88 lines
2.8 KiB
Python
88 lines
2.8 KiB
Python
# cn.py - functions for handling Japanese Corporate Number (CN)
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# coding: utf-8
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#
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# Copyright (C) 2019 Alan Hettinger
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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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"""CN (法人番号, hōjin bangō, Japanese Corporate Number).
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The Corporate Number is assigned by the Japanese National Tax Agency to
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identify government organs, public entities, registered corporations and
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other organisations. The number consists of 13 digits where the first digit
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is a non-zero check digit.
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More information:
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* https://en.wikipedia.org/wiki/Corporate_Number
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* https://www.nta.go.jp/taxes/tetsuzuki/mynumberinfo/houjinbangou/
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>>> validate('5-8356-7825-6246')
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'5835678256246'
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>>> validate('2-8356-7825-6246')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> format('5835678256246')
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'5-8356-7825-6246'
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"""
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from __future__ import annotations
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from stdnum.exceptions import *
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from stdnum.util import clean, isdigits
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def compact(number: str) -> str:
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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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return clean(number, '- ').strip()
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def calc_check_digit(number: str) -> str:
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"""Calculate the check digit. The number passed should not have
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the check digit included."""
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weights = (1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2)
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s = sum(w * int(n) for w, n in zip(weights, reversed(number))) % 9
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return str(9 - s)
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def validate(number: str) -> str:
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"""Check if the number is valid. This checks the length and check
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digit."""
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number = compact(number)
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if len(number) != 13:
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raise InvalidLength()
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if not isdigits(number):
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raise InvalidFormat()
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if calc_check_digit(number[1:]) != number[0]:
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raise InvalidChecksum()
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return number
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def is_valid(number: str) -> bool:
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"""Check if the number is a valid CN."""
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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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def format(number: str) -> str:
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"""Reformat the number to the standard presentation format."""
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number = compact(number)
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return '-'.join(
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(number[0], number[1:5], number[5:9], number[9:13]))
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