better loading indicators for timetables, talk and files

lib/api/marianumcloud/webdav/queries/listFiles/listFiles.dart

@@ -11,9 +11,22 @@ class ListFiles extends WebdavApi<ListFilesParams> {
 
   ListFiles(this.params) : super(params);
 
+  // The Nextcloud root listing is significantly slower than subdirectories on
+  // our instance, so it gets a much longer ceiling. Subfolders fall back to a
+  // tighter timeout to keep the UI responsive.
+  static const Duration _rootTimeout = Duration(minutes: 3);
+  static const Duration _subfolderTimeout = Duration(seconds: 30);
+
+  bool get _isRoot {
+    final p = params.path.replaceAll('/', '').trim();
+    return p.isEmpty;
+  }
+
   @override
   Future<ListFilesResponse> run() async {
-    var davFiles = (await (await WebdavApi.webdav).propfind(PathUri.parse(params.path))).toWebDavFiles();
+    final webdav = await WebdavApi.webdav;
+    final timeout = _isRoot ? _rootTimeout : _subfolderTimeout;
+    final davFiles = (await webdav.propfind(PathUri.parse(params.path)).timeout(timeout)).toWebDavFiles();
     var files = davFiles.map(CacheableFile.fromDavFile).toSet();
 
     // webdav handles subdirectories wrong, this is a fix

lib/api/marianumcloud/webdav/queries/listFiles/listFilesCache.dart

@@ -9,7 +9,19 @@ import 'listFilesResponse.dart';
 class ListFilesCache extends RequestCache<ListFilesResponse> {
   String path;
 
-  ListFilesCache({required void Function(ListFilesResponse) onUpdate, required this.path}) : super(RequestCache.cacheNothing, onUpdate) {
+  ListFilesCache({
+    required void Function(ListFilesResponse) onUpdate,
+    void Function(ListFilesResponse)? onCacheData,
+    void Function(ListFilesResponse)? onNetworkData,
+    void Function(Exception)? onError,
+    required this.path,
+  }) : super(
+          RequestCache.cacheNothing,
+          onUpdate,
+          onError: onError ?? RequestCache.ignore,
+          onCacheData: onCacheData,
+          onNetworkData: onNetworkData,
+        ) {
     var bytes = utf8.encode('MarianumMobile-$path');
     var cacheName = md5.convert(bytes).toString();
     start('wd-folder-$cacheName');