/*  PCSX2 - PS2 Emulator for PCs
 *  Copyright (C) 2002-2014  PCSX2 Dev Team
 *
 *  PCSX2 is free software: you can redistribute it and/or modify it under the terms
 *  of the GNU Lesser General Public License as published by the Free Software Found-
 *  ation, either version 3 of the License, or (at your option) any later version.
 *
 *  PCSX2 is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
 *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
 *  PURPOSE.  See the GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License along with PCSX2.
 *  If not, see <http://www.gnu.org/licenses/>.
 */

#if defined(__APPLE__)

#include <cstring>
#include <cstdlib>
#include <sys/types.h>
#include <sys/sysctl.h>
#include <mach/mach_time.h>
#include <wx/string.h>

#include "common/Pcsx2Types.h"

#define NELEM(x) \
	((sizeof(x) / sizeof(0 [x])) / ((size_t)(!(sizeof(x) % sizeof(0 [x])))))

// Darwin (OSX) is a bit different from Linux when requesting properties of
// the OS because of its BSD/Mach heritage. Helpfully, most of this code
// should translate pretty well to other *BSD systems. (e.g.: the sysctl(3)
// interface).
//
// For an overview of all of Darwin's sysctls, check:
// https://developer.apple.com/library/mac/documentation/Darwin/Reference/ManPages/man3/sysctl.3.html

// Return the total physical memory on the machine, in bytes. Returns 0 on
// failure (not supported by the operating system).
u64 GetPhysicalMemory()
{
	static u64 mem = 0;

	// fetch the total memory only once, as its an expensive system call and
	// doesn't change during the course of the program. Thread-safety is
	// ensured by atomic operations with full-barriers (usually compiled
	// down to XCHG on x86).
	if (__atomic_load_n(&mem, __ATOMIC_SEQ_CST) == 0)
	{
		u64 getmem = 0;
		size_t len = sizeof(getmem);
		int mib[] = {CTL_HW, HW_MEMSIZE};
		if (sysctl(mib, NELEM(mib), &getmem, &len, NULL, 0) < 0)
		{
			perror("sysctl:");
		}
		__atomic_store_n(&mem, getmem, __ATOMIC_SEQ_CST);
	}

	return mem;
}

void InitCPUTicks()
{
}

// returns the performance-counter frequency: ticks per second (Hz)
//
// usage:
//   u64 seconds_passed = GetCPUTicks() / GetTickFrequency();
//   u64 millis_passed = (GetCPUTicks() * 1000) / GetTickFrequency();
//
// NOTE: multiply, subtract, ... your ticks before dividing by
// GetTickFrequency() to maintain good precision.
u64 GetTickFrequency()
{
	static u64 freq = 0;

	// by the time denom is not 0, the structure will have been fully
	// updated and no more atomic accesses are necessary.
	if (__atomic_load_n(&freq, __ATOMIC_SEQ_CST) == 0)
	{
		mach_timebase_info_data_t info;

		// mach_timebase_info() is a syscall, very slow, that's why we take
		// pains to only do it once. On x86(-64), the result is guaranteed
		// to be info.denom == info.numer == 1 (i.e.: the frequency is 1e9,
		// which means GetCPUTicks is just nanoseconds).
		if (mach_timebase_info(&info) != KERN_SUCCESS)
		{
			abort();
		}

		// store the calculated value atomically
		__atomic_store_n(&freq, (u64)1e9 * (u64)info.denom / (u64)info.numer, __ATOMIC_SEQ_CST);
	}

	return freq;
}

// return the number of "ticks" since some arbitrary, fixed time in the
// past. On OSX x86(-64), this is actually the number of nanoseconds passed,
// because mach_timebase_info.numer == denom == 1. So "ticks" ==
// nanoseconds.
u64 GetCPUTicks()
{
	return mach_absolute_time();
}

wxString GetOSVersionString()
{
	wxString version;
	static int initialized = 0;

	// fetch the OS description only once (thread-safely)
	if (__atomic_load_n(&initialized, __ATOMIC_SEQ_CST) == 0)
	{
		char type[32] = {0};
		char release[32] = {0};
		char arch[32] = {0};

#define SYSCTL_GET(var, base, name) \
	do \
	{ \
		int mib[] = {base, name}; \
		size_t len = sizeof(var); \
		sysctl(mib, NELEM(mib), NULL, &len, NULL, 0); \
		sysctl(mib, NELEM(mib), var, &len, NULL, 0); \
	} while (0)

		SYSCTL_GET(release, CTL_KERN, KERN_OSRELEASE);
		SYSCTL_GET(type, CTL_KERN, KERN_OSTYPE);
		SYSCTL_GET(arch, CTL_HW, HW_MACHINE);

#undef SYSCTL_KERN

		// I know strcat is not good, but stpcpy is not universally
		// available yet.
		char buf[128] = {0};
		strcat(buf, type);
		strcat(buf, " ");
		strcat(buf, release);
		strcat(buf, " ");
		strcat(buf, arch);

		version = buf;

		__atomic_store_n(&initialized, 1, __ATOMIC_SEQ_CST);
	}

	return version;
}

void ScreensaverAllow(bool allow)
{
	// no-op
}
#endif