Add validation for agreement accepted on behalf of

If the user has selected that they are accepting the agreement on behalf
of someone else then we need to make the they provide that person’s
details.

If they’ve selected that they are accepting the agreement themselves
then we have to ignore what they might have put in the ‘on behalf of
boxes’ (for example if they filled them out but then changed their
mind).

app/main/forms.py

@@ -1466,6 +1466,23 @@ class GoLiveNotesForm(StripWhitespaceForm):
 
 class AcceptAgreementForm(StripWhitespaceForm):
 
+    @classmethod
+    def from_organisation(cls, org):
+
+        if org.agreement_signed_on_behalf_of_name and org.agreement_signed_on_behalf_of_email_address:
+            who = 'someone-else'
+        elif org.agreement_signed_version:  # only set if user has submitted form previously
+            who = 'me'
+        else:
+            who = None
+
+        return cls(
+            version=org.agreement_signed_version,
+            who=who,
+            on_behalf_of_name=org.agreement_signed_on_behalf_of_name,
+            on_behalf_of_email=org.agreement_signed_on_behalf_of_email_address,
+        )
+
     version = StringField(
         'Which version of the agreement are you accepting?'
     )
@@ -1495,6 +1512,16 @@ class AcceptAgreementForm(StripWhitespaceForm):
         gov_user=False,
     )
 
+    def __validate_if_nominating(self, field):
+        if self.who.data == 'someone-else':
+            if not field.data:
+                raise ValidationError('Can’t be empty')
+        else:
+            field.data = ''
+
+    validate_on_behalf_of_name = __validate_if_nominating
+    validate_on_behalf_of_email = __validate_if_nominating
+
     def validate_version(self, field):
         try:
             float(field.data)

app/main/views/agreement.py

@@ -33,20 +33,10 @@ def service_agreement(service_id):
 @login_required
 def service_accept_agreement(service_id):
 
-    org = current_service.organisation
-
-    if not org:
+    if not current_service.organisation:
         abort(404)
 
-    form = AcceptAgreementForm(
-        version=org.agreement_signed_version,
-        who='someone-else' if (
-            org.agreement_signed_on_behalf_of_name
-            and org.agreement_signed_on_behalf_of_email_address
-        ) else 'me',
-        on_behalf_of_name=org.agreement_signed_on_behalf_of_name,
-        on_behalf_of_email=org.agreement_signed_on_behalf_of_email_address,
-    )
+    form = AcceptAgreementForm.from_organisation(current_service.organisation)
 
     if form.validate_on_submit():
         current_service.organisation.update(