using System;
using System.Runtime.InteropServices;
using Unity.Collections.LowLevel.Unsafe;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

namespace X.Rendering.Feature
{
    [StructLayout(LayoutKind.Sequential)]
    public struct Capsule
    {
        public Vector3 a, b;
        public float radius;
    }

    [StructLayout(LayoutKind.Sequential)]
    public struct Character
    {
        public Vector3 position;
        public float radius;
        public Vector4 lightDir; //xyz:lightDir, w:根据lightColor 算个系数
        public int startID, endID;
    }

    public class CapsuleAO : ScriptableRendererFeature
    {
        [Serializable]
        public class Settings
        {
            public RenderPassEvent RenderPassEvent = RenderPassEvent.BeforeRenderingTransparents;
            public float AmbientIntensity = 0.2f;
            public float ShadowIntensity = 0.4f;
            public float ShadowSharpness = 20;
            [Range(1, 90)]
            public float ConeAngle = 1;
            public Material CapsuleAOMat;
        }

        [SerializeField]
        Settings settings;
        CapsuleAOPass capsuleAOPass;
        public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
        {
            {
                renderer.EnqueuePass(capsuleAOPass);
            }
        }

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

        class CapsuleAOPass : ScriptableRenderPass, IDisposable
        {
            private Settings settings;
            private GraphicsBuffer capsuleDataBuffer;
            private GraphicsBuffer characterDataBuffer;
            private ProfilingSampler profiler;



            public CapsuleAOPass(Settings settings)
            {
                this.settings = settings;
                profiler = new (nameof(CapsuleAOPass));
                renderPassEvent = settings.RenderPassEvent;
            }


            public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescriptor)
            {
                base.Configure(cmd, cameraTextureDescriptor);
                ConfigureInput(ScriptableRenderPassInput.Depth | ScriptableRenderPassInput.Normal);
            }

            public void Dispose()
            {
                capsuleDataBuffer?.Dispose();
                capsuleDataBuffer = null;
                characterDataBuffer?.Dispose();
                characterDataBuffer = null;
            }

            public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
            {
                if (!XRenderFeatureManager.Instance)
                {
                    return;
                }
                ref var characterArray = ref XRenderFeatureManager.Instance.CharacterArray;
                ref var capsuleArray = ref XRenderFeatureManager.Instance.CapsuleArray;
                if (!capsuleArray.IsCreated)
                {
                    return;
                }
                
                if(capsuleDataBuffer == null || capsuleDataBuffer.count != capsuleArray.Length)
                {
                    capsuleDataBuffer?.Release();
                    capsuleDataBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, capsuleArray.Length, UnsafeUtility.SizeOf<Capsule>());
                }
                
                if (characterDataBuffer == null || characterDataBuffer.count != characterArray.Length)
                {
                    characterDataBuffer?.Release();
                    characterDataBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, characterArray.Length, UnsafeUtility.SizeOf<Character>());
                }
                
                capsuleDataBuffer.SetData(capsuleArray);
                characterDataBuffer.SetData(characterArray);

                var cmd = renderingData.commandBuffer;
                using var scp = new ProfilingScope(cmd, profiler);
                cmd.SetGlobalBuffer("_CapsuleData", capsuleDataBuffer);
                cmd.SetGlobalBuffer("_CharacterData", characterDataBuffer);
                cmd.SetGlobalInt("_CapsulesCount", capsuleArray.Length);
                cmd.SetGlobalInt("_CharactersCount", characterArray.Length);
                cmd.SetGlobalFloat("_AmbientIntensity", settings.AmbientIntensity);
                cmd.SetGlobalFloat("_ShadowIntensity", settings.ShadowIntensity);
                cmd.SetGlobalFloat("_ShadowSharpness", settings.ShadowSharpness);
                cmd.SetGlobalFloat("_ConeAngle", settings.ConeAngle);
                var renderer = renderingData.cameraData.renderer;

                cmd.SetRenderTarget(renderer.cameraColorTargetHandle, loadAction: RenderBufferLoadAction.Load, storeAction: RenderBufferStoreAction.Store);
                cmd.DrawProcedural(Matrix4x4.identity, settings.CapsuleAOMat, 0, MeshTopology.Triangles, 3);
            }
        }
    }
}