GSList *
gnomemeeting_local_addressbook_enum_categories (GmAddressbook *addressbook)
{
  GSList *contactlist = NULL;
  GSList *contactlist_iter = NULL;
  GSList *grouplist = NULL;
  GSList *contact_grouplist = NULL;

  gint nbr = 0;

  /* this only makes sense on a local addressbook */
  if (addressbook &&
      !gnomemeeting_addressbook_is_local (addressbook))
    return NULL;

  /* get all contacts of that addressbook (or all if NULL)  */
  contactlist =
    gnomemeeting_addressbook_get_contacts (addressbook,
                                           nbr,
                                           FALSE,
                                           NULL, NULL, NULL, NULL, NULL);

  for (contactlist_iter = contactlist;
       contactlist_iter != NULL;
       contactlist_iter = g_slist_next (contactlist_iter))
    {
      if (contactlist_iter->data)
        {
          /* get all categories from that contact */
          contact_grouplist =
            gmcontact_enum_categories ((const GmContact*) contactlist_iter->data);
          if (contact_grouplist)
            {
              if (grouplist)
                {
                  grouplist =
                    g_slist_concat (grouplist, contact_grouplist);
                  g_slist_free (contact_grouplist);
                }
              else
                grouplist = contact_grouplist;
              contact_grouplist = NULL;
            }
        }
    }

  g_slist_foreach (contactlist,
                   (GFunc) gmcontact_delete,
                   NULL);
  g_slist_free (contactlist);

  grouplist =
    gm_string_gslist_remove_dups (grouplist);

  return grouplist;
}