PHP でリッチテキストエディターに画像ギャラリーを追加する

<link rel="stylesheet" href="/richtexteditor/rte_theme_default.css">
<script src="/richtexteditor/rte.js"></script>
<script src="/richtexteditor/plugins/all_plugins.js"></script>
<script src="/rte-files.js"></script>
<script>
    new RichTextEditor("#editor", {
        toolbar: "full",
        galleryEndpoint: "/rte/gallery",
        maxUploadFileSize: 4000000     // same limit as rte/upload.php, checked before sending
    });
</script>

if ($method === 'GET') {
    return rte_listing(rte_resolve_folder($_GET['folder'] ?? ''));
}

// The listing for one folder, in the shape the gallery dialog expects.
function rte_listing(array $folder): array
{
    $folders = [];
    $images = [];
    $names = scandir($folder['dir']);
    if ($names === false) {
        throw new RteHttpError(500, 'The folder cannot be read.');
    }
    foreach ($names as $name) {
        if ($name === '' || $name[0] === '.') {
            continue; // ".", "..", and hidden files such as .htaccess
        }
        $path = $folder['dir'] . DIRECTORY_SEPARATOR . $name;
        // Skip symlinks and Windows junctions. is_link() alone is not enough: PHP 8.2 on
        // Windows returns false for a junction, so also require realpath() to be unchanged.
        $real = realpath($path);
        $same = DIRECTORY_SEPARATOR === '\\' ? strcasecmp($real ?: '', $path) === 0 : $real === $path;
        if (is_link($path) || !$same) {
            continue;
        }
        $segments = [...$folder['segments'], $name];
        if (is_dir($path)) {
            if (rte_is_valid_name($name) && !rte_is_reserved($segments)) { // only folders the routes accept back
                $folders[] = ['folder' => implode('/', $segments), 'name' => $name];
            }
        } elseif (is_file($path) && in_array(rte_extension($name), RTE_IMAGE_EXTENSIONS, true)) {
            $images[] = [
                'url' => rte_url($folder['root'], $segments),
                'name' => $name,
                'folder' => $folder['virtual'],
                'size' => (int)filesize($path),
            ];
        }
    }
    $byName = fn(array $a, array $b): int => strcasecmp($a['name'], $b['name']) ?: strcmp($a['name'], $b['name']);
    usort($folders, $byName);
    usort($images, $byName);

    $virtual = $folder['virtual'];
    $parent = null;
    if ($virtual !== '') {
        $cut = strrpos($virtual, '/');
        $parent = $cut === false ? '' : substr($virtual, 0, $cut);
    }
    return [
        'currentFolder' => $virtual,
        'currentFolderDisplay' => '/' . $virtual,
        'parentFolder' => $parent,
        'folders' => $folders,
        'images' => $images,
    ];
}

curl "http://localhost:5201/rte/gallery?folder=team"
{"currentFolder":"team","currentFolderDisplay":"/team","parentFolder":"","folders":[],"images":[]}

curl "http://localhost:5201/rte/gallery?folder=blog/2027"
{"error":"Folder not found."}