/***
    Copyright (C) 2023 J Reece Wilson (a/k/a "Reece"). All rights reserved.

    File: AuIOHandle.Unix.cpp
    Date: 2023-8-11
    Author: Reece
***/
#include <RuntimeInternal.hpp>
#include "AuIOHandle.hpp"
#include "AuIOHandle.Unix.hpp"

#include "FS/FS.hpp"
#include "FS/FileAdvisory.Unix.hpp"
#include "FS/FileStream.Unix.hpp"

#include <Source/Grug/AuGrug.hpp>

#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>

#if defined(AURORA_COMPILER_CLANG)
    // warning: enumeration values 'kEnumCount' and 'kEnumInvalid' not handled in switch [-Wswitch
    #pragma clang diagnostic ignored "-Wswitch"
    // Yea, I don't give a shit.
#endif

#if !defined(FD_CLOEXEC)
    #define FD_CLOEXEC 0
#endif

namespace Aurora::IO
{
    AuUInt64 DupHandle(AuUInt64 uOSHandle, bool bWriteAccess, bool bShareAccess)
    {
        int fd = ::dup(uOSHandle);

        if (fd < 0)
        {
            return 0;
        }

        if (!SetFDShareAccess(uOSHandle, bShareAccess))
        {
            ::close(fd);
            return 0;
        }
     
        return AuUInt64(fd);
    }

    AuUInt64 AFileHandle::DupHandle(AuUInt64 uOSHandle, bool bWriteAccess)
    {
        return Aurora::IO::DupHandle(uOSHandle, bWriteAccess, false);
    }

    AuUInt64 AFileHandle::DupHandle(AuUInt64 uOSHandle, bool bWriteAccess, bool bShareAccess)
    {
        return Aurora::IO::DupHandle(uOSHandle, bWriteAccess, bShareAccess);
    }

    int SetFDShareAccess(AuUInt64 uOSHandle, bool bShareAccess)
    {
        int flags = ::fcntl(uOSHandle, F_GETFL, 0);
        if (flags == -1)
        {
            return 0;
        }
        
        if (bShareAccess)
        {
            flags &= ~FD_CLOEXEC;
        }
        else
        {
            flags |= FD_CLOEXEC;
        }
        
        flags = ::fcntl(uOSHandle, F_SETFL, flags);
        if (flags == -1)
        {
            return 0;
        }
        
        return 1;
    }

    void AFileHandle::CloseHandle(AuUInt64 uOSHandle, bool bFlushOnClose)
    {
        int fd = (int)uOSHandle;
        if (fd < 0)
        {
            return;
        }

    #if 0
        if (bFlushOnClose)
        {
            ::fsync(uOSHandle);
        }
        ::close(fd);
    #else
        Grug::CloseHandle(uOSHandle, bFlushOnClose);
    #endif
    }

    void AFileHandle::InitStdIn(bool bSharing)
    {
        this->uOSReadHandle = DupHandle(STDIN_FILENO, false, bSharing);
    }

    void AFileHandle::InitStdOut(bool bError, bool bSharing)
    {
        this->uOSReadHandle = this->uOSWriteHandle = DupHandle(bError ? STDERR_FILENO : STDOUT_FILENO, true, bSharing);
    }

    bool AFileHandle::InitFromPath(HandleCreate create)
    {
        int iFileDescriptor { -1 };

        if (create.path.empty())
        {
            SysPushErrorArg("Cannot open an IO handle to the provided empty path");
            return false;
        }

        if (!FS::EFileOpenModeIsValid(create.eMode))
        {
            SysPushErrorParam("Invalid open mode");
            return false;
        }

        if (!FS::EFileAdvisoryLockLevelIsValid(create.eAdvisoryLevel))
        {
            SysPushErrorParam("Invalid lock mode");
            return false;
        }

        auto pathex = FS::NormalizePathRet(create.path);
        if (pathex.empty())
        {
            SysPushErrorMemory();
            return false;
        }

        if (create.bDirectIOMode)
        {
            this->bDirectIO = true;
        }

        int flags {};

        switch (create.eMode)
        {
        case FS::EFileOpenMode::eRead:
        {

            break;
        }
        case FS::EFileOpenMode::eReadWrite:
        case FS::EFileOpenMode::eWrite:
        {
            if (create.bAlwaysCreateDirTree)
            {
                FS::CreateDirectories(pathex, true);
            }

            if (create.bFailIfNonEmptyFile)
            {
            #if defined(O_EXCL)
                flags = O_EXCL;
            #else
                if (AuFS::FileExists(pathex.c_str()))
                {
                    SysPushErrorResourceExists("File {} already exists", create.path);
                    return false;
                }
            #endif
            }
           
            break;
        }
        };
        
        flags |= create.eMode == FS::EFileOpenMode::eRead ? O_RDONLY : (O_RDWR | O_CREAT);
        flags |= O_CLOEXEC;

