Issue 471: Support WP8.1

Src/GoogleApis.Auth.WP81/OAuth2/GoogleWebAuthorizationBroker.cs

+/*
+Copyright 2014 Google Inc
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Text;
+using System.Threading;
+using System.Threading.Tasks;
+using Windows.Storage;
+
+using Google.Apis.Auth.OAuth2.Flows;
+using Google.Apis.Util.Store;
+
+namespace Google.Apis.Auth.OAuth2
+{
+/// <summary>A helper utility to manage the authorization code flow.</summar
y>
+public class GoogleWebAuthorizationBroker
+{
+/// <summary>Asynchronously authorizes the specified user.</summary>
+/// <remarks>
+/// It uses <see cref="Google.Apis.Util.Store.PasswordVaultDataStore"/>
as the flow's data store by default.
+/// </remarks>
+/// <param name="clientSecretsUri">The client secrets URI.</param>
+/// <param name="scopes">
+/// The scopes which indicate the Google API access your application is
requesting.
+/// </param>
+/// <param name="user">The user to authorize.</param>
+/// <param name="taskCancellationToken">Cancellation token to cancel an
operation.</param>
+/// <returns>User credential.</returns>
+public static async Task<UserCredential> AuthorizeAsync(Uri clientSecret
sUri, IEnumerable<string> scopes,
+string user, CancellationToken taskCancellationToken)
+{
+var clientSecrets = await LoadClientSecrets(clientSecretsUri).Config
ureAwait(false);
+return await AuthorizeAsync(clientSecrets, scopes, user, taskCancell
ationToken).ConfigureAwait(false);
+}
+
+/// <summary>
+/// Asynchronously reauthorizes the user. This method should be called i
f the users want to authorize after·
+/// they revoked the token.
+/// </summary>
+/// <param name="userCredential">The current user credential. Its <see c
ref="UserCredential.Token"/> will be
+/// updated. </param>
+/// <param name="taskCancellationToken">Cancellation token to cancel an
operation.</param>
+public static async Task ReauthorizeAsync(UserCredential userCredential,
+CancellationToken taskCancellationToken)
+{
+var installedApp = new AuthorizationCodeWPInstalledApp(userCredentia
l.Flow);
+// Create an authorization code installed app instance and authorize
the user.
+UserCredential newUserCredential = await installedApp.AuthorizeAsync
(
+userCredential.UserId, taskCancellationToken).ConfigureAwait(fal
se);
+userCredential.Token = newUserCredential.Token;
+}
+
+/// <summary>Asynchronously authorizes the specified user.</summary>
+/// <remarks>
+/// It uses <see cref="Google.Apis.Util.Store.PasswordVaultDataStore"/>
as the flow's data store by default.
+/// </remarks>
+/// <param name="clientSecrets">The client secrets URI.</param>
+/// <param name="scopes">
+/// The scopes which indicate the Google API access your application is
requesting.
+/// </param>
+/// <param name="user">The user to authorize.</param>
+/// <param name="taskCancellationToken">Cancellation token to cancel an
operation.</param>
+/// <returns>User credential.</returns>
+private static async Task<UserCredential> AuthorizeAsync(ClientSecrets c
lientSecrets,
+IEnumerable<string> scopes, string user, CancellationToken taskCance
llationToken)
+{
+var initializer = new GoogleAuthorizationCodeFlow.Initializer
+{
+ClientSecrets = clientSecrets,
+Scopes = scopes,
+DataStore = new PasswordVaultDataStore()
+};
+
+var installedApp = new AuthorizationCodeWPInstalledApp(new GoogleAut
horizationCodeFlow(initializer));
+return await installedApp.AuthorizeAsync(user, taskCancellationToken
).ConfigureAwait(false);
+}
+
+/// <summary>Loads the client secrets from the given URI.</summary>
+/// <param name="clientSecretsUri">The client secrets URI.</param>
+/// <returns>Client secrets.</returns>
+private static async Task<ClientSecrets> LoadClientSecrets(Uri clientSec
retsUri)
+{
+var file = await StorageFile.GetFileFromApplicationUriAsync(clientSe
cretsUri);
+var content = await FileIO.ReadTextAsync(file);
+
+using (var stream = new MemoryStream(Encoding.UTF8.GetBytes(content)
))
+{
+return GoogleClientSecrets.Load(stream).Secrets;
+}
+}
+}
+}