using Echovoid.Runtime.Behavior.Rendering;
using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

namespace SLSUtilities.Rendering.PostProcessing
{
    [System.Serializable, VolumeComponentMenu("SLS/Postprocessing/Anime Bloom")]
    public class AnimeBloom : ScriptablePostProcessorVolume
    {
        // 【核心修改】：放在 ToneMapping 之前执行（BeforePostProcess），配合 ACES 才能彻底解决“高光泛白”问题
        public override CustomPostProcessInjectionPoint InjectionPoint => CustomPostProcessInjectionPoint.BeforePostProcess;
        public override int OrderInInjectionPoint => 5; // 放在 Vignette 之前

        [Header("Glow Settings")]
        [Tooltip("泛光强度。值越大越亮。")]
        public ClampedFloatParameter intensity = new(0f, 0f, 10f);

        [Tooltip("阈值。亮度超过此值的像素才会发光。\n关键：设为 1.1 可以过滤掉白墙(1.0)，只让灯光发光。")]
        public MinFloatParameter threshold = new(1.1f, 0f); // 默认设为 1.1

        [Tooltip("柔膝 (Soft Knee)。让阈值过渡更平滑，避免高光边缘有硬切痕迹。")]
        public ClampedFloatParameter softKnee = new(0.5f, 0f, 1f);

        [Tooltip("最大亮度钳制。防止极亮像素（如太阳）产生乱跳的噪点。")]
        public MinFloatParameter clamp = new(65472f, 1f); // 默认很大，基本不限制

        [Header("Anime Style")]
        [Tooltip("扩散半径。稍微增加扩展范围来弥补低迭代带来的发光不足。")]
        public ClampedFloatParameter scatter = new(0.85f, 0f, 5f); // 推荐增量以适应低迭代

        [Tooltip("迭代次数。针对移动端带宽优化，建议控制在 2~3 次。")]
        public ClampedIntParameter diffusion = new(3, 1, 4); // 移动端性能优化，最高4次

        [Tooltip("泛光染色。可以做粉色霓虹、蓝色科技光等效果。")]
        public ColorParameter tint = new(Color.white, true, true, true);

        // 内部使用的 RT 数组
        private RTHandle[] _bloomPyramidUp;
        private RTHandle[] _bloomPyramidDown;
        private const int k_MaxPyramidSize = 6; // 减少不必要的最大数组长度

        public override string GetShaderName() => "SLS/Postprocessing/AnimeBloom";

        public override void Render(CommandBuffer cmd, ref RenderingData renderingData, RTHandle source, RTHandle destination)
        {
            if (material == null) return;

            var desc = renderingData.cameraData.cameraTargetDescriptor;
            desc.msaaSamples = 1;
            desc.depthBufferBits = 0;

            // 1. 设置参数
            Vector4 bloomParams = new Vector4(intensity.value, threshold.value, softKnee.value, clamp.value);
            material.SetVector(InternalShaderHelpers.ID._BloomParams, bloomParams);
            material.SetVector(InternalShaderHelpers.ID._BloomTint, tint.value);
            material.SetFloat(InternalShaderHelpers.ID._BlurRadius, scatter.value);

            // 2. 初始化金字塔数组
            int iterations = Mathf.Clamp(diffusion.value, 1, k_MaxPyramidSize);
            
            // 确保 RT 数组大小足够
            if (_bloomPyramidUp == null || _bloomPyramidUp.Length != k_MaxPyramidSize)
            {
                _bloomPyramidUp = new RTHandle[k_MaxPyramidSize];
                _bloomPyramidDown = new RTHandle[k_MaxPyramidSize];
            }

            // 3. Prefilter Pass (提取高亮)
            // 先降一半分辨率，节省性能且增加模糊感
            desc.width = Mathf.Max(1, desc.width >> 1);
            desc.height = Mathf.Max(1, desc.height >> 1);
            
            RenderingUtils.ReAllocateIfNeeded(ref _bloomPyramidDown[0], desc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: "_BloomMipDown0");
            RenderingUtils.ReAllocateIfNeeded(ref _bloomPyramidUp[0], desc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: "_BloomMipUp0");

            // Source -> Down[0] (Prefilter)
            Blitter.BlitCameraTexture(cmd, source, _bloomPyramidDown[0], material, 0);

            // 4. Downsample Loop (降采样金字塔)
            int lastDown = 0;
            for (int i = 1; i < iterations; i++)
            {
                // 每次分辨率减半
                desc.width = Mathf.Max(1, desc.width >> 1);
                desc.height = Mathf.Max(1, desc.height >> 1);

                RenderingUtils.ReAllocateIfNeeded(ref _bloomPyramidDown[i], desc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: "_BloomMipDown" + i);
                RenderingUtils.ReAllocateIfNeeded(ref _bloomPyramidUp[i], desc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: "_BloomMipUp" + i);

                // Down[i-1] -> Down[i]
                Blitter.BlitCameraTexture(cmd, _bloomPyramidDown[i - 1], _bloomPyramidDown[i], material, 1);
                lastDown = i;
            }

            // 5. Upsample Loop (升采样并混合)
            // 从最小的一张开始，往上叠加
            // 先把最小的 Down 直接拷给 Up
            Blitter.BlitCameraTexture(cmd, _bloomPyramidDown[lastDown], _bloomPyramidUp[lastDown]);

            for (int i = lastDown - 1; i >= 0; i--)
            {
                // 设置上一级 Up 为输入
                // Upsample Pass 会混合：Up[i+1] (Blur) + Down[i] (High Res Detail)
                // 这里我们稍微简化逻辑：直接把 Up[i+1] 升采样并叠加到 Up[i] 上
                // 第二步：把 Up[i+1] (LowRes) 和 Down[i] (HighRes) 一起传给 Shader
                // 在 Shader 内部执行 Lerp 能量守恒融合，彻底替代会导致死白的 Additive 叠加模式
                material.SetTexture("_BloomMipDown", _bloomPyramidDown[i]);
                Blitter.BlitCameraTexture(cmd, _bloomPyramidUp[i + 1], _bloomPyramidUp[i], material, 2);
            }

            // 6. Composite (合成)
            // 此时 _bloomPyramidUp[0] 包含了最终的泛光纹理
            material.SetTexture(InternalShaderHelpers.ID._BloomTex, _bloomPyramidUp[0]);
            
            // Source + BloomTex -> Destination
            Blitter.BlitCameraTexture(cmd, source, destination, material, 3);
        }
        
        // 清理 RT
        public void Dispose()
        {
            if (_bloomPyramidDown != null)
            {
                for (int i = 0; i < _bloomPyramidDown.Length; i++)
                {
                    if (_bloomPyramidDown[i] != null) _bloomPyramidDown[i].Release();
                    if (_bloomPyramidUp[i] != null) _bloomPyramidUp[i].Release();
                }
            }
        }

        public override bool IsActive() => intensity.value > 0f;
    }
}