private static function filterByCountry($streamers, $country_id)
 {
     $streamer_ids = array();
     $streamers = array_map(function ($streamer) use(&$streamer_ids) {
         $streamer['countries'] = StreamServer::getCountries($streamer['stream_zone']);
         $streamer_ids[] = $streamer['id'];
         return $streamer;
     }, $streamers);
     $filtered_streamers = array_filter($streamers, function ($streamer) use($country_id) {
         return $streamer['stream_zone'] == 0 || array_search($country_id, $streamer['countries']) !== false;
     });
     if (empty($filtered_streamers)) {
         $filtered_streamers = Mysql::getInstance()->select('streaming_servers.*, stream_zones.default_zone')->from('streaming_servers')->join('stream_zones', 'stream_zone', 'stream_zones.id', 'LEFT')->where(array('default_zone' => 1))->in('streaming_servers.id', $streamer_ids)->get()->all();
     }
     return $filtered_streamers;
 }