Make Actions page editable (#9949)

## Summary of the Pull Request

This PR lays the foundation for a new Actions page in the Settings UI as designed in #6900. The Actions page now leverages the `ActionMap` to display all of the key bindings and allow the user to modify the associated key chord or delete the key binding entirely.

## References

#9621 - ActionMap
#9926 - ActionMap serialization
#9428 - ActionMap Spec
#6900 - Actions page
#9427 - Actions page design doc

## Detailed Description of the Pull Request / Additional comments

### Settings Model Changes

- `Command::Copy()` now copies the `ActionAndArgs`
- `ActionMap::RebindKeys()` handles changing the key chord of a key binding. If a conflict occurs, the conflicting key chord is overwritten.
- `ActionMap::DeleteKeyBinding()` "deletes" a key binding by binding "unbound" to the given key chord.
- `ActionMap::KeyBindings()` presents another view (similar to `NameMap`) of the `ActionMap`. It specifically presents a map of key chords to commands. It is generated similar to how `NameMap` is generated.

### Editor Changes

- `Actions.xaml` is mainly split into two parts:
   - `ListView` (as before) holds the list of key bindings. We _could_ explore the idea of an items repeater, but the `ListView` seems to provide some niceties with regards to navigating the list via the key board (though none are selectable).
   - `DataTemplate` is used to represent each key binding inside the `ListView`. This is tricky because it is bound to a `KeyBindingViewModel` which must provide _all_ context necessary to modify the UI and the settings model. We cannot use names to target UI elements inside this template, so we must make the view model smart and force updates to the UI via changes in the view model.
- `KeyBindingViewModel` is a view model object that controls the UI and the settings model. 

There are a number of TODOs in Actions.cpp will be long-term follow-ups and would be nice to have. This includes...
- a binary search by name on `Actions::KeyBindingList`
- presenting an error when the provided key chord is invalid.

## Demo
![Actions Page Demo](https://user-images.githubusercontent.com/11050425/116034988-131d1b80-a619-11eb-8df2-c7e57c6fad86.gif)

src/cascadia/TerminalSettingsEditor/Actions.h

@@ -4,32 +4,85 @@
 #pragma once
 
 #include "Actions.g.h"
+#include "KeyBindingViewModel.g.h"
 #include "ActionsPageNavigationState.g.h"
+#include "RebindKeysEventArgs.g.h"
 #include "Utils.h"
+#include "ViewModelHelpers.h"
 
 namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
 {
-    struct CommandComparator
+    struct KeyBindingViewModelComparator
     {
-        bool operator()(const Model::Command& lhs, const Model::Command& rhs) const
+        bool operator()(const Editor::KeyBindingViewModel& lhs, const Editor::KeyBindingViewModel& rhs) const
         {
             return lhs.Name() < rhs.Name();
         }
     };
 
+    struct RebindKeysEventArgs : RebindKeysEventArgsT<RebindKeysEventArgs>
+    {
+    public:
+        RebindKeysEventArgs(const Control::KeyChord& oldKeys, const Control::KeyChord& newKeys) :
+            _OldKeys{ oldKeys },
+            _NewKeys{ newKeys } {}
+
+        WINRT_PROPERTY(Control::KeyChord, OldKeys, nullptr);
+        WINRT_PROPERTY(Control::KeyChord, NewKeys, nullptr);
+    };
+
+    struct KeyBindingViewModel : KeyBindingViewModelT<KeyBindingViewModel>, ViewModelHelper<KeyBindingViewModel>
+    {
+    public:
+        KeyBindingViewModel(const Control::KeyChord& keys, const Settings::Model::Command& cmd);
+
+        hstring Name() const { return _Command.Name(); }
+        hstring KeyChordText() const { return _KeyChordText; }
+        Settings::Model::Command Command() const { return _Command; };
+
+        // UIA Text
+        hstring EditButtonName() const noexcept;
+        hstring CancelButtonName() const noexcept;
+        hstring AcceptButtonName() const noexcept;
+        hstring DeleteButtonName() const noexcept;
+
+        void EnterHoverMode() { IsHovered(true); };
+        void ExitHoverMode() { IsHovered(false); };
+        void FocusContainer() { IsContainerFocused(true); };
+        void UnfocusContainer() { IsContainerFocused(false); };
+        void FocusEditButton() { IsEditButtonFocused(true); };
+        void UnfocusEditButton() { IsEditButtonFocused(false); };
+        bool ShowEditButton() const noexcept;
+        void ToggleEditMode();
+        void DisableEditMode() { IsInEditMode(false); }
+        void AttemptAcceptChanges();
+        void AttemptAcceptChanges(hstring newKeyChordText);
+        void DeleteKeyBinding() { _DeleteKeyBindingRequestedHandlers(*this, _Keys); }
+
+        VIEW_MODEL_OBSERVABLE_PROPERTY(bool, IsInEditMode, false);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(hstring, ProposedKeys);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(Control::KeyChord, Keys, nullptr);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(Windows::UI::Xaml::Controls::Flyout, AcceptChangesFlyout, nullptr);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(bool, IsAutomationPeerAttached, false);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(bool, IsHovered, false);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(bool, IsContainerFocused, false);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(bool, IsEditButtonFocused, false);
+        VIEW_MODEL_OBSERVABLE_PROPERTY(Windows::UI::Xaml::Media::Brush, ContainerBackground, nullptr);
+        TYPED_EVENT(RebindKeysRequested, Editor::KeyBindingViewModel, Editor::RebindKeysEventArgs);
+        TYPED_EVENT(DeleteKeyBindingRequested, Editor::KeyBindingViewModel, Terminal::Control::KeyChord);
+
+    private:
+        Settings::Model::Command _Command{ nullptr };
+        hstring _KeyChordText{};
+    };
+
     struct ActionsPageNavigationState : ActionsPageNavigationStateT<ActionsPageNavigationState>
     {
     public:
         ActionsPageNavigationState(const Model::CascadiaSettings& settings) :
             _Settings{ settings } {}
 
