CmdPal: Pull out VM bits from ShellPage.xaml.cs (#40479)

ref #40113

Moves a lot of the "model" logic out of `ShellPage.xaml.cs` into
`ShellViewModel`.

The LARGE majority of this code is copy-paste moving code. We're now
using a couple more messages to pass navigation between the VM and the
page. And a couple new messages for passing ETW events.

src/modules/cmdpal/Microsoft.CmdPal.UI/Pages/ShellPage.xaml.cs

@@ -6,11 +6,9 @@ using System.ComponentModel;
 using CommunityToolkit.Mvvm.Messaging;
 using CommunityToolkit.WinUI;
 using ManagedCommon;
-using Microsoft.CmdPal.Common.Services;
 using Microsoft.CmdPal.UI.Events;
 using Microsoft.CmdPal.UI.Settings;
 using Microsoft.CmdPal.UI.ViewModels;
-using Microsoft.CmdPal.UI.ViewModels.MainPage;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
 using Microsoft.CommandPalette.Extensions;
 using Microsoft.Extensions.DependencyInjection;
@@ -28,15 +26,18 @@ namespace Microsoft.CmdPal.UI.Pages;
 /// </summary>
 public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
     IRecipient<NavigateBackMessage>,
-    IRecipient<PerformCommandMessage>,
     IRecipient<OpenSettingsMessage>,
     IRecipient<HotkeySummonMessage>,
     IRecipient<ShowDetailsMessage>,
     IRecipient<HideDetailsMessage>,
     IRecipient<ClearSearchMessage>,
-    IRecipient<HandleCommandResultMessage>,
     IRecipient<LaunchUriMessage>,
     IRecipient<SettingsWindowClosedMessage>,
+    IRecipient<GoHomeMessage>,
+    IRecipient<GoBackMessage>,
+    IRecipient<ShowConfirmationMessage>,
+    IRecipient<ShowToastMessage>,
+    IRecipient<NavigateToPageMessage>,
     INotifyPropertyChanged
 {
     private readonly DispatcherQueue _queue = DispatcherQueue.GetForCurrentThread();
@@ -50,8 +51,6 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
 
     private readonly ToastWindow _toast = new();
 
-    private readonly Lock _invokeLock = new();
-    private Task? _handleInvokeTask;
     private SettingsWindow? _settingsWindow;
 
     public ShellViewModel ViewModel { get; private set; } = App.Current.Services.GetService<ShellViewModel>()!;
@@ -64,8 +63,6 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
 
         // how we are doing navigation around
         WeakReferenceMessenger.Default.Register<NavigateBackMessage>(this);
-        WeakReferenceMessenger.Default.Register<PerformCommandMessage>(this);
-        WeakReferenceMessenger.Default.Register<HandleCommandResultMessage>(this);
         WeakReferenceMessenger.Default.Register<OpenSettingsMessage>(this);
         WeakReferenceMessenger.Default.Register<HotkeySummonMessage>(this);
         WeakReferenceMessenger.Default.Register<SettingsWindowClosedMessage>(this);
@@ -76,6 +73,12 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
         WeakReferenceMessenger.Default.Register<ClearSearchMessage>(this);
         WeakReferenceMessenger.Default.Register<LaunchUriMessage>(this);
 
+        WeakReferenceMessenger.Default.Register<GoHomeMessage>(this);
+        WeakReferenceMessenger.Default.Register<GoBackMessage>(this);
+        WeakReferenceMessenger.Default.Register<ShowConfirmationMessage>(this);
+        WeakReferenceMessenger.Default.Register<ShowToastMessage>(this);
+        WeakReferenceMessenger.Default.Register<NavigateToPageMessage>(this);
+
         RootFrame.Navigate(typeof(LoadingPage), ViewModel);
     }
 
@@ -103,195 +106,72 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
         }
     }
 
