84 lines
2.7 KiB
Python
84 lines
2.7 KiB
Python
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# vat.py - functions for handling Cypriot 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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"""Αριθμός Εγγραφής Φ.Π.Α. (Cypriot VAT number).
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The Cypriot Αριθμός Εγγραφής Φ.Π.Α. (VAT) number consists of 9 digits
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where the last one is a is a letter and functions as a check digit.
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>>> compact('CY-10259033P')
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'10259033P'
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>>> validate('CY-10259033P ')
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'10259033P'
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>>> validate('CY-10259033Z') # invalid check digit
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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"""
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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('CY'):
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number = number[2:]
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return number
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def calc_check_digit(number):
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"""Calculate the check digit. The number passed should not have the
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check digit included."""
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translation = {
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'0': 1, '1': 0, '2': 5, '3': 7, '4': 9,
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'5': 13, '6': 15, '7': 17, '8': 19, '9': 21,
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}
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return 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'[(
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sum(translation[x] for x in number[::2]) +
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sum(int(x) for x in number[1::2])
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) % 26]
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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[:-1].isdigit():
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raise InvalidFormat()
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if len(number) != 9:
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raise InvalidLength()
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if number[0:2] == '12':
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raise InvalidComponent()
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if number[-1] != calc_check_digit(number[:-1]):
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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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