Add support for filterable, nested context menus (#38776)

_targets #38573_

At first I just wanted to add support for nested context menus.

But then I also had to add a search box, so the focus wouldn't get weird.

End result:

![nested-menus-001](https://github.com/user-attachments/assets/4e8f1ec8-4b09-4095-9b81-caf7abde8aea)

This gets rid of the need to have the search box and the command bar both track item keybindings - now it's just in the command bar.

Closes #38299
Closes #38442

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandBarViewModel.cs

@@ -4,18 +4,14 @@
 
 using System.Collections.ObjectModel;
 using CommunityToolkit.Mvvm.ComponentModel;
-using CommunityToolkit.Mvvm.Input;
 using CommunityToolkit.Mvvm.Messaging;
 using Microsoft.CmdPal.UI.ViewModels.Messages;
-using Microsoft.CommandPalette.Extensions;
-using Microsoft.CommandPalette.Extensions.Toolkit;
 using Windows.System;
 
 namespace Microsoft.CmdPal.UI.ViewModels;
 
 public partial class CommandBarViewModel : ObservableObject,
-    IRecipient<UpdateCommandBarMessage>,
-    IRecipient<UpdateItemKeybindingsMessage>
+    IRecipient<UpdateCommandBarMessage>
 {
     public ICommandBarContext? SelectedItem
     {
@@ -53,20 +49,17 @@ public partial class CommandBarViewModel : ObservableObject,
     public partial PageViewModel? CurrentPage { get; set; }
 
     [ObservableProperty]
-    public partial ObservableCollection<CommandContextItemViewModel> ContextCommands { get; set; } = [];
+    public partial ObservableCollection<ContextMenuStackViewModel> ContextMenuStack { get; set; } = [];
 
-    private Dictionary<KeyChord, CommandContextItemViewModel>? _contextKeybindings;
+    public ContextMenuStackViewModel? ContextMenu => ContextMenuStack.LastOrDefault();
 
     public CommandBarViewModel()
     {
         WeakReferenceMessenger.Default.Register<UpdateCommandBarMessage>(this);
-        WeakReferenceMessenger.Default.Register<UpdateItemKeybindingsMessage>(this);
     }
 
     public void Receive(UpdateCommandBarMessage message) => SelectedItem = message.ViewModel;
 
-    public void Receive(UpdateItemKeybindingsMessage message) => _contextKeybindings = message.Keys;
-
     private void SetSelectedItem(ICommandBarContext? value)
     {
         if (value != null)
@@ -111,7 +104,10 @@ public partial class CommandBarViewModel : ObservableObject,
         if (SelectedItem.MoreCommands.Count() > 1)
         {
             ShouldShowContextMenu = true;
-            ContextCommands = [.. SelectedItem.AllCommands.Where(c => c.ShouldBeVisible)];
+
+            ContextMenuStack.Clear();
+            ContextMenuStack.Add(new ContextMenuStackViewModel(SelectedItem));
+            OnPropertyChanged(nameof(ContextMenu));
         }
         else
         {
@@ -125,43 +121,80 @@ public partial class CommandBarViewModel : ObservableObject,
 
     // InvokeItemCommand is what this will be in Xaml due to source generator
     // this comes in when an item in the list is tapped
-    [RelayCommand]
-    private void InvokeItem(CommandContextItemViewModel item) =>
-       WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(item.Command.Model, item.Model));
+    // [RelayCommand]
+    public ContextKeybindingResult InvokeItem(CommandContextItemViewModel item) =>
+        PerformCommand(item);
 
     // this comes in when the primary button is tapped
     public void InvokePrimaryCommand()
     {
-        if (PrimaryCommand != null)
-        {
-            WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(PrimaryCommand.Command.Model, PrimaryCommand.Model));
-        }
+        PerformCommand(SecondaryCommand);
     }
 
