[czachor]

Refs #75

Context

Opening the manager on a directory with thousands of files is slow. Part of the cost is on the server: indexAction does work for every request that is either never displayed or repeated. This PR removes that work without changing what the user sees.

The larger part of the cost is in the browser (full-size originals used as 22 px previews, and a cache-buster that forces them to be downloaded on every load). The cache-buster part is addressed in #167; full-size previews will follow in a separate PR.

Changes

1. Directory tree is built only when it is displayed

Cause: indexAction always called retrieveSubDirectories(), which walks the whole directory tree recursively (and counts files in every folder when show_file_count is on). It did this even with tree: false, where the tree is never rendered.

Change: the tree is built only when $fileManager->getTree() is true; otherwise treeData is null. The JavaScript already initializes the tree only when tree === true, so nothing else changes.

2. Image dimensions are read once per file

Cause: File::getDimension() called getimagesize() on every call, and every call opens and parses the file. With orderby=dimension, usort() calls it twice per comparison, so each image was read O(n log n) times.

Change: the result is memoized in the File object. While touching this method:

• the image check uses an exact extension list, File::IMAGE_EXTENSIONS, instead of an unanchored regex;
• getimagesize() runs through Symfony's ErrorHandler::call() instead of the @ operator. A corrupt or unreadable image still yields false, as before, but unrelated errors are no longer silenced.

3. File previews are built lazily

Cause: the File constructor called FileTypeService::preview(), which renders a Twig template for images, for every entry in the directory.

Change: the preview is built on the first getPreview() call and reused afterwards. isImage() goes through getPreview(). Today every listed file is rendered, so the gain is small, but it means only entries that are actually displayed pay for the render (useful for pagination later).

4. JSON badge does not rescan the directory

Cause: the JSON response (used to refresh the list after an upload) computed badge with $finderFiles->count(). Finder::count() iterates the Finder again, which scans the directory a second time.

Change: count($fileArray) is used. The list is built from the same Finder, so the number is the same.

Refactoring

• Image extensions are defined once, in File::IMAGE_EXTENSIONS, and reused by File, FileTypeService and FileManager::getRegex().
• FileTypeService::fileIcon() compares extensions exactly instead of with unanchored regexes. Before, any extension ending with a known one matched too (e.g. xpdf got the PDF icon). tgz is now listed explicitly, because it used to match only through the gz suffix. The extension is read with SplFileInfo::getExtension() (always a string) instead of pathinfo() (array|string).
• Small controller cleanups: str_starts_with() instead of 0 !== mb_strpos() in the rename and delete path checks (same result, also when realpath() returns false), a strict === comparison, a static closure for the dimension sort and a void return type on dispatch().

Backward compatibility

No configuration, template or public API changes. The only visible difference: with tree: false, the JSON response returns treeData: null instead of an unused tree.

Tests

• vendor/bin/simple-phpunit: 17 tests, 41 assertions, OK (Symfony 7.4).
• New controller tests: JSON response with and without the tree (treeData, badge) and orderby=dimension.
• New Tests/Helpers/FileTest.php: dimensions of a valid, a corrupt and a non-image file, and the preview being built only when needed and only once.