sign in with wordpress

Is there any WordPress login php script like this one?

This script is for signing in with WordPress.com account.

I have followed the documentation to write my script. But it did not provide me the access token when I print the access token. It shows it is null.
This is my code to implement sign in with WordPress.com account:

    session_start();
$client_id     = "2472";
$client_secret ="TaB3JPXeuJA8XsosdkMbZnuJoybxJaBF6WmDD11WFJg8QQme9fmye6l2Kxd45cpx";

$login_url     = "https://public-api.wordpress.com/oauth2/authorize?client_id=$client_id&redirect_uri=http://w3.softwarecookerbd.com/wordpress.php&response_type=code";

function getToken(){
    $curl = curl_init( "https://public-api.wordpress.com/oauth2/token" );
    curl_setopt( $curl, CURLOPT_POST, true );
    curl_setopt( $curl, CURLOPT_POSTFIELDS, array(
        'client_id'     => "2472",
        'redirect_uri'  => "http://w3.softwarecookerbd.com/wordpress.php",
        'client_secret' => "TaB3JPXeuJA8XsosdkMbZnuJoybxJaBF6WmDD11WFJg8QQme9fmye6l2Kxd45cpx",
        'code'          => $_GET['code'], // The code from the previous request
        'grant_type'    => 'authorization_code'
    ) );
    curl_setopt( $curl, CURLOPT_RETURNTRANSFER, 1);
    $auth       = curl_exec( $curl );

    $secret     = json_decode($auth);

    echo "<pre>";
    var_dump($secret);
    exit;
    $access_key = $secret->access_token;

}

if(isset($_GET["code"])&&!empty($_GET["code"])){
    //$url = "https://public-api.wordpress.com/oauth2/token?client_id=$client_id&client_secret=client_secret&redirect_uri=http://w3.softwarecookerbd.com/wordpress.php&code=".$_GET['code']."&grant_type=authorization_code";
    //$response = file_get_contents($url);
    //echo $response;
    getToken();
}else{
    header("Location: ".$login_url);
}