     // this comes in when the secondary button is tapped
     public void InvokeSecondaryCommand()
     {
-        if (SecondaryCommand != null)
+        PerformCommand(SecondaryCommand);
+    }
+
+    public ContextKeybindingResult CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
+    {
+        var matchedItem = ContextMenu?.CheckKeybinding(ctrl, alt, shift, win, key);
+        return matchedItem != null ? PerformCommand(matchedItem) : ContextKeybindingResult.Unhandled;
+    }
+
+    private ContextKeybindingResult PerformCommand(CommandItemViewModel? command)
+    {
+        if (command == null)
         {
-            WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(SecondaryCommand.Command.Model, SecondaryCommand.Model));
+            return ContextKeybindingResult.Unhandled;
+        }
+
+        if (command.HasMoreCommands)
+        {
+            ContextMenuStack.Add(new ContextMenuStackViewModel(command));
+            OnPropertyChanging(nameof(ContextMenu));
+            OnPropertyChanged(nameof(ContextMenu));
+            return ContextKeybindingResult.KeepOpen;
+        }
+        else
+        {
+            WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(command.Command.Model, command.Model));
+            return ContextKeybindingResult.Hide;
         }
     }
 
-    public bool CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
+    public bool CanPopContextStack()
     {
-        if (_contextKeybindings != null)
+        return ContextMenuStack.Count > 1;
+    }
+
+    public void PopContextStack()
+    {
+        if (ContextMenuStack.Count > 1)
         {
-            // Does the pressed key match any of the keybindings?
-            var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
-            if (_contextKeybindings.TryGetValue(pressedKeyChord, out var item))
-            {
-                // TODO GH #245: This is a bit of a hack, but we need to make sure that the keybindings are updated before we send the message
-                // so that the correct item is activated.
-                WeakReferenceMessenger.Default.Send<PerformCommandMessage>(new(item));
-                return true;
-            }
+            ContextMenuStack.RemoveAt(ContextMenuStack.Count - 1);
         }
 
-        return false;
+        OnPropertyChanging(nameof(ContextMenu));
+        OnPropertyChanged(nameof(ContextMenu));
+    }
+
+    public void ClearContextStack()
+    {
+        while (ContextMenuStack.Count > 1)
+        {
+            ContextMenuStack.RemoveAt(ContextMenuStack.Count - 1);
+        }
+
+        OnPropertyChanging(nameof(ContextMenu));
+        OnPropertyChanged(nameof(ContextMenu));
     }
 }
+
+public enum ContextKeybindingResult
+{
+    Unhandled,
+    Hide,
+    KeepOpen,
+}

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/CommandItemViewModel.cs

@@ -48,7 +48,7 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
 
     public List<CommandContextItemViewModel> MoreCommands { get; private set; } = [];
 
-    IEnumerable<CommandContextItemViewModel> ICommandBarContext.MoreCommands => MoreCommands;
+    IEnumerable<CommandContextItemViewModel> IContextMenuContext.MoreCommands => MoreCommands;
 
     public bool HasMoreCommands => MoreCommands.Count > 0;
 
@@ -187,23 +187,26 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         // use Initialize straight up
         MoreCommands.ForEach(contextItem =>
         {
-            contextItem.InitializeProperties();
+            contextItem.SlowInitializeProperties();
         });
 
-        _defaultCommandContextItem = new(new CommandContextItem(model.Command!), PageContext)
+        if (!string.IsNullOrEmpty(model.Command.Name))
         {
-            _itemTitle = Name,
-            Subtitle = Subtitle,
-            Command = Command,
+            _defaultCommandContextItem = new(new CommandContextItem(model.Command!), PageContext)
+            {
+                _itemTitle = Name,
+                Subtitle = Subtitle,
+                Command = Command,
 
-            // TODO this probably should just be a CommandContextItemViewModel(CommandItemViewModel) ctor, or a copy ctor or whatever
-        };
+                // TODO this probably should just be a CommandContextItemViewModel(CommandItemViewModel) ctor, or a copy ctor or whatever
+            };
 
