feat(tui): add SquidStd.Tui — MVVM layer over Terminal.Gui v2

SquidStd.slnx

@@ -41,6 +41,7 @@
         <Project Path="src/SquidStd.Vfs.Abstractions/SquidStd.Vfs.Abstractions.csproj" />
         <Project Path="src/SquidStd.Vfs/SquidStd.Vfs.csproj" />
         <Project Path="src/SquidStd.Secrets.Aws/SquidStd.Secrets.Aws.csproj" />
+        <Project Path="src/SquidStd.Tui/SquidStd.Tui.csproj" />
     </Folder>
     <Folder Name="/samples/">
         <Project Path="samples/SquidStd.Samples.WorkerSystem/SquidStd.Samples.WorkerSystem.csproj" />
@@ -63,6 +64,7 @@
         <Project Path="samples/SquidStd.Samples.Vfs/SquidStd.Samples.Vfs.csproj" />
         <Project Path="samples/SquidStd.Samples.Secrets/SquidStd.Samples.Secrets.csproj" />
         <Project Path="samples/SquidStd.Samples.Actors/SquidStd.Samples.Actors.csproj" />
+        <Project Path="samples/SquidStd.Samples.Tui/SquidStd.Samples.Tui.csproj" />
     </Folder>
     <Folder Name="/tests/">
         <Project Path="tests/SquidStd.Tests/SquidStd.Tests.csproj" />

samples/SquidStd.Samples.Tui/CounterView.cs

@@ -0,0 +1,25 @@
+using SquidStd.Tui;
+using SquidStd.Tui.Binding;
+using Terminal.Gui.Views;
+
+namespace SquidStd.Samples.Tui;
+
+public sealed class CounterView : TuiView<CounterViewModel>
+{
+    private Label _value = null!;
+    private Button _increment = null!;
+
+    protected override void BuildLayout()
+    {
+        _value = new Label { X = 1, Y = 1 };
+        _increment = new Button { X = 1, Y = 3, Text = "_Increment" };
+        Add(_value, _increment);
+    }
+
+    protected override void Bind(ViewBinder binder)
+    {
+        binder.OneWayTitle(ViewModel, x => x.Title, this);
+        binder.OneWayText(ViewModel, x => x.Value, _value);
+        binder.Command(_increment, ViewModel.IncrementCommand);
+    }
+}

samples/SquidStd.Samples.Tui/CounterViewModel.cs

@@ -0,0 +1,20 @@
+using CommunityToolkit.Mvvm.ComponentModel;
+using CommunityToolkit.Mvvm.Input;
+using SquidStd.Tui;
+
+namespace SquidStd.Samples.Tui;
+
+public sealed partial class CounterViewModel : TuiViewModel
+{
+    [ObservableProperty]
+    private string _title = "SquidStd.Tui — Counter";
+
+    [ObservableProperty]
+    private string _value = "0";
+
+    [RelayCommand]
+    private void Increment()
+    {
+        Value = (int.Parse(Value) + 1).ToString();
+    }
+}

samples/SquidStd.Samples.Tui/Program.cs

@@ -0,0 +1,10 @@
+using DryIoc;
+using SquidStd.Samples.Tui;
+using SquidStd.Tui.Extensions;
+using SquidStd.Tui.Hosting;
+
+var container = new Container();
+container.RegisterTui();
+container.RegisterView<CounterView, CounterViewModel>();
+
+await container.Resolve<TuiApplicationHost>().RunAsync<CounterViewModel>();

samples/SquidStd.Samples.Tui/SquidStd.Samples.Tui.csproj

@@ -0,0 +1,14 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+    <PropertyGroup>
+        <OutputType>Exe</OutputType>
+        <TargetFramework>net10.0</TargetFramework>
+        <ImplicitUsings>enable</ImplicitUsings>
+        <Nullable>enable</Nullable>
+    </PropertyGroup>
+
+    <ItemGroup>
+        <ProjectReference Include="..\..\src\SquidStd.Tui\SquidStd.Tui.csproj"/>
+    </ItemGroup>
+
+</Project>

