fields: add Luhn algorithm to string field validation (#35013)

tests/test_widgets.py

@@ -630,6 +630,66 @@ def test_wcsextrastringwidget_builtin_validation():
     mock_form_submission(req, widget, {'test': '1234'})
     assert widget.has_error()
 
+def test_wcsextrastringwidget_siren_validation():
+    class FakeField: pass
+    fakefield = FakeField()
+    fakefield.validation = {'type': 'siren-fr'}
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '443170139'})
+    assert not widget.has_error()
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '443170130'})
+    assert widget.has_error()
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '44317013900036'})
+    assert widget.has_error()
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': 'XXX170130'})
+    assert widget.has_error()
+
+
+def test_wcsextrastringwidget_siret_validation():
+    class FakeField: pass
+    fakefield = FakeField()
+    fakefield.validation = {'type': 'siret-fr'}
+
+    # regular case
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '44317013900036'})
+    assert not widget.has_error()
+
+    # special case la poste
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '35600000000048'})
+    assert not widget.has_error()
+
+    # failing cases
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '44317013900037'})
+    assert widget.has_error()
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': 'ABC17013900037'})
+    assert widget.has_error()
+
+    widget = WcsExtraStringWidget('test', value='foo', required=False)
+    widget.field = fakefield
+    mock_form_submission(req, widget, {'test': '443170139'})
+    assert widget.has_error()
+
+
 def test_wcsextrastringwidget_django_validation():
     class FakeField: pass
     fakefield = FakeField()

wcs/qommon/form.py

@@ -906,6 +906,8 @@ class ValidationWidget(CompositeWidget):
         ('digits', {'title': N_('Digits'), 'regex': '\d+'}),
         ('phone-fr', {'title': N_('Phone Number (France)'), 'regex': '0[\d\.\s]{9}'}),
         ('zipcode-fr', {'title': N_('Zip Code (France)'), 'regex': '\d{5}'}),
+        ('siren-fr', {'title': N_('SIREN Code (France)'), 'function': 'validate_siren'}),
+        ('siret-fr', {'title': N_('SIRET Code (France)'), 'function': 'validate_siret'}),
         ('regex', {'title': N_('Regular Expression')}),
         ('django', {'title': N_('Django Condition')}),
     ])
@@ -965,6 +967,9 @@ class ValidationWidget(CompositeWidget):
                 condition = ValidationCondition(validation['value'], value=value)
                 return condition.evaluate()
             return django_validation
+        validation_method = cls.validation_methods.get(validation['type'])
+        if 'function' in validation_method:
+            return getattr(misc, validation_method['function'])
 
     @classmethod
     def get_validation_pattern(cls, validation):

wcs/qommon/misc.py

@@ -639,3 +639,40 @@ def html2text(text):
     if isinstance(text, (htmltext, str)):
         text = unicode(str(text), get_publisher().site_charset)
     return site_encode(HTMLParser().unescape(strip_tags(text)))
+
+
+def validate_luhn(string_value, length=None):
+    '''Verify Luhn checksum on a string representing a number'''
+    if not string_value:
+        return False
+    if length is not None and len(string_value) != length:
+        return False
+    if not string_value.isdigit():
+        return False
+
+    # take all digits counting from the right, double value for digits pair
+    # index (counting from 1), if double has 2 digits take their sum
+    checksum = 0
+    for i, x in enumerate(reversed(string_value)):
+        if i % 2 == 0:
+            checksum += int(x)
+        else:
+            checksum += sum(int(y) for y in str(2 * int(x)))
+    if checksum % 10 != 0:
+        return False
+    return True
+
+
+def validate_siren(string_value):
+    return validate_luhn(string_value, length=9)
+
+
+def validate_siret(string_value):
+    # special case : La Poste
+    if not string_value.isdigit():
+        return False
+    if (string_value.startswith('356000000')
+            and len(string_value) == 14
+            and sum(int(x) for x in string_value) % 5 == 0):
+        return True
+    return validate_luhn(string_value, length=14)