# pps.py - functions for handling Irish PPS numbers
#
# Copyright (C) 2012 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

"""Module for handling Irish PPS (Personal Public Service) numbers.

The number consists of 8 digits. The first seven are numeric and the last
is the check character. The number is sometimes be followed by an extra
letter, which is ignored for the check algorithm, and can be a 'W', 'T' or
an 'X'.

>>> compact('6433435F')
'6433435F'
>>> is_valid('6433435F')
True
>>> is_valid('6433435E')  # incorrect check digit
False
"""

import re

from stdnum.util import clean
from stdnum.ie import vat


pps_re = re.compile('^\d{7}[A-W][WTX]?$')
"""Regular expression used to check syntax of PPS numbers."""


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 is_valid(number):
    """Checks to see if the number provided is a valid PPS number. This
    checks the length, formatting and check digit."""
    try:
        number = compact(number)
    except:
        return False
    if not pps_re.match(number):
        return False
    return number[7] == vat.calc_check_digit(number[:7])