-    public void Receive(PerformCommandMessage message)
+    public void Receive(NavigateToPageMessage message)
     {
-        PerformCommand(message);
+        // TODO GH #526 This needs more better locking too
+        _ = _queue.TryEnqueue(() =>
+        {
+            // Also hide our details pane about here, if we had one
+            HideDetails();
+
+            // Navigate to the appropriate host page for that VM
+            RootFrame.Navigate(
+                message.Page switch
+                {
+                    ListViewModel => typeof(ListPage),
+                    ContentPageViewModel => typeof(ContentPage),
+                    _ => throw new NotSupportedException(),
+                },
+                message.Page,
+                message.WithAnimation ? _slideRightTransition : _noAnimation);
+
+            PowerToysTelemetry.Log.WriteEvent(new OpenPage(RootFrame.BackStackDepth));
+
+            // Refocus on the Search for continual typing on the next search request
+            SearchBox.Focus(Microsoft.UI.Xaml.FocusState.Programmatic);
+
+            if (!ViewModel.IsNested)
+            {
+                // todo BODGY
+                RootFrame.BackStack.Clear();
+            }
+        });
     }
 
-    private void PerformCommand(PerformCommandMessage message)
+    public void Receive(ShowConfirmationMessage message)
     {
-        var command = message.Command.Unsafe;
-        if (command == null)
+        DispatcherQueue.TryEnqueue(async () =>
+        {
+            try
+            {
+                await HandleConfirmArgsOnUiThread(message.Args);
+            }
+            catch (Exception ex)
+            {
+                Logger.LogError(ex.ToString());
+            }
+        });
+    }
+
+    public void Receive(ShowToastMessage message)
+    {
+        DispatcherQueue.TryEnqueue(() =>
+        {
+            _toast.ShowToast(message.Message);
+        });
+    }
+
+    // This gets called from the UI thread
+    private async Task HandleConfirmArgsOnUiThread(IConfirmationArgs? args)
+    {
+        if (args == null)
         {
             return;
         }
 
