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