Added KW utils and extended civil ID validation

docs/authors.rst

@@ -96,6 +96,7 @@ Authors
 * Matias Dinota
 * Michał Sałaban
 * Mike Lissner
+* Mohammed Al-Abdulhadi
 * Morgane Alonso
 * Naglis Jonaitis
 * Nishit Shah

docs/changelog.rst

@@ -19,6 +19,10 @@ Modifications to existing flavors:
 - Change `Kiev` to `Kyiv` 🇺🇦 according to ISO_3166-2:UA
 - Accept French Postal Services identifiers in forms
   (`gh-505 <https://github.com/django/django-localflavor/pull/505>`_).
+- Extended validation of Kuwaiti Civil ID to avoid allowing invalid century Civil IDs
+  (`gh-511 <https://github.com/django/django-localflavor/pull/511>`_).
+- Added birthdate extraction function from Kuwaiti Civil ID
+  (`gh-511 <https://github.com/django/django-localflavor/pull/511>`_).
 
 Other changes:
 

localflavor/kw/forms.py

@@ -1,14 +1,13 @@
 """Kuwait-specific Form helpers."""
 import re
-import textwrap
-from datetime import date
 
 from django.forms import ValidationError
 from django.forms.fields import RegexField, Select
 from django.utils.translation import gettext_lazy as _
 
 from .kw_areas import AREA_CHOICES
 from .kw_governorates import GOVERNORATE_CHOICES
+from .utils import is_valid_civil_id
 
 id_re = re.compile(r'''^(?P<initial>\d)
                        (?P<yy>\d\d)
@@ -19,16 +18,7 @@
 
 
 def is_valid_kw_civilid_checksum(value):
-    weight = (2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2)
-    calculated_checksum = 0
-    for i in range(11):
-        calculated_checksum += int(value[i]) * weight[i]
-
-    remainder = calculated_checksum % 11
-    checkdigit = 11 - remainder
-    if checkdigit != int(value[11]):
-        return False
-    return True
+    return is_valid_civil_id(value)
 
 
 class KWCivilIDNumberField(RegexField):
@@ -37,6 +27,7 @@ class KWCivilIDNumberField(RegexField):
 
     Checks the following rules to determine the validity of the number:
         * The number consist of 12 digits.
+        * The first(century) digit should be 1, 2, or 3.
         * The birthdate of the person is a valid date.
         * The calculated checksum equals to the last digit of the Civil ID.
     """
@@ -56,22 +47,7 @@ def clean(self, value):
         if value in self.empty_values:
             return value
 
-        cc = value[0]  # Century value
-        yy, mm, dd = textwrap.wrap(value[1:7], 2)  # pylint: disable=unbalanced-tuple-unpacking
-
-        # Fix the dates so that those born
-        # in 2000+ pass the validation check
-        if int(cc) == 3:
-            yy = '20{}'.format(yy)
-        elif int(cc) == 2:
-            yy = '19{}'.format(yy)
-
-        try:
-            date(int(yy), int(mm), int(dd))
-        except ValueError:
-            raise ValidationError(self.error_messages['invalid'], code='invalid')
-
-        if not is_valid_kw_civilid_checksum(value):
+        if not is_valid_civil_id(value):
             raise ValidationError(self.error_messages['invalid'], code='invalid')
 
         return value

localflavor/kw/utils.py

@@ -0,0 +1,46 @@
+from datetime import date
+
+
+def is_valid_civil_id(cid):
+    """
+    Checks the validity of a Kuwaiti Civil ID number
+    by verifying the following:
+      * The number should consist of 12 digits
+      * The first digit should be 1, 2, or 3
+      * The extracted birthdate should be a valid date
+      * The checksum should be equal to the last digit of the Civil ID
+    """
+    # Civil ID can only start with 1, 2, or 3 till year 2100
+    if len(cid) != 12 or not cid.isdigit() or cid[0] not in ('1', '2', '3'):
+        return False
+
+    # calculate the Civil ID checksum
+    weight = (2, 1, 6, 3, 7, 9, 10, 5, 8, 4, 2)
+    initial = sum(x * y for x, y in zip(weight, map(int, cid[:-1]))) % 11
+    checksum = 11 - initial
+
+    # extract birthdate to check if it's a valid date
+    try:
+        get_birthdate_from_civil_id(cid)
+    except ValueError:
+        return False
+
+    # verify if the checksum matches the last digit
+    return checksum == int(cid[11])
+
+
+def get_birthdate_from_civil_id(cid):
+    """
+    Extracts the birthdate from a Kuwaiti Civil ID number
+    """
+    by_century = {
+        '1': '18',
+        '2': '19',
+        '3': '20'
+    }
+    if cid[0] not in ('1', '2', '3'):
+        raise ValueError('Invalid first digit')
+    year = int('{}{}'.format(by_century[cid[0]], cid[1:3]))
+    month = int(cid[3:5])
+    day = int(cid[5:7])
+    return date(year, month, day)

tests/test_kw.py

@@ -1,10 +1,38 @@
+from datetime import date
+
 from django.test import SimpleTestCase
 
 from localflavor.kw.forms import KWAreaSelect, KWCivilIDNumberField, KWGovernorateSelect
+from localflavor.kw.utils import is_valid_civil_id, get_birthdate_from_civil_id
 
 
 class KWLocalFlavorTests(SimpleTestCase):
     maxDiff = None
+
+    def test_civil_id_checksum_valid(self):
+        self.assertTrue(is_valid_civil_id('286101901541'))
+        self.assertTrue(is_valid_civil_id('300092400929'))
+        self.assertTrue(is_valid_civil_id('282040701483'))
+
+    def test_civil_id_checksum_invalid(self):
+        self.assertFalse(is_valid_civil_id('486101910006'))
+        self.assertFalse(is_valid_civil_id('289332013455'))
+        self.assertFalse(is_valid_civil_id('286191911111'))
+
+    def test_get_birthdate_from_civil_id(self):
+        self.assertEqual(
+            get_birthdate_from_civil_id('286101901541'),
+            date(1986, 10, 19)
+        )
+        self.assertEqual(
+            get_birthdate_from_civil_id('304022600325'),
+            date(2004, 2, 26)
+        )
+
+    def test_get_birthdate_from_civil_id_invalid_century(self):
+        self.assertRaises(ValueError, get_birthdate_from_civil_id, '486101910006')
+        self.assertRaises(ValueError, get_birthdate_from_civil_id, '886101910006')
+
     def test_KWCivilIDNumberField(self):
         error_invalid = ['Enter a valid Kuwaiti Civil ID number']
         valid = {
@@ -17,6 +45,8 @@ def test_KWCivilIDNumberField(self):
             '300000000005': error_invalid,
             '289332Ol3455': error_invalid,
             '2*9332013455': error_invalid,
+            '486101911111': error_invalid,
+            '286191911111': error_invalid,
         }
         self.assertFieldOutput(KWCivilIDNumberField, valid, invalid)