-        if (!ViewModel.CurrentPage.IsNested)
-        {
-            // on the main page here
-            ViewModel.PerformTopLevelCommand(message);
-        }
-
-        IExtensionWrapper? extension = null;
-
-        // TODO: Actually loading up the page, or invoking the command -
-        // that might belong in the model, not the view?
-        // Especially considering the try/catch concerns around the fact that the
-        // COM call might just fail.
-        // Or the command may be a stub. Future us problem.
-        try
-        {
-            // In the case that we're coming from a top-level command, the
-            // current page's host is the global instance. We only really want
-            // to use that as the host of last resort.
-            var pageHost = ViewModel.CurrentPage?.ExtensionHost;
-            if (pageHost == CommandPaletteHost.Instance)
-            {
-                pageHost = null;
-            }
-
-            var messageHost = message.ExtensionHost;
-
-            // Use the host from the current page if it has one, else use the
-            // one specified in the PerformMessage for a top-level command,
-            // else just use the global one.
-            CommandPaletteHost host;
-
-            // Top level items can come through without a Extension set on the
-            // message. In that case, the `Context` is actually the
-            // TopLevelViewModel itself, and we can use that to get at the
-            // extension object.
-            extension = pageHost?.Extension ?? messageHost?.Extension ?? null;
-            if (extension == null && message.Context is TopLevelViewModel topLevelViewModel)
-            {
-                extension = topLevelViewModel.ExtensionHost?.Extension;
-                host = pageHost ?? messageHost ?? topLevelViewModel?.ExtensionHost ?? CommandPaletteHost.Instance;
-            }
-            else
-            {
-                host = pageHost ?? messageHost ?? CommandPaletteHost.Instance;
-            }
-
-            if (extension != null)
-            {
-                if (messageHost != null)
-                {
-                    Logger.LogDebug($"Activated top-level command from {extension.ExtensionDisplayName}");
-                }
-                else
-                {
-                    Logger.LogDebug($"Activated command from {extension.ExtensionDisplayName}");
-                }
-            }
-
-            ViewModel.SetActiveExtension(extension);
-
-            if (command is IPage page)
-            {
-                Logger.LogDebug($"Navigating to page");
-
-                // TODO GH #526 This needs more better locking too
-                _ = _queue.TryEnqueue(() =>
-                {
-                    // Also hide our details pane about here, if we had one
-                    HideDetails();
-
-                    WeakReferenceMessenger.Default.Send<UpdateCommandBarMessage>(new(null));
-
-                    var isMainPage = command is MainListPage;
-
-                    // Construct our ViewModel of the appropriate type and pass it the UI Thread context.
-                    PageViewModel pageViewModel = page switch
-                    {
-                        IListPage listPage => new ListViewModel(listPage, _mainTaskScheduler, host)
-                        {
-                            IsNested = !isMainPage,
-                        },
-                        IContentPage contentPage => new ContentPageViewModel(contentPage, _mainTaskScheduler, host),
-                        _ => throw new NotSupportedException(),
-                    };
-
-                    // Kick off async loading of our ViewModel
-                    ViewModel.LoadPageViewModel(pageViewModel);
-
-                    // Navigate to the appropriate host page for that VM
-                    RootFrame.Navigate(
-                        page switch
-                        {
-                            IListPage => typeof(ListPage),
-                            IContentPage => typeof(ContentPage),
-                            _ => throw new NotSupportedException(),
-                        },
-                        pageViewModel,
-                        message.WithAnimation ? _slideRightTransition : _noAnimation);
-
-                    PowerToysTelemetry.Log.WriteEvent(new OpenPage(RootFrame.BackStackDepth));
-
-                    // Refocus on the Search for continual typing on the next search request
-                    SearchBox.Focus(Microsoft.UI.Xaml.FocusState.Programmatic);
-
-                    if (isMainPage)
-                    {
-                        // todo BODGY
-                        RootFrame.BackStack.Clear();
-                    }
-
-                    // Note: Originally we set our page back in the ViewModel here, but that now happens in response to the Frame navigating triggered from the above
-                    // See RootFrame_Navigated event handler.
-                });
-            }
-            else if (command is IInvokableCommand invokable)
-            {
-                Logger.LogDebug($"Invoking command");
-                PowerToysTelemetry.Log.WriteEvent(new BeginInvoke());
-                HandleInvokeCommand(message, invokable);
-            }
-        }
-        catch (Exception ex)
-        {
-            // TODO: It would be better to do this as a page exception, rather
-            // than a silent log message.
-            CommandPaletteHost.Instance.Log(ex.Message);
-        }
-    }
-
-    private void HandleInvokeCommand(PerformCommandMessage message, IInvokableCommand invokable)
-    {
-        // TODO GH #525 This needs more better locking.
-        lock (_invokeLock)
-        {
-            if (_handleInvokeTask != null)
-            {
-                // do nothing - a command is already doing a thing
-            }
-            else
-            {
-                _handleInvokeTask = Task.Run(() =>
-                {
-                    try
-                    {
-                        var result = invokable.Invoke(message.Context);
-                        DispatcherQueue.TryEnqueue(() =>
-                        {
-                            try
-                            {
-                                HandleCommandResultOnUiThread(result);
-                            }
-                            finally
-                            {
-                                _handleInvokeTask = null;
-                            }
-                        });
-                    }
-                    catch (Exception ex)
-                    {
-                        _handleInvokeTask = null;
-
-                        // TODO: It would be better to do this as a page exception, rather
-                        // than a silent log message.
-                        CommandPaletteHost.Instance.Log(ex.Message);
-                    }
-                });
-            }
-        }
-    }
-
-    // This gets called from the UI thread
-    private void HandleConfirmArgs(IConfirmationArgs args)
-    {
         ConfirmResultViewModel vm = new(args, new(ViewModel.CurrentPage));
         var initializeDialogTask = Task.Run(() => { InitializeConfirmationDialog(vm); });
-        initializeDialogTask.Wait();
+        await initializeDialogTask;
 
         var resourceLoader = Microsoft.CmdPal.UI.Helpers.ResourceLoaderInstance.ResourceLoader;
         var confirmText = resourceLoader.GetString("ConfirmationDialog_ConfirmButtonText");
@@ -322,19 +202,16 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
             // };
         }
 