-        // Only set the icon on the context item for us if our command didn't
-        // have its own icon
-        if (!Command.HasIcon)
-        {
-            _defaultCommandContextItem._listItemIcon = _listItemIcon;
+            // Only set the icon on the context item for us if our command didn't
+            // have its own icon
+            if (!Command.HasIcon)
+            {
+                _defaultCommandContextItem._listItemIcon = _listItemIcon;
+            }
         }
 
         Initialized |= InitializedState.SelectionInitialized;
@@ -398,23 +401,6 @@ public partial class CommandItemViewModel : ExtensionObjectViewModel, ICommandBa
         base.SafeCleanup();
         Initialized |= InitializedState.CleanedUp;
     }
-
-    /// <summary>
-    /// Generates a mapping of key -> command item for this particular item's
-    /// MoreCommands. (This won't include the primary Command, but it will
-    /// include the secondary one). This map can be used to quickly check if a
-    /// shortcut key was pressed
-    /// </summary>
-    /// <returns>a dictionary of KeyChord -> Context commands, for all commands
-    /// that have a shortcut key set.</returns>
-    internal Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
-    {
-        return MoreCommands
-            .Where(c => c.HasRequestedShortcut)
-            .ToDictionary(
-            c => c.RequestedShortcut ?? new KeyChord(0, 0, 0),
-            c => c);
-    }
 }
 
 [Flags]

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/ContextMenuStackViewModel.cs

@@ -0,0 +1,82 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.ObjectModel;
+using CommunityToolkit.Mvvm.ComponentModel;
+using Microsoft.CmdPal.UI.ViewModels.Messages;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+using Windows.System;
+
+namespace Microsoft.CmdPal.UI.ViewModels;
+
+public partial class ContextMenuStackViewModel : ObservableObject
+{
+    [ObservableProperty]
+    public partial ObservableCollection<CommandContextItemViewModel> FilteredItems { get; set; }
+
+    private readonly IContextMenuContext _context;
+    private string _lastSearchText = string.Empty;
+
+    // private Dictionary<KeyChord, CommandContextItemViewModel>? _contextKeybindings;
+    public ContextMenuStackViewModel(IContextMenuContext context)
+    {
+        _context = context;
+        FilteredItems = [.. context.AllCommands];
+    }
+
+    public void SetSearchText(string searchText)
+    {
+        if (searchText == _lastSearchText)
+        {
+            return;
+        }
+
+        _lastSearchText = searchText;
+
+        var commands = _context.AllCommands.Where(c => c.ShouldBeVisible);
+        if (string.IsNullOrEmpty(searchText))
+        {
+            ListHelpers.InPlaceUpdateList(FilteredItems, commands);
+            return;
+        }
+
+        var newResults = ListHelpers.FilterList<CommandContextItemViewModel>(commands, searchText, ScoreContextCommand);
+        ListHelpers.InPlaceUpdateList(FilteredItems, newResults);
+    }
+
+    private static int ScoreContextCommand(string query, CommandContextItemViewModel item)
+    {
+        if (string.IsNullOrEmpty(query) || string.IsNullOrWhiteSpace(query))
+        {
+            return 1;
+        }
+
+        if (string.IsNullOrEmpty(item.Title))
+        {
+            return 0;
+        }
+
+        var nameMatch = StringMatcher.FuzzySearch(query, item.Title);
+
+        var descriptionMatch = StringMatcher.FuzzySearch(query, item.Subtitle);
+
+        return new[] { nameMatch.Score, (descriptionMatch.Score - 4) / 2, 0 }.Max();
+    }
+
+    public CommandContextItemViewModel? CheckKeybinding(bool ctrl, bool alt, bool shift, bool win, VirtualKey key)
+    {
+        var keybindings = _context.Keybindings();
+        if (keybindings != null)
+        {
+            // Does the pressed key match any of the keybindings?
+            var pressedKeyChord = KeyChordHelpers.FromModifiers(ctrl, alt, shift, win, key, 0);
+            if (keybindings.TryGetValue(pressedKeyChord, out var item))
+            {
+                return item;
+            }
+        }
+
+        return null;
+    }
+}

