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# cbu.py - functions for handling Argentinian CBU numbers
# coding: utf-8
#
# Copyright (C) 2016 Luciano Rossi
#
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2.1 of the License, or (at your option) any later version.
#
# This library is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
# 02110-1301 USA
"""CBU (Clave Bancaria Uniforme, Argentine bank account number).
CBU it s a code of the Banks of Argentina to identify customer accounts. The
number consists of 22 digits and consists of a 3 digit bank identifier,
followed by a 4 digit branch identifier, a check digit, a 13 digit account
identifier and another check digit.
More information:
* https://es.wikipedia.org/wiki/Clave_Bancaria_Uniforme
>>> validate('2850590940090418135201')
'2850590940090418135201'
>>> format('2850590940090418135201')
'28505909 40090418135201'
>>> validate('2810590940090418135201')
Traceback (most recent call last):
...
InvalidChecksum: ...
"""
from stdnum.exceptions import *
from stdnum.util import clean, isdigits
def compact(number):
"""Convert the number to the minimal representation. This strips the
number of any valid separators and removes surrounding whitespace."""
return clean(number, ' -').strip()
def calc_check_digit(number):
"""Calculate the check digit."""
weights = (3, 1, 7, 9)
check = sum(int(n) * weights[i % 4]
for i, n in enumerate(reversed(number)))
return str((10 - check) % 10)
def validate(number):
"""Check if the number is a valid CBU."""
number = compact(number)
if len(number) != 22:
raise InvalidLength()
if not isdigits(number):
raise InvalidFormat()
if calc_check_digit(number[:7]) != number[7]:
raise InvalidChecksum()
if calc_check_digit(number[8:-1]) != number[-1]:
raise InvalidChecksum()
return number
def is_valid(number):
"""Check if the number is a valid CBU."""
try:
return bool(validate(number))
except ValidationError:
return False
def format(number):
"""Reformat the number to the standard presentation format."""
number = compact(number)
return ' '.join((number[:8], number[8:]))
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