104 lines
3.3 KiB
Python
104 lines
3.3 KiB
Python
# ird.py - functions for handling New Zealand IRD numbers
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# coding: utf-8
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#
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# Copyright (C) 2019 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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"""IRD number (New Zealand Inland Revenue Department (Te Tari Tāke) number).
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The IRD number is used by the New Zealand Inland Revenue Department (Te Tari
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Tāke in Māori) to identify businesses and individuals for tax purposes. The
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number consists of 8 or 9 digits where the last digit is a check digit.
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More information:
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* https://www.ird.govt.nz/
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* https://www.ird.govt.nz/-/media/Project/IR/PDF/2020RWTNRWTSpecificationDocumentv10.pdf
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* https://www.oecd.org/tax/automatic-exchange/crs-implementation-and-assistance/tax-identification-numbers/New%20Zealand-TIN.pdf
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>>> validate('4909185-0')
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'49091850'
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>>> validate('NZ 49-098-576')
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'49098576'
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>>> validate('136410133')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> validate('9125568')
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Traceback (most recent call last):
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...
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InvalidLength: ...
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>>> format('49098576')
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'49-098-576'
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""" # noqa: E501
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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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number = clean(number, ' -').upper().strip()
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if number.startswith('NZ'):
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return number[2:]
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return number
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def calc_check_digit(number: str) -> str:
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"""Calculate the check digit.
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The number passed should not have the check digit included.
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"""
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primary_weights = (3, 2, 7, 6, 5, 4, 3, 2)
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secondary_weights = (7, 4, 3, 2, 5, 2, 7, 6)
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# pad with leading zeros
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number = number.zfill(8)
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s = -sum(w * int(n) for w, n in zip(primary_weights, number)) % 11
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if s != 10:
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return str(s)
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s = -sum(w * int(n) for w, n in zip(secondary_weights, number)) % 11
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return str(s)
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def validate(number: str) -> str:
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"""Check if the number is a valid IRD number."""
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number = compact(number)
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if len(number) not in (8, 9):
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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 not 10000000 < int(number) < 150000000:
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raise InvalidComponent()
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if number[-1] != calc_check_digit(number[:-1]):
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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 IRD 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 '-'.join([number[:-6], number[-6:-3], number[-3:]])
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