"""

IT-specific Form helpers

"""

from django.forms import ValidationError

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

from django.utils.translation import ugettext_lazy as _

from django.utils.encoding import smart_unicode

from django.contrib.localflavor.it.util import ssn_check_digit, vat_number_check_digit

import re

class ITZipCodeField(RegexField):

    default_error_messages = {

        'invalid': _('Enter a valid zip code.'),

    }

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

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

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

class ITRegionSelect(Select):

    """

    A Select widget that uses a list of IT regions as its choices.

    """

    def __init__(self, attrs=None):

        from it_region import REGION_CHOICES

        super(ITRegionSelect, self).__init__(attrs, choices=REGION_CHOICES)

class ITProvinceSelect(Select):

    """

    A Select widget that uses a list of IT provinces as its choices.

    """

    def __init__(self, attrs=None):

        from it_province import PROVINCE_CHOICES

        super(ITProvinceSelect, self).__init__(attrs, choices=PROVINCE_CHOICES)

class ITSocialSecurityNumberField(RegexField):

    """

    A form field that validates Italian Social Security numbers (codice fiscale).

    For reference see http://www.agenziaentrate.it/ and search for

    'Informazioni sulla codificazione delle persone fisiche'.

    """

    default_error_messages = {

        'invalid': _(u'Enter a valid Social Security number.'),

    }

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

        super(ITSocialSecurityNumberField, self).__init__(r'^\w{3}\s*\w{3}\s*\w{5}\s*\w{5}$',

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

    def clean(self, value):

        value = super(ITSocialSecurityNumberField, self).clean(value)

        if value == u'':

            return value

        value = re.sub('\s', u'', value).upper()

        try:

            check_digit = ssn_check_digit(value)

        except ValueError:

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

        if not value[15] == check_digit:

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

        return value

class ITVatNumberField(Field):

    """

    A form field that validates Italian VAT numbers (partita IVA).

    """

    default_error_messages = {

        'invalid': _(u'Enter a valid VAT number.'),

    }

    def clean(self, value):

        value = super(ITVatNumberField, self).clean(value)

        if value == u'':

            return value

        try:

            vat_number = int(value)

        except ValueError:

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

        vat_number = str(vat_number).zfill(11)

        check_digit = vat_number_check_digit(vat_number[0:10])

        if not vat_number[10] == check_digit:

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

        return smart_unicode(vat_number)