acdream/src/AcDream.App/Rendering/FramebufferResizeController.cs

using AcDream.App.Input;
using Silk.NET.Maths;
using Silk.NET.OpenGL;

namespace AcDream.App.Rendering;

internal interface IFramebufferViewportTarget
{
    void ResizeViewport(int width, int height);
}

internal sealed class SilkFramebufferViewportTarget(GL gl)
    : IFramebufferViewportTarget
{
    private readonly GL _gl = gl ?? throw new ArgumentNullException(nameof(gl));

    public void ResizeViewport(int width, int height) =>
        _gl.Viewport(0, 0, (uint)width, (uint)height);
}

internal interface IFramebufferCameraTarget
{
    void SetAspect(float aspect);
}

internal sealed class CameraFramebufferTarget(CameraController camera)
    : IFramebufferCameraTarget
{
    private readonly CameraController _camera = camera
        ?? throw new ArgumentNullException(nameof(camera));

    public void SetAspect(float aspect) => _camera.SetAspect(aspect);
}

internal interface IFramebufferDevToolsTarget
{
    void ResetLayout(int width, int height);
}

internal sealed class DevToolsFramebufferTarget(DevToolsFramePresenter presenter)
    : IFramebufferDevToolsTarget
{
    private readonly DevToolsFramePresenter _presenter = presenter
        ?? throw new ArgumentNullException(nameof(presenter));

    public void ResetLayout(int width, int height) =>
        _presenter.ResetLayout(
            width,
            height,
            DevToolsPanelLayoutCondition.Always);
}

/// <summary>
/// The one framebuffer-size target. Logical gameplay/UI dimensions continue
/// to come from Window.Size; this owner only applies physical framebuffer
/// viewport/aspect changes in the frozen acdream host order.
/// </summary>
internal sealed class FramebufferResizeController
{
    private readonly ViewportAspectState _viewportAspect;
    private IFramebufferViewportTarget? _viewport;
    private IFramebufferCameraTarget? _camera;
    private IFramebufferDevToolsTarget? _devTools;

    public FramebufferResizeController(ViewportAspectState viewportAspect) =>
        _viewportAspect = viewportAspect
            ?? throw new ArgumentNullException(nameof(viewportAspect));

    public void BindViewport(IFramebufferViewportTarget viewport)
    {
        ArgumentNullException.ThrowIfNull(viewport);
        BindOnce(ref _viewport, viewport, "viewport");
    }

    public void BindCamera(IFramebufferCameraTarget camera)
    {
        ArgumentNullException.ThrowIfNull(camera);
        BindOnce(ref _camera, camera, "camera");
    }

    public void BindDevTools(IFramebufferDevToolsTarget devTools)
    {
        ArgumentNullException.ThrowIfNull(devTools);
        BindOnce(ref _devTools, devTools, "developer tools");
    }

    public void UnbindDevTools(IFramebufferDevToolsTarget devTools)
    {
        ArgumentNullException.ThrowIfNull(devTools);
        if (ReferenceEquals(_devTools, devTools))
            _devTools = null;
    }

    public void Resize(Vector2D<int> newSize) => Resize(newSize.X, newSize.Y);

    public void Resize(int width, int height)
    {
        if (width <= 0 || height <= 0)
            return;

        // Frozen order: GL viewport, shared aspect publication, camera, then
        // optional ImGui layout reset. Late binding never replays an earlier
        // resize transition.
        _viewport?.ResizeViewport(width, height);
        _viewportAspect.Update(width, height);
        _camera?.SetAspect(width / (float)height);
        _devTools?.ResetLayout(width, height);
    }

    private static void BindOnce<T>(ref T? slot, T value, string name)
        where T : class
    {
        if (slot is not null && !ReferenceEquals(slot, value))
            throw new InvalidOperationException(
                $"The framebuffer {name} target is already bound.");
        slot = value;
    }
}