Dispose mail webviews when closing the shell

Wino.Mail.WinUI/ShellWindow.xaml.cs

@@ -5,6 +5,7 @@ using System.Threading.Tasks;
 using CommunityToolkit.Mvvm.Input;
 using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.UI.Windowing;
 using Microsoft.UI.Xaml;
 using Microsoft.UI.Xaml.Controls;
 using Windows.UI;
@@ -20,8 +21,10 @@ using Wino.Mail.WinUI.Helpers;
 using Wino.Mail.WinUI.Interfaces;
 using Wino.Mail.WinUI.Models;
 using Wino.Mail.WinUI.Views;
+using Wino.Messaging.Client.Mails;
 using Wino.Messaging.Client.Shell;
 using Wino.Messaging.UI;
+using Wino.Views.Mail;
 using WinUIEx;
 
 namespace Wino.Mail.WinUI;
@@ -356,12 +359,16 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
         SynchronizeTitleBarSearchBox();
     }
 
-    private void OnAppWindowClosing(object sender, Microsoft.UI.Windowing.AppWindowClosingEventArgs e)
+    private async void OnAppWindowClosing(object sender, AppWindowClosingEventArgs e)
     {
         if (_allowClose || (Application.Current as App)?.IsExiting == true)
             return;
 
         e.Cancel = true;
+
+        if (!await PrepareMailModeForHideAsync())
+            return;
+
         var windowManager = WinoApplication.Current.Services.GetService<IWinoWindowManager>();
         windowManager?.HideWindow(this);
     }
@@ -398,6 +405,55 @@ public sealed partial class ShellWindow : WindowEx, IWinoShellWindow,
         UnregisterRecipients();
     }
 
+    private async Task<bool> PrepareMailModeForHideAsync()
+    {
+        if (MainShellFrame.Content is not WinoAppShell shellPage)
+            return true;
+
+        if (shellPage.GetShellFrame().Content is not MailListPage mailListPage)
+            return true;
+
+        var renderingFrame = mailListPage.FindName("RenderingFrame") as Frame;
+
+        if (renderingFrame?.Content is ComposePage composePage)
+        {
+            var closeResult = await MailDialogService.ShowThreeButtonDialogAsync(
+                Translator.DialogMessage_CloseDraftWindowConfirmationTitle,
+                Translator.DialogMessage_CloseDraftWindowConfirmationMessage,
+                Translator.Buttons_Save,
+                Translator.Buttons_Discard,
+                Translator.Buttons_Cancel,
+                WinoCustomMessageDialogIcon.Warning);
+
+            if (closeResult == ThreeButtonDialogResult.Cancel)
+            {
+                return false;
+            }
+
+            try
+            {
+                if (closeResult == ThreeButtonDialogResult.Primary)
+                {
+                    await composePage.ViewModel.SaveDraftAsync();
+                }
+                else
+                {
+                    await composePage.ViewModel.DiscardDraftAsync(requireConfirmation: false);
+                }
+            }
+            catch (Exception ex)
+            {
+                MailDialogService.InfoBarMessage(Translator.GeneralTitle_Error, ex.Message, InfoBarMessageType.Error);
+                return false;
+            }
+        }
+
+        await mailListPage.ViewModel.MailCollection.UnselectAllAsync();
+        WeakReferenceMessenger.Default.Send(new DisposeRenderingFrameRequested());
+
+        return true;
+    }
+
     private void RegisterRecipients()
     {
         WeakReferenceMessenger.Default.Register<TitleBarShellContentUpdated>(this);