using System.Collections.Generic;
using FidelityFX;
using FidelityFX.FSR2;
using UnityEngine.Experimental.Rendering;

namespace UnityEngine.Rendering.HighDefinition.AMD.FSR2
{
    /// <summary>
    /// Custom upscaler plugin that uses the open source port of FSR2 to Unity.
    /// This eschews using native plugins, instead using portable code that will work on any platform that supports compute shaders.
    /// </summary>
    public class FSR2UpscalerPlugin: UpscalerPlugin
    {
        private Fsr2Assets _assets;

        public override string name => "FSR 2.2";

        public override bool isSupported => SystemInfo.supportsComputeShaders;

        public override bool includesSharpening => true;

        public override bool supportsAlpha => true;

        public override bool Load()
        {
            if (_assets != null)
                return true;

            _assets = Resources.Load<Fsr2Assets>("FSR2 Assets");
            return _assets != null;
        }

        public override bool IsLoaded() => _assets != null;

        public override UpscalerContext CreateContext(in FSR2CommandInitializationData initSettings)
        {
            var context = new FSR2UpscalerContext(in initSettings);
            context.Init(_assets);
            return context;
        }

        public override void DestroyContext(UpscalerContext context)
        {
            ((FSR2UpscalerContext)context).Destroy();
        }

        public override bool GetRenderResolutionFromQualityMode(FSR2Quality qualityMode, uint displayWidth, uint displayHeight, out uint renderWidth, out uint renderHeight)
        {
            Fsr2.GetRenderResolutionFromQualityMode(out int rw, out int rh, (int)displayWidth, (int)displayHeight, (Fsr2.QualityMode)((int)qualityMode + 2));
            renderWidth = (uint)rw;
            renderHeight = (uint)rh;
            return true;
        }

        public override float GetUpscaleRatioFromQualityMode(FSR2Quality qualityMode)
        {
            return Fsr2.GetUpscaleRatioFromQualityMode((Fsr2.QualityMode)((int)qualityMode + 2));
        }
    }

    public class FSR2UpscalerContext : UpscalerContext
    {
        private readonly Fsr2Context _context = new();
        private readonly Fsr2.DispatchDescription _dispatchDescription = new();
        private readonly FSR2CommandInitializationData _initData;

        private Texture2DArray _clearTextureArray;

        internal FSR2UpscalerContext(in FSR2CommandInitializationData initSettings)
        {
            _initData = initSettings;
        }

        internal void Init(Fsr2Assets assets)
        {
            Fsr2.InitializationFlags flags = 0;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableHighDynamicRange)) flags |= Fsr2.InitializationFlags.EnableHighDynamicRange;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDisplayResolutionMotionVectors)) flags |= Fsr2.InitializationFlags.EnableDisplayResolutionMotionVectors;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableMotionVectorsJitterCancellation)) flags |= Fsr2.InitializationFlags.EnableMotionVectorsJitterCancellation;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.DepthInverted)) flags |= Fsr2.InitializationFlags.EnableDepthInverted;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDepthInfinite)) flags |= Fsr2.InitializationFlags.EnableDepthInfinite;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableAutoExposure)) flags |= Fsr2.InitializationFlags.EnableAutoExposure;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDynamicResolution)) flags |= Fsr2.InitializationFlags.EnableDynamicResolution;

            //Debug.Log($"Initializing FSR2 with max render size: {_initData.maxRenderSizeWidth}x{_initData.maxRenderSizeHeight}, display size: {_initData.displaySizeWidth}x{_initData.displaySizeHeight}, flags: {flags}");

            _context.Create(new Fsr2.ContextDescription
            {
                DisplaySize = new Vector2Int((int)_initData.displaySizeWidth, (int)_initData.displaySizeHeight),
                MaxRenderSize = new Vector2Int((int)_initData.maxRenderSizeWidth, (int)_initData.maxRenderSizeHeight),
                Flags = flags,
                Shaders = assets.shaders,
            });

            _clearTextureArray = new Texture2DArray(1, 1, TextureXR.slices, GraphicsFormat.R32G32_SFloat, TextureCreationFlags.None);
            for (int i = 0; i < TextureXR.slices; ++i) _clearTextureArray.SetPixels(new[] { Color.clear, }, i);
            _clearTextureArray.Apply();
        }

        internal void Destroy()
        {
            CoreUtils.Destroy(_clearTextureArray);

            _context.Destroy();
        }

        public override void Execute(CommandBuffer cmd, in FSR2CommandExecutionData executeData, in FSR2TextureTable textures)
        {
            bool useTextureArrays = TextureXR.useTexArray && textures.colorInput.dimension == TextureDimension.Tex2DArray;
            ResourceView clearTexture = useTextureArrays ? new ResourceView(_clearTextureArray) : new ResourceView();

            _dispatchDescription.Color = new ResourceView(textures.colorInput);
            _dispatchDescription.Depth = new ResourceView(textures.depth);
            _dispatchDescription.MotionVectors = new ResourceView(textures.motionVectors);
            _dispatchDescription.Exposure = textures.exposureTexture != null ? new ResourceView(textures.exposureTexture) : new ResourceView();
            _dispatchDescription.Reactive = textures.biasColorMask != null ? new ResourceView(textures.biasColorMask) : clearTexture;
            _dispatchDescription.TransparencyAndComposition = textures.transparencyMask != null ? new ResourceView(textures.transparencyMask) : clearTexture;
            _dispatchDescription.Output = new ResourceView(textures.colorOutput);

            _dispatchDescription.JitterOffset = new Vector2(executeData.jitterOffsetX, executeData.jitterOffsetY);
            _dispatchDescription.MotionVectorScale = new Vector2(executeData.MVScaleX, executeData.MVScaleY);
            _dispatchDescription.RenderSize = new Vector2Int((int)executeData.renderSizeWidth, (int)executeData.renderSizeHeight);
            _dispatchDescription.InputResourceSize = new Vector2Int(textures.colorInput.width, textures.colorInput.height);
            _dispatchDescription.EnableSharpening = executeData.enableSharpening != 0;
            _dispatchDescription.Sharpness = executeData.sharpness;
            _dispatchDescription.FrameTimeDelta = executeData.frameTimeDelta / 1000f;
            _dispatchDescription.PreExposure = executeData.preExposure;
            _dispatchDescription.Reset = executeData.reset != 0;
            _dispatchDescription.CameraNear = executeData.cameraNear;
            _dispatchDescription.CameraFar = executeData.cameraFar;
            _dispatchDescription.CameraFovAngleVertical = executeData.cameraFovAngleVertical;
            _dispatchDescription.ViewSpaceToMetersFactor = 1.0f; // 1 unit is 1 meter in Unity
            _dispatchDescription.UseTextureArrays = useTextureArrays;

            _context.Dispatch(_dispatchDescription, cmd);
        }
    }
}