102 lines
3.5 KiB
Python
102 lines
3.5 KiB
Python
|
# dic.py - functions for handling Czech VAT numbers
|
||
|
|
# coding: utf-8
|
||
|
|
#
|
||
|
|
# Copyright (C) 2012, 2013 Arthur de Jong
|
||
|
|
#
|
||
|
|
# 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
|
||
|
|
|
||
|
|
"""DIČ (Daňové identifikační číslo, Czech VAT number).
|
||
|
|
|
||
|
|
The number is an 8, 9 or 10 digit code that includes a check digit and is
|
||
|
|
used to uniquely identify taxpayers for VAT (DPH in Czech). The number can
|
||
|
|
refer to legal entities (8 digit numbers), individuals with a RČ (the 9 or
|
||
|
|
10 digit Czech birth number) or individuals without a RČ (9 digit numbers
|
||
|
|
that begin with a 6).
|
||
|
|
|
||
|
|
>>> compact('CZ 25123891')
|
||
|
|
'25123891'
|
||
|
|
>>> validate('25123891') # legal entity
|
||
|
|
'25123891'
|
||
|
|
>>> validate('25123890') # incorrect check digit
|
||
|
|
Traceback (most recent call last):
|
||
|
|
...
|
||
|
|
InvalidChecksum: ...
|
||
|
|
>>> validate('7103192745') # RČ
|
||
|
|
'7103192745'
|
||
|
|
>>> validate('640903926') # special case
|
||
|
|
'640903926'
|
||
|
|
"""
|
||
|
|
|
||
|
|
from stdnum.cz import rc
|
||
|
|
from stdnum.exceptions import *
|
||
|
|
from stdnum.util import clean
|
||
|
|
|
||
|
|
|
||
|
|
def compact(number):
|
||
|
|
"""Convert the number to the minimal representation. This strips the
|
||
|
|
number of any valid separators and removes surrounding whitespace."""
|
||
|
|
number = clean(number, ' /').upper().strip()
|
||
|
|
if number.startswith('CZ'):
|
||
|
|
number = number[2:]
|
||
|
|
return number
|
||
|
|
|
||
|
|
|
||
|
|
def calc_check_digit_legal(number):
|
||
|
|
"""Calculate the check digit for 8 digit legal entities. The number
|
||
|
|
passed should not have the check digit included."""
|
||
|
|
check = (11 - sum((8 - i) * int(n) for i, n in enumerate(number))) % 11
|
||
|
|
return str((check or 1) % 10)
|
||
|
|
|
||
|
|
|
||
|
|
def calc_check_digit_special(number):
|
||
|
|
"""Calculate the check digit for special cases. The number passed
|
||
|
|
should not have the first and last digits included."""
|
||
|
|
check = (11 - sum((8 - i) * int(n) for i, n in enumerate(number))) % 11
|
||
|
|
return str(9 - check % 10)
|
||
|
|
|
||
|
|
|
||
|
|
def validate(number):
|
||
|
|
"""Checks to see if the number provided is a valid VAT number. This
|
||
|
|
checks the length, formatting and check digit."""
|
||
|
|
number = compact(number)
|
||
|
|
if not number.isdigit():
|
||
|
|
raise InvalidFormat()
|
||
|
|
if len(number) == 8:
|
||
|
|
# legal entities
|
||
|
|
if number.startswith('9'):
|
||
|
|
raise InvalidComponent()
|
||
|
|
if calc_check_digit_legal(number[:-1]) != number[-1]:
|
||
|
|
raise InvalidChecksum()
|
||
|
|
elif len(number) == 9 and number.startswith('6'):
|
||
|
|
# special cases (skip first digit in calculation)
|
||
|
|
if calc_check_digit_special(number[1:-1]) != number[-1]:
|
||
|
|
raise InvalidChecksum()
|
||
|
|
elif len(number) in (9, 10):
|
||
|
|
# 9 or 10 digit individual
|
||
|
|
rc.validate(number)
|
||
|
|
else:
|
||
|
|
raise InvalidLength()
|
||
|
|
return number
|
||
|
|
|
||
|
|
|
||
|
|
def is_valid(number):
|
||
|
|
"""Checks to see if the number provided is a valid VAT number. This
|
||
|
|
checks the length, formatting and check digit."""
|
||
|
|
try:
|
||
|
|
return bool(validate(number))
|
||
|
|
except ValidationError:
|
||
|
|
return False
|