SEBWIN-405: Implemented server failure dialog.

SafeExamBrowser.I18n.Contracts/TextKey.cs

@@ -165,6 +165,11 @@ namespace SafeExamBrowser.I18n.Contracts
 		PasswordDialog_SettingsPasswordRequired,
 		PasswordDialog_SettingsPasswordRequiredTitle,
 		RuntimeWindow_ApplicationRunning,
+		ServerFailureDialog_Abort,
+		ServerFailureDialog_Fallback,
+		ServerFailureDialog_Message,
+		ServerFailureDialog_Retry,
+		ServerFailureDialog_Title,
 		Shell_QuitButton,
 		SystemControl_AudioDeviceInfo,
 		SystemControl_AudioDeviceInfoMuted,

SafeExamBrowser.I18n/Data/de.xml

@@ -453,6 +453,21 @@
     <Entry key="RuntimeWindow_ApplicationRunning">
         SEB wird ausgeführt.
     </Entry>
+    <Entry key="ServerFailureDialog_Abort">
+        Abbrechen
+    </Entry>
+    <Entry key="ServerFailureDialog_Fallback">
+        Fallback
+    </Entry>
+    <Entry key="ServerFailureDialog_Message">
+        Bei der Kommunikation mit dem SEB-Server ist ein Fehler aufgetreten.
+    </Entry>
+    <Entry key="ServerFailureDialog_Retry">
+        Wiederholen
+    </Entry>
+    <Entry key="ServerFailureDialog_Title">
+        SEB-Server-Fehler
+    </Entry>
     <Entry key="Shell_QuitButton">
         Sitzung beenden
     </Entry>

SafeExamBrowser.I18n/Data/en.xml

@@ -453,6 +453,21 @@
     <Entry key="RuntimeWindow_ApplicationRunning">
         SEB is running.
     </Entry>
+    <Entry key="ServerFailureDialog_Abort">
+        Abort
+    </Entry>
+    <Entry key="ServerFailureDialog_Fallback">
+        Fallback
+    </Entry>
+    <Entry key="ServerFailureDialog_Message">
+        An error occurred while trying to communicate with the SEB server.
+    </Entry>
+    <Entry key="ServerFailureDialog_Retry">
+        Retry
+    </Entry>
+    <Entry key="ServerFailureDialog_Title">
+        SEB-Server Error
+    </Entry>
     <Entry key="Shell_QuitButton">
         Terminate Session
     </Entry>

SafeExamBrowser.Runtime/Operations/Events/ServerFailureEventArgs.cs

@@ -16,10 +16,12 @@ namespace SafeExamBrowser.Runtime.Operations.Events
 		public bool Fallback { get; set; }
 		public string Message { get; set; }
 		public bool Retry { get; set; }
+		public bool ShowFallback { get; }
 
-		public ServerFailureEventArgs(string message)
+		public ServerFailureEventArgs(string message, bool showFallback)
 		{
 			Message = message;
+			ShowFallback = showFallback;
 		}
 	}
 }

SafeExamBrowser.Runtime/Operations/ServerOperation.cs

@@ -70,6 +70,7 @@ namespace SafeExamBrowser.Runtime.Operations
 								if (status == LoadStatus.Success)
 								{
 									Context.Next.Settings = settings;
+									Context.Next.Settings.Browser.StartUrl = exam.Url;
 									result = OperationResult.Success;
 								}
 								else
@@ -116,7 +117,7 @@ namespace SafeExamBrowser.Runtime.Operations
 		{
 			var result = OperationResult.Failed;
 
-			if (Context.Current.Settings.SessionMode == SessionMode.Server)
+			if (Context.Current?.Settings.SessionMode == SessionMode.Server)
 			{
 				logger.Info("Finalizing server...");
 				StatusChanged?.Invoke(TextKey.OperationStatus_FinalizeServer);
@@ -192,7 +193,7 @@ namespace SafeExamBrowser.Runtime.Operations
 
 		private bool Retry(string message, out bool abort, out bool fallback)
 		{
-			var args = new ServerFailureEventArgs(message);
+			var args = new ServerFailureEventArgs(message, Context.Next.Settings.Server.PerformFallback);
 
 			ActionRequired?.Invoke(args);
 

