Method authorise

/**
 * Method to check User object authorisation against an access control
 * object and optionally an access extension object
 *
 * @param   string  $action     The name of the action to check for permission.
 * @param   string  $assetname  The name of the asset on which to perform the action.
 *
 * @return  boolean  True if authorised
 *
 * @since   1.7.0
 */
public function authorise($action, $assetname = null)
{
    // Make sure we only check for core.admin once during the run.
    if ($this->isRoot === null) {
        $this->isRoot = false;
        // Check for the configuration file failsafe.
        $rootUser = Factory::getApplication()->get('root_user');
        // The root_user variable can be a numeric user ID or a username.
        if (is_numeric($rootUser) && $this->id > 0 && $this->id == $rootUser) {
            $this->isRoot = true;
        } elseif ($this->username && $this->username == $rootUser) {
            $this->isRoot = true;
        } elseif ($this->id > 0) {
            // Get all groups against which the user is mapped.
            $identities = $this->getAuthorisedGroups();
            array_unshift($identities, $this->id * -1);
            if (Access::getAssetRules(1)->allow('core.admin', $identities)) {
                $this->isRoot = true;
                return true;
            }
        }
    }
    return $this->isRoot ? true : (bool) Access::check($this->id, $action, $assetname);
}