Jason

<?php

class facebook {

    static $app_key;
    static $app_secret;
    static $init = false;

    public static function init() {

    if(self::$init) return true;

    self::$app_key = @sanscode::$config['facebook']['app_id'];
    self::$app_secret = @sanscode::$config['facebook']['app_secret'];

    self::$init = true;
    }

    public static function fetch($login_callback=false, $logout_callback=false) {
    self::init();

    $app_key = self::$app_key;
    $var = <<<EOF
    <div id="fb-root"></div>
    <script src="http://connect.facebook.net/en_US/all.js"></script>
    <script>
        FB.init({appId: '$app_key', status: true, cookie: true, xfbml: true});
        FB.Event.subscribe('auth.sessionChange', function(response) {
        if (response.session) {
             $login_callback
                } else {
             $logout_callback
                }
            });
    </script>
EOF;

    return $var;
    }

    public static function get_facebook_cookie() {
    self::init();

    $app_id = self::$app_key;
    $application_secret = self::$app_secret;

    if(!isset($_COOKIE['fbs_' . $app_id])) return null;

    $args = array();
    parse_str(trim($_COOKIE['fbs_' . $app_id], '\\"'), $args);
    ksort($args);
    $payload = '';
    foreach ($args as $key => $value) {
        if ($key != 'sig') {
        $payload .= $key . '=' . $value;
        }
    }
    if (md5($payload . $application_secret) != $args['sig']) {
        return null;
    }
    return $args;
    }
    public static function user_info(){
    self::init();

    $cookie = self::get_facebook_cookie();
    if($cookie)
    {
        $ch = curl_init();
        curl_setopt($ch, CURLOPT_URL, 'https://graph.facebook.com/me?access_token='.$cookie['access_token']);
        curl_setopt($ch, CURLOPT_PORT , 443);
        curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
        $data = curl_exec($ch);
        $user = json_decode($data);

        return object2array::convert($user);
    }
    return false;
    }

    public static function login_button($perms =false)
    {
    self::init();
    return "<fb:login-button perms=\"$perms\"></fb:login-button>";
    }
    public static function installed(){
    self::init();

    if(!empty(self::$app_key) && !empty(self::$app_secret)) return true;

    return false;
    }

}