"""
Common utilities that have been ported to Python 3.

Ported to Python 3.
"""

from __future__ import unicode_literals
from __future__ import absolute_import
from __future__ import division
from __future__ import print_function

from future.utils import PY2
if PY2:
    from builtins import filter, map, zip, ascii, chr, hex, input, next, oct, open, pow, round, super, bytes, dict, int, list, object, range, str, max, min  # noqa: F401

import os
import time


class TimezoneMixin(object):

    def setTimezone(self, timezone):
        def tzset_if_possible():
            # Windows doesn't have time.tzset().
            if hasattr(time, 'tzset'):
                time.tzset()

        unset = object()
        originalTimezone = os.environ.get('TZ', unset)
        def restoreTimezone():
            if originalTimezone is unset:
                del os.environ['TZ']
            else:
                os.environ['TZ'] = originalTimezone
            tzset_if_possible()

        os.environ['TZ'] = timezone
        self.addCleanup(restoreTimezone)
        tzset_if_possible()

    def have_working_tzset(self):
        return hasattr(time, 'tzset')