public function extend()
{
if ($this->type != self::TYPE_USER) {
throw new Exception\AccessTokenException('Only user access token can be extended.');
}
if ($this->isLong()) {
throw new Exception\AccessTokenException('Long-lived access token cannot be extended.');
}
$request = new \Gajus\Fuss\Request($this->app, 'GET', 'oauth/access_token', ['client_id' => $this->app->getId(), 'client_secret' => $this->app->getSecret(), 'grant_type' => 'fb_exchange_token', 'fb_exchange_token' => $this->access_token]);
$response = $request->make();
$this->access_token = $response['access_token'];
$this->debugToken();
}