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

namespace X.Rendering.Scene
{
    [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 capsuleStartID, capsuleEndID;
        public uint capsuleAOSettingMask;
    }

    [StructLayout(LayoutKind.Sequential), Serializable]
    public struct CapsuleShadowAreaSetting
    {
        public float AmbientIntensity;
        //[Range(1, 90)]
        public float ConeAngle;
        public float ShadowIntensity;
        public float ShadowSharpness;
        public int lightStartID, lightEndID;

        public static CapsuleShadowAreaSetting GetDefault()
        {
            return new CapsuleShadowAreaSetting()
            {
                AmbientIntensity = 0.2f,
                ShadowIntensity = 0.4f,
                ShadowSharpness = 20,
                ConeAngle = 1
            };
        }
    }

    [Serializable]
    public class LightData
    {
        public Vector3 lightPosition;
        public float lightIntensity = 1;
        public bool isPointLight = true;
    }

    internal class CapsuleShadowPass : ScriptableRenderPass, IDisposable
    {
        [Serializable]
        public class CapsuleShadowSettings
        {
            public bool Enable = true;
            public RenderPassEvent RenderPassEvent = RenderPassEvent.BeforeRenderingTransparents;
        }

        private CapsuleShadowSettings settings;
        private readonly SceneEffect sceneEffect;
        private GraphicsBuffer capsuleDataBuffer;
        private GraphicsBuffer characterDataBuffer;
        private GraphicsBuffer capsuleShadowDataBuffer;
        private ProfilingSampler profiler;
        private CommandBuffer commandBuffer;

        public CapsuleShadowPass(CapsuleShadowSettings settings, SceneEffect sceneEffect)
        {
            this.settings = settings;
            this.sceneEffect = sceneEffect;
            profiler = new(nameof(CapsuleShadowPass));
            renderPassEvent = settings.RenderPassEvent;
            commandBuffer = new CommandBuffer();
            commandBuffer.name = nameof(CapsuleShadowPass) + sceneEffect.name;
        }

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

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            ref var characterArray = ref sceneEffect.CharacterArray;
            ref var capsuleArray = ref sceneEffect.CapsuleArray;
            ref var capsuleAOSettingArray = ref sceneEffect.CapsuleAOSettingArray;
            if (!capsuleArray.IsCreated || !capsuleAOSettingArray.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>());
            }

            if (capsuleShadowDataBuffer == null || capsuleShadowDataBuffer.count != capsuleAOSettingArray.Length)
            {
                capsuleShadowDataBuffer?.Release();
                capsuleShadowDataBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, capsuleAOSettingArray.Length, UnsafeUtility.SizeOf<CapsuleShadowAreaSetting>());
            }

            capsuleDataBuffer.SetData(capsuleArray);
            characterDataBuffer.SetData(characterArray);

            var cmd = commandBuffer;
            using var scp = new ProfilingScope(cmd, profiler);
            cmd.SetGlobalBuffer("_CapsuleData", capsuleDataBuffer);
            cmd.SetGlobalBuffer("_CharacterData", characterDataBuffer);

            capsuleShadowDataBuffer.SetData(capsuleAOSettingArray);
            cmd.SetGlobalBuffer("_CapsuleShadowData", capsuleShadowDataBuffer);
            cmd.SetGlobalInt("_CapsuleShadowDataCount", capsuleAOSettingArray.Length);

            cmd.SetGlobalInt("_CapsulesCount", capsuleArray.Length);
            cmd.SetGlobalInt("_CharactersCount", characterArray.Length);
            
            cmd.SetGlobalInt("_CapsuleLightsCount", sceneEffect.CapsuleLightsDirCount);
            
            if(sceneEffect.CapsuleLightsDirCount > 0)
            {
                cmd.SetGlobalVectorArray("_CapsuleLightsDir", sceneEffect.CapsuleLightsDir);
            }
            
            context.ExecuteCommandBuffer(cmd);
            cmd.Clear();
        }
    }
}