Add support for Tunisia TIN

Fixes arthurdejong#309.

stdnum/tn/__init__.py

@@ -0,0 +1,24 @@
+# __init__.py - collection of Tunisian numbers
+# coding: utf-8
+#
+# Copyright (C) 2022 Leandro Regueiro
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""Collection of Tunisian numbers."""
+
+# provide aliases
+from stdnum.tn import mf as vat  # noqa: F401

stdnum/tn/mf.py

@@ -0,0 +1,154 @@
+# pin.py - functions for handling Tunisia MF numbers
+# coding: utf-8
+#
+# Copyright (C) 2022 Leandro Regueiro
+#
+# This library is free software; you can redistribute it and/or
+# modify it under the terms of the GNU Lesser General Public
+# License as published by the Free Software Foundation; either
+# version 2.1 of the License, or (at your option) any later version.
+#
+# This library is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# Lesser General Public License for more details.
+#
+# You should have received a copy of the GNU Lesser General Public
+# License along with this library; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+# 02110-1301 USA
+
+"""MF (Matricule Fiscal, Tunisia tax number).
+
+The MF consists of 4 parts: the "identifiant fiscal", the "code TVA", the "code
+catégorie" and the "numéro d'etablissement secondaire".
+
+The "identifiant fiscal" consists of 2 parts: the "identifiant unique" and the
+"clef de contrôle". The "identifiant unique" is composed of 7 digits. The "clef
+de contrôle" is a letter, excluding "I", "O" and "U" because of their
+similarity to "1", "0" and "4".
+
+The "code TVA" is a letter that tells which VAT regime is being used. The valid
+values are "A", "P", "B", "D" and "N".
+
+The "code catégorie" is a letter that tells the category the contributor
+belongs to. The valid values are "M", "P", "C", "N" and "E".
+
+The "numéro d'etablissement secondaire" consists of 3 digits. It is usually
+"000", but it can be "001", "002"... depending on the branches. If it is not
+"000" then "code catégorie" must be "E".
+
+More information:
+
+* https://futurexpert.tn/2019/10/22/structure-et-utilite-du-matricule-fiscal/
+* https://www.registre-entreprises.tn/
+
+>>> validate('1234567/M/A/E/001')
+'1234567MAE001'
+>>> validate('000 123 LAM 000')
+'0000123LAM000'
+>>> validate('1282182 / W')
+'1282182W'
+>>> validate('121J')
+'0000121J'
+>>> validate('12345')
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> validate('000/M/A/1222334L')
+Traceback (most recent call last):
+    ...
+InvalidLength: ...
+>>> validate('1219773U')
+Traceback (most recent call last):
+    ...
+InvalidFormat: ...
+>>> validate('1234567/M/A/X/000')
+Traceback (most recent call last):
+    ...
+InvalidFormat: ...
+>>> format('1282182 / W')
+'1282182/W'
+>>> format('121J')
+'0000121/J'
+>>> format('1496298 T P N 000')
+'1496298/T/P/N/000'
+"""
+
+from stdnum.exceptions import *
+from stdnum.util import clean, isdigits
+
+
+VALID_CONTROL_KEYS = ('A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'J', 'K', 'L',
+                      'M', 'N', 'P', 'Q', 'R', 'S', 'T', 'V', 'W', 'X', 'Y',
+                      'Z')
+VALID_TVA_CODES = ('A', 'P', 'B', 'D', 'N')
+VALID_CATEGORY_CODES = ('M', 'P', 'C', 'N', 'E')
+
+
+def compact(number):
+    """Convert the number to the minimal representation.
+
+    This strips the number of any valid separators, removes surrounding
+    whitespace.
+    """
+    result = clean(number, ' /.-').upper()
+
+    # Find position of first letter.
+    first_letter_index = 7
+
+    for i, char in enumerate(result):
+        if char not in ('0', '1', '2', '3', '4', '5', '6', '7', '8', '9'):
+            first_letter_index = i
+            break
+
+    # Number must begin with a digit, so abort otherwise.
+    if first_letter_index == 0:
+        return result
+
+    # Pad with enough zeros.
+    if first_letter_index < 7:
+        result = result.zfill(7 + len(result[first_letter_index:]))
+
+    return result
+
+
+def validate(number):
+    """Check if the number is a valid Tunisia MF number.
+
+    This checks the length and formatting.
+    """
+    number = compact(number)
+    if len(number) not in (8, 13):
+        raise InvalidLength()
+    if not isdigits(number[:7]):
+        raise InvalidFormat()
+    if number[7] not in VALID_CONTROL_KEYS:
+        raise InvalidFormat()
+    if len(number) == 8:
+        return number
+    if number[8] not in VALID_TVA_CODES:
+        raise InvalidFormat()
+    if number[9] not in VALID_CATEGORY_CODES:
+        raise InvalidFormat()
+    if not isdigits(number[10:]):
+        raise InvalidFormat()
+    if number[10:] != '000' and number[9] != 'E':
+        raise InvalidFormat()
+    return number
+
+
+def is_valid(number):
+    """Check if the number is a valid Tunisia MF number."""
+    try:
+        return bool(validate(number))
+    except ValidationError:
+        return False
+
+
+def format(number):
+    """Reformat the number to the standard presentation format."""
+    result = compact(number)
+    if len(result) == 8:
+        return '/'.join([result[:7], result[7]])
+    return '/'.join([result[:7], result[7], result[8], result[9], result[10:]])