[ PHP | FB | hacks ] Checking if current user (in a tab!) is a fan of a page

fb_intab_fan.php

<?
function parsePageSignedRequest() {
    if( isset($_REQUEST['signed_request']) ) {
        $encoded_sig = $payload = null;
        list( $encoded_sig, $payload ) = explode(".", $_REQUEST['signed_request'], 2 );
        $sig = base64_decode( strtr( $encoded_sig, '-_', '+/') );
        $data = json_decode( base64_decode( strtr( $payload, '-_', '+/'), true ) );
        return $data;
    } else return null;
}

$page_id="TU WPISZ PAGE ID";
$is_fan = false;
if( $sr = parsePageSignedRequest() ) {
    $pages_math = (bool)($sr->page->id==$page_id);
    if( $sr->page->liked and $pages_math ) $is_fan = true;
}

if( $is_fan ) { /* jest fanem */ }
else { /* fanem nie jest */ }
?>