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

namespace MoonWorksComputeSpriteBatch
{
	public class TestGame : Game
	{
		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"));

			/* Pipeline */

			spritePipeline = new GraphicsPipeline(
				GraphicsDevice,
				new GraphicsPipelineCreateInfo
				{
					AttachmentInfo = new GraphicsPipelineAttachmentInfo(
						new ColorAttachmentDescription(
							GraphicsDevice.GetSwapchainFormat(Window),
							ColorAttachmentBlendState.None
						)
					),
					DepthStencilState = DepthStencilState.Disable,
					VertexShaderInfo = GraphicsShaderInfo.Create<CameraUniforms>(vertexShaderModule, "main", 0),
					VertexInputState = new VertexInputState(
						VertexBinding.Create<VertexPositionTexcoord>(),
						VertexAttribute.Create<VertexPositionTexcoord>("position", 0),
						VertexAttribute.Create<VertexPositionTexcoord>("texcoord", 1),
						VertexAttribute.Create<VertexPositionTexcoord>("color", 2)
					),
					PrimitiveType = PrimitiveType.TriangleList,
					FragmentShaderInfo = GraphicsShaderInfo.Create(fragmentShaderModule, "main", 1),
					RasterizerState = RasterizerState.CW_CullBack,
					MultisampleState = MultisampleState.None
				}
			);

			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 swapchainTexture = commandBuffer.AcquireSwapchainTexture(Window);

			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);
			}

			spriteBatch.Flush(
				commandBuffer,
				new ColorAttachmentInfo(swapchainTexture, Color.Black),
				spritePipeline,
				new CameraUniforms { viewProjectionMatrix = viewProjection }
			);
			GraphicsDevice.Submit(commandBuffer);
		}

		protected override void OnDestroy()
		{

		}
	}
}