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