using System.Runtime.InteropServices;

namespace UnityEngine.Rendering.PostProcessing
{
    internal class SGSR2Upscaler_2PassFS: SGSR2Upscaler
    {
        protected override string VariantName => "SGSR2 2-Pass Fragment";

        private PropertySheet _sheet;
        private readonly RenderTargetIdentifier[] _mrt = new RenderTargetIdentifier[2];

        public override void CreateContext(PostProcessRenderContext context, Upscaling config)
        {
            base.CreateContext(context, config);

            _sheet = new PropertySheet(new Material(context.resources.shaders.sgsr2Upscaler.twoPassFragment));
        }

        public override void DestroyContext()
        {
            _sheet.Release();
            
            base.DestroyContext();
        }

        protected override void DoRender(CommandBuffer cmd, PostProcessRenderContext context, Upscaling config)
        {
            uint frameIndex = _frameCount % 2;

            cmd.SetGlobalTexture("InputColor", context.source);
            _sheet.properties.SetTexture("MotionDepthClipAlphaBuffer", _motionDepthClipAlpha);
            _sheet.properties.SetTexture("PrevOutput", _upscaleHistory[frameIndex ^ 1]);
            _sheet.properties.SetConstantBuffer("cbSGSR2", _paramsBuffer, 0, Marshal.SizeOf<SGSR2.Params>());
            
            cmd.BlitFullscreenTriangle(BuiltinRenderTextureType.None, _motionDepthClipAlpha, _sheet, 0);

            _mrt[0] = context.destination;
            _mrt[1] = _upscaleHistory[frameIndex];
            cmd.BlitFullscreenTriangle(BuiltinRenderTextureType.None, _mrt, BuiltinRenderTextureType.None, _sheet, 1);
        }
    }
}