SEBWIN-308: Implemented basic file system dialog and download configuration for browser.

SafeExamBrowser.Browser/BrowserApplicationInstance.cs

@@ -106,6 +106,7 @@ namespace SafeExamBrowser.Browser
 		private void InitializeControl()
 		{
 			var contextMenuHandler = new ContextMenuHandler();
+			var dialogHandler = new DialogHandler();
 			var displayHandler = new DisplayHandler();
 			var downloadLogger = logger.CloneFor($"{nameof(DownloadHandler)} #{Id}");
 			var downloadHandler = new DownloadHandler(appConfig, settings, downloadLogger);
@@ -117,6 +118,7 @@ namespace SafeExamBrowser.Browser
 
 			Icon = new BrowserIconResource();
 
+			dialogHandler.DialogRequested += DialogHandler_DialogRequested;
 			displayHandler.FaviconChanged += DisplayHandler_FaviconChanged;
 			displayHandler.ProgressChanged += DisplayHandler_ProgressChanged;
 			downloadHandler.ConfigurationDownloadRequested += DownloadHandler_ConfigurationDownloadRequested;
@@ -130,7 +132,7 @@ namespace SafeExamBrowser.Browser
 
 			InitializeRequestFilter(requestFilter);
 
-			control = new BrowserControl(contextMenuHandler, displayHandler, downloadHandler, keyboardHandler, lifeSpanHandler, requestHandler, startUrl);
+			control = new BrowserControl(contextMenuHandler, dialogHandler, displayHandler, downloadHandler, keyboardHandler, lifeSpanHandler, requestHandler, startUrl);
 			control.AddressChanged += Control_AddressChanged;
 			control.LoadingStateChanged += Control_LoadingStateChanged;
 			control.TitleChanged += Control_TitleChanged;
@@ -207,6 +209,23 @@ namespace SafeExamBrowser.Browser
 			TitleChanged?.Invoke(Title);
 		}
 
+		private void DialogHandler_DialogRequested(DialogRequestedEventArgs args)
+		{
+			var dialog = uiFactory.CreateFileSystemDialog(args.Element, args.InitialPath, args.Operation, title: args.Title);
+			var result = dialog.Show(window);
+
+			if (result.Success)
+			{
+				args.FullPath = result.FullPath;
+				args.Success = result.Success;
+				logger.Debug($"User selected path '{result.FullPath}' when asked to {args.Operation}->{args.Element}.");
+			}
+			else
+			{
+				logger.Debug($"User aborted file system dialog to {args.Operation}->{args.Element}.");
+			}
+		}
+
 		private void DisplayHandler_FaviconChanged(string uri)
 		{
 			var request = new HttpRequestMessage(HttpMethod.Head, uri);

SafeExamBrowser.Browser/BrowserControl.cs

@@ -16,6 +16,7 @@ namespace SafeExamBrowser.Browser
 	internal class BrowserControl : ChromiumWebBrowser, IBrowserControl
 	{
 		private IContextMenuHandler contextMenuHandler;
+		private IDialogHandler dialogHandler;
 		private IDisplayHandler displayHandler;
 		private IDownloadHandler downloadHandler;
 		private IKeyboardHandler keyboardHandler;
@@ -49,6 +50,7 @@ namespace SafeExamBrowser.Browser
 
 		public BrowserControl(
 			IContextMenuHandler contextMenuHandler,
+			IDialogHandler dialogHandler,
 			IDisplayHandler displayHandler,
 			IDownloadHandler downloadHandler,
 			IKeyboardHandler keyboardHandler,
@@ -57,6 +59,7 @@ namespace SafeExamBrowser.Browser
 			string url) : base(url)
 		{
 			this.contextMenuHandler = contextMenuHandler;
+			this.dialogHandler = dialogHandler;
 			this.displayHandler = displayHandler;
 			this.downloadHandler = downloadHandler;
 			this.keyboardHandler = keyboardHandler;
@@ -70,6 +73,7 @@ namespace SafeExamBrowser.Browser
 			LoadingStateChanged += (o, args) => loadingStateChanged?.Invoke(args.IsLoading);
 			TitleChanged += (o, args) => titleChanged?.Invoke(args.Title);
 
+			DialogHandler = dialogHandler;
 			DisplayHandler = displayHandler;
 			DownloadHandler = downloadHandler;
 			KeyboardHandler = keyboardHandler;

SafeExamBrowser.Browser/Events/DialogRequestedEventArgs.cs

@@ -0,0 +1,22 @@
+/*
+ * 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.FileSystemDialog;
+
+namespace SafeExamBrowser.Browser.Events
+{
+	internal class DialogRequestedEventArgs
+	{
+		internal FileSystemElement Element { get; set; }
+		internal string InitialPath { get; set; }
+		internal FileSystemOperation Operation { get; set; }
+		internal string FullPath { get; set; }
+		internal bool Success { get; set; }
+		internal string Title { get; set; }
+	}
+}

SafeExamBrowser.Browser/Events/DialogRequestedEventHandler.cs

@@ -0,0 +1,12 @@
+/*
+ * 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.Browser.Events
+{
+	internal delegate void DialogRequestedEventHandler(DialogRequestedEventArgs args);
+}

