idfinal.py

#! /usr/bin/env python
# -*- coding: utf-8 -*-
# vim:ts=8 sts=4 sw=4 expandtab ft=python

#
# Copyright (c) 2013, chys <admin@CHYS.INFO>
#
# Redistribution and use in source and binary forms, with or without
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#   Redistributions of source code must retain the above copyright notice, this
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#   this software without specific prior written permission.
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"""
Calculate or verify the last digit of an
18-digit Chinese ID (second-generation ID) number.

Usage: idfinal <17or18digits> ...
"""

from __future__ import print_function

import sys


def calculate(s):
    '''Given the first 17 digits, return the last digit as a string.

    If something is wrong, return None.
    '''
    if len(s) == 17 and set(s).issubset('0123456789'):
        n = sum(map(lambda a, b: a * int(b),
                (7, 9, 10, 5, 8, 4, 2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2), s)) % 11
        return '10X98765432'[n]
    else:
        return None


def main():

    if len(sys.argv) < 2 or sys.argv[1] == '--help':
        print(__doc__)
        sys.exit(0)

    err = 0

    for s in sys.argv[1:]:
        if len(s) == 17:
            x = calculate(s)
            if x:
                print(s + x)
            else:
                print('Invalid: ', s + '?', file=sys.stderr)
                err = 1
        else:
            x = calculate(s[:17])
            if s == s[:17] + x:
                print('Valid: ', s)
            else:
                print('Invalid: ', s, file=sys.stderr)
                err = 1
    sys.exit(err)


if __name__ == '__main__':
    main()