#include "system_memory_querier.h"

#ifdef Q_OS_WIN
#include <windows.h>
#endif

#ifdef Q_OS_LINUX
#include <QFile>
#include <QRegularExpression>
#include <QTextStream>
#endif

#ifdef Q_OS_MACOS
#include <mach/mach.h>
#include <sys/sysctl.h>
#include <sys/types.h>
#include <unistd.h>
#endif

qulonglong SystemMemoryQuerier::totalMemoryBytes()
{
#if defined(Q_OS_WIN)

    MEMORYSTATUSEX statex;
    statex.dwLength = sizeof(statex);
    if (GlobalMemoryStatusEx(&statex))
        return statex.ullTotalPhys;
    return 0;

#elif defined(Q_OS_LINUX)

    QFile file("/proc/meminfo");
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
        return 0;

    QTextStream in(&file);
    while (!in.atEnd()) {
        QString line = in.readLine();
        if (line.startsWith("MemTotal:")) {
            QStringList parts = line.split(QRegExp("\\s+"), Qt::SkipEmptyParts);
            if (parts.size() >= 2)
                return parts[1].toULongLong() * 1024; // kB → bytes
        }
    }
    return 0;

#elif defined(Q_OS_MACOS)

    int mib[2] = {CTL_HW, HW_MEMSIZE};
    qulonglong memsize = 0;
    size_t len = sizeof(memsize);

    if (sysctl(mib, 2, &memsize, &len, nullptr, 0) == 0)
        return memsize;

    return 0;

#else
    return 0;
#endif
}

qulonglong SystemMemoryQuerier::availableMemoryBytes()
{
#if defined(Q_OS_WIN)

    MEMORYSTATUSEX statex;
    statex.dwLength = sizeof(statex);
    if (GlobalMemoryStatusEx(&statex))
        return statex.ullAvailPhys;
    return 0;

#elif defined(Q_OS_LINUX)

    QFile file("/proc/meminfo");
    if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
        return 0;

    QTextStream in(&file);
    while (!in.atEnd()) {
        QString line = in.readLine();
        if (line.startsWith("MemAvailable:")) {
            QStringList parts = line.split(QRegExp("\\s+"), Qt::SkipEmptyParts);
            if (parts.size() >= 2)
                return parts[1].toULongLong() * 1024;
        }
    }
    return 0;

#elif defined(Q_OS_MACOS)

    vm_size_t pageSize;
    host_page_size(mach_host_self(), &pageSize);

    mach_msg_type_number_t count = HOST_VM_INFO_COUNT;
    vm_statistics64_data_t vmstat;

    if (host_statistics64(mach_host_self(), HOST_VM_INFO, (host_info64_t)&vmstat, &count) != KERN_SUCCESS)
        return 0;

    qulonglong freeBytes = (qulonglong)vmstat.free_count * (qulonglong)pageSize;

    return freeBytes;

#else
    return 0;
#endif
}