$client_id = 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx'; // Client ID
$client_secret = 'XXXXXXXXXXXXXXXXXXXXXXX'; // Client secret
$redirect_uri = 'https://site.ru/social_login_callback/google.php'; // Redirect URI


if (isset($_GET['code'])) {
    $result = false;

    $params = array(
        'client_id'     => $client_id,
        'client_secret' => $client_secret,
        'redirect_uri'  => $redirect_uri,
        'grant_type'    => 'authorization_code',
        'code'          => $_GET['code']
    );

    $url = 'https://accounts.google.com/o/oauth2/token';

    $curl = curl_init();
    curl_setopt($curl, CURLOPT_URL, $url);
    curl_setopt($curl, CURLOPT_POST, 1);
    curl_setopt($curl, CURLOPT_POSTFIELDS, urldecode(http_build_query($params)));
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
    $result = curl_exec($curl);
    curl_close($curl);
    $tokenInfo = json_decode($result, true);

    if (isset($tokenInfo['access_token'])) {
        $params['access_token'] = $tokenInfo['access_token'];

        $userInfo = json_decode(file_get_contents('https://www.googleapis.com/oauth2/v1/userinfo' . '?' . urldecode(http_build_query($params))), true);
        if (isset($userInfo['id'])) {
            $userInfo = $userInfo;
            $result = true;
        }
    }
	
/*	дополнительные данные

    echo "Социальный ID пользователя: " . $userInfo['id'];
    echo "Имя пользователя: " . $userInfo['name'];
    echo "Email: " . $userInfo['email'];
    echo "Ссылка на профиль пользователя: " . $userInfo['link'];
    echo "Пол пользователя: " . $userInfo['gender'];
    echo $userInfo['picture'];
	
*/	
	
	
$email =$userInfo['email']; // почта юзера

}