using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;
using UnityEngine.Experimental.Rendering;

public class BloomRenderFeature : ScriptableRendererFeature
{
    [System.Serializable]
    public class BloomSettings
    {
        public RenderPassEvent passEvent = RenderPassEvent.AfterRenderingPostProcessing;

        public Shader blurShader;
        public Shader compositeShader;

        [Range(0, 4)]
        public int downsample = 1;

        [Range(0.0f, 2.0f)]
        public float threshold = 1.0f;

        [Range(0.0f, 10.0f)]
        public float radius = 1.0f;

        [Range(0.0f, 10.0f)]
        public float intensity = 1.0f;

        // x = w2, y = w1, z = w0   (symmetric 5-tap kernel)
        public Vector3 weights = new Vector3(0.2f, 0.4f, 0.8f);
    }

    BloomPass bloomPass;

    Material blurMat;
    Material compositeMat;

    public BloomSettings settings = new BloomSettings();

    // ────────────────────────────────────────────────────────────────
    // CREATE
    // ────────────────────────────────────────────────────────────────
    public override void Create()
    {
        if (settings.blurShader)
            blurMat = CoreUtils.CreateEngineMaterial(settings.blurShader);

        if (settings.compositeShader)
            compositeMat = CoreUtils.CreateEngineMaterial(settings.compositeShader);

        bloomPass = new BloomPass(settings);
        bloomPass.renderPassEvent = settings.passEvent;
    }


    // ────────────────────────────────────────────────────────────────
    // ONLY enqueue pass here (NO camera target access!)
    // ────────────────────────────────────────────────────────────────
    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        if (blurMat == null || compositeMat == null)
            return;

        // Pass only materials
        bloomPass.Setup(blurMat, compositeMat);
        renderer.EnqueuePass(bloomPass);
    }



    // ======================================================================
    // BLOOM PASS
    // ======================================================================

    class BloomPass : ScriptableRenderPass
    {
        BloomSettings settings;

        Material blurMat;
        Material compositeMat;

        RTHandle rt1;
        RTHandle rt2;

        // final camera target (RenderTargetIdentifier)
        RenderTargetIdentifier source;

        string tag = "BloomPass";

        public BloomPass(BloomSettings settings)
        {
            this.settings = settings;
        }

        public void Setup(Material blurMat, Material compositeMat)
        {
            this.blurMat = blurMat;
            this.compositeMat = compositeMat;
        }


        // ────────────────────────────────────────────────────────────────
        // VALID place to access cameraColorTargetHandle
        // ────────────────────────────────────────────────────────────────
        public override void OnCameraSetup(CommandBuffer cmd, ref RenderingData renderingData)
        {
            // SAFE: this is the correct place to access cameraColorTargetHandle
            source = renderingData.cameraData.renderer.cameraColorTargetHandle;

            float scale = 1f / (1 << settings.downsample);
            Vector2 scaleFactor = new Vector2(scale, scale);

            rt1 = RTHandles.Alloc(
                scaleFactor,
                colorFormat: GraphicsFormat.R16G16B16A16_SFloat,
                filterMode: FilterMode.Bilinear,
                name: "_BloomRT1"
            );

            rt2 = RTHandles.Alloc(
                scaleFactor,
                colorFormat: GraphicsFormat.R16G16B16A16_SFloat,
                filterMode: FilterMode.Bilinear,
                name: "_BloomRT2"
            );
        }


        // ────────────────────────────────────────────────────────────────
        // EXECUTE BLOOM EFFECT
        // ────────────────────────────────────────────────────────────────
        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            if (blurMat == null || compositeMat == null)
                return;

            CommandBuffer cmd = CommandBufferPool.Get(tag);

            // Pass parameters
            blurMat.SetFloat("_Threshold", settings.threshold);
            blurMat.SetFloat("_Radius", settings.radius);
            blurMat.SetFloat("_Intensity", settings.intensity);
            blurMat.SetVector("_Weights", new Vector4(settings.weights.x, settings.weights.y, settings.weights.z, 0));


            // 1. Extract bright areas
            cmd.Blit(source, rt1, blurMat, 0);

            // 2. Blur horizontal
            blurMat.SetVector("_Direction", new Vector4(1, 0, 0, 0));
            cmd.Blit(rt1, rt2, blurMat, 1);

            // 3. Blur vertical
            blurMat.SetVector("_Direction", new Vector4(0, 1, 0, 0));
            cmd.Blit(rt2, rt1, blurMat, 1);

            // 4. Composite bloom back
            compositeMat.SetFloat("_Intensity", settings.intensity);
            cmd.Blit(rt1, source, compositeMat, 0);

            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);
        }


        // ────────────────────────────────────────────────────────────────
        // CLEANUP (Release RTHandles)
        // ────────────────────────────────────────────────────────────────
        public override void OnCameraCleanup(CommandBuffer cmd)
        {
            if (rt1 != null) RTHandles.Release(rt1);
            if (rt2 != null) RTHandles.Release(rt2);
        }
    }
}