using System;
using System.Diagnostics;
using System.IO;
using System.Runtime.InteropServices;
using MoonWorks;
using MoonWorks.Graphics;
using MoonWorks.Math;
using MoonWorks.Window;

namespace MoonWorksComputeSpriteBatch
{
	public class TestGame : Game
	{
		private RenderTarget mainColorTarget;

		private GraphicsPipeline spritePipeline;

		private SpriteBatch spriteBatch;

		private Texture whitePixel;
		private Sampler sampler;

		private const int SPRITECOUNT = SpriteBatch.MAX_SPRITES;
		private Vector3[] positions = new Vector3[SPRITECOUNT];

		private uint windowWidth;
		private uint windowHeight;

		private Random random = new Random();

		public TestGame(WindowCreateInfo windowCreateInfo, PresentMode presentMode, int targetTimestep = 60, bool debugMode = false) : base(windowCreateInfo, presentMode, targetTimestep, debugMode)
		{
			windowWidth = windowCreateInfo.WindowWidth;
			windowHeight = windowCreateInfo.WindowHeight;

			var vertexShaderModule = new ShaderModule(GraphicsDevice, Path.Combine(Environment.CurrentDirectory, "Content", "sprite.vert.spv"));
			var fragmentShaderModule = new ShaderModule(GraphicsDevice, Path.Combine(Environment.CurrentDirectory, "Content", "sprite.frag.spv"));

			mainColorTarget = RenderTarget.CreateBackedRenderTarget(
				GraphicsDevice,
				windowWidth,
				windowHeight,
				TextureFormat.R8G8B8A8,
				false
			);

			/* Pipeline */

			ColorTargetBlendState[] colorTargetBlendStates = new ColorTargetBlendState[1]
			{
				ColorTargetBlendState.None
			};

			ColorBlendState colorBlendState = new ColorBlendState
			{
				LogicOpEnable = false,
				LogicOp = LogicOp.NoOp,
				BlendConstants = new BlendConstants(),
				ColorTargetBlendStates = colorTargetBlendStates
			};

			DepthStencilState depthStencilState = DepthStencilState.Disable;

			ShaderStageState vertexShaderState = new ShaderStageState
			{
				ShaderModule = vertexShaderModule,
				EntryPointName = "main",
				UniformBufferSize = (uint)Marshal.SizeOf<CameraUniforms>()
			};

			ShaderStageState fragmentShaderState = new ShaderStageState
			{
				ShaderModule = fragmentShaderModule,
				EntryPointName = "main",
				UniformBufferSize = 0
			};

			MultisampleState multisampleState = MultisampleState.None;

			GraphicsPipelineLayoutInfo pipelineLayoutInfo = new GraphicsPipelineLayoutInfo
			{
				VertexSamplerBindingCount = 0,
				FragmentSamplerBindingCount = 1
			};

			RasterizerState rasterizerState = RasterizerState.CCW_CullNone;

			var vertexBindings = new VertexBinding[1]
			{
				new VertexBinding
				{
					Binding = 0,
					InputRate = VertexInputRate.Vertex,
					Stride = (uint) Marshal.SizeOf<VertexPositionTexcoord>()
				}
			};

			var vertexAttributes = new VertexAttribute[3]
			{
				new VertexAttribute
				{
					Binding = 0,
					Location = 0,
					Format = VertexElementFormat.Vector3,
					Offset = 0
				},
				new VertexAttribute
				{
					Binding = 0,
					Location = 1,
					Format = VertexElementFormat.Vector2,
					Offset = (uint) Marshal.OffsetOf<VertexPositionTexcoord>("texcoord")
				},
				new VertexAttribute
				{
					Binding = 0,
					Location = 2,
					Format = VertexElementFormat.Vector4,
					Offset = (uint) Marshal.OffsetOf<VertexPositionTexcoord>("color")
				}
			};

			VertexInputState vertexInputState = new VertexInputState
			{
				VertexBindings = vertexBindings,
				VertexAttributes = vertexAttributes
			};

			var viewports = new Viewport[1]
			{
				new Viewport
				{
					X = 0,
					Y = 0,
					W = windowWidth,
					H = windowHeight,
					MinDepth = 0,
					MaxDepth = 1
				}
			};

			var scissors = new Rect[1]
			{
				new Rect
				{
					X = 0,
					Y = 0,
					W = (int) windowWidth,
					H = (int) windowHeight
				}
			};

