PHP get URL string parameters?

First I'd recommend that for English you keep the /en/ in the URL, it will be easier to manage.

Then to extract the language code and replace by an other value you can use

You can use preg_replace (REGEX)

$url = "https://mywebsite.com/en/foo";
$codes = [ 'it', 'fr', ...]; 
$urls = [];
foreach($codes as $code){
    $urls[$code] = preg_replace("(https://mywebsite.com/)[a-z]{2}(.*)", "$1". $code. "$2", $url);
}

Replacement of URL is bad practice. You should make two parts for work with URL:

1. Parsing of language and URI without language
2. A building of any URI with language

For example, parsing of language might be looked like:

function extractLanguage($uri)
{
    if (preg_match('/^\/[a-z]{2}\//', $uri, $matches)) {
        $language = trim($matches[0], '/');
    } else {
       $language = ''; // or default language
    }   
    return $language;
}

extractLanguage('/search/?q=YouTube'); // will return empty string
extractLanguage('/al/search/?qURIuTube'); // will return 'al'

Parsing of URI without language might be looked like

function extractUri($uri)
{
    $uri= preg_replace('/^\/[a-z]{2}\//', '', $uri);
    if ($uri[0] !== '/') {
        $uri = '/' . $uri;
    }
    return $uri;
}

extractUri('/search/?q=YouTube'); // will return '/search/?q=YouTube'
extractUri('/al/search/?q=YouTube'); // will return '/search/?q=YouTube'

If you will have separated language and separated URI you can build target URL, for example with help the following function

function buildUri($path, $params = [], $language = '')
{
   $query = '';
   if (!empty($params)) {
       $query = '?' . http_build_query($params);
   }
   if (!empty($language)) {
       $language = '/' . $language ;
   } 
   return $language . $path . $query;
}

buildUri('/news/search', array('q' => 'YouTube')) // will return '/news/search/?q=YouTube'
buildUri('/news/search', array('q' => 'YouTube'), 'it') // will return 'it/news/search/?q=YouTube'

I've created a function that does this for you. Here is how it works:

1. It removes the chosen language and everything after that from the url and puts that in $startUrl.
2. Takes the original url and removes the first part of it including the language, and puts that into $endUrl.
3. Adds the provided language to the middle and puts all three parts together, naming them $newUrl and returns that.

NOTE: This function requires you to specify language in every url, even for english!

NOTE 2: You might need to change the $key-value in both removing-parts of the function if you change the structure of your base url from https://mywebsite.com/ to, say, https://mywebsite.com/public/. I've added comments in the code about where they´re located.

function createUrl($url, $language){
    /*
    * FIX THE BEGINNING OF THE URL
    */
    // Explode the url into smaller parts and put into an array
    foreach((explode('/', $url)) as $key => $value){
        $expArray[$key] = $value;
    };

    // Remove the last part of the URL (including chosen language)
    foreach($expArray as $key => $value){
        if($key > 0){ /*<--This is one of the values you might need to be changed if your base url structure changes*/
            unset($expArray[$key]); 
        }
    }

    // Implode the array back to a string
    foreach($expArray as $key => $value){
        $startUrl = implode('/', $expArray);
    };

    

    /*
    * FIX THE END OF THE URL
    */
    // Explode the url into smaller parts and put into an array
    foreach((explode('/', $url)) as $key => $value){
        $expArray[$key] = $value;
    };

    // Remove the first part of the URL (including chosen language)
    foreach($expArray as $key => $value){
        if($key < 2){ /*<--This is the other value you might need to be changed if your base url structure changes*/
            unset($expArray[$key]); 
        }
    }

    // Implode the array back to a string
    foreach($expArray as $key => $value){
        $endUrl = implode('/', $expArray);
    };


    /* 
    * Put it all together
    */
    if(isset($endUrl)){
       $newUrl = $startUrl . $language . $endUrl;
       return $newUrl;
    }else{
       $newUrl = $startUrl . $language;
       return $newUrl;
    }
};

To use it in your example you write it like this:

<a class="x" href="<?php echo createUrl($_SERVER["REQUEST_URI"], '/EN/');?>"></a>
<a class="x" href="<?php echo createUrl($_SERVER["REQUEST_URI"], '/AL/');?></a>
<a class="x" href="<?php echo createUrl($_SERVER["REQUEST_URI"], '/IT/');?></a>

My solution! 'not perfect' beaucose if the user is searching on https://example.com/es/news/search/?q=news when i change the language, example from es to en, the url change like this https://example.com/search/?q=news

if(isset($_GET["q"])) {
$qurl = $_GET["q"];
$surl = "/search/?q=";
}else{
$qurl = "";
$surl = "";
}

I suggest to use .htaccess configuration in Apache web server, in which you can handle all type of your request easily with hiding parameters, and you can easily redirect to your other urls.

The below urls will help you.

http://www.htaccess-guide.com/ - official Documentation

https://help.dreamhost.com/hc/en-us/articles/215747748-How-can-I-redirect-and-rewrite-my-URLs-with-an-htaccess-file- - htaccess example