100 lines
3.4 KiB
Python
100 lines
3.4 KiB
Python
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# esr.py - functions for handling Swiss EinzahlungsSchein mit Referenznummer
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# coding: utf-8
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#
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# Copyright (C) 2019 Kurt Keller
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# Copyright (C) 2019 Arthur de Jong
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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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"""ESR, ISR, QR-reference (reference number on Swiss payment slips).
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The ESR (Eizahlungsschein mit Referenznummer), ISR (In-payment Slip with
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Reference Number) or QR-reference refers to the orange payment slip in
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Switzerland with which money can be transferred to an account. The slip
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contains a machine-readable part that contains a participant number and
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reference number. The participant number ensures the crediting to the
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corresponding account. The reference number enables the creditor to identify
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the invoice recipient. In this way, the payment process can be handled
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entirely electronically.
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The number consists of 26 numerical characters followed by a Modulo 10
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recursive check digit. It is printed in blocks of 5 characters (beginning
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with 2 characters, then 5x5-character groups). Leading zeros digits can be
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omitted.
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More information:
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* https://www.paymentstandards.ch/dam/downloads/ig-qr-bill-en.pdf
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>>> validate('21 00000 00003 13947 14300 09017')
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'210000000003139471430009017'
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>>> validate('210000000003139471430009016')
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Traceback (most recent call last):
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...
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InvalidChecksum: ...
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>>> format('18 78583')
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'00 00000 00000 00000 00018 78583'
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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. This strips
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surrounding whitespace and separators."""
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return clean(number, ' ').lstrip('0')
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def calc_check_digit(number: str) -> str:
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"""Calculate the check digit for number. The number passed should
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not have the check digit included."""
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_digits = (0, 9, 4, 6, 8, 2, 7, 1, 3, 5)
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c = 0
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for n in compact(number):
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c = _digits[(int(n) + c) % 10]
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return str((10 - c) % 10)
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def validate(number: str) -> str:
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"""Check if the number is a valid ESR. This checks the length, formatting
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and check digit."""
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number = compact(number)
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if len(number) > 27:
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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[-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 ESR."""
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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).zfill(27)
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return number[:2] + ' ' + ' '.join(
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number[i:i + 5] for i in range(2, len(number), 5))
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