Added graph controls

Microsoft.Toolkit.Services/AssemblyInfo.cs

@@ -11,4 +11,5 @@
 // ******************************************************************
 
 using System.Runtime.CompilerServices;
-[assembly:InternalsVisibleTo("Microsoft.Toolkit.Uwp.Services")]
+[assembly:InternalsVisibleTo("Microsoft.Toolkit.Uwp.Services")]
+[assembly:InternalsVisibleTo("Microsoft.Toolkit.Uwp.UI.Controls.Graph")]

Microsoft.Toolkit.Services/Services/MicrosoftGraph/MicrosoftGraphService.cs

@@ -12,6 +12,7 @@
 
 using System;
 using System.Net.Http.Headers;
+using System.Threading;
 using System.Threading.Tasks;
 using Microsoft.Graph;
 using Microsoft.Identity.Client;
@@ -24,11 +25,18 @@ namespace Microsoft.Toolkit.Services.MicrosoftGraph
     /// </summary>
     public class MicrosoftGraphService
     {
+        private readonly SemaphoreSlim _readLock = new SemaphoreSlim(1, 1);
+
         /// <summary>
         /// Gets or sets Authentication instance.
         /// </summary>
         internal MicrosoftGraphAuthenticationHelper Authentication { get; set; }
 
+        /// <summary>
+        /// Event raised when user logs in our out.
+        /// </summary>
+        public event EventHandler IsAuthenticatedChanged;
+
         /// <summary>
         /// Gets or sets store a reference to an instance of the underlying data provider.
         /// </summary>
@@ -49,10 +57,27 @@ public class MicrosoftGraphService
         /// </summary>
         protected bool IsInitialized { get; set; }
 
+        private bool _isAuthenticated;
+
         /// <summary>
         /// Gets or sets a value indicating whether user is connected.
         /// </summary>
-        protected bool IsConnected { get; set; }
+        public bool IsAuthenticated
+        {
+            get
+            {
+                return _isAuthenticated;
+            }
+
+            protected set
+            {
+                if (_isAuthenticated != value)
+                {
+                    _isAuthenticated = value;
+                    IsAuthenticatedChanged?.Invoke(this, EventArgs.Empty);
+                }
+            }
+        }
 
         /// <summary>
         /// Gets or sets AppClientId.
@@ -175,6 +200,10 @@ public virtual Task<bool> Logout()
             {
                 throw new InvalidOperationException("Microsoft Graph not initialized.");
             }
+
+            IsAuthenticated = false;
+            User = null;
+
 #if WINRT
             var authenticationModel = AuthenticationModel.ToString();
             return Authentication.LogoutAsync(authenticationModel);
@@ -190,7 +219,6 @@ public virtual Task<bool> Logout()
         /// <returns>Returns success or failure of login attempt.</returns>
         public virtual async Task<bool> LoginAsync(string loginHint = null)
         {
-            IsConnected = false;
             if (!IsInitialized)
             {
                 throw new InvalidOperationException("Microsoft Graph not initialized.");
@@ -213,11 +241,10 @@ public virtual async Task<bool> LoginAsync(string loginHint = null)
 
             if (string.IsNullOrEmpty(accessToken))
             {
-                return IsConnected;
+                IsAuthenticated = false;
+                return IsAuthenticated;
             }
 
-            IsConnected = true;
-
 #if WINRT
             User = new MicrosoftGraphUserService(GraphProvider);
 #else
@@ -239,7 +266,85 @@ public virtual async Task<bool> LoginAsync(string loginHint = null)
                 User.InitializeEvent();
             }
 
-            return IsConnected;
+            IsAuthenticated = true;
+            return IsAuthenticated;
+        }
+
+        /// <summary>
+        /// Tries to log in user if not already loged in
+        /// </summary>
+        /// <returns>true if service is already loged in</returns>
+        internal async Task<bool> TryLoginAsync()
+        {
+            if (!IsInitialized)
+            {
+                return false;
+            }
+
+            if (IsAuthenticated)
+            {
+                return true;
+            }
+
+            try
+            {
+                await _readLock.WaitAsync();
+                await LoginAsync();
+            }
+            catch (MsalServiceException ex)
+            {
+                // Swallow error in case of authentication cancellation.
+                if (ex.ErrorCode != "authentication_canceled"
+                    && ex.ErrorCode != "access_denied")
+                {
+                    throw ex;
+                }
+            }
+            finally
+            {
+                _readLock.Release();
+            }
+
+            return IsAuthenticated;
+        }
+
+        internal async Task<bool> ConnectForAnotherUserAsync()
+        {
+            if (!IsInitialized)
+            {
+                throw new InvalidOperationException("Microsoft Graph not initialized.");
+            }
+
+            try
+            {
+                var publicClientApplication = new PublicClientApplication(AppClientId);
+                AuthenticationResult result = await publicClientApplication.AcquireTokenAsync(DelegatedPermissionScopes);
+
+                var signedUser = result.User;
+
+                foreach (var user in publicClientApplication.Users)
+                {
+                    if (user.Identifier != signedUser.Identifier)
+                    {
+                        publicClientApplication.Remove(user);
+                    }
+                }
+
+                await LoginAsync();
+
+                return true;
+            }
+            catch (MsalServiceException ex)
+            {
+                // Swallow error in case of authentication cancellation.
+                if (ex.ErrorCode != "authentication_canceled"
+                    && ex.ErrorCode != "access_denied")
+                {
+                    throw ex;
+                }
+            }
+
+            return false;
         }
 
         /// <summary>