SafeExamBrowser.Runtime/RuntimeController.cs

@@ -417,7 +417,18 @@ namespace SafeExamBrowser.Runtime
 
 		private void AskForServerFailureAction(ServerFailureEventArgs args)
 		{
-			// TODO: Also implement mechanism to retrieve selection via client!!
+			var isStartup = !SessionIsRunning;
+			var isRunningOnDefaultDesktop = SessionIsRunning && Session.Settings.Security.KioskMode == KioskMode.DisableExplorerShell;
+
+			if (isStartup || isRunningOnDefaultDesktop)
+			{
+				TryAskForServerFailureActionViaDialog(args);
+			}
+			else
+			{
+				// TODO: Also implement mechanism to retrieve selection via client!!
+				// TryAskForServerFailureActionViaClient(args);
+			}
 		}
 
 		private void AskIfConfigurationSufficient(ConfigurationCompletedEventArgs args)
@@ -503,15 +514,23 @@ namespace SafeExamBrowser.Runtime
 
 		private void TryAskForExamSelectionViaDialog(ExamSelectionEventArgs args)
 		{
-			var message = TextKey.ExamSelectionDialog_Message;
+			var dialog = uiFactory.CreateExamSelectionDialog(args.Exams);
-			var title = TextKey.ExamSelectionDialog_Title;
-			var dialog = uiFactory.CreateExamSelectionDialog(text.Get(message), text.Get(title), args.Exams);
 			var result = dialog.Show(runtimeWindow);
 
 			args.SelectedExam = result.SelectedExam;
 			args.Success = result.Success;
 		}
 
+		private void TryAskForServerFailureActionViaDialog(ServerFailureEventArgs args)
+		{
+			var dialog = uiFactory.CreateServerFailureDialog(args.Message, args.ShowFallback);
+			var result = dialog.Show(runtimeWindow);
+
+			args.Abort = result.Abort;
+			args.Fallback = result.Fallback;
+			args.Retry = result.Retry;
+		}
+
 		private void TryGetPasswordViaDialog(PasswordRequiredEventArgs args)
 		{
 			var message = default(TextKey);

SafeExamBrowser.Server.Contracts/Exam.cs

@@ -18,6 +18,11 @@ namespace SafeExamBrowser.Server.Contracts
 		/// </summary>
 		public string Id { get; set; }
 
+		/// <summary>
+		/// The name of the learning management system (LMS) on which the exam is running.
+		/// </summary>
+		public string LmsName { get; set; }
+
 		/// <summary>
 		/// The name of the exam.
 		/// </summary>

SafeExamBrowser.Server/ServerProxy.cs

@@ -223,6 +223,7 @@ namespace SafeExamBrowser.Server
 					exams.Add(new Exam
 					{
 						Id = exam["examId"].Value<string>(),
+						LmsName = exam["lmsType"].Value<string>(),
 						Name = exam["name"].Value<string>(),
 						Url = exam["url"].Value<string>()
 					});
@@ -314,7 +315,7 @@ namespace SafeExamBrowser.Server
 
 		private string ToString(HttpResponseMessage response)
 		{
-			return $"{(int) response.StatusCode} {response.StatusCode} {response.ReasonPhrase}";
+			return $"{(int?) response?.StatusCode} {response?.StatusCode} {response?.ReasonPhrase}";
 		}
 	}
 }

SafeExamBrowser.UserInterface.Contracts/IUserInterfaceFactory.cs

@@ -58,7 +58,7 @@ namespace SafeExamBrowser.UserInterface.Contracts
 		/// <summary>
 		/// Creates an exam selection dialog for the given exams.
 		/// </summary>
-		IExamSelectionDialog CreateExamSelectionDialog(string message, string title, IEnumerable<Exam> exams);
+		IExamSelectionDialog CreateExamSelectionDialog(IEnumerable<Exam> exams);
 
 		/// <summary>
 		/// Creates a system control which allows to change the keyboard layout of the computer.
@@ -98,9 +98,13 @@ namespace SafeExamBrowser.UserInterface.Contracts
 		/// <summary>
 		/// Creates a new runtime window which runs on its own thread.
 		/// </summary>
-		/// <returns></returns>
 		IRuntimeWindow CreateRuntimeWindow(AppConfig appConfig);
 
+		/// <summary>
+		/// Creates a new server failure dialog with the given parameters.
+		/// </summary>
+		IServerFailureDialog CreateServerFailureDialog(string info, bool showFallback);
+
 		/// <summary>
 		/// Creates a new splash screen which runs on its own thread.
 		/// </summary>

SafeExamBrowser.UserInterface.Contracts/SafeExamBrowser.UserInterface.Contracts.csproj

