[Webapp Refactor] Group authentications fields into remoting.CredentialsProvider.

remoting/webapp/crd/js/credentials_provider.js

+// Copyright 2015 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.
+
+'use strict';
+
+var remoting = remoting || {};
+
+/** @typedef {{id: string, secret: string}} */
+remoting.PairingInfo;
+
+/** @typedef {{token: string, secret: string}} */
+remoting.ThirdPartyToken;
+
+/**
+ * Parameters for the remoting.CredentialsProvider constructor.
+ *
+ * fetchPin: Called by Me2Me connections when a PIN needs to be obtained
+ *     interactively.
+ *
+ * pairingInfo: The pairing info for Me2Me Connections.
+ *
+ * accessCode: It2Me access code.
+ *
+ * fetchThirdPartyToken: Called when a third party authentication token
+ *     is needed
+ *
+ * @typedef {{
+ *   accessCode: (string|undefined),
+ *   fetchPin: (function(boolean,function(string): void)|undefined),
+ *   pairingInfo: (remoting.PairingInfo|undefined),
+ *   fetchThirdPartyToken:
+ *      (function(string ,string , string,
+ *                function(string, string):void) | undefined)
+ * }}
+ */
+remoting.CredentialsProviderParams;
+
+/**
+ * @param {remoting.CredentialsProviderParams} args
+ * @constructor
+ */
+remoting.CredentialsProvider = function(args) {
+  /** @private */
+  this.fetchPin_ = args.fetchPin;
+  /** @private */
+  this.pairingInfo_ = args.pairingInfo;
+  /** @private */
+  this.accessCode_ = args.accessCode;
+  /** @private */
+  this.fetchThirdPartyToken_ = args.fetchThirdPartyToken;
+};
+
+/** @enum {number} */
+remoting.CredentialsProvider.Methods = {
+  THIRD_PARTY: 0,
+  PAIRING: 1,
+  ACCESS_CODE: 2,
+  PIN: 3
+};
+
+/**
+ * @param {remoting.CredentialsProvider.Methods} method
+ * @returns {boolean} Whether |method| is supported.
+ */
+remoting.CredentialsProvider.prototype.supports = function(method) {
+  var Methods = remoting.CredentialsProvider.Methods;
+  if (method === Methods.PIN) {
+    return Boolean(this.fetchPin_);
+  } else if (method === Methods.ACCESS_CODE) {
+    return Boolean(this.accessCode_);
+  } else if (method === Methods.THIRD_PARTY) {
+    return Boolean(this.fetchThirdPartyToken_);
+  } else if (method === Methods.PAIRING) {
+    return Boolean(this.pairingInfo_);
+  }
+};
+
+/** @returns {string} The It2Me access code */
+remoting.CredentialsProvider.prototype.getSharedSecret = function() {
+  return this.accessCode_ || '';

[Jamie, 2015/02/26 23:20:14]

Would an assert(supports(ACCESS_CODE)) be appropriate here (and similarly
below)?

Also, you've used access-code and shared-secret somewhat interchangeable. Can
you pick one and standardize on it?

[kelvinp, 2015/02/27 01:03:21]

Yes, will use AccessCode instead?
No, the problem is during connect, the plugin will always need an access Code to
be passed in, therefore, we need to return a dummy value.

[Jamie, 2015/02/27 01:53:03]

Maybe a better way of phrasing it would be to ask what's the value of the
supports() method? If callers are expected to invoke that and respect the
result, then the accessor methods should assert (and the case you mention would
need to fall-back on a default of '' explicitly). If the accessors are going to
try to provide sensible defaults, then there's no need for the supports()
method. My preference is for the former because it guards against misuse of the
class and doesn't enforce a single (albeit sensible) default behaviour for all
callers.

[kelvinp, 2015/02/27 19:47:40]

Agreed.  As discussed, this is due to the fact that the client_plugin expects us
to call useAsyncPinDialog when an accessCode is NOT present.  Underneath the
hood, if useAsyncPinDialog is not called, it will internally binds the fetchPIN
callback to the accessCode.
I am going to mimic the same logic in Credentials provider instead.

+};
+
+/** @returns {remoting.PairingInfo}  */
+remoting.CredentialsProvider.prototype.getPairingInfo = function() {
+  return this.pairingInfo_ || { id: '', secret: ''};
+};
+
+/**
+ * @param {boolean} pairingSupported Whether pairing is supported by the host.
+ * @returns {Promise<string>}
+ */
+remoting.CredentialsProvider.prototype.getPIN = function(pairingSupported) {
+  var that = this;
+  if (!this.fetchPin_) {
+    Promise.resolve('');
+  }
+  return new Promise(function(/** function(string) */ resolve) {
+    that.fetchPin_(pairingSupported, resolve);
+  });
+};
+
+/**
+ * @param {string} tokenUrl Token-issue URL received from the host.
+ * @param {string} hostPublicKey Host public key (DER and Base64 encoded).
+ * @param {string} scope OAuth scope to request the token for.
+ *
+ * @returns {Promise<remoting.ThirdPartyToken>}
+ */
+remoting.CredentialsProvider.prototype.getThirdPartyToken = function(
+    tokenUrl, hostPublicKey, scope) {
+  var that = this;
+  if (!this.fetchThirdPartyToken_) {
+    Promise.resolve({token: '', secret: ''});
+  }
+  return new Promise(function(/** Function */ resolve) {
+    var onTokenFetched = function(/** string */ token, /** string */ secret) {
+      resolve({token: token, secret: secret});
+    };
+    that.fetchThirdPartyToken_(tokenUrl, hostPublicKey, scope, onTokenFetched);
+  });
+};
+
+