SafeExamBrowser.Browser/Handlers/DialogHandler.cs

@@ -0,0 +1,73 @@
+/*
+ * 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.Collections.Generic;
+using System.Threading.Tasks;
+using CefSharp;
+using SafeExamBrowser.Browser.Events;
+using SafeExamBrowser.UserInterface.Contracts.FileSystemDialog;
+
+namespace SafeExamBrowser.Browser.Handlers
+{
+	internal class DialogHandler : IDialogHandler
+	{
+		internal event DialogRequestedEventHandler DialogRequested;
+
+		public bool OnFileDialog(IWebBrowser webBrowser, IBrowser browser, CefFileDialogMode mode, CefFileDialogFlags flags, string title, string defaultFilePath, List<string> acceptFilters, int selectedAcceptFilter, IFileDialogCallback callback)
+		{
+			var args = new DialogRequestedEventArgs
+			{
+				Element = ToElement(mode),
+				InitialPath = defaultFilePath,
+				Operation = ToOperation(mode),
+				Title = title
+			};
+
+			Task.Run(() =>
+			{
+				DialogRequested?.Invoke(args);
+
+				using (callback)
+				{
+					if (args.Success)
+					{
+						callback.Continue(selectedAcceptFilter, new List<string> { args.FullPath });
+					}
+					else
+					{
+						callback.Cancel();
+					}
+				}
+			});
+
+			return true;
+		}
+
+		private FileSystemElement ToElement(CefFileDialogMode mode)
+		{
+			switch (mode)
+			{
+				case CefFileDialogMode.OpenFolder:
+					return FileSystemElement.Folder;
+				default:
+					return FileSystemElement.File;
+			}
+		}
+
+		private FileSystemOperation ToOperation(CefFileDialogMode mode)
+		{
+			switch (mode)
+			{
+				case CefFileDialogMode.Save:
+					return FileSystemOperation.Save;
+				default:
+					return FileSystemOperation.Open;
+			}
+		}
+	}
+}

SafeExamBrowser.Browser/Handlers/DownloadHandler.cs

@@ -14,6 +14,7 @@ using CefSharp;
 using SafeExamBrowser.Browser.Contracts.Events;
 using SafeExamBrowser.Configuration.Contracts;
 using SafeExamBrowser.Logging.Contracts;
+using Syroot.Windows.IO;
 using BrowserSettings = SafeExamBrowser.Settings.Browser.BrowserSettings;
 
 namespace SafeExamBrowser.Browser.Handlers
@@ -25,9 +26,9 @@ namespace SafeExamBrowser.Browser.Handlers
 		private ConcurrentDictionary<int, DownloadFinishedCallback> callbacks;
 		private ILogger logger;
 
-		public event DownloadRequestedEventHandler ConfigurationDownloadRequested;
+		internal event DownloadRequestedEventHandler ConfigurationDownloadRequested;
 
-		public DownloadHandler(AppConfig appConfig, BrowserSettings settings, ILogger logger)
+		internal DownloadHandler(AppConfig appConfig, BrowserSettings settings, ILogger logger)
 		{
 			this.appConfig = appConfig;
 			this.callbacks = new ConcurrentDictionary<int, DownloadFinishedCallback>();
@@ -41,7 +42,7 @@ namespace SafeExamBrowser.Browser.Handlers
 			var extension = Path.GetExtension(uri.AbsolutePath);
 			var isConfigFile = String.Equals(extension, appConfig.ConfigurationFileExtension, StringComparison.OrdinalIgnoreCase);
 
-			logger.Debug($"Handling download request for '{uri}'.");
+			logger.Debug($"Detected download request for '{uri}'.");
 
 			if (isConfigFile)
 			{
@@ -49,12 +50,7 @@ namespace SafeExamBrowser.Browser.Handlers
 			}
 			else if (settings.AllowDownloads)
 			{
-				logger.Debug($"Starting download of '{uri}'...");
+				Task.Run(() => HandleFileDownload(downloadItem, callback));
-
-				using (callback)
-				{
-					callback.Continue(null, true);
-				}
 			}
 			else
 			{
@@ -64,6 +60,8 @@ namespace SafeExamBrowser.Browser.Handlers
 
 		public void OnDownloadUpdated(IWebBrowser webBrowser, IBrowser browser, DownloadItem downloadItem, IDownloadItemCallback callback)
 		{
+			// TODO: Show download progress in respective window -> event for BrowserApplicationInstance!
+
 			if (downloadItem.IsComplete || downloadItem.IsCancelled)
 			{
 				if (callbacks.TryRemove(downloadItem.Id, out DownloadFinishedCallback finished) && finished != null)
@@ -72,6 +70,39 @@ namespace SafeExamBrowser.Browser.Handlers
 				}
 
 				logger.Debug($"Download of '{downloadItem.Url}' {(downloadItem.IsComplete ? "is complete" : "was cancelled")}.");
+
+				// TODO: Show success message or download icon like Firefox in respective window!
+			}
+		}
+
+		private void HandleFileDownload(DownloadItem downloadItem, IBeforeDownloadCallback callback)
+		{
+			var filePath = default(string);
+			var showDialog = settings.AllowCustomDownloadLocation;
+
+			logger.Debug($"Handling download of file '{downloadItem.SuggestedFileName}'.");
+
+			if (!string.IsNullOrEmpty(settings.DownloadDirectory))
+			{
+				filePath = Path.Combine(Environment.ExpandEnvironmentVariables(settings.DownloadDirectory), downloadItem.SuggestedFileName);
+			}
+			else
+			{
+				filePath = Path.Combine(KnownFolders.Downloads.ExpandedPath, downloadItem.SuggestedFileName);
+			}
+
+			if (showDialog)
+			{
+				logger.Debug($"Allowing user to select custom download location, with '{filePath}' as suggestion.");
+			}
+			else
+			{
+				logger.Debug($"Automatically downloading file as '{filePath}'.");
+			}
+
+			using (callback)
+			{
+				callback.Continue(filePath, showDialog);
 			}
 		}
 
@@ -79,7 +110,7 @@ namespace SafeExamBrowser.Browser.Handlers
 		{
 			var args = new DownloadEventArgs();
 
