using GlitchyEngine.Content;
using GlitchyEngine.Core;
using GlitchyEngine.Math;
using System;
using System.IO;
using System.Diagnostics;

namespace GlitchyEngine.Renderer
{
	public abstract class Texture : Asset
	{
		protected SamplerState _samplerState ~ _?.ReleaseRef();
	
		public SamplerState SamplerState
		{
			get => _samplerState;
			set
			{
				if(_samplerState == value)
					return;
				
				SetReference!(_samplerState, value);
			}
		}

		public abstract uint32 Width {get;}
		public abstract uint32 Height {get;}
		public abstract uint32 Depth {get;}
		public abstract uint32 ArraySize {get;}
		public abstract uint32 MipLevels {get;}

		public abstract Format Format {get;}

		public abstract TextureDimension Dimension {get;}

		public abstract TextureViewBinding GetViewBinding();
	}

	public struct Texture2DDesc
	{
		public uint32 Width;
		public uint32 Height;
		public uint32 ArraySize;
		public uint32 MipLevels;
		public Format Format;
		public Usage Usage;
		public CPUAccessFlags CpuAccess;

		public this() => this = default;

		public this(uint32 width, uint32 height, Format format, uint32 arraySize = 1, uint32 mipLevels = 1, Usage usage = .Default, CPUAccessFlags cpuAccess = .None)
		{
			Width = width;
			Height = height;
			Format = format;
			ArraySize = arraySize;
			MipLevels = mipLevels;
			Usage = usage;
			CpuAccess = cpuAccess;
		}
	}

	/// Represents the Data of one Texture Slice (a specific mip-level of a array-slice of the texture)
	/// @remarks Basically works like described here: https://learn.microsoft.com/en-us/windows/win32/api/d3d11/ns-d3d11-d3d11_subresource_data
	public struct TextureSliceData
	{
		public void* Data;
		public uint32 LinePitch;
		public uint32 SlicePitch;

		public this(void* data, uint32 linePitch, uint32 slicePitch)
		{
			Data = data;
			LinePitch = linePitch;
			SlicePitch = slicePitch;
		}
	}

	public class Texture2D : Texture
	{
		//public override extern uint32 Width {get;}
		//public override extern uint32 Height {get;}
		public override uint32 Depth => 1;
		//public override extern uint32 ArraySize {get;}
		//public override extern uint32 MipLevels {get;}

		public override TextureDimension Dimension => .Texture2D;

		public this(Texture2DDesc desc)
		{
			PrepareTexturePlatform(desc, false);
		}

		public Result<void> SetData(Span<TextureSliceData> slices)
		{
			if (slices.Length != ArraySize * MipLevels)
			{
				Log.EngineLogger.Error("Not enough slices provided to initialize texture.");
				return .Err;
			}

			return PlatformSetData(slices);
		}

		public void SetData<T>(T* data, uint32 arraySlice = 0, uint32 mipSlice = 0)
		{
			PlatformSetData(data, (.)sizeof(T), 0, 0, Width, Height, arraySlice, mipSlice, .Write);
		}

		public void SetData<T>(T* data, uint32 x, uint32 y, uint32 width, uint32 height, uint32 arraySlice = 0, uint32 mipSlice = 0)
		{
			PlatformSetData(data, (.)sizeof(T), x, y, width, height, arraySlice, mipSlice, .Write);
		}

		/*
		uint32 width, uint32 height, Format format,
		uint32 mipLevels = 1, uint32 arraySize = 1, Usage usage = .Default, CPUAccessFlags cpuAccess = .None
		*/

		/**
		 * Prepares the texture so that a call to SetData can successfully upload the data to the gpu.
		 */
		protected extern void PrepareTexturePlatform(Texture2DDesc desc, bool isRenderTarget);

		protected extern Result<void> PlatformSetData(void* data, uint32 elementSize, uint32 destX,
			uint32 destY, uint32 destWidth, uint32 destHeight, uint32 arraySlice, uint32 mipLevel, GlitchyEngine.Renderer.MapType mapType);
		
		protected extern Result<void> PlatformSetData(Span<TextureSliceData> slices);

