getCanonical() PHP

/*
* Simple rel="canonical" value for all pages (by Corey Northcutt - http://www.northcutt.com)
*
* OPTIONAL VARIABLES:
* $lcase:  set to 1 if you would like to assume that URL's should always be lowercase.
* $trailslash:  1 assumes always a trailing slash on directories.  2 assumes never a slash.
*
* POTENTIAL LIMITATIONS:
* Assumes "www" is the desired version of the site.
* Assumes that you are not using a period in your directory names (trailing slashes feature)
* Assumes GET variables do not determine page contents.
*/
function getCanonical($lcase=0,$trailslash=0) {
    // Set variables
    $requestedurl = $_SERVER["REQUEST_URI"];

    // Force "www"
    if (preg_match("/www/i", $_SERVER["SERVER_NAME"])) $canonical="http://".$_SERVER["SERVER_NAME"].$requestedurl;
    else { $url='www.'.$_SERVER["SERVER_NAME"]; $canonical="http://".$url.$requestedurl; }

    // Hack off GET variables
    if(strstr($canonical,"?")) {
        $explosi0n = explode("?",$canonical);
        $canonical = $explosi0n[0];
    }

    // Force lowercase
    if($lcase == 1) $canonical = strtolower($canonical);

    // Force in a trailing slash on directories
    if($trailslash == 1) {
        $explosi0n = explode("/",$canonical);
        $reverseEx = array_reverse($explosi0n);
        // if URI is a directory name rather than file name
        if(strlen($reverseEx[0] > 0)) {
            if(!strstr($reverseEx[0],".")) {
                if(!$reverseEx[0]{0} == "/") $canonical = $canonical . "/";
            }
        }
    }

    // Force NEVER a trailing slash on directories
    if($trailslash == 2) {
        $explosi0n = explode("/",$canonical);
        $reverseEx = array_reverse($explosi0n);
        // if URI is a directory name rather than file name
        if(strlen($reverseEx[0] > 0)) {
            if(!strstr($reverseEx[0],".")) {
                if(!$reverseEx[0]{0} == "/") $canonical = substr($canonical,0,strlen($canonical)-1);
            }
        }
    }

    // return $canonical
    return $canonical;
}
echo '<link rel="canonical" href="'.getCanonical(1,2).'" />';