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

    File: AuIPCPipe.Linux.cpp
    Date: 2022-4-14
    Author: Reece
***/
#include <Source/RuntimeInternal.hpp>
#include "IPC.hpp"
#include "AuIPCHandle.hpp"
#include "AuIPCPipe.Unix.hpp"
#include <Source/IO/UNIX/FDIpcServer.hpp>
#include <fcntl.h>
#include <sys/ioctl.h>
#include <termios.h>
#include <Source/IO/AuIOHandle.hpp>

namespace Aurora::IO::IPC
{
    //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
    // Pipes
    //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////

    IPCPipeImpl::~IPCPipeImpl()
    {
        int fd {-1};

        if (secondary[0] == -1)
        {
            this->mutex_->Unlock();
            this->event_->Reset();
        }

        if ((fd = AuExchange(fds[0], -1)) != -1)
        {
            IO::UNIX::FDServeEnd(readEnd_);
            //::close(fd);
        }

        if ((fd = AuExchange(fds[1], -1)) != -1)
        {
            IO::UNIX::FDServeEnd(writeEnd_);
            //::close(fd);
        }

        if ((fd = AuExchange(secondary[0], -1)) != -1)
        {
            ::close(fd);
        }

        if ((fd = AuExchange(secondary[1], -1)) != -1)
        {
            ::close(fd);
        }

        fsHandle_.reset();
        fsStream_.reset();

    }
    
    void IPCPipeImpl::DrainOtherFd()
    {
    #if defined(FIONREAD)

        int available {};
        if (::ioctl(this->secondary[0], FIONREAD, &available) < 0)
        {
            return;
        }
        
        if (!available)
        {
            return;
        }

        AuByteBuffer temp(available);
        SysAssert(temp);

        AuUInt uCounter {};
        while (this->ReadEx({temp, uCounter}, true, false))
        {
            temp.writePtr = temp.readPtr = temp.base;
        }

    #else

        AuByteBuffer temp(4096 * 10);
        SysAssert(temp);

        AuUInt uCounter {};
        while (this->ReadEx({temp, uCounter}, true, false))
        {
            temp.writePtr = temp.readPtr = temp.base;
        }

    #endif
    }

    AuUInt IPCPipeImpl::GetPreemptFd()
    {
        return this->eventPreempt_.GetHandle();
    }

    bool IPCPipeImpl::LIOS_PopOne()
    {
        if (!this->bIsSendingZero)
        {
            return false;
        }

        #if defined(FIONREAD)
            int available {};
            if (::ioctl(fds[0], FIONREAD, &available) < 0)
            {
                return false;
            }
            
            if (available)
            {
                return false;
            }
        #endif

        this->FinishFinalize();
        return true;
    }

    void IPCPipeImpl::FinishFinalize()
    {
        this->bIsSendingZero = false;
        this->bHasDied = true;
    }
    
    const AuList<AuUInt> &IPCPipeImpl::GetHandles()
    {
        return this->handles;
    }

    bool IPCPipeImpl::Singular()
    {
        return false;
    }

    bool IPCPipeImpl::OnTrigger(AuUInt handle)
    {
        return true;
    }

    IPCPipeImpl::IPCPipeImpl(int (fds2)[2], int (fds3)[2], IPCToken readEnd, IPCToken writeEnd, AuSPtr<IPCEvent> event, AuSPtr<IPCMutex> mutex) : 
        fds {fds2[0], fds2[1]}, secondary {fds3[0], fds3[1]},
        readEnd_(readEnd), writeEnd_(writeEnd), event_(event), mutex_(mutex),
        eventPreempt_(false, false, true),
        pipeReader_(this),
        pipeWriter_(this)
    {
        this->handles = {fds[0], eventPreempt_.GetHandle()};

    #if defined(AURORA_IS_LINUX_DERIVED)
        if (fds3[0] != -1)
        {
            AuStaticCast<IPCMutexProxy>(mutex)->pMutexClosedHook = this;
        }
    #endif


        this->fsHandle_ = AuIO::IOHandleShared();
        SysAssert(this->fsHandle_);

        this->fsStream_ = AuMakeShared<IO::FS::LinuxAsyncFileStream>();

        AuStaticCast<AFileHandle>(this->fsHandle_)->pIPCPipe = this;

        this->fsHandle_->InitFromPairMove(fds2[0], fds2[1]);
        this->fsStream_->Init(this->fsHandle_);

        this->fsBlockingStream_ = AuFS::OpenBlockingFileStreamFromHandle(this->fsHandle_);
        SysAssert(this->fsBlockingStream_);
    }
    
    AuSPtr<Loop::ILoopSource> IPCPipeImpl::AsReadChannelIsOpen()
    {
        return this->event_;
    }

    AuSPtr<Loop::ILoopSource> IPCPipeImpl::AsReadChannelHasData()
    {
        return AuSharedFromThis();
    }
    
    AuSPtr<IO::IAsyncTransaction> IPCPipeImpl::NewAsyncTransaction()
    {
        return this->fsStream_->NewTransaction();
    }

