Facebook Application Redirect Script

redirect.php

<?php

// Configuration.
$conf = array(
  'domain' => '',
);

if ( isset($_REQUEST['signed_request']) ) {

  // Parse signed request.
  list($encoded_sig, $payload) = explode('.', $_REQUEST['signed_request'], 2);
  $request = json_decode(base64_decode(strtr($payload, '-_', '+/')), true);

  // Redirect on user using Facebook Locale.
  if ( isset($request['user']['locale']) ) {

    // Prevent caching this page.
    header("Last-Modified: " . gmdate("D, d M Y H:i:s") . " GMT");
    header("Cache-Control: no-store, no-cache, must-revalidate");
    header("Cache-Control: post-check=0, pre-check=0", false);
    header("Pragma: no-cache");

    // Choose appropriate language.
    switch ( $request['user']['locale'] ) {
      case 'fr_CA':
      case 'fr_FR':
        $lang = 'fr';
        break;
      default:
        $lang = '';
        break;
    }

    // Redirect visitor to proper language page.
    header('Location: ' . $conf['domain'] . '/' . $lang . '?signed_request=' . $_REQUEST['signed_request']);
  }

}
// Fallback if no signed request is available.
else {
  header('Location: ' . $conf['domain'] . '/');
}