# vim:fileencoding=utf-8:noet
from __future__ import (unicode_literals, division, absolute_import, print_function)

try:
	try:
		# >=python-3.3, Unix
		from time import clock_gettime
		try:
			# >={kernel}-sources-2.6.28
			from time import CLOCK_MONOTONIC_RAW as CLOCK_ID
		except ImportError:
			from time import CLOCK_MONOTONIC as CLOCK_ID

		monotonic = lambda: clock_gettime(CLOCK_ID)
	except ImportError:
		# >=python-3.3
		from time import monotonic
except ImportError:
	import ctypes
	import sys

	try:
		if sys.platform == 'win32':
			# Windows only
			GetTickCount64 = ctypes.windll.kernel32.GetTickCount64
			GetTickCount64.restype = ctypes.c_ulonglong

			def monotonic():
				return GetTickCount64() / 1000

		elif sys.platform == 'darwin':
			# Mac OS X
			from ctypes.util import find_library

			libc_name = find_library('c')
			if not libc_name:
				raise OSError

			libc = ctypes.CDLL(libc_name, use_errno=True)

			mach_absolute_time = libc.mach_absolute_time
			mach_absolute_time.argtypes = ()
			mach_absolute_time.restype = ctypes.c_uint64

			class mach_timebase_info_data_t(ctypes.Structure):
				_fields_ = (
					('numer', ctypes.c_uint32),
					('denom', ctypes.c_uint32),
				)
			mach_timebase_info_data_p = ctypes.POINTER(mach_timebase_info_data_t)

			_mach_timebase_info = libc.mach_timebase_info
			_mach_timebase_info.argtypes = (mach_timebase_info_data_p,)
			_mach_timebase_info.restype = ctypes.c_int

			def mach_timebase_info():
				timebase = mach_timebase_info_data_t()
				_mach_timebase_info(ctypes.byref(timebase))
				return (timebase.numer, timebase.denom)

			timebase = mach_timebase_info()
			factor = timebase[0] / timebase[1] * 1e-9

			def monotonic():
				return mach_absolute_time() * factor
		else:
			# linux only (no librt on OS X)
			import os

			# See <bits/time.h>
			CLOCK_MONOTONIC = 1
			CLOCK_MONOTONIC_RAW = 4

			class timespec(ctypes.Structure):
				_fields_ = (
					('tv_sec', ctypes.c_long),
					('tv_nsec', ctypes.c_long)
				)
			tspec = timespec()

			librt = ctypes.CDLL('librt.so.1', use_errno=True)
			clock_gettime = librt.clock_gettime
			clock_gettime.argtypes = [ctypes.c_int, ctypes.POINTER(timespec)]

			if clock_gettime(CLOCK_MONOTONIC_RAW, ctypes.pointer(tspec)) == 0:
				# >={kernel}-sources-2.6.28
				clock_id = CLOCK_MONOTONIC_RAW
			elif clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(tspec)) == 0:
				clock_id = CLOCK_MONOTONIC
			else:
				raise OSError

			def monotonic():
				if clock_gettime(CLOCK_MONOTONIC, ctypes.pointer(tspec)) != 0:
					errno_ = ctypes.get_errno()
					raise OSError(errno_, os.strerror(errno_))
				return tspec.tv_sec + tspec.tv_nsec / 1e9

	except:
		from time import time as monotonic  # NOQA