-			logger.Debug($"Detected download request for configuration file '{downloadItem.Url}'.");
+			logger.Debug($"Handling download of configuration file '{downloadItem.SuggestedFileName}'.");
 			ConfigurationDownloadRequested?.Invoke(downloadItem.SuggestedFileName, args);
 
 			if (args.AllowDownload)
@@ -89,7 +120,7 @@ namespace SafeExamBrowser.Browser.Handlers
 					callbacks[downloadItem.Id] = args.Callback;
 				}
 
-				logger.Debug($"Starting download of configuration file '{downloadItem.Url}'...");
+				logger.Debug($"Starting download of configuration file '{downloadItem.SuggestedFileName}'...");
 
 				using (callback)
 				{
@@ -98,7 +129,7 @@ namespace SafeExamBrowser.Browser.Handlers
 			}
 			else
 			{
-				logger.Debug($"Download of configuration file '{downloadItem.Url}' was cancelled.");
+				logger.Debug($"Download of configuration file '{downloadItem.SuggestedFileName}' was cancelled.");
 			}
 		}
 	}

SafeExamBrowser.Browser/SafeExamBrowser.Browser.csproj

@@ -54,6 +54,9 @@
     <ErrorReport>prompt</ErrorReport>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="Syroot.KnownFolders, Version=1.2.1.0, Culture=neutral, processorArchitecture=MSIL">
+      <HintPath>..\packages\Syroot.Windows.IO.KnownFolders.1.2.1\lib\net452\Syroot.KnownFolders.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Net.Http" />
@@ -63,6 +66,8 @@
   <ItemGroup>
     <Compile Include="BrowserApplication.cs" />
     <Compile Include="BrowserApplicationInstance.cs" />
+    <Compile Include="Events\DialogRequestedEventArgs.cs" />
+    <Compile Include="Events\DialogRequestedEventHandler.cs" />
     <Compile Include="Events\FaviconChangedEventHandler.cs" />
     <Compile Include="Events\InstanceTerminatedEventHandler.cs" />
     <Compile Include="Events\PopupRequestedEventArgs.cs" />
@@ -78,6 +83,7 @@
       <SubType>Component</SubType>
     </Compile>
     <Compile Include="BrowserIconResource.cs" />
+    <Compile Include="Handlers\DialogHandler.cs" />
     <Compile Include="Handlers\DisplayHandler.cs" />
     <Compile Include="Handlers\DownloadHandler.cs" />
     <Compile Include="Handlers\KeyboardHandler.cs" />

SafeExamBrowser.Browser/packages.config

@@ -4,4 +4,5 @@
   <package id="cef.redist.x86" version="75.1.14" targetFramework="net472" />
   <package id="CefSharp.Common" version="75.1.142" targetFramework="net472" />
   <package id="CefSharp.WinForms" version="75.1.142" targetFramework="net472" />
+  <package id="Syroot.Windows.IO.KnownFolders" version="1.2.1" targetFramework="net472" />
 </packages>

SafeExamBrowser.Configuration/ConfigurationData/DataMapping/BrowserDataMapper.cs

@@ -24,6 +24,9 @@ namespace SafeExamBrowser.Configuration.ConfigurationData.DataMapping
 				case Keys.Browser.AllowConfigurationDownloads:
 					MapAllowConfigurationDownloads(settings, value);
 					break;
+				case Keys.Browser.AllowCustomDownloadLocation:
+					MapAllowCustomDownloadLocation(settings, value);
+					break;
 				case Keys.Browser.AllowDeveloperConsole:
 					MapAllowDeveloperConsole(settings, value);
 					break;
@@ -54,6 +57,9 @@ namespace SafeExamBrowser.Configuration.ConfigurationData.DataMapping
 				case Keys.Browser.AdditionalWindow.WindowWidth:
 					MapWindowWidthAdditionalWindow(settings, value);
 					break;
+				case Keys.Browser.DownloadDirectory:
+					MapDownloadDirectory(settings, value);
+					break;
 				case Keys.Browser.EnableBrowser:
 					MapEnableBrowser(settings, value);
 					break;
@@ -139,6 +145,14 @@ namespace SafeExamBrowser.Configuration.ConfigurationData.DataMapping
 			}
 		}
 
+		private void MapAllowCustomDownloadLocation(AppSettings settings, object value)
+		{
+			if (value is bool allow)
+			{
+				settings.Browser.AllowCustomDownloadLocation = allow;
+			}
+		}
+
 		private void MapAllowDeveloperConsole(AppSettings settings, object value)
 		{
 			if (value is bool allow)
@@ -198,6 +212,14 @@ namespace SafeExamBrowser.Configuration.ConfigurationData.DataMapping
 			}
 		}
 
+		private void MapDownloadDirectory(AppSettings settings, object value)
+		{
+			if (value is string directory)
+			{
+				settings.Browser.DownloadDirectory = directory;
+			}
+		}
+
 		private void MapEnableBrowser(AppSettings settings, object value)
 		{
 			if (value is bool enable)

SafeExamBrowser.Configuration/ConfigurationData/Keys.cs

@@ -42,11 +42,13 @@ namespace SafeExamBrowser.Configuration.ConfigurationData
 		internal static class Browser
 		{
 			internal const string AllowConfigurationDownloads = "downloadAndOpenSebConfig";
+			internal const string AllowCustomDownloadLocation = "allowCustomDownloadLocation";
 			internal const string AllowDeveloperConsole = "allowDeveloperConsole";
 			internal const string AllowDownloads = "allowDownUploads";
 			internal const string AllowPageZoom = "enableZoomPage";
 			internal const string CustomUserAgentDesktop = "browserUserAgentWinDesktopModeCustom";
 			internal const string CustomUserAgentMobile = "browserUserAgentWinTouchModeCustom";
+			internal const string DownloadDirectory = "downloadDirectoryWin";
 			internal const string EnableBrowser = "enableSebBrowser";
 			internal const string PopupPolicy = "newBrowserWindowByLinkPolicy";
 			internal const string PopupBlockForeignHost = "newBrowserWindowByLinkBlockForeign";

