/***
    Copyright (C) 2022 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: IOPipeProcessor.hpp
    Date: 2022-6-6
    Author: Reece
***/
#pragma once

#include <Aurora/Utility/ThroughputCalculator.hpp>

namespace Aurora::IO
{
    struct IOProcessor;
    struct IOPipeWork;
    struct IOPipeProcessor;

    struct IOWorkStart : IIOProcessorWorkUnit
    {
        IOWorkStart(IOPipeWork *parent);

        void OnRun() override;
        void OnCanceled()  override;

        IOPipeWork *parent {};
    };

    struct IOWorkEnd : IIOProcessorWorkUnit
    {
        IOWorkEnd(IOPipeWork *parent);

        void OnRun() override;
        void OnCanceled()  override;

        IOPipeWork *parent {};
    };
    
    struct IOPipeWork :
        IIOPipeWork,
        IIOEventListenerFunctional,
        AuEnableSharedFromThis<IIOPipeWork>
    {
        IOPipeWork(const AuSPtr<IOPipeProcessor> &pParent, const IOPipeRequestAIO &request);
        IOPipeWork(const AuSPtr<IOPipeProcessor> &pParent, const IOPipeRequestBasic &request);

        AuSPtr<IIOProcessorItem> pWatch;

        void Tick_FrameEpilogue() override;
        void Tick_Any()           override;

        void OnFailureCompletion() override;
        void OnNominalCompletion() override;

        virtual bool Start() override;

        virtual bool End() override;

        virtual AuInt64 GetLastTickMS() override;
        virtual AuInt64 GetStartTickMS() override;

        virtual AuUInt64 GetBytesProcessed() override;
        virtual AuUInt64 GetBytesProcessedInterframe() override;

        virtual double GetPredictedThroughput() override;

        virtual AuUInt SetNextFrameTargetLength(AuUInt uLength) override;

        virtual AuUInt GetNextFrameTargetLength() override;

        virtual bool ReallocateLater(AuUInt uLength) override;

        virtual bool IsReallocationPending() override;

        virtual bool DidLastReallocFail() override;

        virtual AuUInt GetSuccessfulReallocations() override;

        virtual AuUInt GetFailedReallocations() override;

        virtual void RunOnThread();
        virtual void TerminateOnThread(bool bError = false);

        // INIT
        void PrepareStream();
        void PrepareAsync();

        // PUMP
        void AsyncPump();
        void StreamPump();

        // END/INIT
        void ReadNext();
        void ReadNextAsync();

        AuUInt32 TryPump();

        void DoReallocTick();
        void FailRealloc();
        void SuccessRealloc();

        AuUInt GetNextFrameLength(AuUInt uBytesMax);
        AuUInt GetNextFrameLength2();

        AuMemoryViewWrite nextWriteAsync_;
        IOPipeRequest request {};
        bool bShouldReadNext { false };
        bool bShouldBypassIOWatch { false };

        bool IsAtRequestedEnd();
        AuByteBuffer *GetBuffer();

        AuSPtr<Protocol::IProtocolStack> pProtocolStack;

    private:
        AuSPtr<IOPipeProcessor> parent_;

        struct /*not a union. the following members are mutex*/
        {
            IOPipeInputData input_;
            AuSPtr<IAsyncTransaction> pAsyncTransaction_;
            AuSPtr<Adapters::IAsyncStreamAdapter> pAsyncAdapter_;
            AuSPtr<Adapters::IAsyncStreamReader> pAsyncStreamReader_;
        };

        IOPipeCallback output;
        IOWorkStart startCallback;
        IOWorkEnd endCallback;
        AuUInt64 iStartTickMS_ {};
        bool bActive {true};
        AuUInt32 uBufferSize_ {};
        AuUInt32 uFrameCap_ {};
        AuUInt uBytesWritten_ {};
        AuUInt uBytesWrittenLimit_ {};
        AuUInt uBytesWrittenTarget_ {};
        AuUInt uBytesPerFrame_ {};
        bool bReadEntireAllocation_ {};
        AuByteBuffer buffer_;
        Aurora::Utility::ThroughputCalculator throughput_;
        AuUInt bytesProcessedInterframe_ {};
        bool bWritingAheadLowLatency {};
        bool bWritingAheadIOUOneTerminate {};
        AuUInt uPendingRealloc_ {};
        AuUInt uReallocs_[2] { 0, 0 };
        bool bLastReallocFail { true };
    };


    struct IOPipeProcessor : IIOPipeProcessor
    {
        IOPipeProcessor(IOProcessor *parent);

        virtual AuSPtr<IIOPipeWork> NewBasicPipe(const IOPipeRequestBasic &request) override;

        virtual AuSPtr<IIOPipeWork> NewAIOPipe(const IOPipeRequestAIO &request) override;
      
        IOProcessor *parent_;
    };
}