$path = "docs/";

function createDir($path = '.')
{
if ($handle = opendir($path))
{
echo "<ul>";

while (false !== ($file = readdir($handle)))
{
if (is_dir($path.$file) && $file != '.' && $file !='..')
printSubDir($file, $path, $queue);
else if ($file != '.' && $file !='..')
$queue[] = $file;
}

printQueue($queue, $path);
echo "</ul>";
}
}

function printQueue($queue, $path)
{
foreach ($queue as $file)
{
printFile($file, $path);
}
}

function printFile($file, $path)
{
echo "<li><a href=\"".$path.$file."\" target=\"_blank \">$file</a></li><br><br>";
}

function printSubDir($dir, $path)
{
echo "<li><span class=\"toggle\">$dir</span>";
createDir($path.$dir."/");
echo "</li>";
}

createDir($path);