Add referer keyword detection

>
function _ii404search_uri(){
	$url = referer_uri();
	// get host name from URL
	preg_match("/^(http:\/\/)?([^\/]+)/i", $url, $matches);
	$host = $matches[2];
	preg_match("/[^\.\/]+\.[^\.\/]+$/", $host, $matches);
	$domain = $matches[0];
	$name = explode('.', $domain);
	$engine = $name[0];
	if ($engine == 'yahoo'){
		//parse yahoo referers to get the query string.
		return '';
	}else if($engine == 'google'){
		//parse google referer to get the query string.
		//from q= to &
		//strip + and -, use explode.
		//http://junk?q=(capture)?
		preg_match("/^(http:\/\/)?([^\/]+)(.*?q=)(.*?)&/i", $url, $matches);
		$keys = $matches[4];
		return implode(" ",explode('+', $keys));
		//preg_match("/(http:\/\/)?([^\/]+)/i", $url, $matches);
	}else
		return '';
}

Above is code that I am working on, I need help with refining it and adding additional referers... Basically I find the 404 module not all that useful in most circumstances because the URL is not that often, unless you want it as such, that descriptive about content. The idea is that we read what the user was searching for at the search engine and then find that content... Hence a much more effective search is rendered for the missing content. There is a version of this module that can be found here for 4.6, probably also works with 4.7: http://drupal.etopian.net/files/ii404search.module.gz