erp5_oauth_google_login: Add comments and minor changes to make the code more readable

bt5/erp5_oauth_google_login/SkinTemplateItem/portal_skins/erp5_oauth_google_login/Base_createOauth2User.py

@@ -7,17 +7,21 @@ context.REQUEST.set('Base_createOauth2User', 1)
 portal = context.getPortalObject()
 
 if portal.portal_activities.countMessageWithTag(tag) > 0:
+  # If activity already exists, it means that the user reloaded the page and
+  # searchUsers() from ERP5ExternalOauth2ExtractionPlugin:186 did not find the user yet
   return
 
 person = portal.Base_getUserValueByUserId(reference)
-if person is not None:
-  context.log("Person already exists please " + \
-              "consider this object: %s" % person.getRelativeUrl())
+current_user = portal.portal_membership.getAuthenticatedMember()
+
+if person is not None or (current_user and current_user is None):
+  # Script should here stop if person exists or the user logged in is a Zope user
   return
 
 activate_kw = {'tag': tag}
+
 # In future we can move this script to another, because this script is generic enough
-# to support Facebook login
+# to support Facebook login, for example.
 assert login_portal_type in ("Google Login",), "Impossible to select a portal type"
 
 if user_id in ("Anonymous User", None):
@@ -27,13 +31,11 @@ if user_id in ("Anonymous User", None):
                                            last_name=last_name,
                                            default_email_coordinate_text=email,
                                            activate_kw=activate_kw)
-  # Support erp5_credential
-  getDuration = getattr(portal.portal_preferences,
-                        "getPreferredCredentialAssignmentDuration",
-                        None)
-  assignment_duration = getDuration and getDuration() or 365
+  duration = getattr(portal.portal_preferences,
+                     "getPreferredCredentialAssignmentDuration",
+                     lambda: 0)() or 365
   today = DateTime()
-  delay = today + assignment_duration
+  delay = today + duration
 
   # Support erp5_credential
   getAssignmentCategoryList = getattr(portal.portal_preferences,