-        void RequestOpenJson(const Model::SettingsTarget target)
-        {
-            _OpenJsonHandlers(nullptr, target);
-        }
-
         WINRT_PROPERTY(Model::CascadiaSettings, Settings, nullptr)
-        TYPED_EVENT(OpenJson, Windows::Foundation::IInspectable, Model::SettingsTarget);
     };
 
     struct Actions : ActionsT<Actions>
@@ -38,16 +91,21 @@ namespace winrt::Microsoft::Terminal::Settings::Editor::implementation
         Actions();
 
         void OnNavigatedTo(const winrt::Windows::UI::Xaml::Navigation::NavigationEventArgs& e);
+        Windows::UI::Xaml::Automation::Peers::AutomationPeer OnCreateAutomationPeer();
+        void KeyChordEditor_PreviewKeyDown(Windows::Foundation::IInspectable const& sender, Windows::UI::Xaml::Input::KeyRoutedEventArgs const& e);
 
-        Windows::Foundation::Collections::IObservableVector<winrt::Microsoft::Terminal::Settings::Model::Command> FilteredActions();
-
+        WINRT_CALLBACK(PropertyChanged, Windows::UI::Xaml::Data::PropertyChangedEventHandler);
         WINRT_PROPERTY(Editor::ActionsPageNavigationState, State, nullptr);
+        WINRT_PROPERTY(Windows::Foundation::Collections::IObservableVector<Editor::KeyBindingViewModel>, KeyBindingList);
 
     private:
-        friend struct ActionsT<Actions>; // for Xaml to bind events
-        Windows::Foundation::Collections::IObservableVector<winrt::Microsoft::Terminal::Settings::Model::Command> _filteredActions{ nullptr };
+        void _ViewModelPropertyChangedHandler(const Windows::Foundation::IInspectable& senderVM, const Windows::UI::Xaml::Data::PropertyChangedEventArgs& args);
+        void _ViewModelDeleteKeyBindingHandler(const Editor::KeyBindingViewModel& senderVM, const Control::KeyChord& args);
+        void _ViewModelRebindKeysHandler(const Editor::KeyBindingViewModel& senderVM, const Editor::RebindKeysEventArgs& args);
+
+        std::optional<uint32_t> _GetContainerIndexByKeyChord(const Control::KeyChord& keys);
 
-        void _OpenSettingsClick(const IInspectable& sender, const Windows::UI::Xaml::RoutedEventArgs& eventArgs);
+        bool _AutomationPeerAttached{ false };
     };
 }
 

src/cascadia/TerminalSettingsEditor/Actions.idl

@@ -5,19 +5,53 @@ import "EnumEntry.idl";
 
 namespace Microsoft.Terminal.Settings.Editor
 {
+    runtimeclass RebindKeysEventArgs
+    {
+        Microsoft.Terminal.Control.KeyChord OldKeys { get; };
+        Microsoft.Terminal.Control.KeyChord NewKeys { get; };
+    }
+
+    runtimeclass KeyBindingViewModel : Windows.UI.Xaml.Data.INotifyPropertyChanged
+    {
+        // Settings Model side
+        String Name { get; };
+        String KeyChordText { get; };
+
+        // UI side
+        Boolean ShowEditButton { get; };
+        Boolean IsInEditMode { get; };
+        String ProposedKeys;
+        Windows.UI.Xaml.Controls.Flyout AcceptChangesFlyout;
+        String EditButtonName { get; };
+        String CancelButtonName { get; };
+        String AcceptButtonName { get; };
+        String DeleteButtonName { get; };
+        Windows.UI.Xaml.Media.Brush ContainerBackground { get; };
+
+        void EnterHoverMode();
+        void ExitHoverMode();
+        void FocusContainer();
+        void UnfocusContainer();
+        void FocusEditButton();
+        void UnfocusEditButton();
+        void ToggleEditMode();
+        void AttemptAcceptChanges();
+        void DeleteKeyBinding();
+
+        event Windows.Foundation.TypedEventHandler<KeyBindingViewModel, RebindKeysEventArgs> RebindKeysRequested;
+        event Windows.Foundation.TypedEventHandler<KeyBindingViewModel, Microsoft.Terminal.Control.KeyChord> DeleteKeyBindingRequested;
+    }
+
     runtimeclass ActionsPageNavigationState
     {
         Microsoft.Terminal.Settings.Model.CascadiaSettings Settings;
-        void RequestOpenJson(Microsoft.Terminal.Settings.Model.SettingsTarget target);
-        event Windows.Foundation.TypedEventHandler<Object, Microsoft.Terminal.Settings.Model.SettingsTarget> OpenJson;
     };
 
     [default_interface] runtimeclass Actions : Windows.UI.Xaml.Controls.Page
     {
         Actions();
         ActionsPageNavigationState State { get; };
 
-        IObservableVector<Microsoft.Terminal.Settings.Model.Command> FilteredActions { get; };
-
+        IObservableVector<KeyBindingViewModel> KeyBindingList { get; };
     }
 }