private function get_callback()
{
switch ($_REQUEST['action']) {
case self::ACTION_CONNECT_EXISTING:
return [$this, 'handle_connect_existing_post'];
case self::ACTION_CONNECT_NEW:
return [$this, 'handle_connect_new_post'];
case self::ACTION_DISCONNECT:
return [$this, 'handle_disconnect_post'];
}
return null;
}