SafeExamBrowser.I18n.Contracts/TextKey.cs

@@ -23,6 +23,18 @@ namespace SafeExamBrowser.I18n.Contracts
 		BrowserWindow_DeveloperConsoleMenuItem,
 		BrowserWindow_ZoomMenuItem,
 		Build,
+		FileSystemDialog_Cancel,
+		FileSystemDialog_LoadError,
+		FileSystemDialog_Loading,
+		FileSystemDialog_OpenFileMessage,
+		FileSystemDialog_OpenFolderMessage,
+		FileSystemDialog_OverwriteWarning,
+		FileSystemDialog_OverwriteWarningTitle,
+		FileSystemDialog_SaveAs,
+		FileSystemDialog_SaveFileMessage,
+		FileSystemDialog_SaveFolderMessage,
+		FileSystemDialog_Select,
+		FileSystemDialog_Title,
 		FolderDialog_ApplicationLocation,
 		LockScreen_AllowOption,
 		LockScreen_Message,

SafeExamBrowser.I18n/Text.xml

@@ -27,6 +27,42 @@
     <Entry key="Build">
         Build
     </Entry>
+    <Entry key="FileSystemDialog_Cancel">
+        Cancel
+    </Entry>
+    <Entry key="FileSystemDialog_LoadError">
+        Failed to load data!
+    </Entry>
+    <Entry key="FileSystemDialog_Loading">
+        Loading...
+    </Entry>
+    <Entry key="FileSystemDialog_OpenFileMessage">
+        Please select a file to open.
+    </Entry>
+    <Entry key="FileSystemDialog_OpenFolderMessage">
+        Please select a folder.
+    </Entry>
+    <Entry key="FileSystemDialog_OverwriteWarning">
+        The selected file already exists! Would you really like to overwrite it?
+    </Entry>
+    <Entry key="FileSystemDialog_OverwriteWarningTitle">
+        Overwrite?
+    </Entry>
+    <Entry key="FileSystemDialog_SaveAs">
+        Save as:
+    </Entry>
+    <Entry key="FileSystemDialog_SaveFileMessage">
+        Please select a location to save the file.
+    </Entry>
+    <Entry key="FileSystemDialog_SaveFolderMessage">
+        Please select a location to save the folder.
+    </Entry>
+    <Entry key="FileSystemDialog_Select">
+        Select
+    </Entry>
+    <Entry key="FileSystemDialog_Title">
+        File System Access
+    </Entry>
     <Entry key="FolderDialog_ApplicationLocation">
         Application "%%NAME%%" could not be found on the system! Please locate the folder containing the main executable "%%EXECUTABLE%%".
     </Entry>

SafeExamBrowser.Settings/Browser/BrowserSettings.cs

@@ -26,6 +26,11 @@ namespace SafeExamBrowser.Settings.Browser
 		/// </summary>
 		public bool AllowConfigurationDownloads { get; set; }
 
+		/// <summary>
+		/// Determines whether the user will be allowed to select a custom location when downloading a file (excluding configuration files).
+		/// </summary>
+		public bool AllowCustomDownloadLocation { get; set; }
+
 		/// <summary>
 		/// Determines whether the user will be allowed to download files (excluding configuration files).
 		/// </summary>
@@ -46,6 +51,11 @@ namespace SafeExamBrowser.Settings.Browser
 		/// </summary>
 		public string CustomUserAgent { get; set; }
 
+		/// <summary>
+		/// Defines a custom directory for file downloads. If not defined, all downloads will be saved in the current user's download directory.
+		/// </summary>
+		public string DownloadDirectory { get; set; }
+
 		/// <summary>
 		/// Determines whether the user is allowed to use the integrated browser application.
 		/// </summary>

SafeExamBrowser.UserInterface.Contracts/FileSystemDialog/FileSystemDialogResult.cs

@@ -0,0 +1,26 @@
+/*
+ * 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.FileSystemDialog
+{
+	/// <summary>
+	/// Defines the user interaction result of an <see cref="IFileSystemDialog"/>.
+	/// </summary>
+	public class FileSystemDialogResult
+	{
+		/// <summary>
+		/// The full path of the item selected by the user, or <c>null</c> if the interaction was unsuccessful.
+		/// </summary>
+		public string FullPath { get; set; }
+
+		/// <summary>
+		/// Indicates whether the user confirmed the dialog or not.
+		/// </summary>
+		public bool Success { get; set; }
+	}
+}

SafeExamBrowser.UserInterface.Contracts/FileSystemDialog/FileSystemElement.cs

@@ -0,0 +1,26 @@
+/*
+ * 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.FileSystemDialog
+{
+	/// <summary>
+	/// Defines all elements supported by an <see cref="IFileSystemDialog"/>
+	/// </summary>
+	public enum FileSystemElement
+	{
+		/// <summary>
+		/// A dialog to perform an operation with a file.
+		/// </summary>
+		File,
+
+		/// <summary>
+		/// A dialog to perform an operation with a folder.
+		/// </summary>
+		Folder
+	}
+}

SafeExamBrowser.UserInterface.Contracts/FileSystemDialog/FileSystemOperation.cs

@@ -0,0 +1,26 @@
+/*
+ * 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.FileSystemDialog
+{
+	/// <summary>
+	/// Defines all operations supported by an <see cref="IFileSystemDialog"/>
+	/// </summary>
+	public enum FileSystemOperation
+	{
+		/// <summary>
+		/// A dialog to open a file system element.
+		/// </summary>
+		Open,
+
+		/// <summary>
+		/// A dialog to save a file system element.
+		/// </summary>
+		Save
+	}
+}

