api and storage restructure

lib/api/marianumcloud/talk/chat/getChatCache.dart

@@ -1,36 +1,26 @@
-import 'dart:convert';
-
 import '../../../requestCache.dart';
 import 'getChat.dart';
 import 'getChatParams.dart';
 import 'getChatResponse.dart';
 
-class GetChatCache extends RequestCache<GetChatResponse> {
-  String chatToken;
-
+class GetChatCache extends SimpleCache<GetChatResponse> {
   GetChatCache({
     required void Function(GetChatResponse) onUpdate,
-    void Function(Exception)? onError,
-    required this.chatToken,
+    super.onError,
+    required String chatToken,
   }) : super(
-          RequestCache.cacheNothing,
-          onUpdate,
-          onError: onError ?? RequestCache.ignore,
+          cacheTime: RequestCache.cacheNothing,
+          loader: () => GetChat(
+            chatToken,
+            GetChatParams(
+              lookIntoFuture: GetChatParamsSwitch.off,
+              setReadMarker: GetChatParamsSwitch.on,
+              limit: 200,
+            ),
+          ).run(),
+          fromJson: GetChatResponse.fromJson,
+          onUpdate: onUpdate,
         ) {
     start('nc-chat-$chatToken');
   }
-
-  @override
-  Future<GetChatResponse> onLoad() => GetChat(
-      chatToken,
-      GetChatParams(
-        lookIntoFuture: GetChatParamsSwitch.off,
-        setReadMarker: GetChatParamsSwitch.on,
-        limit: 200,
-      )
-    ).run();
-
-  @override
-  GetChatResponse onLocalData(String json) => GetChatResponse.fromJson(jsonDecode(json));
-
 }