# Date/time manipulation

import datetime

import dateutil.tz

import time

utc = dateutil.tz.tzutc()

local = dateutil.tz.tzlocal()

def naive2utc(datetime_):

    assert datetime_.tzinfo == None

    return datetime_.replace(tzinfo=utc)

def aware2local(datetime_): return datetime_.astimezone(local)

def from_timestamp(utc_timestamp):

    return naive2utc(datetime.datetime.utcfromtimestamp(utc_timestamp))

def timestamp(datetime_): return time.mktime(aware2local(datetime_).timetuple())

epoch = from_timestamp(0)

def now(): return datetime.datetime.now(utc)

def strftime(format, datetime_):

    '''datetime.strftime() can't handle years before 1900'''

    return (datetime_.replace(year=epoch.year, day=1).strftime(format

        .replace('%Y', '%%Y')

        .replace('%d', '%%d')

        )

        .replace('%Y', '%04d' % datetime_.year)

        .replace('%d', '%02d' % datetime_.day)

        )

def total_seconds(timedelta_): return timestamp(epoch + timedelta_)