using System;
using System.Collections.Generic;
using FidelityFX;
using FidelityFX.FSR3;
using UnityEngine.Experimental.Rendering;
#if UNITY_STANDALONE_WIN
using AMDUP = UnityEngine.AMD;
#endif

namespace UnityEngine.Rendering.HighDefinition.AMD.FSR3
{
    /// <summary>
    /// Custom upscaler plugin that uses the open source port of FSR3 to Unity.
    /// This eschews using native plugins, instead using portable code that will work on any platform that supports compute shaders.
    /// </summary>
    public class FSR3UpscalerPlugin: UpscalerPlugin
    {
        public static bool EnableDebugView { get; set; } = false;

        private Fsr3UpscalerAssets _assets;
        private bool _nativePluginLoaded;

        public override string name => "FSR 3.1";

        public override bool isSupported => SystemInfo.supportsComputeShaders;

        public override bool includesSharpening => true;

        public override bool supportsAlpha => !_nativePluginLoaded; // Managed Unity port has alpha upscaling built-in, the native AMD implementation doesn't

        public override bool Load()
        {
            // Guess we're using native plugins after all!
            // On Windows with supported graphics APIs, we use a drop-in replacement for Unity's plugin that implements FSR 3.1 through AMD's upgradable FidelityFX API.
            // This allows AMD's GPU driver to hijack the plugin and transparently upgrade our implementation to FSR4 on supported graphics cards!
            _nativePluginLoaded = false;
#if UNITY_STANDALONE_WIN
            if (!Application.isEditor && SystemInfo.operatingSystemFamily == OperatingSystemFamily.Windows && SystemInfo.graphicsDeviceType is GraphicsDeviceType.Direct3D12 or GraphicsDeviceType.Vulkan)
            {
                try
                {
                    if (AMDUP.AMDUnityPlugin.IsLoaded() || AMDUP.AMDUnityPlugin.Load())
                    {
                        _nativePluginLoaded = AMDUP.GraphicsDevice.device != null || AMDUP.GraphicsDevice.CreateGraphicsDevice() != null;
                        if (_nativePluginLoaded)
                            return true;
                    }
                }
                catch (DllNotFoundException)
                {
                    _nativePluginLoaded = false;
                }
            }
#endif

            if (_assets != null)
                return true;

            _assets = Resources.Load<Fsr3UpscalerAssets>("FSR3 Upscaler Assets");
            return _assets != null;
        }

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

        public override UpscalerContext CreateContext(in FSR2CommandInitializationData initSettings)
        {
#if UNITY_STANDALONE_WIN
            if (_nativePluginLoaded)
            {
                var context = new FSR3NativeUpscalerContext(in initSettings);
                context.Init();
                return context;
            }
            else
#endif
            {
                var context = new FSR3UpscalerContext(in initSettings);
                context.Init(_assets);
                return context;
            }
        }

        public override void DestroyContext(UpscalerContext context)
        {
            switch (context)
            {
#if UNITY_STANDALONE_WIN
                case FSR3NativeUpscalerContext nativeContext:
                    nativeContext.Destroy();
                    break;
#endif
                case FSR3UpscalerContext managedContext:
                    managedContext.Destroy();
                    break;
            }
        }

        public override bool GetRenderResolutionFromQualityMode(FSR2Quality qualityMode, uint displayWidth, uint displayHeight, out uint renderWidth, out uint renderHeight)
        {
            Fsr3Upscaler.GetRenderResolutionFromQualityMode(out int rw, out int rh, (int)displayWidth, (int)displayHeight, (Fsr3Upscaler.QualityMode)((int)qualityMode + 2));
            renderWidth = (uint)rw;
            renderHeight = (uint)rh;
            return true;
        }

        public override float GetUpscaleRatioFromQualityMode(FSR2Quality qualityMode)
        {
            return Fsr3Upscaler.GetUpscaleRatioFromQualityMode((Fsr3Upscaler.QualityMode)((int)qualityMode + 2));
        }
    }

    public class FSR3UpscalerContext : UpscalerContext
    {
        private readonly Fsr3UpscalerContext _context = new();
        private readonly Fsr3Upscaler.DispatchDescription _dispatchDescription = new();
        private readonly FSR2CommandInitializationData _initData;

        private Texture2DArray _clearTextureArray;

        internal FSR3UpscalerContext(in FSR2CommandInitializationData initSettings)
        {
            _initData = initSettings;
        }

