/**
 * Supports OpenGraphProtocol
 */
function ttcn_opengraph(&$vars) {
  if (arg(0) == 'node') {
    $node = menu_get_object();
    if ($node->field_thumbnail[0]['value']) {
      $image = $node->field_thumbnail[0]['value'];
    }
    elseif (!empty($node->field_thumbnail_image[0]['filepath'])) {
      $image = '/' . $node->field_thumbnail_image[0]['filepath'];
    }
    elseif (!empty($node->field_product_image[0]['filepath'])) {
      $image = '/' . $node->field_product_image[0]['filepath'];
    }
  }
  elseif (arg(0) == 'user') {
    $user = menu_get_object('user_uid_optional');
    if ($user->picture) {
      $image = '/' . $user->picture;
    }
  }
  if (empty($image)) {
    $image = '/sites/default/files/misc/icon.png';
  }

  if ($title = drupal_get_title()) {
    $vars['head'] .= '<meta property="og:title" content="' . str_replace('"', '&quot;', strip_tags($title)) .'" />' . "\n";
  }
  if (strpos($image, '://') === FALSE) {
    $image = 'http://vtcdn.com' . str_replace('/files/', '/files/imagecache/s180/', $image);
  }
  $vars['head'] .= '<meta property="og:image" content="' . $image . '" />' . "\n";

  if (request_uri() == '/') {
    $type = 'website';
  }
  elseif (arg(0) == 'blogs') {
    $type = 'blog';
  }
  else {
    $type = 'article';
  }
  $vars['head'] .= '<meta property="og:type" content="' . $type . '" />' . "\n";

  $vars['head'] .= '<meta property="og:url" content="' . token_replace('[metatags-url-alias]') . '" />' . "\n";
}