    AuSPtr<IO::IIOHandle> IPCPipeImpl::GetCurrentSharedDuplexHandles()
    {
        return this->fsHandle_;
    }

    bool IPCPipeImpl::Read(const Memory::MemoryViewStreamWrite &write, bool nonblock)
    {
        return this->ReadEx(write, nonblock, true);   
    }

    bool IPCPipeImpl::ReadEx(const Memory::MemoryViewStreamWrite &write, bool nonblock, bool bSide)
    {
        auto handle = bSide ? this->fds[0] : this->secondary[0];

        auto control = ::fcntl(handle, F_GETFL);
        auto ref = control;

        if (control < 0)
        {
            return false;
        }

        if (nonblock)
        {
            control |= O_NONBLOCK;
        }
        else
        {
            control &= ~O_NONBLOCK;
        }

        if (ref != control)
        {
            ::fcntl(handle, F_SETFL, control);
        }

        if (!write.ptr)
        {
        #if defined(FIONREAD)
            int available {};
            if (::ioctl(handle, FIONREAD, &available) < 0)
            {
                return false;
            }
            
            write.outVariable = available;
            return true;
        #else
            SysPushErrorHAL("Cannot pull bytes available in the IPC on this UNIX platform");
            return false;
        #endif
        }
        
        int tmp;
        do
        {
            tmp = ::read(handle, write.ptr, write.length);
        }
        while ((tmp == -1 && errno == EINTR));

        if (tmp <= 0)
        {
            if (tmp == 0)
            {
                return nonblock;
            }
        
            SysPushErrorMem();
            return false;
        }

        write.outVariable = tmp;
        return true;
    }

    bool IPCPipeImpl::Write(const Memory::MemoryViewStreamRead &read)//, bool nonblock)
    {
        bool nonblock = true;
        auto handle = this->fds[1];
        auto control = ::fcntl(handle, F_GETFL);
        auto ref = control;

        if (nonblock)
        {
            control |= O_NONBLOCK;
        }
        else
        {
            control &= ~O_NONBLOCK;
        }

        if (ref != control)
        {
            ::fcntl(handle, F_SETFL, control);
        }

        int tmp;
        do
        {
            tmp = ::write(handle, read.ptr, read.length);
        }
        while ((tmp == -1 && errno == EINTR));

        if (tmp <= 0)
        {
            if (tmp == 0)
            {
                return nonblock;
            }
        
            SysPushErrorMem();
            return false;
        }

        read.outVariable = tmp;
        return true;
    }

    bool IPCPipeImpl::IsSignaled()
    {
        return LSHandle::IsSignaled();
    }

    bool IPCPipeImpl::WaitOn(AuUInt32 timeout)
    {
        return LSHandle::WaitOn(timeout);
    }

    Loop::ELoopSource IPCPipeImpl::GetType()
    {
        return Loop::ELoopSource::eSourceIPCReadPipe;
    }

#if defined(AURORA_IS_LINUX_DERIVED)
    bool IPCPipeImpl::OnClosed()
    {
        if (this->bHasDied)
        {
            this->DrainOtherFd();
            this->bHasDied = false;
            this->eventPreempt_.Reset();
            this->event_->Reset();
            return true;
        }

        this->SendTerminateSignal();
        return false;
    }
#endif

    void IPCPipeImpl::SendTerminateSignal()
    {
        this->bIsSendingZero = true;
        this->eventPreempt_.Set();
        this->event_->Reset();
    }

    AuString IPCPipeImpl::ExportToString()
    {
        IPC::IPCHandle handle;

        handle.PushId(EIPCHandleType::eIPCPipe, AuStaticCast<IPCEventProxy>(this->event_)->handle_.values[0].token);
        #if defined(AURORA_IS_LINUX_DERIVED)
            auto that = AuStaticCast<IPCMutexProxy>(this->mutex_);
            handle.PushId(EIPCHandleType::eIPCPrimitiveMutex, that->token_);
            SysAssert(that->mem_);
            handle.PushId(EIPCHandleType::eIPCMemory, AuStaticCast<IPCSharedMemoryImpl>(that->mem_)->handle_.values[0].token);
            handle.values[1].token.word = that->index_;
        #else
            handle.PushId(EIPCHandleType::eIPCPrimitiveMutex, ->handle_.values[0].token);
        #endif
        handle.PushId(EIPCHandleType::eIPCPipeEnd, this->readEnd_);
        handle.PushId(EIPCHandleType::eIPCPipeEnd, this->writeEnd_);

        return handle.ToString();
    }

    AuSPtr<IO::FS::IFileStream> IPCPipeImpl::ToFileStream()
    {
        return this->fsBlockingStream_;
    }

    AuSPtr<IStreamReader> IPCPipeImpl::ToStreamReader()
    {
        return AuSPtr<IStreamReader>(this->SharedFromThis(), &this->pipeReader_);
    }

    AuSPtr<IStreamWriter> IPCPipeImpl::ToStreamWriter()
    {
        return AuSPtr<IStreamWriter>(this->SharedFromThis(), &this->pipeWriter_);
    }

