called with
  36  *     an OAuth2 access token when WCS has been loaded.
  37  * @param {function(remoting.Error):void} onError Function to invoke with an
  38  *     error code on failure.
  39  * @return {void} Nothing.
  40  */
  41 remoting.WcsLoader.load = function(onReady, onError) {
  42   if (!remoting.wcsLoader) {
  43     remoting.wcsLoader = new remoting.WcsLoader();
  44   }
  45   /** @param {string} token The OAuth2 access token. */
  46   var start = function(token) {
  47     remoting.wcsLoader.start_(token, onReady, onError);
  48   };
  49   remoting.oauth2.callWithToken(start, onError);
  50 };
  51
  52 /**
  53  * The URL of the GTalk gadget.
  54  * @type {string}
  55  * @private
  56  */
  57 remoting.WcsLoader.prototype.TALK_GADGET_URL_ =
  58     'https://chromoting-client.talkgadget.google.com/talkgadget/';
  59
  60 /**
  61  * The id of the script node.
  62  * @type {string}
  63  * @private
  64  */
  65 remoting.WcsLoader.prototype.SCRIPT_NODE_ID_ = 'wcs-script-node';
  66
  67 /**
  68  * The attribute name indicating that the WCS has finished loading.
  69  * @type {string}
  70  * @private
  71  */
  72 remoting.WcsLoader.prototype.SCRIPT_NODE_LOADED_FLAG_ = 'wcs-script-loaded';
  73
  74 /**
  75  * Starts loading the WCS IQ client.
  76  *
  77  * When it's loaded, construct remoting.wcs as a wrapper for it.
  78  * When the WCS connection is ready, or on error, call |onReady| or |onError|,
  79  * respectively.
  80  *
  81  * @param {string} token An OAuth2 access token.
  82  * @param {function(string): void} onReady The callback function, called with
  83  *     an OAuth2 access token when WCS has been loaded.
  84  * @param {function(remoting.Error):void} onError Function to invoke with an
  85  *     error code on failure.
  86  * @return {void} Nothing.
  87  * @private
  88  */
  89 remoting.WcsLoader.prototype.start_ = function(token, onReady, onError) {
  90   var node = document.getElementById(this.SCRIPT_NODE_ID_);
  91   if (!node) {
  92     // The first time, there will be no script node, so create one.
  93     node = document.createElement('script');
  94     node.id = this.SCRIPT_NODE_ID_;
  95     node.src = this.TALK_GADGET_URL_ + 'iq?access_token=' + token;
  96     node.type = 'text/javascript';
  97     document.body.insertBefore(node, document.body.firstChild);
  98   } else if (node.hasAttribute(this.SCRIPT_NODE_LOADED_FLAG_)) {
  99     // Subsequently, explicitly invoke onReady if onload has already fired.
 100     // TODO(jamiewalch): It's possible that the WCS client has not finished
 101     // initializing. Add support for multiple callbacks to the remoting.Wcs
 102     // class to address this.
 103     onReady(token);
 104     return;
 105   }
 106   /** @type {remoting.WcsLoader} */
 107   var that = this;
 108   var onLoad = function() {
 109     var typedNode = /** @type {Element} */ (node);
 110     typedNode.setAttribute(that.SCRIPT_NODE_LOADED_FLAG_, true);
 111     that.constructWcs_(token, onReady);
 112   };
 113   var onLoadError = function(event) {
 114     // The DOM Event object has no detail on the nature of the error, so try to
 115     // validate the token to get a better idea.
 116     /** @param {remoting.Error} error Error code. */
 117     var onValidateError = function(error) {
 118       var typedNode = /** @type {Element} */ (node);
 119       typedNode.parentNode.removeChild(node);
 120       onError(error);
 121     };
 122     var onValidateOk = function() {
 123       // We can reach the authentication server and validate the token. Either
 124       // there's something wrong with the talkgadget service, or there is a
 125       // cookie problem. Only the cookie problem can be fixed by the user, so
 126       // suggest that fix.
 127       onValidateError(remoting.Error.AUTHENTICATION_FAILED);
 128     }
 129     remoting.oauth2.validateToken(token, onValidateOk, onValidateError);
 130   }
 131   node.addEventListener('load', onLoad, false);
 132   node.addEventListener('error', onLoadError, false);
 133 };
 134
 135 /**
 136  * Constructs the remoting.wcs object.
 137  *
 138  * @param {string} token An OAuth2 access token.
 139  * @param {function(string): void} onReady The callback function, called with
 140  *     an OAuth2 access token when WCS has been loaded.
 141  * @return {void} Nothing.
 142  * @private
 143  */
 144 remoting.WcsLoader.prototype.constructWcs_ = function(token, onReady) {
 145   remoting.wcs = new remoting.Wcs(
 146       remoting.wcsLoader.wcsIqClient,
 147       token,
 148       function() { onReady(token); });
 149 };