"""

FI-specific Form helpers

"""

import re

from django.forms import ValidationError

from django.forms.fields import Field, RegexField, Select, EMPTY_VALUES

from django.utils.translation import ugettext_lazy as _

class FIZipCodeField(RegexField):

    default_error_messages = {

        'invalid': _('Enter a zip code in the format XXXXX.'),

    }

    def __init__(self, *args, **kwargs):

        super(FIZipCodeField, self).__init__(r'^\d{5}$',

            max_length=None, min_length=None, *args, **kwargs)

class FIMunicipalitySelect(Select):

    """

    A Select widget that uses a list of Finnish municipalities as its choices.

    """

    def __init__(self, attrs=None):

        from fi_municipalities import MUNICIPALITY_CHOICES

        super(FIMunicipalitySelect, self).__init__(attrs, choices=MUNICIPALITY_CHOICES)

class FISocialSecurityNumber(Field):

    default_error_messages = {

        'invalid': _('Enter a valid Finnish social security number.'),

    }

    def clean(self, value):

        super(FISocialSecurityNumber, self).clean(value)

        if value in EMPTY_VALUES:

            return u''

        checkmarks = "0123456789ABCDEFHJKLMNPRSTUVWXY"

        result = re.match(r"""^

            (?P<date>([0-2]\d|3[01])

            (0\d|1[012])

            (\d{2}))

            [A+-]

            (?P<serial>(\d{3}))

            (?P<checksum>[%s])$""" % checkmarks, value, re.VERBOSE | re.IGNORECASE)

        if not result:

            raise ValidationError(self.error_messages['invalid'])

        gd = result.groupdict()

        checksum = int(gd['date'] + gd['serial'])

        if checkmarks[checksum % len(checkmarks)] == gd['checksum'].upper():

            return u'%s' % value.upper()

        raise ValidationError(self.error_messages['invalid'])