php return last version

index.php

<?php

$folderVersion = 'versions';
$version = retunVersion($folderVersion);
$file_BIN = 'file.BIN';

$link = 'http://localhost:801/test/upgrade/versions/';
echo viewFileBin($link,$version, $file_BIN);

function viewFileBin($link,$version, $file_BIN){
	if(empty($version)){
		return "no_new";
	}
	return $link.$version.'/'.$file_BIN;
}

function retunVersion($folderVersion){
	$lastVerion  = getLastversion($folderVersion);
	if(isset($_GET['v'])){
		if($_GET['v'] == $lastVerion){
			return '';
		}
	}
	return $lastVerion;
}

function getLastversion($folderVersion){
	$images = array_diff(scandir($folderVersion), array('..', '.'));
	natsort($images); //sort 1,2,3
	$images = array_values($images); //reindex
	//var_dump($images);

	$count = count($images)-1;
	$lastVersion = $images[$count];
	return $lastVersion;
}


//http://localhost:801/test/upgrade/
//return
//http://localhost:801/test/upgrade/versions/10/file.BIN

//http://localhost:801/test/upgrade/?v=10
//return
//"no_new"

//http://localhost:801/test/upgrade/?v=6
//return
//http://localhost:801/test/upgrade/versions/10/file.BIN

structure folder.txt

versions
├───1
│       file.BIN
│
├───10
│       file.BIN
│
├───2
│       file.BIN
│
├───3.4
│       file.BIN
│
├───4.4
│       file.BIN
│
├───5.6
│       file.BIN
│
└───7
        file.BIN