function other_referrers($m) {
  $s = ['twitter.com', 'instagram.com', 'tumblr.com', 'pinterest.com', 'youtube.com', 'linkedin.com'];
  foreach ($s as $source)
   {
       if ($m === $source ) {
         return $source;
       }
   }
}


function parse_referrer($referrer) {
 $domain = parse_url($referrer);
 //strip www off the URL
 $url = preg_replace('#^www\.(.+\.)#i', '$1', $domain['host']);
 //set match to url
 $m = $url;

 switch ($m):
   case 'www.google.com':
     return '60647'; //google adwords
     break;
   case 'www.facebook.com':
     return '8889'; //facebook
     break;
   case other_referrers($m):
     return ''; //no code for other social
     break;
   case 'themaxchallenge.com':
     return '8891'; //website
     break;
   default:
       return '60678'; //organic
 endswitch;
}