-        DispatcherQueue.TryEnqueue(async () =>
+        var result = await dialog.ShowAsync();
+        if (result == ContentDialogResult.Primary)
         {
-            var result = await dialog.ShowAsync();
-            if (result == ContentDialogResult.Primary)
-            {
-                var performMessage = new PerformCommandMessage(vm);
-                PerformCommand(performMessage);
-            }
-            else
-            {
-                // cancel
-            }
-        });
+            var performMessage = new PerformCommandMessage(vm);
+            WeakReferenceMessenger.Default.Send(performMessage);
+        }
+        else
+        {
+            // cancel
+        }
     }
 
     private void InitializeConfirmationDialog(ConfirmResultViewModel vm)
@@ -342,79 +219,6 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
         vm.SafeInitializePropertiesSynchronous();
     }
 
-    private void HandleCommandResultOnUiThread(ICommandResult? result)
-    {
-        try
-        {
-            if (result != null)
-            {
-                var kind = result.Kind;
-                Logger.LogDebug($"handling {kind.ToString()}");
-                PowerToysTelemetry.Log.WriteEvent(new CmdPalInvokeResult(kind));
-                switch (kind)
-                {
-                    case CommandResultKind.Dismiss:
-                        {
-                            // Reset the palette to the main page and dismiss
-                            GoHome(withAnimation: false, focusSearch: false);
-                            WeakReferenceMessenger.Default.Send<DismissMessage>();
-                            break;
-                        }
-
-                    case CommandResultKind.GoHome:
-                        {
-                            // Go back to the main page, but keep it open
-                            GoHome();
-                            break;
-                        }
-
-                    case CommandResultKind.GoBack:
-                        {
-                            GoBack();
-                            break;
-                        }
-
-                    case CommandResultKind.Hide:
-                        {
-                            // Keep this page open, but hide the palette.
-                            WeakReferenceMessenger.Default.Send<DismissMessage>();
-                            break;
-                        }
-
-                    case CommandResultKind.KeepOpen:
-                        {
-                            // Do nothing.
-                            break;
-                        }
-
-                    case CommandResultKind.Confirm:
-                        {
-                            if (result.Args is IConfirmationArgs a)
-                            {
-                                HandleConfirmArgs(a);
-                            }
-
-                            break;
-                        }
-
-                    case CommandResultKind.ShowToast:
-                        {
-                            if (result.Args is IToastArgs a)
-                            {
-                                _toast.ShowToast(a.Message);
-                                HandleCommandResultOnUiThread(a.Result);
-                            }
-
-                            break;
-                        }
-                }
-            }
-        }
-        catch
-        {
-        }
-    }
-
     public void Receive(OpenSettingsMessage message)
     {
         _ = DispatcherQueue.TryEnqueue(() =>
@@ -467,14 +271,6 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
 
     public void Receive(LaunchUriMessage message) => _ = global::Windows.System.Launcher.LaunchUriAsync(message.Uri);
 
-    public void Receive(HandleCommandResultMessage message)
-    {
-        DispatcherQueue.TryEnqueue(() =>
-        {
-            HandleCommandResultOnUiThread(message.Result.Unsafe);
-        });
-    }
-
     private void HideDetails()
     {
         ViewModel.Details = null;
@@ -554,6 +350,11 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
         WeakReferenceMessenger.Default.Send<FocusSearchBoxMessage>();
     }
 
+    public void Receive(GoBackMessage message)
+    {
+        _ = DispatcherQueue.TryEnqueue(() => GoBack(message.WithAnimation, message.FocusSearch));
+    }
+
     private void GoBack(bool withAnimation = true, bool focusSearch = true)
     {
         HideDetails();
@@ -591,14 +392,17 @@ public sealed partial class ShellPage : Microsoft.UI.Xaml.Controls.Page,
         }
     }
 
+    public void Receive(GoHomeMessage message)
+    {
+        _ = DispatcherQueue.TryEnqueue(() => GoHome(withAnimation: message.WithAnimation, focusSearch: message.FocusSearch));
+    }
+
     private void GoHome(bool withAnimation = true, bool focusSearch = true)
     {
         while (RootFrame.CanGoBack)
         {
             GoBack(withAnimation, focusSearch);
         }
-
-        WeakReferenceMessenger.Default.Send<GoHomeMessage>();
     }
 
     private void BackButton_Tapped(object sender, Microsoft.UI.Xaml.Input.TappedRoutedEventArgs e) => WeakReferenceMessenger.Default.Send<NavigateBackMessage>(new());