python pretty time with localization

python_pretty_time

# coding: utf-8
from datetime import datetime
from datetime import timedelta

def calc_diff(delta):    
    delta = abs( delta )
    return { 
        'year'   : int(delta.days / 365),
        'month'  : int(delta.days % 365) / 30,
        'day'    : int(delta.days % 365) % 30,
        'hour'   : int(delta.seconds / 3600),
        'minute' : int(delta.seconds / 60) % 60,
        'second' : delta.seconds % 60,
        'microsecond' : delta.microseconds
    }

def localize(u):
    return {
        'year': 'жил',
        'month' : 'сар',
        'day': 'өдөр',
        'hour': 'цаг',
        'minute': 'минут',
        'second': 'секунд',
        'microsecond': 'микросекунд'
    }.get(u, '')


def pretty_date(dt, length=3, past_tense='{}-н өмнө', future_tense='{}-н дараа '):    
    delta = dt
    if type(dt) is not type(timedelta()):
        delta = datetime.now() - dt
     
    the_tense = past_tense
    if delta < timedelta(0):
        the_tense = future_tense

    d = calc_diff( delta )
    hlist = [] 
    count = 0
    units = ( 'year', 'month', 'day', 'hour', 'minute', 'second', 'microsecond' )
    for unit in units:
        if count >= length: break 
        if d[ unit ] == 0: continue         
        l = localize(unit)       
        hlist.append( '%s %s' % ( d[unit], l ) )
        count += 1
    pretty_delta = ' '.join( hlist )
    return the_tense.format(pretty_delta) 


date_past = datetime(
  year = 2012,
  month=6,
  day=8,
  hour=6,
  minute=54,
  second=33,
  microsecond=4000
 )

date_future = datetime(
  year = 2018,
  month=10,
  day=14,
  hour=6,
  minute=54,
  second=33,
  microsecond=4000
 )

print pretty_date(date_past, 3)
print pretty_date(date_future, 3)