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

namespace Framework.RenderFeature
{
    public class GaussBlurPass : ScriptableRenderPass
    {
        private GaussBlurFeature.Setting _setting;
        int                              tmpId1;

        RenderTargetIdentifier tmpRT1;

        // RTHandle                    rth_tempTex;
        RTHandle                    cameraColorTarget;
        string                      profilerTag;
        private static readonly int blurOffset  = Shader.PropertyToID ("_blurOffset");
        private static readonly int grayOffset  = Shader.PropertyToID ("_grayOffset");
        private static readonly int grayOffsetR = Shader.PropertyToID ("_grayOffsetR");
        private static readonly int grayOffsetG = Shader.PropertyToID ("_grayOffsetG");
        private static readonly int grayOffsetB = Shader.PropertyToID ("_grayOffsetB");
        private static readonly int overlyColor = Shader.PropertyToID ("_overlyColor");

        public GaussBlurPass Init (GaussBlurFeature.Setting setting, string cmdName)
        {
            this._setting    = setting;
            this.profilerTag = cmdName;
            return this;
        }

        public override void OnCameraSetup (CommandBuffer cmd, ref RenderingData renderingData)
        {
            if (this._setting is not { enable: true } || this.cameraColorTarget == null)
                return;
            RenderTextureDescriptor opaqueDesc = renderingData.cameraData.cameraTargetDescriptor;
            opaqueDesc.depthBufferBits = 0; //Color and depth cannot be combined in RTHandles
            // RenderingUtils.ReAllocateIfNeeded (ref rth_tempTex, opaqueDesc, FilterMode.Bilinear, TextureWrapMode.Clamp, name: "_TempTex");

            var width  = opaqueDesc.width  / 2;
            var height = opaqueDesc.height / 2;

            tmpId1 = Shader.PropertyToID ("tmpBlurRT1");
            cmd.GetTemporaryRT (tmpId1, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGB32);
            // cmd.GetTemporaryRT(this.cameraColorTarget, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGB32);
            tmpRT1 = new RenderTargetIdentifier (tmpId1);

            // (父类函数)指定pass的render target
            ConfigureTarget (this.cameraColorTarget);
        }


        public override void Execute (ScriptableRenderContext context, ref RenderingData renderingData)
        {
#if UNITY_EDITOR
            if (!UnityEditor.EditorApplication.isPlaying)
            {
                return;
            }
#endif
            if (!this._setting.enable)
                return;

            if (this.cameraColorTarget == null || this.cameraColorTarget.rt == null)
            {
                return;
            }

            CommandBuffer cmd = CommandBufferPool.Get (profilerTag);
            if (this._setting.isBlur && this._setting.blurProgress > 0 && this._setting.blurMaterial != null)
            {
                this._setting.blurMaterial.SetFloat (blurOffset, this._setting.blurProgress);
                for (int i = 1; i < this._setting.blurPasses; ++i)
                {
                    cmd.Blit (cameraColorTarget , tmpRT1 , _setting.blurMaterial);
                    cmd.Blit (tmpRT1 , cameraColorTarget);
                }
            }

            if (this._setting.isGray)
            {
                this._setting.grayMaterial.SetFloat (grayOffset, this._setting.grayScale);
                this._setting.grayMaterial.SetFloat (grayOffsetR, this._setting.colorChannel_R);
                this._setting.grayMaterial.SetFloat (grayOffsetG, this._setting.colorChannel_G);
                this._setting.grayMaterial.SetFloat (grayOffsetB, this._setting.colorChannel_B);
                this._setting.grayMaterial.SetColor (overlyColor, this._setting.grayColor);
                cmd.Blit (cameraColorTarget , tmpRT1 , _setting.grayMaterial);
                cmd.Blit (tmpRT1 , cameraColorTarget);
            }

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


        public void SetTarget (RTHandle rendererCameraColorTargetHandle)
        {
            this.cameraColorTarget = rendererCameraColorTargetHandle;
        }
    }
}