Method authorise

/**
 * Check if the user can access the application
 *
 * @param   integer  $itemid  The item ID to check authorisation for
 *
 * @return  void
 *
 * @since   3.2
 *
 * @throws  \Exception When you are not authorised to view the home page menu item
 */
protected function authorise($itemid)
{
    $menus = $this->getMenu();
    $user = Factory::getUser();
    if (!$menus->authorise($itemid)) {
        if ($user->get('id') == 0) {
            // Set the data
            $this->setUserState('users.login.form.data', array('return' => Uri::getInstance()->toString()));
            $url = Route::_('index.php?option=com_users&view=login', false);
            $this->enqueueMessage(Text::_('JGLOBAL_YOU_MUST_LOGIN_FIRST'), 'error');
            $this->redirect($url);
        } else {
            // Get the home page menu item
            $home_item = $menus->getDefault($this->getLanguage()->getTag());
            // If we are already in the homepage raise an exception
            if ($menus->getActive()->id == $home_item->id) {
                throw new \Exception(Text::_('JERROR_ALERTNOAUTHOR'), 403);
            }
            // Otherwise redirect to the homepage and show an error
            $this->enqueueMessage(Text::_('JERROR_ALERTNOAUTHOR'), 'error');
            $this->redirect(Route::_('index.php?Itemid=' . $home_item->id, false));
        }
    }
}