using UnityEngine;
using UnityEngine.Experimental.Rendering;

namespace FidelityFX.FrameGen
{
    internal class OpticalFlowResources: FfxResourcesBase
    {
        public readonly RenderTexture[][] OpticalFlowInputLevels = 
        {
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
        };
        
        public readonly RenderTexture[][] OpticalFlowLevels = 
        {
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
            new RenderTexture[2],
        };
        
        public RenderTexture OpticalFlowSCDHistogram;
        public RenderTexture OpticalFlowSCDPreviousHistogram;
        public RenderTexture OpticalFlowSCDTemp;
        
        public void Create(in OpticalFlow.ContextDescription contextDescription)
        {
            Vector2Int opticalFlowInputTextureSize = contextDescription.resolution;
            Vector2Int opticalFlowTextureSize = OpticalFlow.GetOpticalFlowTextureSize(contextDescription.resolution, OpticalFlow.MinBlockSize);
            
            for (int level = 0; level < OpticalFlow.OpticalFlowMaxPyramidLevels; ++level)
            {
                CreateDoubleBufferedResource(OpticalFlowInputLevels[level], $"OPTICALFLOW_OpticalFlowInputLevel{level}-", opticalFlowInputTextureSize, GraphicsFormat.R8_UInt);
                CreateDoubleBufferedResource(OpticalFlowLevels[level], $"OPTICALFLOW_OpticalFlowLevel{level}-", opticalFlowTextureSize, GraphicsFormat.R16G16_SInt);

                opticalFlowTextureSize = NextLevelSize(opticalFlowTextureSize);
                opticalFlowInputTextureSize = new Vector2Int(opticalFlowInputTextureSize.x >> 1, opticalFlowInputTextureSize.y >> 1);
            }

            OpticalFlowSCDHistogram = CreateResource("OPTICALFLOW_OpticalFlowSCDHistogram", new Vector2Int(OpticalFlow.GetSCDHistogramTextureWidth(), 1), GraphicsFormat.R32_UInt);
            OpticalFlowSCDPreviousHistogram = CreateResource("OPTICALFLOW_OpticalFlowSCDPreviousHistogram", new Vector2Int(OpticalFlow.GetSCDHistogramTextureWidth(), 1), GraphicsFormat.R32_SFloat);
            OpticalFlowSCDTemp = CreateResource("OPTICALFLOW_OpticalFlowSCDTemp", new Vector2Int(3, 1), GraphicsFormat.R32_UInt);
        }

        public void Destroy()
        {
            DestroyResource(ref OpticalFlowSCDTemp);
            DestroyResource(ref OpticalFlowSCDPreviousHistogram);
            DestroyResource(ref OpticalFlowSCDHistogram);

            for (int level = 0; level < OpticalFlow.OpticalFlowMaxPyramidLevels; ++level)
            {
                DestroyResource(OpticalFlowLevels[level]);
                DestroyResource(OpticalFlowInputLevels[level]);
            }
        }

        private static Vector2Int NextLevelSize(Vector2Int size)
        {
            return new Vector2Int(AlignUp(size.x, 2) / 2, AlignUp(size.y, 2) / 2);
        }

        private static int AlignUp(int x, int y)
        {
            return (x + (y - 1)) & ~(y - 1);
        }
    }
}