UI Framework

using Brine2D.UI;
using System.Numerics;

public class MenuScene : Scene
{
    private readonly UICanvas _canvas;

    public MenuScene(UICanvas canvas)
    {
        _canvas = canvas;
    }

    protected override Task OnLoadAsync(CancellationToken ct)
    {
        var playButton = new UIButton("Play", new Vector2(350, 250), new Vector2(100, 40));

        playButton.OnClick += () =>
        {
            Logger.LogInformation("Play button clicked!");
        };

        _canvas.Add(playButton);

        return Task.CompletedTask;
    }

    protected override void OnUpdate(GameTime gameTime)
    {
        _canvas.Update((float)gameTime.DeltaTime);
    }

    protected override void OnRender(GameTime gameTime)
    {
        _canvas.Render(Renderer);
    }
}

// Register as scoped (per-scene)
builder.Services.AddUICanvas();

// Inject in scene
public class MenuScene : Scene
{
    private readonly UICanvas _canvas;

    public MenuScene(UICanvas canvas)
    {
        _canvas = canvas;
    }
}

var button = new UIButton("Start Game", new Vector2(350, 250), new Vector2(100, 40))
{
    NormalColor = Color.Blue,
    TextColor = Color.White
};

button.OnClick += () =>
{
    Logger.LogInformation("Button clicked!");
};

_canvas.Add(button);

var nameInput = new UITextInput(new Vector2(300, 200), new Vector2(200, 30))
{
    Placeholder = "Enter your name..."
};

nameInput.OnTextChanged += text =>
{
    Logger.LogInformation("Name: {Name}", text);
};

_canvas.Add(nameInput);

var volumeSlider = new UISlider(new Vector2(300, 250), new Vector2(200, 20))
{
    MinValue = 0f,
    MaxValue = 1f,
    Value = 0.8f
};

volumeSlider.OnValueChanged += value =>
{
    _audio.SetMasterVolume(value);
    Logger.LogInformation("Volume: {Volume:P0}", value);
};

_canvas.Add(volumeSlider);

var dialog = new UIDialog("Quit Game?", "Are you sure you want to quit?", new Vector2(300, 150));

dialog.AddButton("Yes", () =>
{
    Application.Quit();
});

dialog.AddButton("No", () =>
{
    dialog.Visible = false;
});

_canvas.Add(dialog);

var healthLabel = new UILabel("Health:", new Vector2(10, 10))
{
    Color = Color.White
};

var healthBar = new UIProgressBar(new Vector2(80, 10), new Vector2(200, 20))
{
    MinValue = 0,
    MaxValue = 100,
    Value = 75,
    FillColor = Color.Green,
    BackgroundColor = new Color(50, 50, 50)
};

_canvas.Add(healthLabel);
_canvas.Add(healthBar);

// Update health each frame
healthBar.Value = _playerHealth;

// Automatic vertical layout
var menu = new UIStackPanel(new Vector2(350, 200))
{
    Orientation = StackOrientation.Vertical,
    Spacing = 10
};

menu.AddChild(new UIButton("Play",    new Vector2(0, 0), new Vector2(100, 40)));
menu.AddChild(new UIButton("Options", new Vector2(0, 0), new Vector2(100, 40)));
menu.AddChild(new UIButton("Quit",    new Vector2(0, 0), new Vector2(100, 40)));

_canvas.Add(menu);
// Buttons are automatically positioned vertically with 10 px spacing

protected override Task OnLoadAsync(CancellationToken ct)
{
    // Register canvas as a high-priority input layer (priority 1000)
    _inputLayerManager.RegisterLayer(_canvas);

    // Build UI...
    return Task.CompletedTask;
}

// ✅ Good pattern
protected override Task OnLoadAsync(CancellationToken ct)
{
    CreateMenuUI();
    return Task.CompletedTask;
}

protected override void OnUpdate(GameTime gameTime)
{
    _canvas.Update((float)gameTime.DeltaTime);
}

protected override void OnRender(GameTime gameTime)
{
    DrawGameObjects();
    _canvas.Render(Renderer); // UI renders on top
}

// ❌ Bad: hardcoded for 1280×720
var button = new UIButton("Play", new Vector2(640, 360), new Vector2(100, 40));

// ✅ Good: anchored to center
var button = new UIButton("Play", Vector2.Zero, new Vector2(100, 40))
{
    Anchor = UIAnchor.MiddleCenter,
    AnchorOffset = new Vector2(-50, -20)
};

var button = new UIButton("Custom", new Vector2(10, 10), new Vector2(120, 40))
{
    NormalColor  = new Color(50, 50, 50, 255),
    HoverColor   = new Color(70, 70, 70, 255),
    PressedColor = new Color(30, 30, 30, 255),
    TextColor    = Color.White
};

var label = new UILabel("Custom Font", new Vector2(100, 100))
{
    Font  = await _assets.GetOrLoadFontAsync("assets/fonts/custom.ttf", 24),
    Color = Color.Gold
};

var label = new UILabel("Score: 0", Vector2.Zero)
{
    Anchor       = UIAnchor.TopRight,
    AnchorOffset = new Vector2(-120, 10)   // 120 px from right edge, 10 px from top
};

_canvas.Add(label);
// UICanvas resolves the anchor position automatically during Render

protected override void OnUpdate(GameTime gameTime)
{
    _canvas.Update((float)gameTime.DeltaTime);  // Must be called!
}

_canvas.Add(button);  // Don't forget!

_inputLayerManager.RegisterLayer(_canvas);

_canvas.Add(background);  // Lower (rendered first)
_canvas.Add(button);      // Higher (receives input first)

protected override void OnRender(GameTime gameTime)
{
    _canvas.Render(Renderer);  // Must be called!
}

Logger.LogDebug("Button at {Pos}", button.Position);

button.Visible = true;  // Defaults to true

if (button.Font == null)
    Logger.LogWarning("Button has no font: using renderer default");

button.TextColor = Color.White;  // Not transparent!