127 lines
4.2 KiB
Python
127 lines
4.2 KiB
Python
# uscc.py - functions for handling Chinese USCC 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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"""USCC (Unified Social Credit Code, 统一社会信用代码, China tax number).
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This number consists of 18 digits or uppercase English letters (excluding the
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letters I, O, Z, S, V). The number is comprised of several parts:
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* Digit 1 represents the registering authority,
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* Digit 2 represents the registered entity type,
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* Digits 3 through 8 represent the registering region code,
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* Digits 9 through 17 represent the organisation code,
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* Digit 18 is a check digit (either a number or letter).
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The registering authority digit most often is a 9, which represents the State
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Administration for Industry and Commerce (SAIC) as the registering authority.
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The registered entity type indicates the type of business (or entity). The
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most common entity types in China are:
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* Wholly Foreign-Owned Enterprises (WFOE): 外商独资企业
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* Joint Ventures (JV): 合资
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* Representative Office: 代表处
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* State-Owned Enterprise (SOE): 国有企业
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* Private Enterprise: 民营企业
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* Individually-Owned: 个体户
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The registering region code, sometimes referred to as the "administrative
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division code", is a string of six numbers that indicates where the company
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is registered. It roughly follows the organisation of the official Chinese
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regions.
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The organisation code comes directly from the China Organization Code
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certificate, an alternative document to the China Business License. It can
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contain letters or digits.
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More information:
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* https://zh.wikipedia.org/wiki/统一社会信用代码
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* https://zh.wikipedia.org/wiki/校验码
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* https://www.oecd.org/tax/automatic-exchange/crs-implementation-and-assistance/tax-identification-numbers/China-TIN.pdf
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>>> validate('91110000600037341L')
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'91110000600037341L'
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>>> validate('A1110000600037341L')
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Traceback (most recent call last):
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...
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InvalidFormat: ...
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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('9 1 110000 600037341L')
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'91110000600037341L'
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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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_alphabet = '0123456789ABCDEFGHJKLMNPQRTUWXY'
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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, ' -').upper().strip()
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def calc_check_digit(number: str) -> str:
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"""Calculate the check digit for the number."""
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weights = (1, 3, 9, 27, 19, 26, 16, 17, 20, 29, 25, 13, 8, 24, 10, 30, 28)
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number = compact(number)
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total = sum(_alphabet.index(n) * w for n, w in zip(number, weights))
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return _alphabet[(31 - total) % 31]
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def validate(number: str) -> str:
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"""Check if the number is a valid USCC.
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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) != 18:
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raise InvalidLength()
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if not isdigits(number[:8]):
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raise InvalidFormat()
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if any(c not in _alphabet for c in number[8:]):
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raise InvalidFormat()
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if number[-1] != calc_check_digit(number):
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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 USCC."""
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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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