using Ryujinx.Graphics.GAL;
using Ryujinx.Graphics.Vulkan.Queries;
using Silk.NET.Vulkan;
using System;
using System.Collections.Generic;

namespace Ryujinx.Graphics.Vulkan
{
    class PipelineFull : PipelineBase, IPipeline
    {
        private const ulong MinByteWeightForFlush = 256 * 1024 * 1024; // MiB

        private readonly List<(QueryPool, bool)> _activeQueries;
        private CounterQueueEvent _activeConditionalRender;

        private readonly List<BufferedQuery> _pendingQueryCopies;

        private ulong _byteWeight;

        private readonly List<BufferHolder> _backingSwaps;

        public PipelineFull(VulkanRenderer gd, Device device) : base(gd, device)
        {
            _activeQueries = new List<(QueryPool, bool)>();
            _pendingQueryCopies = new();
            _backingSwaps = new();

            CommandBuffer = (Cbs = gd.CommandBufferPool.Rent()).CommandBuffer;
        }

        private void CopyPendingQuery()
        {
            foreach (var query in _pendingQueryCopies)
            {
                query.PoolCopy(Cbs);
            }

            _pendingQueryCopies.Clear();
        }

        public void ClearRenderTargetColor(int index, int layer, int layerCount, uint componentMask, ColorF color)
        {
            if (FramebufferParams == null)
            {
                return;
            }

            if (componentMask != 0xf)
            {
                // We can't use CmdClearAttachments if not writing all components,
                // because on Vulkan, the pipeline state does not affect clears.
                var dstTexture = FramebufferParams.GetAttachment(index);
                if (dstTexture == null)
                {
                    return;
                }

                Span<float> clearColor = stackalloc float[4];
                clearColor[0] = color.Red;
                clearColor[1] = color.Green;
                clearColor[2] = color.Blue;
                clearColor[3] = color.Alpha;

                // TODO: Clear only the specified layer.
                Gd.HelperShader.Clear(
                    Gd,
                    dstTexture,
                    clearColor,
                    componentMask,
                    (int)FramebufferParams.Width,
                    (int)FramebufferParams.Height,
                    FramebufferParams.AttachmentFormats[index],
                    FramebufferParams.GetAttachmentComponentType(index),
                    ClearScissor);
            }
            else
            {
                ClearRenderTargetColor(index, layer, layerCount, color);
            }
        }

        public void EndHostConditionalRendering()
        {
            if (Gd.Capabilities.SupportsConditionalRendering)
            {
                // Gd.ConditionalRenderingApi.CmdEndConditionalRendering(CommandBuffer);
            }
            else
            {
                // throw new NotSupportedException();
            }

            _activeConditionalRender?.ReleaseHostAccess();
            _activeConditionalRender = null;
        }

        public bool TryHostConditionalRendering(ICounterEvent value, ulong compare, bool isEqual)
        {
            // Compare an event and a constant value.
            if (value is CounterQueueEvent evt)
            {
                // Easy host conditional rendering when the check matches what GL can do:
                //  - Event is of type samples passed.
                //  - Result is not a combination of multiple queries.
                //  - Comparing against 0.
                //  - Event has not already been flushed.

                if (compare == 0 && evt.Type == CounterType.SamplesPassed && evt.ClearCounter)
                {
                    if (!value.ReserveForHostAccess())
                    {
                        // If the event has been flushed, then just use the values on the CPU.
                        // The query object may already be repurposed for another draw (eg. begin + end).
                        return false;
                    }

                    if (Gd.Capabilities.SupportsConditionalRendering)
                    {
                        // var buffer = evt.GetBuffer().Get(Cbs, 0, sizeof(long)).Value;
                        // var flags = isEqual ? ConditionalRenderingFlagsEXT.InvertedBitExt : 0;

                        // var conditionalRenderingBeginInfo = new ConditionalRenderingBeginInfoEXT
                        // {
                        //     SType = StructureType.ConditionalRenderingBeginInfoExt,
                        //     Buffer = buffer,
                        //     Flags = flags,
                        // };

                        // Gd.ConditionalRenderingApi.CmdBeginConditionalRendering(CommandBuffer, conditionalRenderingBeginInfo);
                    }

                    _activeConditionalRender = evt;
                    return true;
                }
            }

            // The GPU will flush the queries to CPU and evaluate the condition there instead.

