# dni.py - functions for handling Spanish personal identity codes
# coding: utf-8
#
# Copyright (C) 2012, 2013 Arthur de Jong
#
# 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

"""DNI (Documento Nacional de Identidad, Spanish personal identity codes).

The DNI is a 9 digit number used to identify Spanish citizens. The last
digit is a checksum letter.

Foreign nationals, since 2010 are issued an NIE (Número de Identificación
de Extranjeros, Foreigner's Identity Number) instead.

>>> validate('54362315-K')
'54362315K'
>>> validate('54362315Z')  # invalid check digit
Traceback (most recent call last):
    ...
InvalidChecksum: ...
>>> validate('54362315')  # digit missing
Traceback (most recent call last):
    ...
InvalidLength: ...
"""

from stdnum.exceptions import *
from stdnum.util import clean, isdigits


def compact(number):
    """Convert the number to the minimal representation. This strips the
    number of any valid separators and removes surrounding whitespace."""
    return clean(number, ' -').upper().strip()


def calc_check_digit(number):
    """Calculate the check digit. The number passed should not have the
    check digit included."""
    return 'TRWAGMYFPDXBNJZSQVHLCKE'[int(number) % 23]


def validate(number):
    """Check if the number provided is a valid DNI number. This checks the
    length, formatting and check digit."""
    number = compact(number)
    if not isdigits(number[:-1]):
        raise InvalidFormat()
    if len(number) != 9:
        raise InvalidLength()
    if calc_check_digit(number[:-1]) != number[-1]:
        raise InvalidChecksum()
    return number


def is_valid(number):
    """Check if the number provided is a valid DNI number. This checks the
    length, formatting and check digit."""
    try:
        return bool(validate(number))
    except ValidationError:
        return False