135 lines
4.3 KiB
Python
135 lines
4.3 KiB
Python
# bankaccount.py - functions for handling Czech bank account numbers
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# coding: utf-8
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#
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# Copyright (C) 2022 Petr Přikryl
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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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"""Czech bank account number.
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The Czech bank account numbers consist of up to 20 digits:
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UUUUUK-MMMMMMMMKM/XXXX
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The first part is prefix that is up to 6 digits. The following part is from 2 to 10 digits.
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Both parts could be filled with zeros from left if missing.
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The final 4 digits represent the bank code.
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More information:
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* https://www.penize.cz/osobni-ucty/424173-tajemstvi-cisla-uctu-klicem-pro-banky-je-11
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* https://www.zlatakoruna.info/zpravy/ucty/cislo-uctu-v-cr
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>>> validate('34278-0727558021/0100')
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'034278-0727558021/0100'
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>>> validate('4278-727558021/0100') # invalid check digits (prefix)
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> validate('34278-727558021/0000') # invalid bank
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Traceback (most recent call last):
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...
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InvalidComponent: ...
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>>> format('34278-727558021/0100')
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'034278-0727558021/0100'
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>>> to_bic('34278-727558021/0100')
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'KOMBCZPP'
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"""
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from __future__ import annotations
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import re
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from stdnum.exceptions import *
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from stdnum.util import clean
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_bankaccount_re = re.compile(
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r'((?P<prefix>[0-9]{0,6})-)?(?P<root>[0-9]{2,10})\/(?P<bank>[0-9]{4})')
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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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number = clean(number).strip()
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match = _bankaccount_re.match(number)
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if match:
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# zero-pad valid numbers
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prefix = (match.group('prefix') or '').zfill(6)
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root = match.group('root').zfill(10)
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number = ''.join((prefix, '-', root, '/', match.group('bank')))
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return number
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def _split(number: str) -> tuple[str | None, str, str]:
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"""Split valid numbers into prefix, root and bank parts of the number."""
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match = _bankaccount_re.match(number)
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if not match:
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raise InvalidFormat()
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return match.group('prefix'), match.group('root'), match.group('bank')
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def _info(bank: str) -> dict[str, str]:
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"""Look up information for the bank."""
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from stdnum import numdb
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info = {}
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for _nr, found in numdb.get('cz/banks').info(bank):
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info.update(found)
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return info
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def info(number: str) -> dict[str, str]:
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"""Return a dictionary of data about the supplied number. This typically
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returns the name of the bank and branch and a BIC if it is valid."""
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prefix, root, bank = _split(compact(number))
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return _info(bank)
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def to_bic(number: str) -> str | None:
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"""Return the BIC for the bank that this number refers to."""
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return info(number).get('bic')
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def _calc_checksum(number: str) -> int:
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weights = (6, 3, 7, 9, 10, 5, 8, 4, 2, 1)
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return sum(w * int(n) for w, n in zip(weights, number.zfill(10))) % 11
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def validate(number: str) -> str:
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"""Check if the number provided is a valid bank account number."""
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number = compact(number)
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prefix, root, bank = _split(number)
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# guaranteed to be present because compacts adds a missing prefix
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assert prefix
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if _calc_checksum(prefix) != 0:
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raise InvalidChecksum()
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if _calc_checksum(root) != 0:
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raise InvalidChecksum()
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if 'bank' not in _info(bank):
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raise InvalidComponent()
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return number
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def is_valid(number: str) -> bool:
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"""Check if the number provided is a valid bank account 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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