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# nip.py - functions for handling Polish VAT numbers
#
# Copyright (C) 2012 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
"""NIP (Numer Identyfikacji Podatkowej, Polish VAT number).
The NIP (Numer Identyfikacji Podatkowej) number consists of 10 digit with
a straightforward weighted checksum.
>>> compact('PL 8567346215')
'8567346215'
>>> is_valid('PL 8567346215')
True
>>> is_valid('PL 8567346216') # invalid check digits
False
>>> format('PL 8567346215')
'856-734-62-15'
"""
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('PL'):
number = number[2:]
return number
def checksum(number):
"""Calculate the checksum."""
weights = (6, 5, 7, 2, 3, 4, 5, 6, 7, -1)
return sum(weights[i] * int(n) for i, n in enumerate(number)) % 11
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:
number = compact(number)
except:
return False
return number.isdigit() and len(number) == 10 and \
checksum(number) == 0
def format(number):
"""Reformat the passed number to the standard format."""
number = compact(number)
return '-'.join((number[0:3], number[3:6], number[6:8], number[8:]))
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