using System.Runtime.InteropServices;

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

        private Material _material;
        private readonly RenderTargetIdentifier[] _mrt = new RenderTargetIdentifier[2];

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

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

        public override void DestroyContext()
        {
            RuntimeUtilities.Destroy(_material);
            
            base.DestroyContext();
        }

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

            // TODO: try using a PropertySheet here again, now that PPV2 is functional 
            cmd.SetGlobalTexture("InputColor", context.source);
            cmd.SetGlobalTexture("MotionDepthClipAlphaBuffer", _motionDepthClipAlpha);
            cmd.SetGlobalTexture("PrevOutput", _upscaleHistory[frameIndex ^ 1]);
            cmd.SetGlobalConstantBuffer(_paramsBuffer, "cbSGSR2", 0, Marshal.SizeOf<SGSR2.Params>());

            cmd.SetRenderTarget(_motionDepthClipAlpha, context.source);
            cmd.DrawMesh(RuntimeUtilities.fullscreenTriangle, Matrix4x4.identity, _material, 0, 0);
            
            _mrt[0] = context.destination;
            _mrt[1] = _upscaleHistory[frameIndex];
            cmd.SetRenderTarget(_mrt, context.destination);
            cmd.DrawMesh(RuntimeUtilities.fullscreenTriangle, Matrix4x4.identity, _material, 0, 1);
        }
    }
}