    #if defined(O_DIRECT)
        flags |= this->bDirectIO ? O_DIRECT : 0;
    #else
        // TBD
    #endif

        iFileDescriptor = ::open(pathex.c_str(),
                                 flags,
                                 0664);

        if (iFileDescriptor < 0)
        {
            if (create.bFailIfNonEmptyFile)
            {
                if (errno == EEXIST)
                {
                    SysPushErrorResourceExists("File {} already exists", create.path);
                    return false;
                }
            }

            if (errno != EISDIR &&
                errno != ENOENT)
            {
                RuntimeWaitForSecondaryTick();

                iFileDescriptor = ::open(pathex.c_str(),
                                         flags,
                                         0664);
            }

            if (iFileDescriptor < 0)
            {
                if (errno == EEXIST)
                {
                    SysPushErrorResourceExists("File {} already exists", create.path);
                    return false;
                }

                if (errno == EISDIR)
                {
                    flags &= ~(O_WRONLY | O_RDWR);
                    iFileDescriptor = ::open(pathex.c_str(),
                                             flags,
                                             0664);
                }

                if (iFileDescriptor < 0)
                {
                    if (errno == ENFILE)
                    {
                        SysPushErrorIOResourceFailure("low resources");
                        return false;
                    }

                    SysPushErrorIO("Couldn't open file: {} ({}) {}", path, pathex, errno);
                    return false;
                }
            }
        }

        if (!FS::ApplyDumbAdvisoryLock(iFileDescriptor, create.eAdvisoryLevel))
        {
            SysPushErrorIO("Couldn't open file: {}. File node (not section) is locked.", path);
            ::close(iFileDescriptor);
            return false;
        }

        if (create.bFailIfNonEmptyFile)
        {
            if (PosixGetLength(iFileDescriptor))
            {
                SysPushErrorResourceExists("File {} already exists", create.path);
                ::close(iFileDescriptor);
                return false;
            }
        }

        switch (create.eMode)
        {
        case FS::EFileOpenMode::eRead:
        {
            this->uOSReadHandle = AuUInt64(iFileDescriptor);
            break;
        }
        case FS::EFileOpenMode::eReadWrite:
        {
            this->uOSWriteHandle = AuUInt64(iFileDescriptor);
            this->uOSReadHandle = AuUInt64(iFileDescriptor);
            break;
        }
        case FS::EFileOpenMode::eWrite:
        {
            this->uOSWriteHandle = AuUInt64(iFileDescriptor);
            break;
        }
        };

        this->bIsAsync = create.bAsyncHandle;

        this->path = create.path;

        return this->IsValid();
    }

    AUKN_SYM bool IsHandleTTY(AuUInt uHandle)
    {
        if ((AuSInt)uHandle < 0)
        {
            SysPushErrorArg();
            return false;
        }

        return ::isatty((int)uHandle);
    }

    AUKN_SYM bool IsHandlePipe(AuUInt uHandle)
    {
        struct stat st;

        if ((AuSInt)uHandle < 0)
        {
            SysPushErrorArg();
            return false;
        }

        if (::fstat((int)uHandle, &st) != 0)
        {
            SysPushErrorIO("fstat failed");
            return false;
        }

        return S_ISFIFO(st.st_mode);
    }

    AUKN_SYM bool IsHandleFile(AuUInt uHandle)
    {
        struct stat st;

        if ((AuSInt)uHandle < 0)
        {
            SysPushErrorArg();
            return false;
        }

        if (::fstat((int)uHandle, &st) != 0)
        {
            SysPushErrorIO("fstat failed");
            return false;
        }

        return S_ISREG(st.st_mode);
    }
}