		/**
		 * Copies the texel-data of this texture to the given destination texture.
		 */
		public static extern void CopySubresourceRegion(Texture2D source, Texture2D destination,
			ResourceBox sourceBox = default, uint32 destX = 0, uint32 destY = 0,
			uint32 srcArraySlice = 0, uint32 srcMipSlice = 0, uint32 destArraySlice = 0, uint32 destMipSlice = 0);

		/**
		 * Copies the data to the given destination.
		 */
		public extern void CopyTo(Texture2D destination);

		public override TextureViewBinding GetViewBinding()
		{
			return PlatformGetViewBinding();
		}

		protected extern TextureViewBinding PlatformGetViewBinding();
	}

	public enum TextureCubeFace
	{
		PositiveX = 0,
		NegativeX = 1,
		PositiveY = 2,
		NegativeY = 3,
		PositiveZ = 4,
		NegativeZ = 5,
	}

	public class TextureCube : Texture
	{
		protected String _path ~ delete _;
		
		// public override extern uint32 Width {get;}
		// public override extern uint32 Height {get;}
		public override uint32 Depth => 1;
		// public override extern uint32 ArraySize {get;}
		// public override extern uint32 MipLevels {get;}
		
		public override TextureDimension Dimension => .TextureCube;

		public this(Texture2DDesc desc)
		{
			PrepareTexturePlatform(desc, false);
		}
		
		public void SetData(void* data, int elementSize, TextureCubeFace cubeFace, uint32 arraySlice = 0, uint32 mipSlice = 0)
		{
			PlatformSetData(data, (.)elementSize, 0, 0, Width, Height, arraySlice * 6 + (uint32)cubeFace, mipSlice, .Write);
		}

		public void SetData<T>(T* data, TextureCubeFace cubeFace, uint32 arraySlice = 0, uint32 mipSlice = 0)
		{
			PlatformSetData(data, (.)sizeof(T), 0, 0, Width, Height, arraySlice * 6 + (uint32)cubeFace, mipSlice, .Write);
		}

		public void SetData<T>(T* data, uint32 x, uint32 y, uint32 width, uint32 height, TextureCubeFace cubeFace, uint32 arraySlice = 0, uint32 mipSlice = 0)
		{
			PlatformSetData(data, (.)sizeof(T), x, y, width, height, arraySlice * 6 + (uint32)cubeFace, mipSlice, .Write);
		}

		protected extern void CreateTexturePlatform(Texture2DDesc desc, bool isRenderTarget, void* data, uint32 linePitch);

		/**
		 * Prepares the texture so that a call to SetData can successfully upload the data to the gpu.
		 */
		protected extern void PrepareTexturePlatform(Texture2DDesc desc, bool isRenderTarget);

		protected extern Result<void> PlatformSetData(void* data, uint32 elementSize, uint32 destX,
			uint32 destY, uint32 destWidth, uint32 destHeight, uint32 arraySlice, uint32 mipLevel, GlitchyEngine.Renderer.MapType mapType);

		/**
		 * Copies the texel-data of this texture to the given destination texture.
		 */
		public static extern void CopySubresourceRegion(Texture2D source, Texture2D destination,
			ResourceBox sourceBox = default, uint32 destX = 0, uint32 destY = 0,
			uint32 srcArraySlice = 0, uint32 srcMipSlice = 0, uint32 destArraySlice = 0, uint32 destMipSlice = 0);

		/**
		 * Copies the data to the given destination.
		 */
		//public extern void CopyTo(TextureCube destination);

		public override TextureViewBinding GetViewBinding()
		{
			return PlatformGetViewBinding();
		}

		protected extern TextureViewBinding PlatformGetViewBinding();
	}
}