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/ListViewModel.cs

@@ -344,8 +344,6 @@ public partial class ListViewModel : PageViewModel, IDisposable
            {
                WeakReferenceMessenger.Default.Send<UpdateCommandBarMessage>(new(item));
 
-               WeakReferenceMessenger.Default.Send<UpdateItemKeybindingsMessage>(new(item.Keybindings()));
-
                if (ShowDetails && item.HasDetails)
                {
                    WeakReferenceMessenger.Default.Send<ShowDetailsMessage>(new(item.Details));

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Messages/TryCommandKeybindingMessage.cs

@@ -2,8 +2,11 @@
 // The Microsoft Corporation licenses this file to you under the MIT license.
 // See the LICENSE file in the project root for more information.
 
-using Microsoft.CommandPalette.Extensions;
+using Windows.System;
 
 namespace Microsoft.CmdPal.UI.ViewModels.Messages;
 
-public record UpdateItemKeybindingsMessage(Dictionary<KeyChord, CommandContextItemViewModel>? Keys);
+public record TryCommandKeybindingMessage(bool Ctrl, bool Alt, bool Shift, bool Win, VirtualKey Key)
+{
+    public bool Handled { get; set; }
+}

src/modules/cmdpal/Microsoft.CmdPal.UI.ViewModels/Messages/UpdateCommandBarMessage.cs

@@ -3,6 +3,7 @@
 // See the LICENSE file in the project root for more information.
 
 using System.ComponentModel;
+using Microsoft.CommandPalette.Extensions;
 
 namespace Microsoft.CmdPal.UI.ViewModels.Messages;
 
@@ -13,22 +14,42 @@ public record UpdateCommandBarMessage(ICommandBarContext? ViewModel)
 {
 }
 
-// Represents everything the command bar needs to know about to show command
-// buttons at the bottom.
-//
-// This is implemented by both ListItemViewModel and ContentPageViewModel,
-// the two things with sub-commands.
-public interface ICommandBarContext : INotifyPropertyChanged
+public interface IContextMenuContext : INotifyPropertyChanged
 {
     public IEnumerable<CommandContextItemViewModel> MoreCommands { get; }
 
     public bool HasMoreCommands { get; }
 
+    public List<CommandContextItemViewModel> AllCommands { get; }
+
+    /// <summary>
+    /// Generates a mapping of key -> command item for this particular item's
+    /// MoreCommands. (This won't include the primary Command, but it will
+    /// include the secondary one). This map can be used to quickly check if a
+    /// shortcut key was pressed
+    /// </summary>
+    /// <returns>a dictionary of KeyChord -> Context commands, for all commands
+    /// that have a shortcut key set.</returns>
+    public Dictionary<KeyChord, CommandContextItemViewModel> Keybindings()
+    {
+        return MoreCommands
+            .Where(c => c.HasRequestedShortcut)
+            .ToDictionary(
+            c => c.RequestedShortcut ?? new KeyChord(0, 0, 0),
+            c => c);
+    }
+}
+
+// Represents everything the command bar needs to know about to show command
+// buttons at the bottom.
+//
+// This is implemented by both ListItemViewModel and ContentPageViewModel,
+// the two things with sub-commands.
+public interface ICommandBarContext : IContextMenuContext
+{
     public string SecondaryCommandName { get; }
 
     public CommandItemViewModel? PrimaryCommand { get; }
 
     public CommandItemViewModel? SecondaryCommand { get; }
-
-    public List<CommandContextItemViewModel> AllCommands { get; }
 }