using System;
using UnityEngine.Experimental.Rendering;
#if UNITY_PS5
using WW1.PlayStation;
#endif

namespace UnityEngine.Rendering.PostProcessing
{
	internal class PSSRUpscaler : Upscaler
	{
#if UNITY_PS5
		public static bool IsSupported => UnityEngine.PS5.Utility.isTrinityMode && PluginInitialized;
		
		private static readonly bool PluginInitialized;
		private static uint _currentContext;

		private readonly PSSRPlugin.NativeData<PSSRPlugin.DispatchParams> _dispatchParams = new();
		private readonly PSSRPlugin.NativeData<PSSRPlugin.DestroyParams> _destroyParams = new();

		private RenderTexture _inputColor;
		private readonly RenderTexture[] _inputDepth = new RenderTexture[2];
		private readonly RenderTexture[] _inputMotionVectors = new RenderTexture[2];
		private Texture2D _outputColor;
		
		private bool _contextInitialized;
		private uint _frameCount;

		static PSSRUpscaler()
		{
			try
			{
				if (PSSRPlugin.Init() < 0)
				{
					Debug.LogError("Failed to initialize PSSR plugin!");
					PluginInitialized = false;
					return;
				}
			}
			catch (DllNotFoundException)
			{
				Debug.LogError("PSSR plugin not found!");
				PluginInitialized = false;
				return;
			}
			
			PluginInitialized = true;
			_currentContext = 0;
		}

		public override void CreateContext(PostProcessRenderContext context, Upscaling config)
		{
			if (!PluginInitialized)
			{
				Debug.LogWarning("PSSR plugin is not initialized!");
				return;
			}

			PSSRPlugin.InitParams initParams;
			initParams.contextIndex = _currentContext;
			initParams.displayWidth = (uint)config.UpscaleSize.x;
			initParams.displayHeight = (uint)config.UpscaleSize.y;
			initParams.maxRenderWidth = (uint)config.MaxRenderSize.x;
			initParams.maxRenderHeight = (uint)config.MaxRenderSize.y;
			initParams.autoKeepCopies = 0u;		// We use double buffered depth and motion vector copies created by Unity

			CreateRenderTexture(ref _inputColor, "PSSR Input Color", config.MaxRenderSize, context.sourceFormat, true);
			CreateRenderTextureArray(_inputDepth, "PSSR Input Depth", config.MaxRenderSize, GraphicsFormat.R32_SFloat, true);
			CreateRenderTextureArray(_inputMotionVectors, "PSSR Input Motion Vectors", config.MaxRenderSize, GraphicsFormat.R16G16_SFloat, true);

			if (PSSRPlugin.CreateContext(ref initParams, out IntPtr outputColorTexturePtr) >= 0 && outputColorTexturePtr != IntPtr.Zero)
			{
				// PSSR requires an output color texture in a very particular format (k11_11_10Float with kStandard256B tile mode and a specific alignment) that Unity cannot create directly.
				// So instead we let the plugin create that texture and then import it into Unity as a generic 32bpp texture from a native pointer.
				_outputColor = Texture2D.CreateExternalTexture(config.UpscaleSize.x, config.UpscaleSize.y, TextureFormat.RGBA32, false, true, outputColorTexturePtr);
				_dispatchParams.Initialize();
				_destroyParams.Initialize();
				_contextInitialized = true;
			}
		}

		public override void DestroyContext()
		{
			base.DestroyContext();
			
			if (_contextInitialized)
			{
				// Rotate between contexts to reduce the risk of race conditions between old and new contexts
				uint previousContext = _currentContext;
				_currentContext = (_currentContext + 1) % PSSRPlugin.MaxNumContexts;
				
				CommandBuffer cmd = new();
				PSSRPlugin.IssuePluginEvent(cmd, PSSRPlugin.Event.Destroy, new IntPtr(previousContext));
				Graphics.ExecuteCommandBuffer(cmd);
				cmd.Release();
				
				_contextInitialized = false;
			}

			if (_outputColor != null)
			{
				Object.Destroy(_outputColor);
				_outputColor = null;
			}

			DestroyRenderTextureArray(_inputMotionVectors);
			DestroyRenderTextureArray(_inputDepth);
			DestroyRenderTexture(ref _inputColor);

