##############################################################################
#
# Copyright (c) 2008 Zope Foundation and Contributors.
# All Rights Reserved.
#
# This software is subject to the provisions of the Zope Public License,
# Version 2.1 (ZPL). A copy of the ZPL should accompany this distribution.
# THIS SOFTWARE IS PROVIDED "AS IS" AND ANY AND ALL EXPRESS OR IMPLIED
# WARRANTIES ARE DISCLAIMED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
# WARRANTIES OF TITLE, MERCHANTABILITY, AGAINST INFRINGEMENT, AND FITNESS
# FOR A PARTICULAR PURPOSE.
#
##############################################################################
"""
"""
import zope.interface
from . import interfaces
[docs]def isValidCreditCard(cardNum):
"""Returns True if the credit card number is a valid Luhn (Mod 10) number
and False if not. This, of course, does not validate the number, but
will catch typos. There is the chance that two typographic errors could
return a false positive if they offset one another, but the likelihood
is low and pre-validating is fast"""
financialIndustries = ['3', '4', '5', '6']
if cardNum[0] not in financialIndustries:
return False
total = pos = 0
for digit in cardNum[::-1]:
if pos % 2 == 0:
multiplier = 1
else:
multiplier = 2
product = int(digit) * multiplier
total += product // 10 + product % 10
pos += 1
if total % 10 == 0:
return True
return False
[docs]@zope.interface.implementer(interfaces.IISO7812CreditCard)
class ISO7812CreditCard(zope.schema.TextLine):
"""A valid ISO 7812 credit card number."""
__doc__ = interfaces.IISO7812CreditCard.__doc__
def constraint(self, value):
allDigits = True
for char in value[:]:
if not char.isdigit():
allDigits = False
return '\n' not in value and '\r' not in value and allDigits
def _validate(self, value):
super(ISO7812CreditCard, self)._validate(value)
if not isValidCreditCard(value):
raise interfaces.NotValidISO7812CreditCard(value)