    AUKN_SYM AuSPtr<IPCPipe>      NewPipeEx(AuUInt32 uPipeLength)
    {
        IPCToken readEnd, writeEnd;
        int fds1[2];
        int fds2[2];

        auto event = NewEvent(false, false);
        if (!event)
        {
            SysPushErrorNested();
            return {};
        }

        auto mutex = NewMutex();
        if (!mutex)
        {
            SysPushErrorNested();
            return {};
        }

        if (::pipe(fds1) == -1)
        {
            SysPushErrorIO("no pipe");
            return {};
        }

        if (::pipe(fds2) == -1)
        {
            SysPushErrorIO("no pipe");
            ::close(fds1[0]);
            ::close(fds1[1]);
            return {};
        }

    #if defined(F_SETPIPE_SZ)
        if (uPipeLength)
        {
            uPipeLength = AuPageRound(uPipeLength, AuHwInfo::GetPageSize());

            if (fcntl(fds1[1], F_SETPIPE_SZ, uPipeLength) == -1 ||
                fcntl(fds2[1], F_SETPIPE_SZ, uPipeLength) == -1)
            {
                SysPushErrorIO("couldnt expand pipe");
                ::close(fds1[0]);
                ::close(fds1[1]);
                ::close(fds2[0]);
                ::close(fds2[1]);
                return {};
            }
        }
    #endif

        if (!IO::UNIX::FDServe(fds1[0], readEnd))
        {
            SysPushErrorIO();
            ::close(fds1[0]);
            ::close(fds1[1]);
            ::close(fds2[0]);
            ::close(fds2[1]);
            return {};
        }

        if (!IO::UNIX::FDServe(fds2[1], writeEnd))
        {
            SysPushErrorIO();
            IO::UNIX::FDServeEnd(readEnd);
            ::close(fds1[0]);
            ::close(fds1[1]);
            ::close(fds2[0]);
            ::close(fds2[1]);
            return {};
        }

        int serverPair[2] {fds2[0], fds1[1]};
        int clientPair[2] {fds1[0], fds2[1]};

        auto handle = AuMakeShared<IPCPipeImpl>(serverPair, clientPair, readEnd, writeEnd, event, mutex);
        if (!handle)
        {
            SysPushErrorMem();
            IO::UNIX::FDServeEnd(readEnd);
            IO::UNIX::FDServeEnd(writeEnd);
            ::close(fds1[0]);
            ::close(fds1[1]);
            ::close(fds2[0]);
            ::close(fds2[1]);
            return {};
        }

        return handle;
    }

    AUKN_SYM AuSPtr<IPCPipe>      NewPipe()
    {
        return NewPipeEx(0);
    }

    AUKN_SYM AuSPtr<IPCPipe>      ImportPipe(const AuString &handleString)
    {
        int fds[2] {-1, -1};

        IPCHandle handle;

        if (!handle.FromString(handleString))
        {
            SysPushErrorParseError();
            return {};
        }

        auto eventVal = handle.GetToken(IPC::EIPCHandleType::eIPCPipe, 0);
        if (!eventVal)
        {
            SysPushErrorParseError();
            return {};
        }

        auto mutexVal = handle.GetToken(IPC::EIPCHandleType::eIPCPrimitiveMutex, 1);
        if (!mutexVal)
        {
            SysPushErrorParseError();
            return {};
        }

        int offset {};

    #if defined(AURORA_IS_LINUX_DERIVED)
        offset = 1;

        auto ipcMem = handle.GetToken(IPC::EIPCHandleType::eIPCMemory, 2);
        if (!ipcMem)
        {
            SysPushErrorParseError();
            return {};
        }
    #endif

        auto readVal = handle.GetToken(IPC::EIPCHandleType::eIPCPipeEnd, 2 + offset);
        if (!readVal)
        {
            SysPushErrorParseError();
            return {};
        }

        auto writeVal = handle.GetToken(IPC::EIPCHandleType::eIPCPipeEnd, 3 + offset);
        if (!writeVal)
        {
            SysPushErrorParseError();
            return {};
        }

        auto event = ImportEventEx(eventVal->token);
        if (!event)
        {
            return {};
        }

        auto mutex = ImportMutexEx(mutexVal->token, ipcMem->token, mutexVal->token.word);
        if (!mutex)
        {
            return {};
        }

        if (!IO::UNIX::FDAccept(readVal->token, fds[0]))
        {
            SysPushErrorNested();
            return {};
        }

        if (!IO::UNIX::FDAccept(writeVal->token, fds[1]))
        {
            ::close(fds[0]);
            SysPushErrorNested();
            return {};
        }

        int dummy[2] {-1, -1};
        auto object = AuMakeShared<IPCPipeImpl>(fds,
                                                dummy,
                                                readVal->token,
                                                writeVal->token,
                                                event,
                                                mutex);
        if (!object)
        {
            SysPushErrorMem();
            ::close(fds[0]);
            ::close(fds[1]);
            return {};
        }

        mutex->WaitOn(0);

        if (event->IsSignaled())
        {
            mutex->Unlock();
            SysPushErrorIO("Pipe Busy");
            ::close(fds[0]);
            ::close(fds[1]);
            return {};  
        }

        event->Set();


        return object;
    }
}