            FlushPendingQuery(); // The thread will be stalled manually flushing the counter, so flush commands now.
            return false;
        }

        public bool TryHostConditionalRendering(ICounterEvent value, ICounterEvent compare, bool isEqual)
        {
            FlushPendingQuery(); // The thread will be stalled manually flushing the counter, so flush commands now.
            return false;
        }

        private void FlushPendingQuery()
        {
            if (AutoFlush.ShouldFlushQuery())
            {
                FlushCommandsImpl();
            }
        }

        public CommandBufferScoped GetPreloadCommandBuffer()
        {
            PreloadCbs ??= Gd.CommandBufferPool.Rent();

            return PreloadCbs.Value;
        }

        public void FlushCommandsIfWeightExceeding(IAuto disposedResource, ulong byteWeight)
        {
            bool usedByCurrentCb = disposedResource.HasCommandBufferDependency(Cbs);

            if (PreloadCbs != null && !usedByCurrentCb)
            {
                usedByCurrentCb = disposedResource.HasCommandBufferDependency(PreloadCbs.Value);
            }

            if (usedByCurrentCb)
            {
                // Since we can only free memory after the command buffer that uses a given resource was executed,
                // keeping the command buffer might cause a high amount of memory to be in use.
                // To prevent that, we force submit command buffers if the memory usage by resources
                // in use by the current command buffer is above a given limit, and those resources were disposed.
                _byteWeight += byteWeight;

                if (_byteWeight >= MinByteWeightForFlush)
                {
                    FlushCommandsImpl();
                }
            }
        }

        private void TryBackingSwaps()
        {
            CommandBufferScoped? cbs = null;

            _backingSwaps.RemoveAll(holder => holder.TryBackingSwap(ref cbs));

            cbs?.Dispose();
        }

        public void AddBackingSwap(BufferHolder holder)
        {
            _backingSwaps.Add(holder);
        }

        public void Restore()
        {
            if (Pipeline != null)
            {
                Gd.Api.CmdBindPipeline(CommandBuffer, Pbp, Pipeline.Get(Cbs).Value);
            }

            SignalCommandBufferChange();

            DynamicState.ReplayIfDirty(Gd.Api, CommandBuffer);
        }

        public void FlushCommandsImpl()
        {
            AutoFlush.RegisterFlush(DrawCount);
            EndRenderPass();

            foreach ((var queryPool, _) in _activeQueries)
            {
                Gd.Api.CmdEndQuery(CommandBuffer, queryPool, 0);
            }

            _byteWeight = 0;

            if (PreloadCbs != null)
            {
                PreloadCbs.Value.Dispose();
                PreloadCbs = null;
            }

            CommandBuffer = (Cbs = Gd.CommandBufferPool.ReturnAndRent(Cbs)).CommandBuffer;
            Gd.RegisterFlush();

            // Restore per-command buffer state.

            foreach ((var queryPool, var isOcclusion) in _activeQueries)
            {
                bool isPrecise = Gd.Capabilities.SupportsPreciseOcclusionQueries && isOcclusion;

                Gd.Api.CmdResetQueryPool(CommandBuffer, queryPool, 0, 1);
                Gd.Api.CmdBeginQuery(CommandBuffer, queryPool, 0, isPrecise ? QueryControlFlags.PreciseBit : 0);
            }

            Gd.ResetCounterPool();

            TryBackingSwaps();

            Restore();
        }

        public void BeginQuery(BufferedQuery query, QueryPool pool, bool needsReset, bool isOcclusion, bool fromSamplePool)
        {
            if (needsReset)
            {
                EndRenderPass();

                Gd.Api.CmdResetQueryPool(CommandBuffer, pool, 0, 1);

                if (fromSamplePool)
                {
                    // Try reset some additional queries in advance.

                    Gd.ResetFutureCounters(CommandBuffer, AutoFlush.GetRemainingQueries());
                }
            }

            bool isPrecise = Gd.Capabilities.SupportsPreciseOcclusionQueries && isOcclusion;
            Gd.Api.CmdBeginQuery(CommandBuffer, pool, 0, isPrecise ? QueryControlFlags.PreciseBit : 0);

            _activeQueries.Add((pool, isOcclusion));
        }

        public void EndQuery(QueryPool pool)
        {
            Gd.Api.CmdEndQuery(CommandBuffer, pool, 0);

            for (int i = 0; i < _activeQueries.Count; i++)
            {
                if (_activeQueries[i].Item1.Handle == pool.Handle)
                {
                    _activeQueries.RemoveAt(i);
                    break;
                }
            }
        }

        public void CopyQueryResults(BufferedQuery query)
        {
            _pendingQueryCopies.Add(query);

            if (AutoFlush.RegisterPendingQuery())
            {
                FlushCommandsImpl();
            }
        }

        protected override void SignalAttachmentChange()
        {
            if (AutoFlush.ShouldFlushAttachmentChange(DrawCount))
            {
                FlushCommandsImpl();
            }
        }

        protected override void SignalRenderPassEnd()
        {
            CopyPendingQuery();
        }
    }
}