using MoonWorks.Graphics;
using MoonWorks.Math.Float;

namespace MoonWorks.Test
{
	class Texture3DGame : Game
	{
		private GraphicsPipeline pipeline;
		private GpuBuffer vertexBuffer;
		private GpuBuffer indexBuffer;
		private Texture texture;
		private Sampler sampler;

		private int currentDepth = 0;

		struct FragUniform
		{
			public float Depth;

			public FragUniform(float depth)
			{
				Depth = depth;
			}
		}

		public Texture3DGame() : base(TestUtils.GetStandardWindowCreateInfo(), TestUtils.GetStandardFrameLimiterSettings(), TestUtils.PreferredBackends, 60, true)
		{
			Logger.LogInfo("Press Left and Right to cycle between depth slices");

			// Load the shaders
			ShaderModule vertShaderModule = new ShaderModule(GraphicsDevice, TestUtils.GetShaderPath("TexturedQuad.vert"));
			ShaderModule fragShaderModule = new ShaderModule(GraphicsDevice, TestUtils.GetShaderPath("TexturedQuad3D.frag"));

			// Create the graphics pipeline
			GraphicsPipelineCreateInfo pipelineCreateInfo = TestUtils.GetStandardGraphicsPipelineCreateInfo(
				MainWindow.SwapchainFormat,
				vertShaderModule,
				fragShaderModule
			);
			pipelineCreateInfo.VertexInputState = VertexInputState.CreateSingleBinding<PositionTextureVertex>();
			pipelineCreateInfo.FragmentShaderInfo = GraphicsShaderInfo.Create<FragUniform>(fragShaderModule, "main", 1);
			pipeline = new GraphicsPipeline(GraphicsDevice, pipelineCreateInfo);

			// Create samplers
			sampler = new Sampler(GraphicsDevice, SamplerCreateInfo.PointClamp);

			// Create and populate the GPU resources
			var resourceUploader = new ResourceUploader(GraphicsDevice);

			vertexBuffer = resourceUploader.CreateBuffer(
				[
					new PositionTextureVertex(new Vector3(-1, -1, 0), new Vector2(0, 0)),
					new PositionTextureVertex(new Vector3(1, -1, 0), new Vector2(1, 0)),
					new PositionTextureVertex(new Vector3(1, 1, 0), new Vector2(1, 1)),
					new PositionTextureVertex(new Vector3(-1, 1, 0), new Vector2(0, 1))
				],
				BufferUsageFlags.Vertex
			);

			indexBuffer = resourceUploader.CreateBuffer<ushort>(
				[
					0, 1, 2,
					0, 2, 3,
				],
				BufferUsageFlags.Index
			);

			texture = Texture.CreateTexture3D(
				GraphicsDevice,
				16,
				16,
				7,
				TextureFormat.R8G8B8A8,
				TextureUsageFlags.Sampler
			);

			// Load each depth subimage of the 3D texture
			for (uint i = 0; i < texture.Depth; i += 1)
			{
				var region = new TextureRegion
				{
					TextureSlice = new TextureSlice
					{
						Texture = texture,
						MipLevel = 0,
						Layer = 0
					},
					X = 0,
					Y = 0,
					Z = i,
					Width = texture.Width,
					Height = texture.Height,
					Depth = 1
				};

				resourceUploader.SetTextureDataFromCompressed(
					region,
					TestUtils.GetTexturePath($"tex3d_{i}.png")
				);
			}

			resourceUploader.Upload();
			resourceUploader.Dispose();
		}

		protected override void Update(System.TimeSpan delta)
		{
			int prevDepth = currentDepth;

			if (TestUtils.CheckButtonPressed(Inputs, TestUtils.ButtonType.Left))
			{
				currentDepth -= 1;
				if (currentDepth < 0)
				{
					currentDepth = (int) texture.Depth - 1;
				}
			}

			if (TestUtils.CheckButtonPressed(Inputs, TestUtils.ButtonType.Right))
			{
				currentDepth += 1;
				if (currentDepth >= texture.Depth)
				{
					currentDepth = 0;
				}
			}

			if (prevDepth != currentDepth)
			{
				Logger.LogInfo("Setting depth to: " + currentDepth);
			}
		}

		protected override void Draw(double alpha)
		{
			FragUniform fragUniform = new FragUniform((float)currentDepth / texture.Depth + 0.01f);

			CommandBuffer cmdbuf = GraphicsDevice.AcquireCommandBuffer();
			Texture? backbuffer = cmdbuf.AcquireSwapchainTexture(MainWindow);
			if (backbuffer != null)
			{
				cmdbuf.BeginRenderPass(new ColorAttachmentInfo(backbuffer, WriteOptions.Cycle, Color.Black));
				cmdbuf.BindGraphicsPipeline(pipeline);
				cmdbuf.BindVertexBuffers(vertexBuffer);
				cmdbuf.BindIndexBuffer(indexBuffer, IndexElementSize.Sixteen);
				cmdbuf.BindFragmentSamplers(new TextureSamplerBinding(texture, sampler));
				cmdbuf.PushFragmentShaderUniforms(fragUniform);
				cmdbuf.DrawIndexedPrimitives(0, 0, 2);
				cmdbuf.EndRenderPass();
			}
			GraphicsDevice.Submit(cmdbuf);
		}

		public static void Main(string[] args)
		{
			Texture3DGame game = new Texture3DGame();
			game.Run();
		}
	}
}
