--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/app/django/contrib/localflavor/de/forms.py	Fri Jul 18 18:22:23 2008 +0000
@@ -0,0 +1,83 @@
+"""
+DE-specific Form helpers
+"""
+
+from django.newforms import ValidationError
+from django.newforms.fields import Field, RegexField, Select, EMPTY_VALUES
+from django.utils.translation import ugettext
+import re
+
+id_re = re.compile(r"^(?P<residence>\d{10})(?P<origin>\w{1,3})[-\ ]?(?P<birthday>\d{7})[-\ ]?(?P<validity>\d{7})[-\ ]?(?P<checksum>\d{1})$")
+
+class DEZipCodeField(RegexField):
+    default_error_messages = {
+        'invalid': ugettext('Enter a zip code in the format XXXXX.'),
+    }
+    def __init__(self, *args, **kwargs):
+        super(DEZipCodeField, self).__init__(r'^\d{5}$',
+            max_length=None, min_length=None, *args, **kwargs)
+
+class DEStateSelect(Select):
+    """
+    A Select widget that uses a list of DE states as its choices.
+    """
+    def __init__(self, attrs=None):
+        from de_states import STATE_CHOICES
+        super(DEStateSelect, self).__init__(attrs, choices=STATE_CHOICES)
+
+class DEIdentityCardNumberField(Field):
+    """
+    A German identity card number.
+
+    Checks the following rules to determine whether the number is valid:
+
+        * Conforms to the XXXXXXXXXXX-XXXXXXX-XXXXXXX-X format.
+        * No group consists entirely of zeroes.
+        * Included checksums match calculated checksums
+
+    Algorithm is documented at http://de.wikipedia.org/wiki/Personalausweis
+    """
+    default_error_messages = {
+        'invalid': ugettext('Enter a valid German identity card number in XXXXXXXXXXX-XXXXXXX-XXXXXXX-X format.'),
+    }
+
+    def has_valid_checksum(self, number):
+        given_number, given_checksum = number[:-1], number[-1]
+        calculated_checksum = 0
+        fragment = ""
+        parameter = 7
+
+        for i in range(len(given_number)):
+            fragment = str(int(given_number[i]) * parameter)
+            if fragment.isalnum():
+                calculated_checksum += int(fragment[-1])
+            if parameter == 1:
+                parameter = 7
+            elif parameter == 3:
+                parameter = 1
+            elif parameter ==7:
+                parameter = 3
+
+        return str(calculated_checksum)[-1] == given_checksum
+
+    def clean(self, value):
+        super(DEIdentityCardNumberField, self).clean(value)
+        if value in EMPTY_VALUES:
+            return u''
+        match = re.match(id_re, value)
+        if not match:
+            raise ValidationError(self.error_messages['invalid'])
+
+        gd = match.groupdict()
+        residence, origin = gd['residence'], gd['origin']
+        birthday, validity, checksum = gd['birthday'], gd['validity'], gd['checksum']
+
+        if residence == '0000000000' or birthday == '0000000' or validity == '0000000':
+            raise ValidationError(self.error_messages['invalid'])
+
+        all_digits = u"%s%s%s%s" % (residence, birthday, validity, checksum)
+        if not self.has_valid_checksum(residence) or not self.has_valid_checksum(birthday) or \
+            not self.has_valid_checksum(validity) or not self.has_valid_checksum(all_digits):
+                raise ValidationError(self.error_messages['invalid'])
+
+        return u'%s%s-%s-%s-%s' % (residence, origin, birthday, validity, checksum)