import datetime
class Denomination(object):
    def __init__(self, value):
        self.value = list(set(value or self.default))
        self.value.sort()
        for item in self.value:
            if item not in self.default:
                raise ValueError("%r is not allowed" % item)
    def next(self, now, remainder=0):
        T = getattr(now, type(self).__name__.lower()) + remainder
        try:
            return next(v for v in self.value if v >= T), 0
        except StopIteration:
            return next(iter(self.value)), 1  # self.value[0]
class Second(Denomination):
    default = range(0, 60)
class Minute(Denomination):
    default = range(0, 60)
class Hour(Denomination):
    default = range(0, 24)
class Schedule(object):
    def __init__(self, second=None, minute=None, hour=None):
        self.second = Second(second)
        self.minute = Minute(minute)
        self.hour = Hour(hour)
    def __iter__(self):
        return self
    def next(self):
        """ Returns the datetime object representing when we'll fire next. """
        now = datetime.datetime.utcnow()
        s, remainder = self.second.next(now)
        m, remainder = self.minute.next(now, remainder)
        h, remainder = self.hour.next(now, remainder)
        return datetime.datetime(now.year, now.month, now.day, h, m, s) + \
            datetime.timedelta(days=remainder)
    # For nice rendering
    def __str__(self):
        return str(self.next() - datetime.datetime.utcnow())
    def __repr__(self):
        "<Schedule, fires next in %s>" % str(self)
    # For serialization
    def __json__(self):
        return float(self)
    # For usage in 'time.sleep(self)'
    def __float__(self):
        """ Return the number of seconds until we should fire next """
        return (self.next() - datetime.datetime.utcnow()).total_seconds()
import time
import unittest
import freezegun
import nose.tools
class TestSchedule(unittest.TestCase):
    @freezegun.freeze_time('2012-01-14 00:00:00')
    def test_basic(self):
        s = Schedule(minute=[15], hour=[5])
        self.assertEquals(float(s), 5 * 60 * 60 + 15 * 60)
    @freezegun.freeze_time('2012-01-14 12:00:00')
    def test_wrap_day(self):
        s = Schedule(minute=[15], hour=[5])
        self.assertEquals(float(s), 17 * 60 * 60 + 15 * 60)
    @freezegun.freeze_time('2012-01-14 12:15:00')
    def test_wrap_day_match_minute(self):
        s = Schedule(minute=[15], hour=[5])
        self.assertEquals(float(s), 17 * 60 * 60)
    @freezegun.freeze_time('2012-01-14 12:16:00')
    def test_wrap_day_wrap_minute(self):
        s = Schedule(minute=[15], hour=[5])
        self.assertEquals(float(s), 16 * 60 * 60 + 59 * 60)
    @freezegun.freeze_time('2012-01-14 00:00:00')
    def test_working_with_time_sleep(self):
        s = Schedule(second=[1])
        time.sleep(s)  # Let's just make sure this doesn't crash
    @nose.tools.raises(ValueError)
    def test_wrap_invalid_item(self):
        Schedule(minute=['lol'])
    @nose.tools.raises(TypeError)
    def test_wrap_invalid_item_int(self):
        Schedule(minute=1)
if __name__ == '__main__':
    unittest.main()