SafeExamBrowser.UserInterface.Contracts/FileSystemDialog/IFileSystemDialog.cs

@@ -0,0 +1,20 @@
+/*
+ * 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;
+
+namespace SafeExamBrowser.UserInterface.Contracts.FileSystemDialog
+{
+	public interface IFileSystemDialog
+	{
+		/// <summary>
+		/// Shows the dialog to the user. If a parent window is specified, the dialog is rendered modally for the given parent.
+		/// </summary>
+		FileSystemDialogResult Show(IWindow parent = null);
+	}
+}

SafeExamBrowser.UserInterface.Contracts/IUserInterfaceFactory.cs

@@ -18,6 +18,7 @@ using SafeExamBrowser.SystemComponents.Contracts.Keyboard;
 using SafeExamBrowser.SystemComponents.Contracts.PowerSupply;
 using SafeExamBrowser.SystemComponents.Contracts.WirelessNetwork;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
+using SafeExamBrowser.UserInterface.Contracts.FileSystemDialog;
 using SafeExamBrowser.UserInterface.Contracts.Shell;
 using SafeExamBrowser.UserInterface.Contracts.Windows;
 using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
@@ -49,6 +50,11 @@ namespace SafeExamBrowser.UserInterface.Contracts
 		/// </summary>
 		IBrowserWindow CreateBrowserWindow(IBrowserControl control, BrowserSettings settings, bool isMainWindow);
 
+		/// <summary>
+		/// Creates a file system dialog according to the given parameters.
+		/// </summary>
+		IFileSystemDialog CreateFileSystemDialog(FileSystemElement element, string initialPath, FileSystemOperation operation, string message = default(string), string title = default(string));
+
 		/// <summary>
 		/// Creates a folder dialog with the given message.
 		/// </summary>

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

@@ -60,6 +60,10 @@
     <Compile Include="Browser\IBrowserControl.cs" />
     <Compile Include="Browser\IBrowserWindow.cs" />
     <Compile Include="Events\ActionRequestedEventHandler.cs" />
+    <Compile Include="FileSystemDialog\FileSystemDialogResult.cs" />
+    <Compile Include="FileSystemDialog\FileSystemElement.cs" />
+    <Compile Include="FileSystemDialog\FileSystemOperation.cs" />
+    <Compile Include="FileSystemDialog\IFileSystemDialog.cs" />
     <Compile Include="IProgressIndicator.cs" />
     <Compile Include="IUserInterfaceFactory.cs" />
     <Compile Include="MessageBox\IMessageBox.cs" />

SafeExamBrowser.UserInterface.Desktop/FileSystemDialog.xaml

@@ -0,0 +1,45 @@
+<Window x:Class="SafeExamBrowser.UserInterface.Desktop.FileSystemDialog"
+        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"
+        mc:Ignorable="d" Height="500" Width="750" ResizeMode="NoResize">
+    <Window.Resources>
+        <ResourceDictionary>
+            <ResourceDictionary.MergedDictionaries>
+                <ResourceDictionary Source="./Templates/Colors.xaml" />
+            </ResourceDictionary.MergedDictionaries>
+        </ResourceDictionary>
+    </Window.Resources>
+    <Grid>
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="*" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="Auto" />
+        </Grid.RowDefinitions>
+        <WrapPanel Grid.Row="0" Margin="20,10">
+            <fa:ImageAwesome Name="OperationIcon" Foreground="LightGray" Height="25" Icon="FileOutline"/>
+            <TextBlock Name="Message" Margin="10,0,0,0" VerticalAlignment="Center" />
+        </WrapPanel>
+        <TreeView Grid.Row="1" Name="FileSystem" Margin="10,0" TreeViewItem.Expanded="FileSystem_Expanded" />
+        <TextBlock Grid.Row="2" Name="SelectedElement" Margin="10,5,10,5" TextTrimming="CharacterEllipsis" VerticalAlignment="Center" />
+        <Grid Grid.Row="3" Name="NewElement" Margin="10,0,10,10">
+            <Grid.ColumnDefinitions>
+                <ColumnDefinition Width="Auto" />
+                <ColumnDefinition Width="*" />
+            </Grid.ColumnDefinitions>
+            <TextBlock Grid.Column="0" Name="NewElementLabel" VerticalAlignment="Center"/>
+            <TextBox Grid.Column="1" Name="NewElementName" Height="25" Margin="5,0,0,0" VerticalContentAlignment="Center" />
+        </Grid>
+        <Grid Grid.Row="4" Background="{StaticResource BackgroundBrush}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
+            <WrapPanel Orientation="Horizontal" Margin="20" HorizontalAlignment="Right" VerticalAlignment="Center">
+                <Button Name="SelectButton" Cursor="Hand" IsEnabled="False" Margin="10,0" Padding="10,5" MinWidth="75" />
+                <Button Name="CancelButton" Cursor="Hand" Padding="20,5" MinWidth="75" />
+            </WrapPanel>
+        </Grid>
+    </Grid>
+</Window>