src/SquidStd.Tui/Binding/ViewBinder.AutoBind.cs

@@ -0,0 +1,81 @@
+using System.ComponentModel;
+using System.Reflection;
+using System.Windows.Input;
+using SquidStd.Tui.Internal;
+using Terminal.Gui.ViewBase;
+using Terminal.Gui.Views;
+
+namespace SquidStd.Tui.Binding;
+
+public sealed partial class ViewBinder
+{
+    /// <summary>
+    /// Convention binding: for each named subview, binds it to a matching ViewModel member by name
+    /// (e.g. <c>NameField</c> ↔ <c>Name</c>, <c>SaveButton</c> ↔ <c>SaveCommand</c>). Explicit bindings
+    /// declared before AutoBind win; AutoBind only fills the gaps it recognises (Label, TextField, Button).
+    /// </summary>
+    public void AutoBind(View view, INotifyPropertyChanged viewModel)
+    {
+        var vmType = viewModel.GetType();
+
+        foreach (var subview in view.SubViews)
+        {
+            var id = subview.Id;
+
+            if (string.IsNullOrEmpty(id))
+            {
+                continue;
+            }
+
+            switch (subview)
+            {
+                case Button button:
+                    BindCommandByName(vmType, viewModel, ConventionNames.CommandName(id), button);
+                    break;
+                case TextField field:
+                    BindStringByName(vmType, viewModel, ConventionNames.MemberName(id), field, twoWay: true, null);
+                    break;
+                case Label label:
+                    BindStringByName(vmType, viewModel, ConventionNames.MemberName(id), null, twoWay: false, label);
+                    break;
+            }
+        }
+    }
+
+    private void BindCommandByName(Type vmType, INotifyPropertyChanged vm, string memberName, Button button)
+    {
+        var property = vmType.GetProperty(memberName, BindingFlags.Public | BindingFlags.Instance);
+
+        if (property is not null && property.GetValue(vm) is ICommand command)
+        {
+            Command(button, command);
+        }
+    }
+
+    private void BindStringByName(
+        Type vmType, INotifyPropertyChanged vm, string memberName, TextField? field, bool twoWay, Label? label
+    )
+    {
+        var property = vmType.GetProperty(memberName, BindingFlags.Public | BindingFlags.Instance);
+
+        if (property is null || property.PropertyType != typeof(string))
+        {
+            return;
+        }
+
+        if (twoWay && field is not null)
+        {
+            TwoWay(
+                vm,
+                memberName,
+                () => field.Text = (string)(property.GetValue(vm) ?? string.Empty),
+                callback => field.ValueChanged += (_, _) => callback(),
+                () => property.SetValue(vm, field.Text)
+            );
+        }
+        else if (label is not null)
+        {
+            OneWay(vm, memberName, () => label.Text = (string)(property.GetValue(vm) ?? string.Empty));
+        }
+    }
+}

src/SquidStd.Tui/Binding/ViewBinder.Expressions.cs

@@ -0,0 +1,49 @@
+using System.ComponentModel;
+using System.Linq.Expressions;
+using SquidStd.Tui.Internal;
+
+namespace SquidStd.Tui.Binding;
+
+public sealed partial class ViewBinder
+{
+    /// <summary>One-way bind a source property to a target member, by expression.</summary>
+    public void OneWay<TSource, TTarget, TValue>(
+        TSource source,
+        Expression<Func<TSource, TValue>> sourceProperty,
+        TTarget target,
+        Expression<Func<TTarget, TValue>> targetProperty
+    )
+        where TSource : INotifyPropertyChanged
+    {
+        var name = PropertyPath.NameOf(sourceProperty);
+        var read = sourceProperty.Compile();
+        var write = PropertyPath.Setter(targetProperty);
+
+        OneWay(source, name, () => write(target, read(source)));
+    }
+
+    /// <summary>Two-way bind a source property to a target member, by expression, given the target's change event.</summary>
+    public void TwoWay<TSource, TTarget, TValue>(
+        TSource source,
+        Expression<Func<TSource, TValue>> sourceProperty,
+        TTarget target,
+        Expression<Func<TTarget, TValue>> targetProperty,
+        Action<Action> subscribeTargetChanged
+    )
+        where TSource : INotifyPropertyChanged
+    {
+        var name = PropertyPath.NameOf(sourceProperty);
+        var read = sourceProperty.Compile();
+        var readTarget = targetProperty.Compile();
+        var write = PropertyPath.Setter(targetProperty);
+        var writeSource = PropertyPath.Setter(sourceProperty);
+
+        TwoWay(
+            source,
+            name,
+            () => write(target, read(source)),
+            subscribeTargetChanged,
+            () => writeSource(source, readTarget(target))
+        );
+    }
+}

src/SquidStd.Tui/Binding/ViewBinder.Widgets.cs

@@ -0,0 +1,42 @@
+using System.ComponentModel;
+using System.Linq.Expressions;
+using System.Windows.Input;
+using Terminal.Gui.Views;
+
+namespace SquidStd.Tui.Binding;
+
+/// <summary>Convenience overloads that wire the core binder to concrete Terminal.Gui widgets.</summary>
+public sealed partial class ViewBinder
+{
+    /// <summary>One-way bind a source string property to a <see cref="Label" />'s text.</summary>
+    public void OneWayText<TSource>(TSource source, Expression<Func<TSource, string>> property, Label label)
+        where TSource : INotifyPropertyChanged
+    {
+        OneWay(source, property, label, l => l.Text);
+    }
+
+    /// <summary>One-way bind a source string property to a <see cref="Window" />'s title.</summary>
+    public void OneWayTitle<TSource>(TSource source, Expression<Func<TSource, string>> property, Window window)
+        where TSource : INotifyPropertyChanged
+    {
+        OneWay(source, property, window, w => w.Title);
+    }
+
+    /// <summary>Two-way bind a source string property to a <see cref="TextField" />.</summary>
+    public void TwoWay<TSource>(TSource source, Expression<Func<TSource, string>> property, TextField field)
+        where TSource : INotifyPropertyChanged
+    {
+        // Terminal.Gui 2.4.16 exposes ValueChanged (EventHandler<ValueChangedEventArgs<string?>>)
+        // rather than a TextChanged event.
+        TwoWay(source, property, field, f => f.Text, callback => field.ValueChanged += (_, _) => callback());
+    }
+
+    /// <summary>Bind a command to a <see cref="Button" />: Accepted triggers it, CanExecute drives Enabled.</summary>
+    public void Command(Button button, ICommand command)
+    {
+        // Use Accepted (post-accept, non-cancellable) rather than Accepting for this side-effect-only
+        // handler; Terminal.Gui 2.4.16 docs mark subscribing side effects to the cancellable Accepting
+        // phase as incorrect.
+        Command(command, enabled => button.Enabled = enabled, callback => button.Accepted += (_, _) => callback());
+    }
+}

