public function updateCMSFields(FieldList $fields)
 {
     $services = SiteConfig::config()->available_services;
     if (!$services) {
         $services = array_keys(self::listAvailableMediaServices());
     }
     if (in_array('twitter', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('TwitterUsername', _t('Socialstream.TwitterUsername', 'Twitter Username')));
     }
     if (in_array('twitter_hashtag', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('TwitterHashtag', _t('Socialstream.TwitterHashtag', 'Twitter Hashtag')));
     }
     if (in_array('facebook_page', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('FacebookPage', _t('Socialstream.FacebookPage', 'Facebook Page')));
     }
     if (in_array('vimeo', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('VimeoUsername', _t('Socialstream.VimeoUsername', 'Vimeo Username')));
     }
     if (in_array('youtube', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('YoutubeUsername', _t('Socialstream.YoutubeUsername', 'Youtube Username')));
     }
     if (in_array('dailymotion', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('DailymotionUsername', _t('Socialstream.DailymotionUsername', 'Dailymotion Username')));
     }
     if (in_array('rss', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('RssFeed', _t('Socialstream.RssFeed', 'Rss Feed')));
     }
     if (in_array('flickr', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('FlickrUsername', _t('Socialstream.FlickrUsername', 'Flickr Username')));
     }
     if (in_array('github', $services)) {
         $fields->addFieldToTab('Root.Social', new TextField('GithubUsername', _t('Socialstream.GithubUsername', 'Github Username')));
     }
     $fields->addFieldToTab('Root.Social', $wl = new ListboxField('LifestreamWhitelist', _t('Socialstream.LifestreamWhitelist', 'Lifestream Whitelist'), array_combine($services, $services)));
     $wl->setMultiple(true);
     $wl->setDescription('A list of services to display on the Lifestream. If left blank, all configured streams will be used.');
     $fields->addFieldToTab('Root.Social', new NumericField('LifestreamItems', _t('Socialstream.LifestreamItems', 'Lifestream Items')));
     return $fields;
 }