#include "shared_mem_buffer.h"

#include <QDebug>
#include <atomic>

#ifdef QT_POSIX_IPC
    // The POSIX backend can be explicitly selected using the -feature-ipc_posix
    // option to the Qt configure script. If it is enabled, the QT_POSIX_IPC
    // macro will be defined. -> we use SystemV shared memory
#error "QT_POSIX_IPC defined"
#else
#ifdef __linux__
#include <sys/ipc.h>    // ftok
#endif
#endif

//static bool shdMemFirstUse;


//QSharedMemory *SharedMemBuffer::getShm(std::size_t size) {
QSharedMemory *SharedMem::getShm(std::size_t size) {
    static QSharedMemory shMem;
    if (size > 0) {
#ifdef __linux__
        //static const long nativeKey = ftok("/etc/os-release", 'H');
        //static const QString fkey = std::to_string(nativeKey).c_str();
        static const QString fkey = "0123456?000=7";
#else
        static const QString fkey = "0123456?000=9";
#endif

        shMem.setKey(fkey);
        if (!shMem.isAttached()) {
            if (shMem.create(size)) {
                return &shMem;
            } else {
                if (shMem.error() == QSharedMemory::AlreadyExists) {
                    if (shMem.attach()) {
                        return &shMem;
                    }
                }
            }
            qCritical() << shMem.nativeKey() << shMem.key() << shMem.data()
                        << shMem.error() << shMem.errorString();
            return nullptr;
        }
    }
    return &shMem;
}


// std::atomic_bool SharedMemBuffer::__sharedMemLocked{false};
/*
//QSharedMemory *SharedMemBuffer::getShm(std::size_t size) {
QSharedMemory *SharedMem::getShm(std::size_t size) {

    static QSharedMemory shMem;
    if (size > 0) {
#ifdef __linux__
        static const long nativeKey = ftok("/etc/os-release", 'H');
        static const QString fkey = std::to_string(nativeKey).c_str();
#else
        static const QString fkey = "0123456?000=9";
#endif
        shdMemFirstUse=false;
        shMem.setKey(fkey);
        if (!shMem.isAttached())
        {
            if (shMem.create(size))
            {
                //  sm was created successful, did not exist before
                shdMemFirstUse=true;
                return &shMem;
            } else
            {
                // create was false because mem already existed
                if (shMem.error() == QSharedMemory::AlreadyExists)
                {
                    if (shMem.attach())
                    {
                        return &shMem;
                    }
                }
            }
            qCritical() << shMem.nativeKey() << shMem.key() << shMem.data()
                        << shMem.error() << shMem.errorString();
            return nullptr;
        }
    }
    return &shMem;
}


bool shdMem_firstUse(void)
{
    return shdMemFirstUse;
}
*/