			_destroyParams.Destroy();
			_dispatchParams.Destroy();
		}

		public override void Render(PostProcessRenderContext context, Upscaling config)
		{
			var cmd = context.command;
			if (!PluginInitialized || !_contextInitialized)
			{
				cmd.BlitFullscreenTriangle(context.source, context.destination);
				return;
			}
			
			cmd.BeginSample("PSSR");

			if (config.Reset || _frameCount == 0)
			{
				cmd.SetRenderTarget(_inputDepth[0]);
				cmd.ClearRenderTarget(false, true, Color.clear);
				cmd.SetRenderTarget(_inputDepth[1]);
				cmd.ClearRenderTarget(false, true, Color.clear);
				cmd.SetRenderTarget(_inputMotionVectors[0]);
				cmd.ClearRenderTarget(false, true, Color.clear);
				cmd.SetRenderTarget(_inputMotionVectors[1]);
				cmd.ClearRenderTarget(false, true, Color.clear);
			}

			int frameIndex = (int)(_frameCount++ % 2);
			
			// We need to provide copies of the previous depth and motion vector buffers anyway, so we can turn this otherwise wasteful copying into a benefit
			PrepareInputs(cmd, context, config, _inputColor, _inputDepth[frameIndex], _inputMotionVectors[frameIndex]);

			Texture reactiveMask = config.transparencyAndCompositionMask;
			if (config.autoGenerateReactiveMask || config.autoGenerateTransparencyAndComposition)
			{
				reactiveMask = GenerateReactiveMask(cmd, context, config);
			}

			var flags = PSSRPlugin.OptionFlags.None;
			if (SystemInfo.usesReversedZBuffer) flags |= PSSRPlugin.OptionFlags.ReverseDepth;
			if (config.exposureSource == Upscaling.ExposureSource.Auto) flags |= PSSRPlugin.OptionFlags.AutoExposure;

			ref var dispatchParams = ref _dispatchParams.Value;
			dispatchParams.contextIndex = _currentContext;
			dispatchParams.color = ToNativePtr(_inputColor);
			dispatchParams.depth = ToNativePtr(_inputDepth[frameIndex]);
			dispatchParams.prevDepth = ToNativePtr(_inputDepth[frameIndex ^ 1]);
			dispatchParams.motionVectors = ToNativePtr(_inputMotionVectors[frameIndex]);
			dispatchParams.prevMotionVectors = ToNativePtr(_inputMotionVectors[frameIndex ^ 1]);
			dispatchParams.exposure = ToNativePtr(config.exposureSource switch
			{
				Upscaling.ExposureSource.Manual when config.exposure != null => config.exposure,
				Upscaling.ExposureSource.Unity => context.autoExposureTexture,
				_ => null,
			});
			dispatchParams.reactiveMask = ToNativePtr(reactiveMask);
			dispatchParams.outputColor = ToNativePtr(_outputColor);

			var scaledRenderSize = config.GetScaledRenderSize(context.camera);
			dispatchParams.renderWidth = (uint)scaledRenderSize.x;
			dispatchParams.renderHeight = (uint)scaledRenderSize.y;
			dispatchParams.jitter = config.JitterOffset;
			dispatchParams.motionVectorScale = new Vector2(-scaledRenderSize.x, -scaledRenderSize.y);
			dispatchParams.FromCamera(context.camera);
			dispatchParams.preExposure = config.preExposure;
			dispatchParams.resetHistory = config.Reset ? 1u : 0u;
			dispatchParams.flags = flags;
			
			PSSRPlugin.IssuePluginEvent(cmd, PSSRPlugin.Event.Dispatch, _dispatchParams);
			
			if (config.performSharpenPass)
			{
				// PSSR output is already pretty sharp, and we don't want to over-sharpen the image, so cut the sharpness range by half
				ApplySharpening(cmd, context, config.UpscaleSize, config.sharpness * 0.5f, _outputColor, context.destination);
			}
			else
			{
				// Convert the PSSR output from R11G11B10 to the expected destination format
				cmd.BlitFullscreenTriangle(_outputColor, context.destination);
			}
			
			cmd.EndSample("PSSR");
		}
		
		private static IntPtr ToNativePtr(Texture texture)
		{
			return texture != null ? texture.GetNativeTexturePtr() : IntPtr.Zero;
		}
#else
		public static bool IsSupported => false;
		
		public override void CreateContext(PostProcessRenderContext context, Upscaling config)
		{
			throw new NotImplementedException();
		}
		
		public override void DestroyContext()
		{
			base.DestroyContext();
		}
		
		public override void Render(PostProcessRenderContext context, Upscaling config)
		{
			throw new NotImplementedException();
		}
#endif
	}
}