implemented scheduled updates for widgets

lib/view/settings/devToolsSettings.dart

@@ -1,14 +1,18 @@
 
+import 'package:background_fetch/background_fetch.dart';
 import 'package:filesize/filesize.dart';
 import 'package:flutter/material.dart';
 import 'package:hydrated_bloc/hydrated_bloc.dart';
 import 'package:provider/provider.dart';
+import 'package:shared_preferences/shared_preferences.dart';
 
+import '../../background_tasks/scheduledTask.dart';
 import '../../storage/base/settingsProvider.dart';
 import '../../widget/centeredLeading.dart';
 import '../../widget/confirmDialog.dart';
 import '../../widget/debug/cacheView.dart';
 import '../../widget/debug/jsonViewer.dart';
+import '../../widget/infoDialog.dart';
 
 class DevToolsSettings extends StatefulWidget {
   final SettingsProvider settings;
@@ -22,6 +26,84 @@ class _DevToolsSettingsState extends State<DevToolsSettings> {
   @override
   Widget build(BuildContext context) => Column(
       children: [
+        ListTile(
+          leading: const CenteredLeading(Icon(Icons.task_outlined)),
+          title: const Text('Background app fetch task'),
+          trailing: const Icon(Icons.arrow_right),
+          onTap: () {
+            showDialog(context: context, builder: (context) => AlertDialog(
+              title: Text('Background fetch task'),
+              content: Column(
+                mainAxisSize: MainAxisSize.min,
+                mainAxisAlignment: MainAxisAlignment.start,
+                children: [
+                  FutureBuilder(future: BackgroundFetch.status, builder: (context, snapshot) {
+                    if(snapshot.hasData) {
+                      var fetchStatus = switch(snapshot.data) {
+                        BackgroundFetch.STATUS_AVAILABLE => 'STATUS_AVAILABLE, Background updates are available for the app.',
+                        BackgroundFetch.STATUS_DENIED => 'STATUS_DENIED, The user explicitly disabled background behavior for this app or for the whole system.',
+                        BackgroundFetch.STATUS_RESTRICTED => 'STATUS_RESTRICTED, Background updates are unavailable and the user cannot enable them again. For example, this status can occur when parental controls are in effect for the current user.',
+                        _ => 'UNKNOWN',
+                      };
+                      return Text('(${snapshot.data}): $fetchStatus');
+                    }
+                    return LinearProgressIndicator();
+                  }),
+                  const Divider(),
+                  const Text('There is no indicator if the Fetch-API is currently running or not!'),
+                  const Divider(),
+                  FutureBuilder(
+                    future: SharedPreferences.getInstance(),
+                    builder: (context, snapshot) {
+                      if(!snapshot.hasData) return LinearProgressIndicator();
+                      return Text('Last fetch timestamp: ${snapshot.data?.getStringList(ScheduledTask.fetchApiLastRunTimestampKey)?.last ?? 'No entry'}');
+                    },
+                  )
+                ],
+              ),
+              actions: [
+                FutureBuilder(future: SharedPreferences.getInstance(), builder: (context, snapshot) {
+                  if(!snapshot.hasData) return LinearProgressIndicator();
+                  return TextButton(
+                    onPressed: () {
+                      InfoDialog.show(
+                        context,
+                        (snapshot.data!.getStringList(ScheduledTask.fetchApiLastRunTimestampKey) ?? []).reversed.join('\n')
+                      );
+                    },
+                    child: Text('Fetch history')
+                  );
+                }),
+                TextButton(
+                  onPressed: () => ConfirmDialog(
+                    title: 'Warning',
+                    content: 'Background Fetch worker will be started! This basically happens on every app startup.',
+                    onConfirm: BackgroundFetch.start
+                  ).asDialog(context),
+                  child: Text('Fetch-API Start')
+                ),
+                TextButton(
+                  onPressed: () => ConfirmDialog(
+                    title: 'Warning',
+                    content: 'Background Fetch worker will be terminated. This will result in outdated Information when App is not in foreground!',
+                    onConfirm: BackgroundFetch.stop
+                  ).asDialog(context),
+                  child: Text('Fetch-API Stop')
+                ),
+                TextButton(
+                  onPressed: () => ConfirmDialog(
+                    title: 'Warning',
+                    content: 'Background fetch will run now! This happens in the application layer and does not interact with the Fetch-API!',
+                    confirmButton: 'Run',
+                    onConfirm: ScheduledTask.backgroundFetch
+                  ).asDialog(context),
+                  child: Text('Run task manually')
+                ),
+                TextButton(onPressed: () => Navigator.of(context).pop(), child: Text('Zurück'))
+              ],
+            ));
+          },
+        ),
         ListTile(
           leading: const CenteredLeading(Icon(Icons.speed_outlined)),
           title: const Text('Performance overlays'),