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Microsoft's Graph API SDK Helper
//Copyright (c) Microsoft. All rights reserved. Licensed under the MIT license.
//See LICENSE in the project root for license information.
using System;
using System.Diagnostics;
using System.Net.Http.Headers;
using System.Net.Http;
using System.Linq;
using System.Threading.Tasks;
using Windows.Security.Authentication.Web;
using Windows.Security.Authentication.Web.Core;
using Windows.Security.Credentials;
using Windows.Storage;
using Microsoft.Graph;
using Microsoft.Identity.Client;
using App6_MSA;
namespace Microsoft_Graph_UWP_Connect_SDK
{
public class AuthenticationHelper
{
// The Client ID is used by the application to uniquely identify itself to the v2.0 authentication endpoint.
static string clientId = App.Current.Resources["ida:ClientID"].ToString();
public static string[] Scopes = { "User.Read", "Mail.Send", "Files.ReadWrite" };
public static PublicClientApplication IdentityClientApp = new PublicClientApplication(clientId);
public static string TokenForUser = null;
public static DateTimeOffset Expiration;
private static GraphServiceClient graphClient = null;
// Get an access token for the given context and resourceId. An attempt is first made to
// acquire the token silently. If that fails, then we try to acquire the token by prompting the user.
public static GraphServiceClient GetAuthenticatedClient()
{
if (graphClient == null)
{
// Create Microsoft Graph client.
try
{
graphClient = new GraphServiceClient(
"https://graph.microsoft.com/v1.0",
new DelegateAuthenticationProvider(
async (requestMessage) =>
{
var token = await GetTokenForUserAsync();
requestMessage.Headers.Authorization = new AuthenticationHeaderValue("bearer", token);
// This header has been added to identify our sample in the Microsoft Graph service. If extracting this code for your project please remove.
requestMessage.Headers.Add("SampleID", "uwp-csharp-connect-sample");
}));
return graphClient;
}
catch (Exception ex)
{
Debug.WriteLine("Could not create a graph client: " + ex.Message);
}
}
return graphClient;
}
/// <summary>
/// Get Token for User.
/// </summary>
/// <returns>Token for user.</returns>
public static async Task<string> GetTokenForUserAsync()
{
AuthenticationResult authResult;
try
{
authResult = await IdentityClientApp.AcquireTokenSilentAsync(Scopes, IdentityClientApp.Users.First());
TokenForUser = authResult.AccessToken;
}
catch (Exception)
{
if (TokenForUser == null || Expiration <= DateTimeOffset.UtcNow.AddMinutes(5))
{
authResult = await IdentityClientApp.AcquireTokenAsync(Scopes);
TokenForUser = authResult.AccessToken;
Expiration = authResult.ExpiresOn;
}
}
return TokenForUser;
}
/// <summary>
/// Signs the user out of the service.
/// </summary>
public static void SignOut()
{
foreach (var user in IdentityClientApp.Users)
{
IdentityClientApp.Remove(user);
}
graphClient = null;
TokenForUser = null;
}
}
}
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