#include "ruby.h"
#ifdef __APPLE__
# include <mach/mach.h>
# include <mach/message.h>
# include <mach/kern_return.h>
# include <mach/task_info.h>
#elif defined _WIN32
# include <psapi.h>
#endif

static VALUE cMemoryStatus;

static VALUE
read_status(VALUE self)
{
    VALUE size = INT2FIX(0);
#if defined __APPLE__
    VALUE rss;
    kern_return_t error;
# if defined MACH_TASK_BASIC_INFO
    const task_flavor_t flavor = MACH_TASK_BASIC_INFO;
    mach_msg_type_number_t out_count = MACH_TASK_BASIC_INFO_COUNT;
    mach_task_basic_info_data_t taskinfo;
# else
    const task_flavor_t flavor = TASK_BASIC_INFO;
    mach_msg_type_number_t out_count = TASK_BASIC_INFO_COUNT;
    task_basic_info_data_t taskinfo;
# endif

    taskinfo.virtual_size = 0;
    taskinfo.resident_size = 0;
    error = task_info(mach_task_self(), flavor,
		      (task_info_t)&taskinfo, &out_count);
    if (error != KERN_SUCCESS) return Qnil;
#ifndef ULL2NUM
/* "long long" does not exist here, use size_t instead.  */
#define ULL2NUM SIZET2NUM
#endif
    size = ULL2NUM(taskinfo.virtual_size);
    rss = ULL2NUM(taskinfo.resident_size);
    rb_struct_aset(self, INT2FIX(1), rss);
#elif defined _WIN32
    VALUE peak;
    PROCESS_MEMORY_COUNTERS c;
    c.cb = sizeof(c);
    if (!GetProcessMemoryInfo(GetCurrentProcess(), &c, c.cb))
	return Qnil;
    size = SIZET2NUM(c.PagefileUsage);
    peak = SIZET2NUM(c.PeakWorkingSetSize);
    rb_struct_aset(self, INT2FIX(1), peak);
#endif
    rb_struct_aset(self, INT2FIX(0), size);
    return self;
}

void
Init_memory_status(void)
{
    VALUE mMemory = rb_define_module("Memory");
    cMemoryStatus =
	rb_struct_define_under(mMemory, "Status", "size",
#if defined __APPLE__
			       "rss",
#elif defined _WIN32
			       "peak",
#endif
			       (char *)NULL);
    rb_define_method(cMemoryStatus, "_update", read_status, 0);
}