Google API Shortener

<?php
/**
 * Define google url shortener api
 */
define("API_URL", "https://www.googleapis.com/urlshortener/v1/url?key=");	
class GoogleURL
{

    /**
     *
     * @var string
     */
    private $_apiUrl;

    /**
     *
     * @var string
     */
    private $_shortUrl;

    public function  __construct($apiKey) {
        //Google URL Shortener 
        $this->_apiUrl = API_URL.$apiKey;
    }
    public function shorten($longUrl)
    {
        $data = $this->getContent($longUrl);
        $this->_shortUrl = $data->id;
        return $data->id;
    }
    public function expand($shortUrl)
    {
        $data = $this->getContent($shortUrl, "expand");
        $this->_shortUrl = $data->id;
        return $data->longUrl;
    }
    public function getLongUrlCliks(){
       $data = $this->getContent($this->_shortUrl, 'info');
       return $data->analytics->allTime->longUrlClicks;
    }
    public function getShortUrlClicks(){
       $data = $this->getContent($this->_shortUrl, 'info');
       return $data->analytics->allTime->shortUrlClicks;
    }

    private function getContent( $url, $requestType = "shorten" ){

        $curl = curl_init();
        
        if( $requestType === "expand" ){
            curl_setopt($curl, CURLOPT_URL, $this->_apiUrl.'&shortUrl='.$url);
        }else if( $requestType === "info" ){
             curl_setopt($curl, CURLOPT_URL, $this->_apiUrl.'&shortUrl='.$url.'&projection=FULL');
        }else{
            curl_setopt($curl, CURLOPT_URL, $this->_apiUrl);
            curl_setopt($curl, CURLOPT_POST, 1);
            curl_setopt($curl, CURLOPT_POSTFIELDS, json_encode(array('longUrl' => $url)));
        }
        
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, 0);
        curl_setopt($curl, CURLOPT_HEADER, 0);
        curl_setopt($curl, CURLOPT_HTTPHEADER, array('Content-type:application/json'));
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        $response = curl_exec($curl);
        curl_close($curl);
        //change the response json string to object
        return json_decode($response);
    }
}
// Example
$url = new GoogleURL('your_google_shortener_api_key');
echo $url->expand($url->shorten("http://www.google.com/")),'<br/>';
echo $url->getLongUrlCliks(), "<br/>";
echo $url->getShortUrlClicks(), "<br/>";
?>