SafeExamBrowser.UserInterface.Desktop/FileSystemDialog.xaml.cs

@@ -0,0 +1,382 @@
+/*
+ * 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;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Windows;
+using System.Windows.Controls;
+using System.Windows.Input;
+using System.Windows.Media;
+using FontAwesome.WPF;
+using SafeExamBrowser.I18n.Contracts;
+using SafeExamBrowser.UserInterface.Contracts.FileSystemDialog;
+using SafeExamBrowser.UserInterface.Contracts.Windows;
+using SafeExamBrowser.UserInterface.Shared.Utilities;
+
+namespace SafeExamBrowser.UserInterface.Desktop
+{
+	public partial class FileSystemDialog : Window, IFileSystemDialog
+	{
+		private FileSystemElement element;
+		private string initialPath;
+		private string message;
+		private FileSystemOperation operation;
+		private IText text;
+		private string title;
+
+		public FileSystemDialog(
+			FileSystemElement element,
+			string initialPath,
+			FileSystemOperation operation,
+			IText text,
+			string message = default(string),
+			string title = default(string))
+		{
+			this.element = element;
+			this.initialPath = initialPath;
+			this.message = message;
+			this.operation = operation;
+			this.text = text;
+			this.title = title;
+
+			InitializeComponent();
+			InitializeDialog();
+		}
+
+		public FileSystemDialogResult Show(IWindow parent = null)
+		{
+			return Dispatcher.Invoke(() =>
+			{
+				var result = new FileSystemDialogResult();
+
+				if (parent is Window)
+				{
+					Owner = parent as Window;
+					WindowStartupLocation = WindowStartupLocation.CenterOwner;
+				}
+
+				if (ShowDialog() == true)
+				{
+					result.FullPath = BuildFullPath();
+					result.Success = true;
+				}
+
+				return result;
+			});
+		}
+
+		private void CancelButton_Click(object sender, RoutedEventArgs e)
+		{
+			DialogResult = false;
+			Close();
+		}
+
+		private void FileSystem_Expanded(object sender, RoutedEventArgs e)
+		{
+			if (e.Source is TreeViewItem item && item.Items.Count == 1 && !(item.Items[0] is TreeViewItem))
+			{
+				Load(item);
+			}
+		}
+
+		private void FileSystem_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
+		{
+			if (e.NewValue is TreeViewItem item)
+			{
+				if (item.Tag is DirectoryInfo directory)
+				{
+					SelectButton.IsEnabled = element == FileSystemElement.Folder || operation == FileSystemOperation.Save;
+					SelectedElement.Text = directory.FullName;
+					SelectedElement.ToolTip = directory.FullName;
+				}
+				else if (item.Tag is FileInfo file)
+				{
+					SelectButton.IsEnabled = element == FileSystemElement.File;
+					SelectedElement.Text = file.FullName;
+					SelectedElement.ToolTip = file.FullName;
+				}
+				else
+				{
+					SelectButton.IsEnabled = false;
+				}
+			}
+		}
+
+		private void NewElementName_KeyUp(object sender, KeyEventArgs e)
+		{
+			if (e.Key == Key.Enter && IsValid())
+			{
+				DialogResult = true;
+				Close();
+			}
+		}
+
+		private void SelectButton_Click(object sender, RoutedEventArgs e)
+		{
+			if (IsValid())
+			{
+				DialogResult = true;
+				Close();
+			}
+		}
+
+		private string BuildFullPath()
+		{
+			var fullPath = SelectedElement.Text;
+
+			if (operation == FileSystemOperation.Save)
+			{
+				fullPath = Path.Combine(SelectedElement.Text, NewElementName.Text);
+
+				if (element == FileSystemElement.File)
+				{
+					var extension = Path.GetExtension(initialPath);
+
+					if (!fullPath.EndsWith(extension))
+					{
+						fullPath = $"{fullPath}{extension}";
+					}
+				}
+			}
+
+			return fullPath;
+		}
+
+		private bool IsValid()
+		{
+			var fullPath = BuildFullPath();
+			var isValid = true;
+
+			if (element == FileSystemElement.File && operation == FileSystemOperation.Save && File.Exists(fullPath))
+			{
+				var message = text.Get(TextKey.FileSystemDialog_OverwriteWarning);
+				var title = text.Get(TextKey.FileSystemDialog_OverwriteWarningTitle);
+				var result = System.Windows.MessageBox.Show(this, message, title, MessageBoxButton.YesNo, MessageBoxImage.Warning);
+
+				isValid = result == MessageBoxResult.Yes;
+			}
+
+			return isValid;
+		}
+
+		private void Load(TreeViewItem item)
+		{
+			item.Items.Clear();
+
+			if (item.Tag is DirectoryInfo directory)
+			{
+				FileSystem.Cursor = Cursors.Wait;
+				item.BeginInit();
+
+				try
+				{
+					foreach (var subDirectory in directory.GetDirectories())
+					{
+						if (!subDirectory.Attributes.HasFlag(FileAttributes.Hidden))
+						{
+							item.Items.Add(CreateItem(subDirectory));
+						}
+					}
+
+					foreach (var file in directory.GetFiles())
+					{
+						if (!file.Attributes.HasFlag(FileAttributes.Hidden))
+						{
+							item.Items.Add(CreateItem(file));
+						}
+					}
+				}
+				catch (Exception e)
+				{
+					item.Items.Add(CreateErrorItem(e));
+				}
+
+				item.EndInit();
