using System;
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 RenderPass mainRenderPass;
        private RenderTarget mainColorTarget;
        private Framebuffer mainFramebuffer;
        private Rect mainRenderArea;

        private GraphicsPipeline spritePipeline;

        private SpriteBatch spriteBatch;

        private Texture whitePixel;
        private Sampler sampler;

        private const int SPRITECOUNT = 8092;
        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"));

            ColorTargetDescription colorTargetDescription = new ColorTargetDescription
            {
                Format = TextureFormat.R8G8B8A8,
                MultisampleCount = SampleCount.One,
                LoadOp = LoadOp.Clear,
                StoreOp = StoreOp.Store
            };

            mainRenderPass = new RenderPass(GraphicsDevice, colorTargetDescription);

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

            mainFramebuffer = new Framebuffer(
                GraphicsDevice,
                windowWidth,
                windowHeight,
                mainRenderPass,
                null,
                mainColorTarget
            );

            mainRenderArea = new Rect
            {
                X = 0,
                Y = 0,
                W = (int) windowWidth,
                H = (int) windowHeight
            };

            /* 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[2]
            {
                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")
                }
            };

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

            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]);
                spriteBatch.Add(new Sprite(new Rect { X = 0, Y = 0, W = 0, H = 0 }, 128, 128), transform);
            }

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

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