using System;
using Unity.Mathematics;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using static UnityEngine.Rendering.Universal.UniversalRenderPipeline.Profiling.Pipeline;

namespace X.Rendering.Feature
{
    public class SoftShadowMask : ScriptableRendererFeature
    {
        [Serializable]
        private class Settings
        {
            public bool BlurMask = false;
            public Material MaskMat = null;
            public Material BlurMat = null;
            public int BlurIterations = 3;
            public float BlurSpread = 0.6f;
        }

        [SerializeField]
        private Settings settings = new();
        SoftShadowMaskPass shadowMaskPass;

        public override void Create()
        {
            shadowMaskPass = new(settings);
        }

        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            renderer.EnqueuePass(shadowMaskPass);
        }


        class SoftShadowMaskPass : ScriptableRenderPass
        {
            internal static readonly int SoftShadowMaskTextureId = Shader.PropertyToID("_SoftShadowMaskTexture");
            internal static readonly GlobalKeyword softShadowMaskKeyword = GlobalKeyword.Create("_SOFTSHADOW_MASK");

            private Settings settings;
            private ProfilingSampler profiler;
            Vector4[] offsetArray = new Vector4[4];
            RTHandle softShadowMask;
            RTHandle buffer0;
            RTHandle buffer1;
            public SoftShadowMaskPass(Settings settings)
            {
                this.settings = settings;
                renderPassEvent = RenderPassEvent.AfterRenderingPrePasses;
                profiler = new(nameof(SoftShadowMaskPass));
            }

            public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
            {
                var cmd = renderingData.commandBuffer;
                using var scp = new ProfilingScope(cmd, profiler);
                cmd.EnableKeyword(softShadowMaskKeyword);
                var w = renderingData.cameraData.cameraTargetDescriptor.width;
                var h = renderingData.cameraData.cameraTargetDescriptor.height;
                float2 wh = new float2 { x = w, y = h };
                {
                    offsetArray[0] = new float4(new float2(-1, 1) / wh, new float2(1, 1) / wh);
                    offsetArray[1] = new float4(new float2(-1, -1) / wh, new float2(1, -1) / wh);
                    offsetArray[2] = new float4(new float2(-2, -2) / wh, new float2(2, 2) / wh);
                    offsetArray[3] = new float4(new float2(-2, 2) / wh, new float2(2, -2) / wh);
                    cmd.SetGlobalVectorArray("_Offset5", offsetArray);
                }
                cmd.SetGlobalVector("_MaskSizeAndInvRenderSize", new Vector4(w / 4, h / 4, 1f / w, 1f / h));
                var desc = new RenderTextureDescriptor()
                {
                    bindMS = false,
                    colorFormat = RenderTextureFormat.R8,
                    width = w / 4,
                    height = h / 4,
                    enableRandomWrite = false,
                    depthBufferBits = 0,
                    dimension = TextureDimension.Tex2D,
                    msaaSamples = 1,
                };
                RenderingUtils.ReAllocateIfNeeded(ref softShadowMask, desc);
                cmd.SetGlobalTexture("_CameraDepthTexture", renderingData.cameraData.renderer.cameraDepthTargetHandle);
                cmd.SetRenderTarget(softShadowMask, loadAction: RenderBufferLoadAction.DontCare, storeAction: RenderBufferStoreAction.Store);
                cmd.DrawProcedural(Matrix4x4.identity, settings.MaskMat, 0, MeshTopology.Triangles, 3);
                if (settings.BlurMask)
                {
                    cmd.BeginSample("SoftShadowMask Blur");
                    //desc.memoryless = RenderTextureMemoryless.Color;
                    RenderingUtils.ReAllocateIfNeeded(ref buffer0, desc, name: "buffer0");
                    RenderingUtils.ReAllocateIfNeeded(ref buffer1, desc, name: "buffer1");

                    cmd.SetGlobalTexture("_MainTex", softShadowMask);
                    for (int i = 0; i < settings.BlurIterations; i++)
                    {
                        settings.BlurMat.SetFloat("_BlurSize", i * settings.BlurSpread);
                        cmd.SetRenderTarget(buffer0, loadAction: RenderBufferLoadAction.DontCare, storeAction: RenderBufferStoreAction.Store);
                        cmd.DrawProcedural(Matrix4x4.identity, settings.BlurMat, 0, MeshTopology.Triangles, 3);
                        cmd.SetGlobalTexture("_MainTex", buffer0);

                        cmd.SetRenderTarget(buffer1, loadAction: RenderBufferLoadAction.DontCare, storeAction: RenderBufferStoreAction.Store);
                        cmd.DrawProcedural(Matrix4x4.identity, settings.BlurMat, 1, MeshTopology.Triangles, 3);
                        cmd.SetGlobalTexture("_MainTex", buffer1);
                    }
                    cmd.EndSample("SoftShadowMask Blur");
                    cmd.SetGlobalTexture(SoftShadowMaskTextureId, buffer1);
                }
                else
                {
                    cmd.SetGlobalTexture(SoftShadowMaskTextureId, softShadowMask);
                }
            }

            public override void OnFinishCameraStackRendering(CommandBuffer cmd)
            {
                base.OnFinishCameraStackRendering(cmd);
                cmd.DisableKeyword(softShadowMaskKeyword);
            }
        }
    }
}