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

    File: IOSubmit.Linux.hpp
    Date: 2022-4-12
    Author: Reece
    Note: I want APCs, overlapped, and event based IO on Linux. Gib. 
***/
#pragma once

#include <linux/aio_abi.h>
#include <poll.h>

namespace Aurora::IO::UNIX
{
    struct ASubmittable
    {
        ASubmittable();
        ~ASubmittable();

        virtual void LIOS_Process(AuUInt32 read, bool failure, int err, bool mark) = 0;

        void LIOS_SendProcess(AuUInt32 read, bool failure, int err, bool mark = false);
        void LIOS_Init(const AuSPtr<void> &pin);
        void LIOS_Reset();
        bool LIOS_Cancel();
        bool HasState();

        void LIOS_ProcessStack(AuUInt32 read, bool failure, int err, bool mark);
    #if defined(__AUHAS_COROUTINES_CO_AWAIT) && defined(AU_LANG_CPP_20_)
        AuVoidTask LIOS_ProcessStack_(AuUInt32 read, bool failure, int err, bool mark);
    #endif

        void SetMemory(const AuMemoryViewRead &view);
        void SetMemory(const AuMemoryViewWrite &view);

        AuUInt64 GetData();
        AuUInt64 GetBuf();
        AuUInt   GetBufLength();

        iocb &   GetIOCB();

        int GetOrCreateFdPollForBlockingRead(int fd);

        // Hack for blocking reads
        bool bIsReadPending {};
        bool bIsWritePending {};
        AuUInt64 offset2 {};
        int fd2 {};
        AuLoop::ILSEvent *optEvent2 {};
        aio_context_t abortContext {};

    // TODO:
        AuSPtr<void> pin_;
        AuSPtr<void> memPin_;
        AuMemoryViewRead readView;
        AuMemoryViewWrite writeView;
    private:
        AuUInt64 dataPtr_ {};
        AuUInt dataLen_ {};
        int tempEPoll {-1};
        iocb cb {};
    };

    // Yield/Wait shims
    bool LinuxOverlappedWaitForOne       (AuUInt32 timeout, AuUInt read, AuUInt write, bool &bReadTriggered, bool &bWriteTriggered);
    bool LinuxOverlappedWaitForAtleastOne(AuUInt32 timeout, const AuList<AuUInt> &handles, const AuList<AuUInt> &handlesWrite, AuUInt &one, AuUInt &two);

    bool LinuxOverlappedPoll     (AuUInt32 timeout);

    int  LinuxOverlappedEpollShim(int epfd, struct epoll_event *events,
                                  int maxevents, int timeout);
    // TODO: 
    //int  LinuxOverlappedPosixPoll(struct pollfd *pPollFDs, nfds_t uCount, int timeout);

    bool LinuxOverlappedYield(bool bUserspaceOnly = false);



    // Work queue
    bool LinuxOverlappedSubmitRead (int fd, AuUInt offset, ASubmittable *context, AuLoop::ILSEvent *optEvent, bool bWaitForRead = false /* use on unsupported blocking interfaces. costs an epoll to work around >current< limitiations in io_submit*/);
    bool LinuxOverlappedSubmitWrite(int fd, AuUInt offset, ASubmittable *context, AuLoop::ILSEvent *optEvent);
    // TODO: Stream copy operations

    // Bookkeeping
    bool SendIOBuffers();
}