116 lines
3.6 KiB
Python
116 lines
3.6 KiB
Python
# mst.py - functions for handling Vietnam MST 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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"""MST (Mã số thuế, Vietnam tax number).
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This number consists of 10 digits. Branches have a 13 digit number,
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where the first ten digits are the same as the parent company's.
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The first two digits is the province code where the business was
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established. If an enterprise relocates its head office from one
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province to another, the MST will remain unchanged.
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The following seven digits are a sequential number from 0000001 to
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9999999.
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The tenth digit is the check digit for the first nine digits, which is
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used to verify the number was correctly typed.
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The last optional three digits are a sequence from 001 to 999
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indicating branches of the enterprise. These digits are usually
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separated from the first ten digits using a dash (-)
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More information:
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* https://vi.wikipedia.org/wiki/Thuế_Việt_Nam#Mã_số_thuế_(MST)_của_doanh_nghiệp
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* https://easyinvoice.vn/ma-so-thue/
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* https://ub.com.vn/threads/huong-dan-tra-cuu-ma-so-thue-doanh-nghiep-moi-nhat.261393/
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>>> validate('0100233488')
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'0100233488'
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>>> validate('0314409058-002')
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'0314409058002'
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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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>>> validate('0100233480')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> format('01.00.112.437')
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'0100112437'
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>>> format('0312 68 78 78 - 001')
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'0312687878-001'
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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_check_digit(number: str) -> str:
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"""Calculate the check digit."""
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weights = (31, 29, 23, 19, 17, 13, 7, 5, 3)
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total = sum(w * int(n) for w, n in zip(weights, number))
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return str(10 - (total % 11))
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def validate(number: str) -> str:
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"""Check if the number is a valid Vietnam MST 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) not in (10, 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 number[2:9] == '0000000':
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raise InvalidComponent()
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if len(number) == 13 and number[-3:] == '000':
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raise InvalidComponent()
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if number[9] != 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 Vietnam MST 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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number = compact(number)
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return number if len(number) == 10 else '-'.join([number[:10], number[10:]])
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