using System.Collections.Generic;
using UnityEngine.Experimental.Rendering;
using UnityEngine.Experimental.Rendering.RenderGraphModule;
using UnityEngine.Rendering.Universal.Internal;

namespace UnityEngine.Rendering.Universal
{
    internal class DecalDrawGBufferSystem : DecalDrawSystem
    {
        public DecalDrawGBufferSystem(DecalEntityManager entityManager) : base("DecalDrawGBufferSystem.Execute", entityManager) { }
        protected override int GetPassIndex(DecalCachedChunk decalCachedChunk) => decalCachedChunk.passIndexGBuffer;
    }

    internal class DecalGBufferRenderPass : ScriptableRenderPass
    {
        private FilteringSettings m_FilteringSettings;
        private ProfilingSampler m_ProfilingSampler;
        private List<ShaderTagId> m_ShaderTagIdList;
        private DecalDrawGBufferSystem m_DrawSystem;
        private DecalScreenSpaceSettings m_Settings;
        private DeferredLights m_DeferredLights;
        private RTHandle[] m_GbufferAttachments;
        private bool m_DecalLayers;
        private PassData m_PassData;

        public DecalGBufferRenderPass(DecalScreenSpaceSettings settings, DecalDrawGBufferSystem drawSystem, bool decalLayers)
        {
            renderPassEvent = RenderPassEvent.AfterRenderingGbuffer;

            m_DrawSystem = drawSystem;
            m_Settings = settings;
            m_ProfilingSampler = new ProfilingSampler("Decal GBuffer Render");
            m_FilteringSettings = new FilteringSettings(RenderQueueRange.opaque, -1);
            m_DecalLayers = decalLayers;

            m_ShaderTagIdList = new List<ShaderTagId>();
            if (drawSystem == null)
                m_ShaderTagIdList.Add(new ShaderTagId(DecalShaderPassNames.DecalGBufferProjector));
            else
                m_ShaderTagIdList.Add(new ShaderTagId(DecalShaderPassNames.DecalGBufferMesh));

            m_PassData = new PassData();
        }

        internal void Setup(DeferredLights deferredLights)
        {
            m_DeferredLights = deferredLights;
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
        {
            if (m_DeferredLights.UseRenderPass)
            {
                m_GbufferAttachments = new RTHandle[]
                {
                    m_DeferredLights.GbufferAttachments[0], m_DeferredLights.GbufferAttachments[1],
                    m_DeferredLights.GbufferAttachments[2], m_DeferredLights.GbufferAttachments[3]
                };

                if (m_DecalLayers)
                {
                    var deferredInputAttachments = new RTHandle[]
                    {
                        m_DeferredLights.GbufferAttachments[m_DeferredLights.GbufferDepthIndex],
                        m_DeferredLights.GbufferAttachments[m_DeferredLights.GBufferRenderingLayers],
                    };

                    var deferredInputIsTransient = new bool[]
                    {
                        true, false, // TODO: Make rendering layers transient
                    };

                    ConfigureInputAttachments(deferredInputAttachments, deferredInputIsTransient);
                }
                else
                {
                    var deferredInputAttachments = new RTHandle[]
                    {
                        m_DeferredLights.GbufferAttachments[m_DeferredLights.GbufferDepthIndex],
                    };

                    var deferredInputIsTransient = new bool[]
                    {
                        true,
                    };

                    ConfigureInputAttachments(deferredInputAttachments, deferredInputIsTransient);
                }
            }
            else
            {
                m_GbufferAttachments = new RTHandle[]
                {
                        m_DeferredLights.GbufferAttachments[0], m_DeferredLights.GbufferAttachments[1],
                        m_DeferredLights.GbufferAttachments[2], m_DeferredLights.GbufferAttachments[3]
                };
            }

            ConfigureTarget(m_GbufferAttachments, m_DeferredLights.DepthAttachmentHandle);
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            InitPassData(ref m_PassData);