src/SquidStd.Tui/Binding/ViewBinder.cs

@@ -0,0 +1,133 @@
+using System.ComponentModel;
+using System.Windows.Input;
+using SquidStd.Tui.Internal;
+
+namespace SquidStd.Tui.Binding;
+
+/// <summary>
+/// Wires ViewModel (<see cref="INotifyPropertyChanged" />) properties and commands to view targets, and
+/// owns the lifetime of every subscription it creates. Dispose to release them all.
+/// </summary>
+public sealed partial class ViewBinder : IDisposable
+{
+    private readonly List<IDisposable> _subscriptions = new();
+    private readonly Action<Action> _marshal;
+
+    /// <summary>Initialises the binder with an optional marshal action for UI-thread dispatch.</summary>
+    /// <param name="marshal">
+    /// Runs an update on the UI thread. Defaults to running inline; the host passes a delegate over
+    /// <c>Application.Invoke</c> so updates raised from background threads reach the Terminal.Gui loop.
+    /// </param>
+    public ViewBinder(Action<Action>? marshal = null)
+    {
+        _marshal = marshal ?? (action => action());
+    }
+
+    /// <summary>Applies <paramref name="apply" /> now and whenever <paramref name="propertyName" /> changes.</summary>
+    public void OneWay(INotifyPropertyChanged source, string propertyName, Action apply)
+    {
+        apply();
+
+        void Handler(object? sender, PropertyChangedEventArgs e)
+        {
+            if (e.PropertyName is null || string.Equals(e.PropertyName, propertyName, StringComparison.Ordinal))
+            {
+                _marshal(apply);
+            }
+        }
+
+        source.PropertyChanged += Handler;
+        _subscriptions.Add(new Unsubscriber(() => source.PropertyChanged -= Handler));
+    }
+
+    /// <summary>
+    /// Binds a source property both ways. <paramref name="applyToTarget" /> runs on source changes;
+    /// <paramref name="writeToSource" /> runs when the target raises a change. A reentrancy guard stops
+    /// the source→target→source feedback loop.
+    /// </summary>
+    public void TwoWay(
+        INotifyPropertyChanged source,
+        string propertyName,
+        Action applyToTarget,
+        Action<Action> subscribeTargetChanged,
+        Action writeToSource
+    )
+    {
+        var guard = new ReentryGuard();
+
+        applyToTarget();
+
+        void SourceHandler(object? sender, PropertyChangedEventArgs e)
+        {
+            if (e.PropertyName is not null && !string.Equals(e.PropertyName, propertyName, StringComparison.Ordinal))
+            {
+                return;
+            }
+
+            if (guard.IsBusy)
+            {
+                return;
+            }
+
+            _marshal(() =>
+            {
+                using (guard.Enter())
+                {
+                    applyToTarget();
+                }
+            });
+        }
+
+        source.PropertyChanged += SourceHandler;
+        _subscriptions.Add(new Unsubscriber(() => source.PropertyChanged -= SourceHandler));
+
+        subscribeTargetChanged(() =>
+        {
+            if (guard.IsBusy)
+            {
+                return;
+            }
+
+            using (guard.Enter())
+            {
+                writeToSource();
+            }
+        });
+    }
+
+    /// <summary>
+    /// Binds a command to a control: <paramref name="subscribeTrigger" /> activates the command (when it
+    /// can execute), and <paramref name="setEnabled" /> tracks <see cref="ICommand.CanExecute" />.
+    /// </summary>
+    public void Command(ICommand command, Action<bool> setEnabled, Action<Action> subscribeTrigger)
+    {
+        setEnabled(command.CanExecute(null));
+
+        void CanHandler(object? sender, EventArgs e)
+        {
+            _marshal(() => setEnabled(command.CanExecute(null)));
+        }
+
+        command.CanExecuteChanged += CanHandler;
+        _subscriptions.Add(new Unsubscriber(() => command.CanExecuteChanged -= CanHandler));
+
+        subscribeTrigger(() =>
+        {
+            if (command.CanExecute(null))
+            {
+                command.Execute(null);
+            }
+        });
+    }
+
+    /// <summary>Disposes all active subscriptions created by this binder.</summary>
+    public void Dispose()
+    {
+        for (var i = 0; i < _subscriptions.Count; i++)
+        {
+            _subscriptions[i].Dispose();
+        }
+
+        _subscriptions.Clear();
+    }
+}