URI handler function

This function was written by myself. My skills are not very good, so please let me know if there are any inappropriate parts

function modifyUri($param = '', $value = '') {
 2 //Get the current page URI
 3 $uri = $_SERVER['REQUEST_URI'];
 4 $uri = (parse_url($ uri));
 5 //Split URI into arrays and delete duplicate items in the array
 6 $uri = explode('&', $uri['query']);
 7 $uri = array_unique($uri) ;
 8 //Determine whether the function has a value passed in, and if so, perform replacement/insertion
 9 if ('' != $param && '' != $value) {
10 $param .= '=';
11 $param_erge = '/'.$param.'.*/';
12 //Check whether the URI to be replaced already exists in the URI, and replace it if it exists
13 $uri = preg_replace($param_erge,$param.$value, $uri);
14 //If it does not exist, add it to the end
15 if('1' != in_array($param.$value, $uri)) array_push($uri, $param.$value);
16 }
17 //Convert the array to a string and return
18 $uri = implode('&', $uri);
19 $u = substr($_SERVER['REQUEST_URI'] , 0 , strpos($_SERVER[ 'REQUEST_URI'] , '?'));
20 $uri = "{$u}?".$uri;
21 return $uri;
22 }