Termina 0.1.0-beta1

Termina

Termina is a reactive terminal UI (TUI) framework for .NET built on top of Spectre.Console. It provides an MVVM architecture with source-generated reactive properties, ASP.NET Core-style routing, and seamless integration with Microsoft.Extensions.Hosting.

Features

• Reactive MVVM Architecture - ViewModels with [Reactive] attribute for source-generated observable properties
• ASP.NET Core-Style Routing - Route templates with parameters (/tasks/{id:int}) and type constraints
• Source Generators - AOT-compatible code generation for reactive properties and route parameter injection
• Dependency Injection - Full integration with Microsoft.Extensions.DependencyInjection
• Hosting Integration - Works with Microsoft.Extensions.Hosting for clean application lifecycle management
• Spectre.Console Rendering - Beautiful terminal UIs with full Spectre.Console component support

Installation

dotnet add package Termina

Quick Start

1. Define a ViewModel

using Termina.Reactive;

public partial class CounterViewModel : ReactiveViewModel
{
    [Reactive] private int _count;
    [Reactive] private string _message = "Press Up/Down to change count";

    public override void OnActivated()
    {
        Input.OfType<KeyPressed>()
            .Subscribe(HandleKey)
            .DisposeWith(Subscriptions);
    }

    private void HandleKey(KeyPressed key)
    {
        switch (key.KeyInfo.Key)
        {
            case ConsoleKey.UpArrow:
                Count++;
                Message = $"Count: {Count}";
                break;
            case ConsoleKey.DownArrow:
                Count--;
                Message = $"Count: {Count}";
                break;
            case ConsoleKey.Q:
                Shutdown();
                break;
        }
    }
}

The [Reactive] attribute generates:

• A BehaviorSubject<T> backing field
• A public property Count with get/set
• An IObservable<T> property CountChanged for subscriptions

2. Define a Page

using Spectre.Console;
using Spectre.Console.Rendering;
using Termina.Pages;

public class CounterPage : ReactivePage<CounterViewModel>
{
    protected override IRenderable Render(CounterViewModel vm)
    {
        return new Panel(
            new Rows(
                new FigletText(vm.Count.ToString()).Color(Color.Cyan1),
                new Text(vm.Message)
            ))
            .Header("Counter Demo")
            .Border(BoxBorder.Rounded);
    }
}

3. Configure and Run

using Microsoft.Extensions.Hosting;
using Termina.Hosting;

var builder = Host.CreateApplicationBuilder(args);

builder.Services.AddTermina("/counter", termina =>
{
    termina.RegisterRoute<CounterPage, CounterViewModel>("/counter");
    termina.RegisterRoute<TodoListPage, TodoListViewModel>("/todos");
    termina.RegisterRoute<TodoDetailPage, TodoDetailViewModel>("/todos/{id:int}");
});

await builder.Build().RunAsync();

Routing

Termina uses ASP.NET Core-style route templates with parameter support.

Route Templates

// Simple routes
termina.RegisterRoute<HomePage, HomeViewModel>("/");
termina.RegisterRoute<TasksPage, TasksViewModel>("/tasks");

// Routes with parameters
termina.RegisterRoute<TaskDetailPage, TaskDetailViewModel>("/tasks/{id:int}");
termina.RegisterRoute<UserPage, UserViewModel>("/users/{name}");
termina.RegisterRoute<DocumentPage, DocumentViewModel>("/docs/{id:guid}");

Supported Type Constraints

Route Parameter Injection

Use [FromRoute] to automatically inject route parameters into your ViewModel:

public partial class TaskDetailViewModel : ReactiveViewModel
{
    [FromRoute] private int _id;  // Injected from route before OnActivated

    public override void OnActivated()
    {
        // Id property is already populated
        LoadTask(Id);
    }
}

Navigation

// Navigate by path
Navigate("/tasks/42");

// Navigate with route values (type-safe)
NavigateWithParams("/tasks/{id}", new { id = 42 });

// Go back
// (handled by framework when CanGoBack is true)

Reactive Properties

The [Reactive] attribute on private fields generates observable properties:

public partial class MyViewModel : ReactiveViewModel
{
    [Reactive] private string _name = "default";
    [Reactive] private int _count;
    [Reactive] private IReadOnlyList<Item> _items = Array.Empty<Item>();
}

Generated code provides:

• Name, Count, Items - public properties with get/set
• NameChanged, CountChanged, ItemsChanged - IObservable<T> for subscriptions

Pages automatically re-render when any reactive property changes.

Page Lifecycle

public partial class MyViewModel : ReactiveViewModel
{
    public override void OnActivated()
    {
        // Called when navigating TO this page
        // Set up subscriptions here
    }

    public override void OnDeactivating()
    {
        // Called when navigating AWAY from this page
        // Clean up if needed (Subscriptions auto-dispose)
    }
}

Navigation Behavior

Control how pages behave when navigated to:

// Reset state each time (default)
termina.RegisterRoute<MyPage, MyViewModel>("/page", NavigationBehavior.ResetOnNavigation);

// Preserve state across navigations
termina.RegisterRoute<MyPage, MyViewModel>("/page", NavigationBehavior.PreserveState);

Testing

Termina includes VirtualInputSource for automated testing:

var scriptedInput = new VirtualInputSource();
builder.Services.AddTerminaVirtualInput(scriptedInput);

// Queue up scripted input
scriptedInput.EnqueueKey(ConsoleKey.UpArrow);
scriptedInput.EnqueueKey(ConsoleKey.Enter);
scriptedInput.EnqueueKey(ConsoleKey.Q);
scriptedInput.Complete();

await host.RunAsync();

Requirements

• .NET 10.0 or later
• AOT-compatible (Native AOT publishing supported)

License

Apache 2.0 - See LICENSE for details.

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.