+				FileSystem.Cursor = Cursors.Arrow;
+			}
+		}
+
+		private TreeViewItem CreateErrorItem(Exception e)
+		{
+			var item = new TreeViewItem();
+
+			item.Foreground = Brushes.Red;
+			item.Header = $"{text.Get(TextKey.FileSystemDialog_LoadError)} {e.Message}";
+			item.ToolTip = e.GetType() + Environment.NewLine + e.StackTrace;
+
+			return item;
+		}
+
+		private TreeViewItem CreateItem(DirectoryInfo directory)
+		{
+			var header = new StackPanel { Orientation = Orientation.Horizontal, Margin = new Thickness(2) };
+			var image = new Image
+			{
+				Height = 16,
+				Source = IconLoader.LoadIconFor(directory)
+			};
+			var item = new TreeViewItem();
+			var textBlock = new TextBlock { Margin = new Thickness(5, 0, 0, 0), Text = directory.Name, VerticalAlignment = VerticalAlignment.Center };
+
+			header.Children.Add(image);
+			header.Children.Add(textBlock);
+
+			item.Cursor = Cursors.Hand;
+			item.Header = header;
+			item.Tag = directory;
+			item.ToolTip = directory.FullName;
+			item.Items.Add(text.Get(TextKey.FileSystemDialog_Loading));
+
+			return item;
+		}
+
+		private TreeViewItem CreateItem(FileInfo file)
+		{
+			var header = new StackPanel { Orientation = Orientation.Horizontal, Margin = new Thickness(2) };
+			var image = new Image
+			{
+				Height = 20,
+				Source = IconLoader.LoadIconFor(file)
+			};
+			var item = new TreeViewItem();
+			var textBlock = new TextBlock { Margin = new Thickness(5, 0, 0, 0), Text = file.Name, VerticalAlignment = VerticalAlignment.Center };
+
+			header.Children.Add(image);
+			header.Children.Add(textBlock);
+
+			item.Header = header;
+			item.Tag = file;
+			item.ToolTip = file.FullName;
+
+			if (element == FileSystemElement.File && operation == FileSystemOperation.Open)
+			{
+				item.Cursor = Cursors.Hand;
+			}
+			else
+			{
+				item.Cursor = Cursors.No;
+				item.Focusable = false;
+				textBlock.Foreground = Brushes.Gray;
+			}
+
+			return item;
+		}
+
+		private void InitializeDialog()
+		{
+			CancelButton.Click += CancelButton_Click;
+			CancelButton.Content = text.Get(TextKey.FileSystemDialog_Cancel);
+			FileSystem.SelectedItemChanged += FileSystem_SelectedItemChanged;
+			NewElement.Visibility = operation == FileSystemOperation.Save ? Visibility.Visible : Visibility.Collapsed;
+			NewElementLabel.Text = text.Get(TextKey.FileSystemDialog_SaveAs);
+			NewElementName.KeyUp += NewElementName_KeyUp;
+			OperationIcon.Icon = operation == FileSystemOperation.Save ? FontAwesomeIcon.Download : FontAwesomeIcon.Search;
+			SelectButton.Click += SelectButton_Click;
+			SelectButton.Content = text.Get(TextKey.FileSystemDialog_Select);
+
+			InitializeText();
+			InitializeFileSystem();
+		}
+
+		private void InitializeFileSystem()
+		{
+			foreach (var drive in DriveInfo.GetDrives())
+			{
+				FileSystem.Items.Add(CreateItem(drive.RootDirectory));
+			}
+
+			if (FileSystem.HasItems && FileSystem.Items[0] is TreeViewItem item)
+			{
+				item.IsSelected = true;
+			}
+
+			if (!string.IsNullOrEmpty(initialPath))
+			{
+				var pathRoot = Path.GetPathRoot(initialPath);
+				var directories = initialPath.Replace(pathRoot, "").Split(Path.DirectorySeparatorChar);
+				var segments = new List<string>();
+
+				segments.Add(pathRoot);
+				segments.AddRange(directories);
+
+				AutoSelect(FileSystem.Items, segments);
+
+				if (element == FileSystemElement.File && operation == FileSystemOperation.Save)
+				{
+					NewElementName.Text = Path.GetFileName(initialPath);
+				}
+			}
+		}
+
+		private void AutoSelect(ItemCollection items, List<string> segments)
+		{
+			var segment = segments.FirstOrDefault();
+
+			if (segment != default(string))
+			{
+				foreach (var item in items)
+				{
+					if (item is TreeViewItem i && i.Tag is DirectoryInfo d && d.Name.Equals(segment))
+					{
+						i.IsExpanded = true;
+						i.IsSelected = true;
+						i.BringIntoView();
+
+						AutoSelect(i.Items, segments.Skip(1).ToList());
+
+						break;
+					}
+				}
+			}
+		}
+
+		private void InitializeText()
+		{
+			if (string.IsNullOrEmpty(message))
+			{
+				if (element == FileSystemElement.File)
+				{
+					if (operation == FileSystemOperation.Open)
+					{
+						Message.Text = text.Get(TextKey.FileSystemDialog_OpenFileMessage);
+					}
+					else
+					{
+						Message.Text = text.Get(TextKey.FileSystemDialog_SaveFileMessage);
+					}
+				}
+				else
+				{
+					if (operation == FileSystemOperation.Open)
+					{
+						Message.Text = text.Get(TextKey.FileSystemDialog_OpenFolderMessage);
+					}
+					else
+					{
+						Message.Text = text.Get(TextKey.FileSystemDialog_SaveFolderMessage);
+					}
+				}
+			}
+			else
+			{
+				Message.Text = message;
+			}
+
+			if (string.IsNullOrEmpty(title))
+			{
+				Title = text.Get(TextKey.FileSystemDialog_Title);
+			}
+			else
+			{
+				Title = title;
+			}
+		}
+	}
+}

