"""

Polish-specific form helpers

"""

import re

from django.forms import ValidationError

from django.forms.fields import Select, RegexField

from django.utils.translation import ugettext_lazy as _

class PLProvinceSelect(Select):

    """

    A select widget with list of Polish administrative provinces as choices.

    """

    def __init__(self, attrs=None):

        from pl_voivodeships import VOIVODESHIP_CHOICES

        super(PLProvinceSelect, self).__init__(attrs, choices=VOIVODESHIP_CHOICES)

class PLCountySelect(Select):

    """

    A select widget with list of Polish administrative units as choices.

    """

    def __init__(self, attrs=None):

        from pl_administrativeunits import ADMINISTRATIVE_UNIT_CHOICES

        super(PLCountySelect, self).__init__(attrs, choices=ADMINISTRATIVE_UNIT_CHOICES)

class PLPESELField(RegexField):

    """

    A form field that validates as Polish Identification Number (PESEL).

    Checks the following rules:

        * the length consist of 11 digits

        * has a valid checksum

    The algorithm is documented at http://en.wikipedia.org/wiki/PESEL.

    """

    default_error_messages = {

        'invalid': _(u'National Identification Number consists of 11 digits.'),

        'checksum': _(u'Wrong checksum for the National Identification Number.'),

    }

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

        super(PLPESELField, self).__init__(r'^\d{11}$',

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

    def clean(self,value):

        super(PLPESELField, self).clean(value)

        if not self.has_valid_checksum(value):

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

        return u'%s' % value

    def has_valid_checksum(self, number):

        """

        Calculates a checksum with the provided algorithm.

        """

        multiple_table = (1, 3, 7, 9, 1, 3, 7, 9, 1, 3, 1)

        result = 0

        for i in range(len(number)):

            result += int(number[i]) * multiple_table[i]

        return result % 10 == 0

class PLNIPField(RegexField):

    """

    A form field that validates as Polish Tax Number (NIP).

    Valid forms are: XXX-XXX-YY-YY or XX-XX-YYY-YYY.

    Checksum algorithm based on documentation at

    http://wipos.p.lodz.pl/zylla/ut/nip-rego.html

    """

    default_error_messages = {

        'invalid': _(u'Enter a tax number field (NIP) in the format XXX-XXX-XX-XX or XX-XX-XXX-XXX.'),

        'checksum': _(u'Wrong checksum for the Tax Number (NIP).'),

    }

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

        super(PLNIPField, self).__init__(r'^\d{3}-\d{3}-\d{2}-\d{2}$|^\d{2}-\d{2}-\d{3}-\d{3}$',

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

    def clean(self,value):

        super(PLNIPField, self).clean(value)

        value = re.sub("[-]", "", value)

        if not self.has_valid_checksum(value):

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

        return u'%s' % value

    def has_valid_checksum(self, number):

        """

        Calculates a checksum with the provided algorithm.

        """

        multiple_table = (6, 5, 7, 2, 3, 4, 5, 6, 7)

        result = 0

        for i in range(len(number)-1):

            result += int(number[i]) * multiple_table[i]

        result %= 11

        if result == int(number[-1]):

            return True

        else:

            return False

class PLREGONField(RegexField):

    """

    A form field that validates its input is a REGON number.

    Valid regon number consists of 9 or 14 digits.

    See http://www.stat.gov.pl/bip/regon_ENG_HTML.htm for more information.

    """

    default_error_messages = {

        'invalid': _(u'National Business Register Number (REGON) consists of 9 or 14 digits.'),

        'checksum': _(u'Wrong checksum for the National Business Register Number (REGON).'),

    }

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

        super(PLREGONField, self).__init__(r'^\d{9,14}$',

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

    def clean(self,value):

        super(PLREGONField, self).clean(value)

        if not self.has_valid_checksum(value):

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

        return u'%s' % value

    def has_valid_checksum(self, number):

        """

        Calculates a checksum with the provided algorithm.

        """

        weights = (

            (8, 9, 2, 3, 4, 5, 6, 7, -1),

            (2, 4, 8, 5, 0, 9, 7, 3, 6, 1, 2, 4, 8, -1),

            (8, 9, 2, 3, 4, 5, 6, 7, -1, 0, 0, 0, 0, 0),

        )

        weights = [table for table in weights if len(table) == len(number)]

        for table in weights:

            checksum = sum([int(n) * w for n, w in zip(number, table)])

            if checksum % 11 % 10:

                return False

        return bool(weights)

class PLPostalCodeField(RegexField):

    """

    A form field that validates as Polish postal code.

    Valid code is XX-XXX where X is digit.

    """

    default_error_messages = {

        'invalid': _(u'Enter a postal code in the format XX-XXX.'),

    }

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

        super(PLPostalCodeField, self).__init__(r'^\d{2}-\d{3}$',

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