using Avalonia;
using Avalonia.Controls;
using Avalonia.Data;
using Avalonia.Media;
using Avalonia.OpenGL;
using Avalonia.Platform;
using Avalonia.Rendering.SceneGraph;
using Avalonia.Skia;
using Avalonia.Threading;
using OpenTK.Graphics.OpenGL;
using Ryujinx.Common.Configuration;
using SkiaSharp;
using SPB.Graphics;
using SPB.Graphics.OpenGL;
using SPB.Platform;
using SPB.Windowing;
using System;

namespace Ryujinx.Ava.Ui.Controls
{
    public class RendererControl : Control
    {
        private int _image;

        static RendererControl()
        {
            AffectsRender<RendererControl>(ImageProperty);
        }

        public readonly static StyledProperty<int> ImageProperty =
            AvaloniaProperty.Register<RendererControl, int>(nameof(Image), 0, inherits: true, defaultBindingMode: BindingMode.TwoWay);

        protected int Image
        {
            get => _image;
            set => SetAndRaise(ImageProperty, ref _image, value);
        }

        public event EventHandler<EventArgs> GlInitialized;
        public event EventHandler<Size> SizeChanged;

        protected Size RenderSize { get; private set; }
        public bool IsStarted { get; private set; }

        public int Major { get; }
        public int Minor { get; }
        public GraphicsDebugLevel DebugLevel { get; }
        public OpenGLContextBase GameContext { get; set; }

        public static OpenGLContextBase PrimaryContext => AvaloniaLocator.Current.GetService<IPlatformOpenGlInterface>().PrimaryContext.AsOpenGLContextBase();

        private SwappableNativeWindowBase _gameBackgroundWindow;

        private bool _isInitialized;

        private IntPtr _fence;

        private GlDrawOperation _glDrawOperation;

        public RendererControl(int major, int minor, GraphicsDebugLevel graphicsDebugLevel)
        {
            Major = major;
            Minor = minor;
            DebugLevel = graphicsDebugLevel;
            IObservable<Rect> resizeObservable = this.GetObservable(BoundsProperty);

            resizeObservable.Subscribe(Resized);

            Focusable = true;
        }

        private void Resized(Rect rect)
        {
            SizeChanged?.Invoke(this, rect.Size);

            if (!rect.IsEmpty)
            {
                RenderSize = rect.Size * VisualRoot.RenderScaling;

                _glDrawOperation?.Dispose();
                _glDrawOperation = new GlDrawOperation(this);
            }
        }

        public override void Render(DrawingContext context)
        {
            if (!_isInitialized)
            {
                CreateWindow();

                OnGlInitialized();
                _isInitialized = true;
            }

            if (GameContext == null || !IsStarted || Image == 0)
            {
                return;
            }

            if (_glDrawOperation != null)
            {
                context.Custom(_glDrawOperation);
            }

            base.Render(context);
        }

        protected void OnGlInitialized()
        {
            GlInitialized?.Invoke(this, EventArgs.Empty);
        }

        public void QueueRender()
        {
            Program.RenderTimer.TickNow();
        }

        internal void Present(object image)
        {
            Dispatcher.UIThread.InvokeAsync(() =>
            {
                Image = (int)image;
            }).Wait();

            if (_fence != IntPtr.Zero)
            {
                GL.DeleteSync(_fence);
            }

            _fence = GL.FenceSync(SyncCondition.SyncGpuCommandsComplete, WaitSyncFlags.None);

            QueueRender();

            _gameBackgroundWindow.SwapBuffers();
        }

        internal void Start()
        {
            IsStarted = true;
            QueueRender();
        }

        internal void Stop()
        {
            IsStarted = false;
        }

        public void DestroyBackgroundContext()
        {
            _image = 0;

            if (_fence != IntPtr.Zero)
            {
                _glDrawOperation.Dispose();
                GL.DeleteSync(_fence);
            }

            GlDrawOperation.DeleteFramebuffer();

            GameContext?.Dispose();

            _gameBackgroundWindow?.Dispose();
        }

        internal void MakeCurrent()
        {
            GameContext.MakeCurrent(_gameBackgroundWindow);
        }

        internal void MakeCurrent(SwappableNativeWindowBase window)
        {
            GameContext.MakeCurrent(window);
        }

        protected void CreateWindow()
        {
            var flags = OpenGLContextFlags.Compat;
            if (DebugLevel != GraphicsDebugLevel.None)
            {
                flags |= OpenGLContextFlags.Debug;
            }
            _gameBackgroundWindow = PlatformHelper.CreateOpenGLWindow(FramebufferFormat.Default, 0, 0, 100, 100);
            _gameBackgroundWindow.Hide();

            GameContext = PlatformHelper.CreateOpenGLContext(FramebufferFormat.Default, Major, Minor, flags, shareContext: PrimaryContext);
            GameContext.Initialize(_gameBackgroundWindow);
        }

        private class GlDrawOperation : ICustomDrawOperation
        {
            private static int _framebuffer;

            public Rect Bounds { get; }

            private readonly RendererControl _control;

            public GlDrawOperation(RendererControl control)
            {
                _control = control;
                Bounds = _control.Bounds;
            }

            public void Dispose() { }

            public static void DeleteFramebuffer()
            {
                if (_framebuffer == 0)
                {
                    GL.DeleteFramebuffer(_framebuffer);
                }

                _framebuffer = 0;
            }

            public bool Equals(ICustomDrawOperation other)
            {
                return other is GlDrawOperation operation && Equals(this, operation) && operation.Bounds == Bounds;
            }

            public bool HitTest(Point p)
            {
                return Bounds.Contains(p);
            }

            private void CreateRenderTarget()
            {
                _framebuffer = GL.GenFramebuffer();
            }

            public void Render(IDrawingContextImpl context)
            {
                if (_control.Image == 0)
                {
                    return;
                }

                if (_framebuffer == 0)
                {
                    CreateRenderTarget();
                }

                int currentFramebuffer = GL.GetInteger(GetPName.FramebufferBinding);

                var image = _control.Image;
                var fence = _control._fence;

                GL.BindFramebuffer(FramebufferTarget.Framebuffer, _framebuffer);
                GL.FramebufferTexture2D(FramebufferTarget.Framebuffer, FramebufferAttachment.ColorAttachment0, TextureTarget.Texture2D, image, 0);
                GL.BindFramebuffer(FramebufferTarget.Framebuffer, currentFramebuffer);

                if (context is not ISkiaDrawingContextImpl skiaDrawingContextImpl)
                {
                    return;
                }

                var imageInfo = new SKImageInfo((int)_control.RenderSize.Width, (int)_control.RenderSize.Height, SKColorType.Rgba8888);
                var glInfo = new GRGlFramebufferInfo((uint)_framebuffer, SKColorType.Rgba8888.ToGlSizedFormat());

                GL.WaitSync(fence, WaitSyncFlags.None, ulong.MaxValue);

                using var backendTexture = new GRBackendRenderTarget(imageInfo.Width, imageInfo.Height, 1, 0, glInfo);
                using var surface = SKSurface.Create(skiaDrawingContextImpl.GrContext, backendTexture, GRSurfaceOrigin.BottomLeft, SKColorType.Rgba8888);

                if (surface == null)
                {
                    return;
                }

                var rect = new Rect(new Point(), _control.RenderSize);

                using var snapshot = surface.Snapshot();
                skiaDrawingContextImpl.SkCanvas.DrawImage(snapshot, rect.ToSKRect(), _control.Bounds.ToSKRect(), new SKPaint());
            }
        }
    }
}
