遍历目录的所有子目录

我有一个应该很简单的任务，

• 给定路径，搜索less文件夹的所有子目录(1级深)。
• 如果找到文件夹，将完整路径作为键添加到数组
• 将密钥的值设置为相同的路径，但将less替换为css
• 在less目录内递归循环所有子目录
• 以与原始目录相同的方式添加子目录

那么，给定这个结构

注意:下面除randomfile外的所有项都是目录

matthew@vaio:/var/www/constructor/public/bundles$ tree
.
├── first
│   └── less
│       ├── secondtester
│       └── tester
│           ├── anothersubtester
│           ├── randomfile
│           └── subtester
├── second
│   └── less
│       ├── secondtester
│       └── tester
│           ├── anothersubtester
│           ├── randomfile
│           └── subtester
└── third
    └── noless
        ├── secondtester
        └── tester
            ├── anothersubtester
            ├── randomfile
            └── subtester
18 directories, 3 files

我想以这个数组结束(注意，我已经截断了这里的路径，只是为了更容易阅读)

Array
    (
    [/b/second/less] => /b/second/css
    [/b/second/less/secondtester] => /b/second/css/secondtester
    [/b/second/less/tester] => /b/second/css/tester
    [/b/second/less/tester/subtester] => /b/second/css/tester/subtester
    [/b/second/less/tester/anothersubtester] => /b/second/css/tester/anothersubtester
    [/b/first/less] => /b/first/css
    [/b/first/less/secondtester] => /b/first/css/secondtester
    [/b/first/less/tester] => /b/first/css/tester
    [/b/first/less/tester/subtester] => /b/first/css/tester/subtester
    [/b/first/less/tester/anothersubtester] => /b/first/css/tester/anothersubtester
)

现在我有下面的代码，但我不认为这是优化的，例如，我知道有RecursiveIteratorIterators等，但我不知道如何使用它们来完成这个任务，所以不得不求助于递归函数来提升。基本上，我想知道我怎样才能把这个写得更好:

$directories = array();
$bundlePath = realpath('/public/bundles');
function lessSearcher($lessPath, $cssPath){
    $directories = array($lessPath => $cssPath);
    $lessDirs = new DirectoryIterator($lessPath);
    foreach ($lessDirs as $lessDir) {
        //we only want the directories and not the .'s
        if ($lessDir->isDot() || !$lessDir->isDir()) continue;
        $lessCurrent = $lessPath . '/' . $lessDir->getFileName();
        $cssCurrent = $cssPath . '/' . $lessDir->getFileName();
        $directories[$lessCurrent] = $cssCurrent;
        $directories = array_merge($directories, lessSearcher($lessCurrent, $cssCurrent));
    }
    return $directories;
}
$bundles = new DirectoryIterator($bundlePath);
foreach ($bundles as $bundle) {
    //we only want the directories and not the .'s
    if($bundle->isDot() || !$bundle->isDir()) continue;
    //we only want the directories that have a less directory
    if(!realpath($bundlePath.'/'.$bundle->getFileName().'/less')) continue;
    $lessPath = realpath($bundlePath . '/' . $bundle->getFileName()) . '/less';
    $cssPath = realpath($bundlePath . '/' . $bundle->getFileName()) . '/css';
    $directories = array_merge($directories, lessSearcher($lessPath, $cssPath));
}