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

[CreateAssetMenu]
public class GammaUIFix : ScriptableRendererFeature
{
    public Material material;

    public GammaUIFix()
    {
    }

    public override void Create()
    {
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        DrawUIIntoRTPass d = new DrawUIIntoRTPass(RenderPassEvent.BeforeRenderingTransparents);
        BlitPass b = new BlitPass(RenderPassEvent.AfterRenderingTransparents, material);

        renderer.EnqueuePass(d);
        renderer.EnqueuePass(b);
    }

    //-------------------------------------------------------------------------

    class DrawUIIntoRTPass : ScriptableRenderPass
    {
        //The temporary UI texture
        public static int m_uiRTid = Shader.PropertyToID("_MainTex");
        public static RenderTargetIdentifier m_uiRT = new RenderTargetIdentifier(m_uiRTid);

        public DrawUIIntoRTPass(RenderPassEvent renderPassEvent)
        {
            this.renderPassEvent = renderPassEvent;
        }

        public override void Configure(CommandBuffer cmd, RenderTextureDescriptor cameraTextureDescripor)
        {
            RenderTextureDescriptor descriptor = cameraTextureDescripor;
            descriptor.colorFormat = RenderTextureFormat.Default;
            cmd.GetTemporaryRT(m_uiRTid, descriptor);
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            CommandBuffer cmd = CommandBufferPool.Get("Draw UI Into RT Pass");

            cmd.SetRenderTarget(m_uiRT);
            cmd.ClearRenderTarget(true,true,Color.clear);

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

        public override void FrameCleanup(CommandBuffer cmd)
        {
            if (cmd == null)
                throw new ArgumentNullException("cmd");

            base.FrameCleanup(cmd);
        }
    }

    //-------------------------------------------------------------------------

    class BlitPass : ScriptableRenderPass
    {
        Material material;

        public BlitPass(RenderPassEvent renderPassEvent, Material mat)
        {
            this.renderPassEvent = renderPassEvent;
            this.material = mat;
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            CommandBuffer cmd = CommandBufferPool.Get("Blit Pass");

            cmd.Blit(DrawUIIntoRTPass.m_uiRT,renderingData.cameraData.renderer.cameraColorTargetHandle,material);

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

        public override void FrameCleanup(CommandBuffer cmd)
        {
            if (cmd == null)
                throw new ArgumentNullException("cmd");

            cmd.ReleaseTemporaryRT(DrawUIIntoRTPass.m_uiRTid);

            base.FrameCleanup(cmd);
        }
    }

    //-------------------------------------------------------------------------
}