@@ -89,12 +89,14 @@
     <Compile Include="Windows\Data\ExamSelectionDialogResult.cs" />
     <Compile Include="Windows\Data\LockScreenOption.cs" />
     <Compile Include="Windows\Data\LockScreenResult.cs" />
+    <Compile Include="Windows\Data\ServerFailureDialogResult.cs" />
     <Compile Include="Windows\Events\WindowClosingEventHandler.cs" />
     <Compile Include="Windows\IExamSelectionDialog.cs" />
     <Compile Include="Windows\ILockScreen.cs" />
     <Compile Include="Windows\IPasswordDialog.cs" />
     <Compile Include="Windows\Data\PasswordDialogResult.cs" />
     <Compile Include="Windows\IRuntimeWindow.cs" />
+    <Compile Include="Windows\IServerFailureDialog.cs" />
     <Compile Include="Windows\ISplashScreen.cs" />
     <Compile Include="Windows\IWindow.cs" />
   </ItemGroup>

SafeExamBrowser.UserInterface.Contracts/Windows/Data/ServerFailureDialogResult.cs

@@ -0,0 +1,36 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+namespace SafeExamBrowser.UserInterface.Contracts.Windows.Data
+{
+	/// <summary>
+	/// Defines the user interaction result of an <see cref="IServerFailureDialog"/>.
+	/// </summary>
+	public class ServerFailureDialogResult
+	{
+		/// <summary>
+		/// Indicates whether the user wants to abort the operation.
+		/// </summary>
+		public bool Abort { get; set; }
+
+		/// <summary>
+		/// Indicates whether the user wants to performa a fallback.
+		/// </summary>
+		public bool Fallback { get; set; }
+
+		/// <summary>
+		/// Indicates whether the user wants to retry the operation.
+		/// </summary>
+		public bool Retry { get; set; }
+
+		/// <summary>
+		/// Indicates whether the user confirmed the dialog or not.
+		/// </summary>
+		public bool Success { get; set; }
+	}
+}

SafeExamBrowser.UserInterface.Contracts/Windows/IExamSelectionDialog.cs

@@ -11,7 +11,7 @@ using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
 namespace SafeExamBrowser.UserInterface.Contracts.Windows
 {
 	/// <summary>
-	/// Defines the functionality of an exam selection dialog.
+	/// The dialog shown to let the user select which server exam to start.
 	/// </summary>
 	public interface IExamSelectionDialog
 	{

SafeExamBrowser.UserInterface.Contracts/Windows/IServerFailureDialog.cs

@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
+
+namespace SafeExamBrowser.UserInterface.Contracts.Windows
+{
+	/// <summary>
+	/// The dialog shown in case a communication failure with a server occurs.
+	/// </summary>
+	public interface IServerFailureDialog
+	{
+		/// <summary>
+		/// Shows the dialog as topmost window. If a parent window is specified, the dialog is rendered modally for the given parent.
+		/// </summary>
+		ServerFailureDialogResult Show(IWindow parent = null);
+	}
+}

SafeExamBrowser.UserInterface.Desktop/SafeExamBrowser.UserInterface.Desktop.csproj

@@ -168,6 +168,9 @@
     <Compile Include="Windows\RuntimeWindow.xaml.cs">
       <DependentUpon>RuntimeWindow.xaml</DependentUpon>
     </Compile>
+    <Compile Include="Windows\ServerFailureDialog.xaml.cs">
+      <DependentUpon>ServerFailureDialog.xaml</DependentUpon>
+    </Compile>
     <Compile Include="Windows\SplashScreen.xaml.cs">
       <DependentUpon>SplashScreen.xaml</DependentUpon>
     </Compile>
@@ -347,6 +350,10 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="Windows\ServerFailureDialog.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="Windows\Taskview.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>

SafeExamBrowser.UserInterface.Desktop/UserInterfaceFactory.cs

@@ -82,9 +82,9 @@ namespace SafeExamBrowser.UserInterface.Desktop
 			return Application.Current.Dispatcher.Invoke(() => new BrowserWindow(control, settings, isMainWindow, text));
 		}
 
-		public IExamSelectionDialog CreateExamSelectionDialog(string message, string title, IEnumerable<Exam> exams)
+		public IExamSelectionDialog CreateExamSelectionDialog(IEnumerable<Exam> exams)
 		{
-			return Application.Current.Dispatcher.Invoke(() => new ExamSelectionDialog(message, title, text, exams));
+			return Application.Current.Dispatcher.Invoke(() => new ExamSelectionDialog(exams, text));
 		}
 
 		public ISystemControl CreateKeyboardLayoutControl(IKeyboard keyboard, Location location)
@@ -167,6 +167,11 @@ namespace SafeExamBrowser.UserInterface.Desktop
 			return Application.Current.Dispatcher.Invoke(() => new RuntimeWindow(appConfig, text));
 		}
 