			ViewportState viewportState = new ViewportState
			{
				Viewports = viewports,
				Scissors = scissors
			};

			var colorAttachmentDescriptions = new ColorAttachmentDescription[1]
			{
				new ColorAttachmentDescription
				{
					format = TextureFormat.R8G8B8A8,
					sampleCount = SampleCount.One
				}
			};

			GraphicsPipelineAttachmentInfo graphicsPipelineAttachmentInfo = new GraphicsPipelineAttachmentInfo
			{
				colorAttachmentDescriptions = colorAttachmentDescriptions,
				colorAttachmentCount = 1,
				hasDepthStencilAttachment = false,
				depthStencilFormat = 0
			};

			var graphicsPipelineCreateInfo = new GraphicsPipelineCreateInfo
			{
				ColorBlendState = colorBlendState,
				DepthStencilState = depthStencilState,
				VertexShaderState = vertexShaderState,
				FragmentShaderState = fragmentShaderState,
				MultisampleState = multisampleState,
				PipelineLayoutInfo = pipelineLayoutInfo,
				RasterizerState = rasterizerState,
				PrimitiveType = PrimitiveType.TriangleList,
				VertexInputState = vertexInputState,
				ViewportState = viewportState,
				AttachmentInfo = graphicsPipelineAttachmentInfo
			};

			spritePipeline = new GraphicsPipeline(GraphicsDevice, graphicsPipelineCreateInfo);

			spriteBatch = new SpriteBatch(GraphicsDevice);

			whitePixel = Texture.CreateTexture2D(GraphicsDevice, 1, 1, TextureFormat.R8G8B8A8, TextureUsageFlags.Sampler);

			var commandBuffer = GraphicsDevice.AcquireCommandBuffer();
			commandBuffer.SetTextureData(whitePixel, new Color[] { Color.White });
			GraphicsDevice.Submit(commandBuffer);

			sampler = new Sampler(GraphicsDevice, SamplerCreateInfo.PointWrap);
		}

		protected override void Update(TimeSpan dt)
		{
			for (var i = 0; i < SPRITECOUNT; i += 1)
			{
				positions[i].X = (float)(random.NextDouble() * windowWidth) - 64;
				positions[i].Y = (float)(random.NextDouble() * windowHeight) - 64;
			}
		}

		protected override void Draw(TimeSpan dt, double alpha)
		{
			var commandBuffer = GraphicsDevice.AcquireCommandBuffer();

			var viewProjection = Matrix4x4.CreateLookAt(new Vector3(windowWidth / 2, windowHeight / 2, 1), new Vector3(windowWidth / 2, windowHeight / 2, 0), Vector3.Up) * Matrix4x4.CreateOrthographic(windowWidth, windowHeight, 0.1f, 1000);
			spriteBatch.Start(whitePixel, sampler);

			for (var i = 0; i < SPRITECOUNT; i += 1)
			{
				var transform = Matrix4x4.CreateTranslation(positions[i]);
				var color = new Color((float)random.NextDouble(), (float)random.NextDouble(), (float)random.NextDouble(), 255f);
				spriteBatch.Add(new Sprite(new Rect { X = 0, Y = 0, W = 0, H = 0 }, 128, 128), transform, color);
			}

			var colorAttachmentInfo = new ColorAttachmentInfo
			{
				renderTarget = mainColorTarget,
				clearColor = Color.Black,
				loadOp = LoadOp.Clear,
				storeOp = StoreOp.DontCare
			};

			spriteBatch.Flush(commandBuffer, colorAttachmentInfo, spritePipeline, new CameraUniforms { viewProjectionMatrix = viewProjection });

			commandBuffer.QueuePresent(mainColorTarget.TextureSlice, Filter.Nearest, Window);
			GraphicsDevice.Submit(commandBuffer);
		}

		protected override void OnDestroy()
		{

		}
	}
}