#include "memory.h"
#include "common/debug.h"
#include "common/sysctl.h"

#include <errno.h>
#include <string.h>
#include <sys/param.h>
#include <uvm/uvm_extern.h>

const char* ffDetectMemory(FFMemoryResult* ram) {
    struct uvmexp_sysctl buf;
    size_t length = sizeof(buf);
    if (sysctl((int[]) { CTL_VM, VM_UVMEXP2 }, 2, &buf, &length, nullptr, 0) < 0) {
        FF_DEBUG("sysctl(CTL_VM, VM_UVMEXP2) failed: %s", strerror(errno));
        return "sysctl(CTL_VM, VM_UVMEXP2) failed";
    }

    ram->bytesTotal = (uint64_t) buf.npages << instance.state.platform.sysinfo.pageSizeShift;
    ram->bytesUsed = ((uint64_t) buf.active + (uint64_t) buf.inactive + (uint64_t) buf.wired) << instance.state.platform.sysinfo.pageSizeShift;

    int64_t bytesArc = ffSysctlGetInt64("kstat.zfs.misc.arcstats.size", 0);
    if (bytesArc > 0) bytesArc -= ffSysctlGetInt64("kstat.zfs.misc.arcstats.c_min", 0);
    if (bytesArc > 0 && (uint64_t) bytesArc < ram->bytesUsed) {
        ram->bytesUsed -= (uint64_t) bytesArc;
    }

    return nullptr;
}