96 lines
2.8 KiB
Python
96 lines
2.8 KiB
Python
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# ubn.py - functions for handling Taiwanese UBN numbers
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# coding: utf-8
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#
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# Copyright (C) 2020 Leandro Regueiro
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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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"""UBN (Unified Business Number, 統一編號, Taiwanese tax number).
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The Unified Business Number (UBN, 統一編號) is the number assigned to businesses
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within Taiwan for tax (VAT) purposes. The number consists of 8 digits, the
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last being a check digit.
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More information:
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* https://zh.wikipedia.org/wiki/統一編號
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* https://findbiz.nat.gov.tw/fts/query/QueryBar/queryInit.do?request_locale=en
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>>> validate('00501503')
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'00501503'
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>>> validate('00501502')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> validate('12345')
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Traceback (most recent call last):
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...
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InvalidLength: ...
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>>> format(' 0050150 3 ')
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'00501503'
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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.
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This strips the number of any valid separators and removes surrounding
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whitespace.
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"""
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return clean(number, ' -').strip()
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def calc_checksum(number: str) -> int:
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"""Calculate the checksum over the number."""
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# convert to numeric first, then sum individual digits
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weights = (1, 2, 1, 2, 1, 2, 4, 1)
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number = ''.join(str(w * int(n)) for w, n in zip(weights, number))
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return sum(int(n) for n in number) % 10
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def validate(number: str) -> str:
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"""Check if the number is a valid Taiwan UBN number.
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This checks the length, formatting and check digit.
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"""
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number = compact(number)
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if len(number) != 8:
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raise InvalidLength()
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if not isdigits(number):
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raise InvalidFormat()
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checksum = calc_checksum(number)
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if not (checksum == 0 or (checksum == 9 and number[6] == '7')):
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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 Taiwan UBN number."""
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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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return compact(number)
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