Cache messages, use cache if exists, load in background

flutter/lib/pages/channel_list/channel_list.dart

@@ -8,21 +8,26 @@ import 'package:simplecloudnotifier/state/app_auth.dart';
 import 'package:simplecloudnotifier/pages/channel_list/channel_list_item.dart';
 
 class ChannelRootPage extends StatefulWidget {
-  const ChannelRootPage({super.key});
+  const ChannelRootPage({super.key, required this.isVisiblePage});
+
+  final bool isVisiblePage;
 
   @override
   State<ChannelRootPage> createState() => _ChannelRootPageState();
 }
 
 class _ChannelRootPageState extends State<ChannelRootPage> {
-  final PagingController<int, Channel> _pagingController = PagingController(firstPageKey: 0);
+  final PagingController<int, Channel> _pagingController = PagingController.fromValue(PagingState(nextPageKey: null, itemList: [], error: null), firstPageKey: 0);
+
+  bool _isInitialized = false;
 
   @override
   void initState() {
-    _pagingController.addPageRequestListener((pageKey) {
-      _fetchPage(pageKey);
-    });
     super.initState();
+
+    _pagingController.addPageRequestListener(_fetchPage);
+
+    if (widget.isVisiblePage && !_isInitialized) realInitState();
   }
 
   @override
@@ -31,9 +36,29 @@ class _ChannelRootPageState extends State<ChannelRootPage> {
     super.dispose();
   }
 
+  @override
+  void didUpdateWidget(ChannelRootPage oldWidget) {
+    super.didUpdateWidget(oldWidget);
+
+    if (oldWidget.isVisiblePage != widget.isVisiblePage && widget.isVisiblePage) {
+      if (!_isInitialized) {
+        realInitState();
+      } else {
+        //TODO background refresh
+      }
+    }
+  }
+
+  void realInitState() {
+    _pagingController.refresh();
+    _isInitialized = true;
+  }
+
   Future<void> _fetchPage(int pageKey) async {
     final acc = Provider.of<AppAuth>(context, listen: false);
 
+    ApplicationLog.debug('Start ChannelList::_pagingController::_fetchPage [ ${pageKey} ]');
+
     if (!acc.isAuth()) {
       _pagingController.error = 'Not logged in';
       return;