+		public IServerFailureDialog CreateServerFailureDialog(string info, bool showFallback)
+		{
+			return Application.Current.Dispatcher.Invoke(() => new ServerFailureDialog(info, showFallback, text));
+		}
+
 		public ISplashScreen CreateSplashScreen(AppConfig appConfig = null)
 		{
 			var window = default(SplashScreen);

SafeExamBrowser.UserInterface.Desktop/Windows/ExamSelectionDialog.xaml

@@ -39,7 +39,7 @@
                                     <StackPanel Orientation="Horizontal">
                                         <TextBlock Margin="0,0,5,0" Text="{Binding Id}" />
                                         <TextBlock Margin="0,0,5,0" Text="-" />
-                                        <TextBlock FontStyle="Italic" Text="{Binding Url}" />
+                                        <TextBlock FontStyle="Italic" Text="{Binding LmsName}" />
                                     </StackPanel>
                                 </StackPanel>
                             </DataTemplate>

SafeExamBrowser.UserInterface.Desktop/Windows/ExamSelectionDialog.xaml.cs

@@ -20,12 +20,12 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 	{
 		private readonly IText text;
 
-		public ExamSelectionDialog(string message, string title, IText text, IEnumerable<Exam> exams)
+		public ExamSelectionDialog(IEnumerable<Exam> exams, IText text)
 		{
 			this.text = text;
 
 			InitializeComponent();
-			InitializeExamSelectionDialog(message, title, exams);
+			InitializeExamSelectionDialog(exams);
 		}
 
 		public ExamSelectionDialogResult Show(IWindow parent = null)
@@ -50,10 +50,10 @@ namespace SafeExamBrowser.UserInterface.Desktop.Windows
 			});
 		}
 
-		private void InitializeExamSelectionDialog(string message, string title, IEnumerable<Exam> exams)
+		private void InitializeExamSelectionDialog(IEnumerable<Exam> exams)
 		{
-			Message.Text = message;
+			Message.Text = text.Get(TextKey.ExamSelectionDialog_Message);
-			Title = title;
+			Title = text.Get(TextKey.ExamSelectionDialog_Title);
 			WindowStartupLocation = WindowStartupLocation.CenterScreen;
 
 			CancelButton.Content = text.Get(TextKey.ExamSelectionDialog_Cancel);

SafeExamBrowser.UserInterface.Desktop/Windows/ServerFailureDialog.xaml

@@ -0,0 +1,42 @@
+<Window x:Class="SafeExamBrowser.UserInterface.Desktop.Windows.ServerFailureDialog"
+        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+        xmlns:fa="http://schemas.fontawesome.io/icons/"
+        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+        xmlns:local="clr-namespace:SafeExamBrowser.UserInterface.Desktop.Windows"
+        mc:Ignorable="d" Height="250" Width="450" ResizeMode="NoResize" Topmost="True">
+    <Window.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="../Templates/Colors.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Window.Resources>
+    <Grid FocusManager.FocusedElement="{Binding ElementName=RetryButton}">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="2*" />
+            <RowDefinition Height="1*" />
+        </Grid.RowDefinitions>
+        <Grid Grid.Row="0">
+            <Grid>
+                <Grid.ColumnDefinitions>
+                    <ColumnDefinition Width="Auto" />
+                    <ColumnDefinition Width="*" />
+                </Grid.ColumnDefinitions>
+                <fa:ImageAwesome Grid.Column="0" Foreground="LightGray" Icon="Warning" Margin="25" Width="50" />
+                <WrapPanel Grid.Column="1" Margin="0,0,25,0" Orientation="Vertical" VerticalAlignment="Center">
+                    <TextBlock x:Name="Message" TextWrapping="WrapWithOverflow" />
+                    <TextBlock x:Name="Info" FontFamily="Courier New" Margin="0,10,0,0" TextWrapping="WrapWithOverflow" />
+                </WrapPanel>
+            </Grid>
+        </Grid>
+        <Grid Grid.Row="1" Background="{StaticResource BackgroundBrush}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
+            <WrapPanel Orientation="Horizontal" Margin="25,0" HorizontalAlignment="Right" VerticalAlignment="Center">
+                <Button x:Name="RetryButton" Cursor="Hand" Margin="10,0" Padding="10,5" MinWidth="75" />
+                <Button x:Name="FallbackButton" Cursor="Hand" Margin="0,0,10,0" Padding="10,5" MinWidth="75" />
+                <Button x:Name="AbortButton" Cursor="Hand" Padding="10,5" MinWidth="75" />
+            </WrapPanel>
+        </Grid>
+    </Grid>
+</Window>