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

@@ -145,6 +145,9 @@
     <Compile Include="Controls\TaskviewWindowControl.xaml.cs">
       <DependentUpon>TaskviewWindowControl.xaml</DependentUpon>
     </Compile>
+    <Compile Include="FileSystemDialog.xaml.cs">
+      <DependentUpon>FileSystemDialog.xaml</DependentUpon>
+    </Compile>
     <Compile Include="FolderDialog.cs" />
     <Compile Include="LockScreen.xaml.cs">
       <DependentUpon>LockScreen.xaml</DependentUpon>
@@ -322,6 +325,10 @@
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>
     </Page>
+    <Page Include="FileSystemDialog.xaml">
+      <SubType>Designer</SubType>
+      <Generator>MSBuild:Compile</Generator>
+    </Page>
     <Page Include="LockScreen.xaml">
       <SubType>Designer</SubType>
       <Generator>MSBuild:Compile</Generator>

SafeExamBrowser.UserInterface.Desktop/UserInterfaceFactory.cs

@@ -23,6 +23,7 @@ using SafeExamBrowser.SystemComponents.Contracts.PowerSupply;
 using SafeExamBrowser.SystemComponents.Contracts.WirelessNetwork;
 using SafeExamBrowser.UserInterface.Contracts;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
+using SafeExamBrowser.UserInterface.Contracts.FileSystemDialog;
 using SafeExamBrowser.UserInterface.Contracts.Shell;
 using SafeExamBrowser.UserInterface.Contracts.Windows;
 using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
@@ -72,7 +73,12 @@ namespace SafeExamBrowser.UserInterface.Desktop
 
 		public IBrowserWindow CreateBrowserWindow(IBrowserControl control, BrowserSettings settings, bool isMainWindow)
 		{
-			return new BrowserWindow(control, settings, isMainWindow, text);
+			return Application.Current.Dispatcher.Invoke(() => new BrowserWindow(control, settings, isMainWindow, text));
+		}
+
+		public IFileSystemDialog CreateFileSystemDialog(FileSystemElement element, string initialPath, FileSystemOperation operation, string message = default(string), string title = default(string))
+		{
+			return Application.Current.Dispatcher.Invoke(() => new FileSystemDialog(element, initialPath, operation, text, message, title));
 		}
 
 		public IFolderDialog CreateFolderDialog(string message)

SafeExamBrowser.UserInterface.Mobile/UserInterfaceFactory.cs

@@ -23,6 +23,7 @@ using SafeExamBrowser.SystemComponents.Contracts.PowerSupply;
 using SafeExamBrowser.SystemComponents.Contracts.WirelessNetwork;
 using SafeExamBrowser.UserInterface.Contracts;
 using SafeExamBrowser.UserInterface.Contracts.Browser;
+using SafeExamBrowser.UserInterface.Contracts.FileSystemDialog;
 using SafeExamBrowser.UserInterface.Contracts.Shell;
 using SafeExamBrowser.UserInterface.Contracts.Windows;
 using SafeExamBrowser.UserInterface.Contracts.Windows.Data;
@@ -75,6 +76,11 @@ namespace SafeExamBrowser.UserInterface.Mobile
 			return new BrowserWindow(control, settings, isMainWindow, text);
 		}
 
+		public IFileSystemDialog CreateFileSystemDialog(FileSystemElement element, string initialPath, FileSystemOperation operation, string message = default(string), string title = default(string))
+		{
+			throw new System.NotImplementedException();
+		}
+
 		public IFolderDialog CreateFolderDialog(string message)
 		{
 			return new FolderDialog(message);

SafeExamBrowser.UserInterface.Shared/SafeExamBrowser.UserInterface.Shared.csproj

@@ -72,6 +72,7 @@
     <Compile Include="Properties\AssemblyInfo.cs">
       <SubType>Code</SubType>
     </Compile>
+    <Compile Include="Utilities\IconLoader.cs" />
     <Compile Include="Utilities\IconResourceLoader.cs" />
     <Compile Include="Utilities\Thumbnail.cs" />
     <Compile Include="Utilities\VisualExtensions.cs" />

SafeExamBrowser.UserInterface.Shared/Utilities/IconLoader.cs

@@ -0,0 +1,62 @@
+/*
+ * 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;
+using System.IO;
+using System.Runtime.InteropServices;
+using System.Windows;
+using System.Windows.Interop;
+using System.Windows.Media;
+using System.Windows.Media.Imaging;
+
+namespace SafeExamBrowser.UserInterface.Shared.Utilities
+{
+	public static class IconLoader
+	{
+		private const uint SHGFI_ICON = 0x100;
+		private const uint SHGFI_LARGEICON = 0x0;
+		private const uint SHGFI_SMALLICON = 0x1;
+
+		public static ImageSource LoadIconFor(DirectoryInfo directory)
+		{
+			var fileInfo = new SHFILEINFO();
+			var result = SHGetFileInfo(directory.FullName, 0, ref fileInfo, (uint) Marshal.SizeOf(fileInfo), SHGFI_ICON | SHGFI_SMALLICON);
+			var imageSource = Imaging.CreateBitmapSourceFromHIcon(fileInfo.hIcon, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
+
+			DestroyIcon(fileInfo.hIcon);
+
+			return imageSource;
+		}
+
+		public static ImageSource LoadIconFor(FileInfo file)
+		{
+			using (var icon = System.Drawing.Icon.ExtractAssociatedIcon(file.FullName))
+			{
+				return Imaging.CreateBitmapSourceFromHIcon(icon.Handle, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
+			}
+		}
+
+		[DllImport("user32.dll")]
+		private static extern int DestroyIcon(IntPtr hIcon);
+
+		[DllImport("shell32.dll")]
+		private static extern IntPtr SHGetFileInfo(string pszPath, uint dwFileAttributes, ref SHFILEINFO psfi, uint cbSizeFileInfo, uint uFlags);
+
+		[StructLayout(LayoutKind.Sequential)]
+		private struct SHFILEINFO
+		{
+			public IntPtr hIcon;
+			public IntPtr iIcon;
+			public uint dwAttributes;
+			[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 260)]
+			public string szDisplayName;
+			[MarshalAs(UnmanagedType.ByValTStr, SizeConst = 80)]
+			public string szTypeName;
+		};
+	}
+}