            SortingCriteria sortingCriteria = renderingData.cameraData.defaultOpaqueSortFlags;
            DrawingSettings drawingSettings = RenderingUtils.CreateDrawingSettings(m_ShaderTagIdList, ref renderingData, sortingCriteria);
            var param = new RendererListParams(renderingData.cullResults, drawingSettings, m_FilteringSettings);
            var rendererList = context.CreateRendererList(ref param);
            using (new ProfilingScope(renderingData.commandBuffer, m_ProfilingSampler))
            {
                ExecutePass(CommandBufferHelpers.GetRasterCommandBuffer(renderingData.commandBuffer), m_PassData, rendererList, ref renderingData);
            }
        }

        private class PassData
        {
            internal DecalDrawGBufferSystem drawSystem;
            internal DecalScreenSpaceSettings settings;
            internal bool decalLayers;

            internal RenderingData renderingData;
            internal RendererListHandle rendererList;
        }

        private void InitPassData(ref PassData passData)
        {
            passData.drawSystem = m_DrawSystem;
            passData.settings = m_Settings;
            passData.decalLayers = m_DecalLayers;
        }

        private static void ExecutePass(RasterCommandBuffer cmd, PassData passData, RendererList rendererList, ref RenderingData renderingData)
        {
            NormalReconstruction.SetupProperties(cmd, renderingData.cameraData);

            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendLow, passData.settings.normalBlend == DecalNormalBlend.Low);
            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendMedium, passData.settings.normalBlend == DecalNormalBlend.Medium);
            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendHigh, passData.settings.normalBlend == DecalNormalBlend.High);

            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalLayers, passData.decalLayers);

            passData.drawSystem?.Execute(cmd);
            cmd.DrawRendererList(rendererList);
        }

        public override void RecordRenderGraph(RenderGraph renderGraph, FrameResources frameResources, ref RenderingData renderingData)
        {
            UniversalRenderer renderer = (UniversalRenderer)renderingData.cameraData.renderer;

            TextureHandle cameraDepthTexture = frameResources.GetTexture(UniversalResource.CameraDepthTexture);

            RenderGraphUtils.SetGlobalTexture(renderGraph, Shader.PropertyToID("_CameraDepthTexture"), cameraDepthTexture);

            using (var builder = renderGraph.AddRasterRenderPass<PassData>("Decal GBuffer Pass", out var passData, m_ProfilingSampler))
            {
                InitPassData(ref passData);
                passData.renderingData = renderingData;

                builder.UseTextureFragment(frameResources.GetTexture(UniversalResource.GBuffer0), 0, IBaseRenderGraphBuilder.AccessFlags.Write);
                builder.UseTextureFragment(frameResources.GetTexture(UniversalResource.GBuffer1), 1, IBaseRenderGraphBuilder.AccessFlags.Write);
                builder.UseTextureFragment(frameResources.GetTexture(UniversalResource.GBuffer2), 2, IBaseRenderGraphBuilder.AccessFlags.Write);
                builder.UseTextureFragment(frameResources.GetTexture(UniversalResource.GBuffer3), 3, IBaseRenderGraphBuilder.AccessFlags.Write);
                builder.UseTextureFragmentDepth(renderer.activeDepthTexture, IBaseRenderGraphBuilder.AccessFlags.Read);

                if (cameraDepthTexture.IsValid())
                    builder.UseTexture(cameraDepthTexture, IBaseRenderGraphBuilder.AccessFlags.Read);


                SortingCriteria sortingCriteria = renderingData.cameraData.defaultOpaqueSortFlags;
                DrawingSettings drawingSettings = RenderingUtils.CreateDrawingSettings(m_ShaderTagIdList, ref renderingData, sortingCriteria);
                var param = new RendererListParams(renderingData.cullResults, drawingSettings, m_FilteringSettings);
                passData.rendererList = renderGraph.CreateRendererList(param);
                builder.UseRendererList(passData.rendererList);

                builder.AllowGlobalStateModification(true);

                builder.SetRenderFunc((PassData data, RasterGraphContext rgContext) =>
                {
                    ExecutePass(rgContext.cmd, data, data.rendererList, ref data.renderingData);
                });
            }
        }

        public override void OnCameraCleanup(CommandBuffer cmd)
        {
            if (cmd == null)
            {
                throw new System.ArgumentNullException("cmd");
            }

            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendLow, false);
            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendMedium, false);
            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalNormalBlendHigh, false);
            CoreUtils.SetKeyword(cmd, ShaderKeywordStrings.DecalLayers, false);
        }
    }
}