98 lines
3.3 KiB
Python
98 lines
3.3 KiB
Python
# tva.py - functions for handling French TVA numbers
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# coding: utf-8
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#
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# Copyright (C) 2012-2015 Arthur de Jong
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#
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# This library is free software; you can redistribute it and/or
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# modify it under the terms of the GNU Lesser General Public
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# License as published by the Free Software Foundation; either
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# version 2.1 of the License, or (at your option) any later version.
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#
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# This library is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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# Lesser General Public License for more details.
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#
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# You should have received a copy of the GNU Lesser General Public
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# License along with this library; if not, write to the Free Software
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# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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# 02110-1301 USA
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"""n° TVA (taxe sur la valeur ajoutée, French VAT number).
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The n° TVA (Numéro d'identification à la taxe sur la valeur ajoutée) is the
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SIREN (Système d’Identification du Répertoire des Entreprises) prefixed by
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two digits. In old style numbers the two digits are numeric, with new
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style numbers at least one is a alphabetic.
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>>> compact('Fr 40 303 265 045')
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'40303265045'
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>>> validate('23334175221')
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'23334175221'
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>>> validate('84 323 140 391')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> validate('K7399859412') # new-style number
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'K7399859412'
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>>> validate('4Z123456782') # new-style number starting with digit
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'4Z123456782'
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>>> validate('IO334175221') # the letters cannot by I or O
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Traceback (most recent call last):
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...
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InvalidFormat: ...
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"""
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from stdnum.exceptions import *
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from stdnum.fr import siren
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from stdnum.util import clean
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# the valid characters for the first two digits (O and I are missing)
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_alphabet = '0123456789ABCDEFGHJKLMNPQRSTUVWXYZ'
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def compact(number):
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"""Convert the number to the minimal representation. This strips the
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number of any valid separators and removes surrounding whitespace."""
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number = clean(number, ' -.').upper().strip()
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if number.startswith('FR'):
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number = number[2:]
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return number
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def validate(number):
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"""Checks to see if the number provided is a valid VAT number. This
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checks the length, formatting and check digit."""
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number = compact(number)
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if not all(x in _alphabet for x in number[:2]):
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raise InvalidFormat()
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if len(number) != 11:
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raise InvalidLength()
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siren.validate(number[2:])
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if number.isdigit():
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# all-numeric digits
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if int(number[:2]) != (int(number[2:] + '12') % 97):
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raise InvalidChecksum()
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else:
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# one of the first two digits isn't a number
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if number[0].isdigit():
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check = (
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_alphabet.index(number[0]) * 24 +
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_alphabet.index(number[1]) - 10)
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else:
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check = (
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_alphabet.index(number[0]) * 34 +
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_alphabet.index(number[1]) - 100)
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if (int(number[2:]) + 1 + check // 11) % 11 != (check % 11):
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raise InvalidChecksum()
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return number
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def is_valid(number):
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"""Checks to see if the number provided is a valid VAT number. This
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checks the length, formatting and check digit."""
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try:
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return bool(validate(number))
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except ValidationError:
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return False
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