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

    File: AuProcessSectionFileMapView.Unix.cpp
    Date: 2022-08-09
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "AuProcessSectionFileMapView.Unix.hpp"
#include "AuProcessSectionViewReserved.Unix.hpp"
#include "AuProcessSectionView.Unix.hpp"
#include <sys/mman.h>

namespace Aurora::Process
{
    ProcessSectionFileMapView::ProcessSectionFileMapView(AuUInt uAddress,
                                                         AuUInt uLength,
                                                         bool bShouldUnmap,
                                                         int optFd) :
        uAddress_(uAddress),
        uLength_(uLength),
        bShouldUnmap_(bShouldUnmap),
        optFd_(optFd)
    {
    
    }

    ProcessSectionFileMapView::~ProcessSectionFileMapView()
    {
        Unmap();
    }

    void ProcessSectionFileMapView::Unmap()
    {
        AU_LOCK_GUARD(this->mutex_);

        if (AuAtomicLoad(&this->uInUse_))
        {
            SysPushErrorResourceLocked("Cannot unmap memory while it's in use");
            return;
        }

        if (AuExchange(this->bIsDead_, true))
        {
            return;
        }

        if (this->uAddress_)
        {
            if (this->pSharedSectionHint)
            {
                AuStaticCast<ProcessSectionViewReserved>(this->pSharedSectionHint)->Release(this->uAddress_);
            }
          
            if (this->bShouldUnmap_)
            {
                ::munmap(this->GetBasePointer(), this->uLength_);
            }
            else
            {
                if (!::mmap(this->GetBasePointer(), this->uLength_, PROT_NONE, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0))
                {
                    ::mmap(this->GetBasePointer(), this->uLength_, PROT_READ /*coping*/, MAP_ANONYMOUS | MAP_PRIVATE | MAP_FIXED, 0, 0);
                }
            }

            this->uAddress_ = 0;
        }

    // TODO: posix explicitly states this isnt necessary
        int fd {-1};
        if ((fd = AuExchange(this->optFd_, -1)) != -1)
        {
            ::close(fd);
        }
    }

    bool ProcessSectionFileMapView::Flush(AuUInt uOffset, AuUInt uLength)
    {
        return ::msync(this->GetPointer(uOffset), uLength, MS_SYNC) == 0;
    }

    AuMemoryViewWrite ProcessSectionFileMapView::ToWriteView()
    {
        return AuMemoryViewWrite((char *)this->uAddress_, this->uLength_, &this->uInUse_);
    }

    AuMemoryViewRead ProcessSectionFileMapView::ToReadView()
    {
        return AuMemoryViewRead((char *)this->uAddress_, this->uLength_, &this->uInUse_);
    }

    AuUInt ProcessSectionFileMapView::GetBaseAddress()
    {
        return this->uAddress_;
    }

    AuUInt ProcessSectionFileMapView::GetAddress(AuUInt uOffset)
    {
        return this->uAddress_ && this->uLength_ > uOffset ?
            this->uAddress_ + uOffset :
            0;
    }

    AuUInt8 *ProcessSectionFileMapView::GetBasePointer()
    {
        return AuReinterpretCast<AuUInt8 *>(this->uAddress_);
    }

    AuUInt8 *ProcessSectionFileMapView::GetPointer(AuUInt uOffset)
    {
        return this->uAddress_ && this->uLength_ > uOffset ?
            AuReinterpretCast<AuUInt8 *>(this->uAddress_) + uOffset :
            0;
    }

    bool ProcessSectionFileMapView::LockSwap()
    {
        if (!this->uAddress_)
        {
            return false;
        }

        return AuMemory::SwapLock::Lock({ { this->uAddress_, this->uLength_ } });
    }

    bool ProcessSectionFileMapView::UnlockSwap()
    {
        if (!this->uAddress_)
        {
            return false;
        }

        return AuMemory::SwapLock::Unlock({ { this->uAddress_, this->uLength_ } });
    }
}