using System.Collections.Generic;

namespace UnityEngine.Rendering.HighDefinition.AMD.FSR3
{
    public class FSR3Upscaler: UpscalerPlugin
    {
        private static FSR3GraphicsDevice sGraphicsDeviceInstance;
        
        public override bool Load() => true;

        public override bool IsLoaded() => true;

        public override GraphicsDevice CreateGraphicsDevice()
        {
            if (sGraphicsDeviceInstance != null)
            {
                sGraphicsDeviceInstance.Shutdown();
                sGraphicsDeviceInstance.Initialize();
                return sGraphicsDeviceInstance;
            }

            var graphicsDevice = new FSR3GraphicsDevice();
            if (graphicsDevice.Initialize())
            {
                sGraphicsDeviceInstance = graphicsDevice;
                return graphicsDevice;
            }

            Debug.LogWarning("Failed to initialize FSR3 Graphics Device");
            return null;
        }

        public override GraphicsDevice device => sGraphicsDeviceInstance;
    }

    public class FSR3GraphicsDevice : GraphicsDevice
    {
        private static readonly Stack<FSR3Context> sContextPool = new();
        
        internal bool Initialize()
        {
            // TODO
            return false;
        }

        internal void Shutdown()
        {
            // TODO
        }
        
        public override FSR2Context CreateFeature(CommandBuffer cmd, in FSR2CommandInitializationData initSettings)
        {
            var context = sContextPool.Count != 0 ? sContextPool.Pop() : new FSR3Context();
            context.Init(initSettings); // TODO might need some way to distinguish between contexts (see featureSlot)
            return context;
        }

        public override void DestroyFeature(CommandBuffer cmd, FSR2Context fsrContext)
        {
            var context = (FSR3Context)fsrContext;
            context.Reset();
            sContextPool.Push(context);
        }

        public override void ExecuteFSR2(CommandBuffer cmd, FSR2Context fsrContext, in FSR2TextureTable textures)
        {
            ((FSR3Context)fsrContext).Draw(cmd, in textures);
        }

        public override bool GetRenderResolutionFromQualityMode(FSR2Quality qualityMode, uint displayWidth, uint displayHeight, out uint renderWidth, out uint renderHeight)
        {
            throw new System.NotImplementedException();
        }

        public override float GetUpscaleRatioFromQualityMode(FSR2Quality qualityMode)
        {
            throw new System.NotImplementedException();
        }
    }

    public class FSR3Context : FSR2Context
    {
        private FSR2CommandInitializationData _initData;
        public override ref FSR2CommandInitializationData initData => ref _initData;

        private FSR2CommandExecutionData _executeData;
        public override ref FSR2CommandExecutionData executeData => ref _executeData;

        internal void Init(in FSR2CommandInitializationData initSettings)
        {
            // TODO: create internal context data
            _initData = initSettings;
        }

        internal void Reset()
        {
            // TODO: destroy internal context data
            _initData = new FSR2CommandInitializationData();
            _executeData = new FSR2CommandExecutionData();
        }

        internal void Draw(CommandBuffer cmd, in FSR2TextureTable textures)
        {
            
        }
    }
}