import re

from django import forms
from django.utils.translation import ugettext_lazy as _

CREDIT_CARD_RE = r'^(?:4[0-9]{12}(?:[0-9]{3})?|5[1-5][0-9]{14}|6(?:011|5[0-9][0-9])[0-9]{12}|3[47][0-9]{13}|3(?:0[0-5]|[68][0-9])[0-9]{11}|(?:2131|1800|35\\d{3})\d{11})$'


class CreditCardField(forms.CharField):
    """
    Form field that validates credit card numbers.
    """

    default_error_messages = {
        'required': _(u'Номер карты обязателен.'),
        'invalid': _(u'Неверный номер карты.'),
    }

    def clean(self, value):
        value = value.replace(' ', '').replace('-', '')
        if self.required and not value:
            raise forms.utils.ValidationError(self.error_messages['required'])
        if value and not re.match(CREDIT_CARD_RE, value):
            raise forms.utils.ValidationError(self.error_messages['invalid'])
        return value