SafeExamBrowser.UserInterface.Desktop/Windows/ServerFailureDialog.xaml.cs

@@ -0,0 +1,96 @@
+/*
+ * Copyright (c) 2020 ETH Zürich, Educational Development and Technology (LET)
+ * 
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+using System.Windows;
+using SafeExamBrowser.I18n.Contracts;
+using SafeExamBrowser.UserInterface.Contracts.Windows;
+using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
+
+namespace SafeExamBrowser.UserInterface.Desktop.Windows
+{
+	public partial class ServerFailureDialog : Window, IServerFailureDialog
+	{
+		private readonly IText text;
+
+		public ServerFailureDialog(string info, bool showFallback, IText text)
+		{
+			this.text = text;
+
+			InitializeComponent();
+			InitializeDialog(info, showFallback);
+		}
+
+		public ServerFailureDialogResult Show(IWindow parent = null)
+		{
+			return Dispatcher.Invoke(() =>
+			{
+				var result = new ServerFailureDialogResult { Success = false };
+
+				if (parent is Window)
+				{
+					Owner = parent as Window;
+					WindowStartupLocation = WindowStartupLocation.CenterOwner;
+				}
+
+				if (ShowDialog() is true)
+				{
+					result.Abort = Tag as string == nameof(AbortButton);
+					result.Fallback = Tag as string == nameof(FallbackButton);
+					result.Retry = Tag as string == nameof(RetryButton);
+					result.Success = true;
+				}
+				else
+				{
+					result.Abort = true;
+				}
+
+				return result;
+			});
+		}
+
+		private void InitializeDialog(string info, bool showFallback)
+		{
+			Info.Text = info;
+			Message.Text = text.Get(TextKey.ServerFailureDialog_Message);
+			Title = text.Get(TextKey.ServerFailureDialog_Title);
+
+			AbortButton.Click += AbortButton_Click;
+			AbortButton.Content = text.Get(TextKey.ServerFailureDialog_Abort);
+
+			FallbackButton.Click += FallbackButton_Click;
+			FallbackButton.Content = text.Get(TextKey.ServerFailureDialog_Fallback);
+			FallbackButton.Visibility = showFallback ? Visibility.Visible : Visibility.Collapsed;
+
+			Loaded += (o, args) => Activate();
+
+			RetryButton.Click += RetryButton_Click;
+			RetryButton.Content = text.Get(TextKey.ServerFailureDialog_Retry);
+		}
+
+		private void AbortButton_Click(object sender, RoutedEventArgs e)
+		{
+			DialogResult = true;
+			Tag = nameof(AbortButton);
+			Close();
+		}
+
+		private void FallbackButton_Click(object sender, RoutedEventArgs e)
+		{
+			DialogResult = true;
+			Tag = nameof(FallbackButton);
+			Close();
+		}
+
+		private void RetryButton_Click(object sender, RoutedEventArgs e)
+		{
+			DialogResult = true;
+			Tag = nameof(RetryButton);
+			Close();
+		}
+	}
+}

SafeExamBrowser.UserInterface.Mobile/UserInterfaceFactory.cs

@@ -82,7 +82,7 @@ namespace SafeExamBrowser.UserInterface.Mobile
 			return Application.Current.Dispatcher.Invoke(() => new BrowserWindow(control, settings, isMainWindow, text));
 		}
 
-		public IExamSelectionDialog CreateExamSelectionDialog(string message, string title, IEnumerable<Exam> exams)
+		public IExamSelectionDialog CreateExamSelectionDialog(IEnumerable<Exam> exams)
 		{
 			// TODO
 			throw new System.NotImplementedException();
@@ -168,6 +168,12 @@ namespace SafeExamBrowser.UserInterface.Mobile
 			return Application.Current.Dispatcher.Invoke(() => new RuntimeWindow(appConfig, text));
 		}
 
+		public IServerFailureDialog CreateServerFailureDialog(string info, bool showFallback)
+		{
+			// TODO
+			throw new System.NotImplementedException();
+		}
+
 		public ISplashScreen CreateSplashScreen(AppConfig appConfig = null)
 		{
 			var window = default(SplashScreen);