        internal void Init(Fsr3UpscalerAssets assets)
        {
            Fsr3Upscaler.InitializationFlags flags = 0;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableHighDynamicRange)) flags |= Fsr3Upscaler.InitializationFlags.EnableHighDynamicRange;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDisplayResolutionMotionVectors)) flags |= Fsr3Upscaler.InitializationFlags.EnableDisplayResolutionMotionVectors;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableMotionVectorsJitterCancellation)) flags |= Fsr3Upscaler.InitializationFlags.EnableMotionVectorsJitterCancellation;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.DepthInverted)) flags |= Fsr3Upscaler.InitializationFlags.EnableDepthInverted;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDepthInfinite)) flags |= Fsr3Upscaler.InitializationFlags.EnableDepthInfinite;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableAutoExposure)) flags |= Fsr3Upscaler.InitializationFlags.EnableAutoExposure;
            if (_initData.GetFlag(FfxFsr2InitializationFlags.EnableDynamicResolution)) flags |= Fsr3Upscaler.InitializationFlags.EnableDynamicResolution;

            //Debug.Log($"Initializing FSR3 with max render size: {_initData.maxRenderSizeWidth}x{_initData.maxRenderSizeHeight}, display size: {_initData.displaySizeWidth}x{_initData.displaySizeHeight}, flags: {flags}");

            _context.Create(new Fsr3Upscaler.ContextDescription
            {
                MaxUpscaleSize = 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.UpscaleSize = new Vector2Int((int)_initData.displaySizeWidth, (int)_initData.displaySizeHeight);
            _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.Flags = FSR3UpscalerPlugin.EnableDebugView ? Fsr3Upscaler.DispatchFlags.DrawDebugView : 0;
            _dispatchDescription.UseTextureArrays = useTextureArrays;

            _context.Dispatch(_dispatchDescription, cmd);
        }
    }

#if UNITY_STANDALONE_WIN
    public class FSR3NativeUpscalerContext : UpscalerContext
    {
        private AMDUP.FSR2Context _nativeContext;
        private readonly FSR2CommandInitializationData _initData;

        internal FSR3NativeUpscalerContext(in FSR2CommandInitializationData initSettings)
        {
            _initData = initSettings;
        }

        internal void Init()
        {
            AMDUP.FSR2CommandInitializationData initSettings = new()
            {
                maxRenderSizeWidth = _initData.maxRenderSizeWidth,
                maxRenderSizeHeight = _initData.maxRenderSizeHeight,
                displaySizeWidth = _initData.displaySizeWidth,
                displaySizeHeight = _initData.displaySizeHeight,
                ffxFsrFlags = (AMDUP.FfxFsr2InitializationFlags)_initData.ffxFsrFlags,
            };

            CommandBuffer cmd = new();
            _nativeContext = AMDUP.GraphicsDevice.device.CreateFeature(cmd, in initSettings);
            Graphics.ExecuteCommandBuffer(cmd);
            cmd.Release();
        }

        internal void Destroy()
        {
            if (_nativeContext == null)
                return;

            CommandBuffer cmd = new();
            AMDUP.GraphicsDevice.device.DestroyFeature(cmd, _nativeContext);
            Graphics.ExecuteCommandBuffer(cmd);
            cmd.Release();

            _nativeContext = null;
        }

        public override void Execute(CommandBuffer cmd, in FSR2CommandExecutionData executeData, in FSR2TextureTable textures)
        {
            ref var execData = ref _nativeContext.executeData;
            execData.jitterOffsetX = executeData.jitterOffsetX;
            execData.jitterOffsetY = executeData.jitterOffsetY;
            execData.MVScaleX = executeData.MVScaleX;
            execData.MVScaleY = executeData.MVScaleY;
            execData.renderSizeWidth = executeData.renderSizeWidth;
            execData.renderSizeHeight = executeData.renderSizeHeight;
            execData.enableSharpening = executeData.enableSharpening;
            execData.sharpness = executeData.sharpness;
            execData.frameTimeDelta = executeData.frameTimeDelta;
            execData.preExposure = executeData.preExposure;
            execData.reset = executeData.reset;
            execData.cameraNear = executeData.cameraNear;
            execData.cameraFar = executeData.cameraFar;
            execData.cameraFovAngleVertical = executeData.cameraFovAngleVertical;

            AMDUP.FSR2TextureTable textureTable = new()
            {
                colorInput = textures.colorInput,
                depth = textures.depth,
                motionVectors = textures.motionVectors,
                exposureTexture = textures.exposureTexture,
                biasColorMask = textures.biasColorMask,
                reactiveMask = textures.reactiveMask,
                transparencyMask = textures.transparencyMask,
                colorOutput = textures.colorOutput,
            };

            AMDUP.GraphicsDevice.device.ExecuteFSR2(cmd, _nativeContext, in textureTable);
        }
    }
#endif
}