added support for multiple accounts with an account switcher in settings

lib/model/session_wipe.dart

@@ -4,11 +4,9 @@ import 'dart:io';
 
 import 'package:firebase_messaging/firebase_messaging.dart';
 import 'package:flutter_app_badge/flutter_app_badge.dart';
-import 'package:hydrated_bloc/hydrated_bloc.dart';
 import 'package:path_provider/path_provider.dart';
 import 'package:shared_preferences/shared_preferences.dart';
 
-import '../api/cache_store.dart';
 import '../api/marianumcloud/talk/share_files_to_chat.dart';
 import '../background/widget_background_task.dart';
 import '../notification/notification_service.dart';
@@ -18,20 +16,14 @@ import '../push/push_keypair.dart';
 import '../push/push_tap_router.dart';
 import '../routing/app_routes.dart';
 import '../share_intent/share_intent_listener.dart';
-import '../state/app/modules/breaker/bloc/breaker_bloc.dart';
-import '../state/app/modules/capabilities/bloc/capabilities_cubit.dart';
-import '../state/app/modules/chat/bloc/chat_bloc.dart';
-import '../state/app/modules/chat_list/bloc/chat_list_bloc.dart';
-import '../state/app/modules/nextcloud_capabilities/bloc/nextcloud_capabilities_cubit.dart';
-import '../state/app/modules/timetable/bloc/timetable_bloc.dart';
 import '../utils/app_paths.dart';
 import '../utils/downloads/download_manager.dart';
 import '../utils/file_clipboard.dart';
 import '../widget_data/widget_sync.dart';
 
-/// Removes everything the signed-out account left on the device. Every step
-/// is isolated: one failing step used to skip all later ones and leave the
-/// previous account's data behind.
+/// Removes what an account leaves on the device outside its own storage (see
+/// `AccountStorage` for that). Every step is isolated: one failing step used
+/// to skip all later ones and leave the previous account's data behind.
 abstract final class SessionWipe {
   static Future<void>? _running;
 
@@ -39,8 +31,9 @@ abstract final class SessionWipe {
   /// wipe could clear what the next account just stored (widget job, caches).
   static Future<void> get done => _running ?? Future.value();
 
-  /// State that must be gone before the next frame (a login screen can be
-  /// reached right away): pending navigation and in-memory singletons.
+  /// State that must be gone before the next frame (a login screen or another
+  /// account can be reached right away): pending navigation and in-memory
+  /// singletons.
   static void clearImmediate() {
     _step('share intents', ShareIntentListener.instance.clearAll);
     _step('share folder cache', resetTalkShareFolderCache);
@@ -52,66 +45,17 @@ abstract final class SessionWipe {
     _step('downloads', DownloadManager.instance.clearAll);
   }
 
-  static Future<void> run({
-    required TimetableBloc timetableBloc,
-    required ChatListBloc chatListBloc,
-    required ChatBloc chatBloc,
-    required BreakerBloc breakerBloc,
-    required CapabilitiesCubit capabilitiesCubit,
-    required NextcloudCapabilitiesCubit nextcloudCapabilitiesCubit,
-  }) {
-    final wipe = _run(
-      timetableBloc: timetableBloc,
-      chatListBloc: chatListBloc,
-      chatBloc: chatBloc,
-      breakerBloc: breakerBloc,
-      capabilitiesCubit: capabilitiesCubit,
-      nextcloudCapabilitiesCubit: nextcloudCapabilitiesCubit,
-    );
-    _running = wipe;
-    return wipe.whenComplete(() {
-      if (identical(_running, wipe)) _running = null;
-    });
-  }
-
-  static Future<void> _run({
-    required TimetableBloc timetableBloc,
-    required ChatListBloc chatListBloc,
-    required ChatBloc chatBloc,
-    required BreakerBloc breakerBloc,
-    required CapabilitiesCubit capabilitiesCubit,
-    required NextcloudCapabilitiesCubit nextcloudCapabilitiesCubit,
-  }) async {
-    // SettingsCubit is deliberately left alone: its BlocBuilder wraps
-    // MaterialApp, and emitting a fresh state here tore down the freshly
-    // mounted Login tree (blank screen until the next interaction).
-    await Future.wait([
-      _stepAsync('timetable', timetableBloc.reset),
-      _stepAsync('chat list', chatListBloc.reset),
-      _stepAsync('chat', chatBloc.reset),
-      _stepAsync('breakers', breakerBloc.reset),
-      _stepAsync('capabilities', capabilitiesCubit.reset),
-      _stepAsync('nc capabilities', nextcloudCapabilitiesCubit.reset),
-    ]);
-    await _stepAsync('shared preferences', () async {
-      await (await SharedPreferences.getInstance()).clear();
-    });
-    await _stepAsync('hydrated storage', HydratedBloc.storage.clear);
-    await _stepAsync('request cache', CacheStore.instance.clear);
-    await _stepAsync('chat background', () async {
-      final image = File(AppPaths.chatBackgroundImage);
-      if (image.existsSync()) await image.delete();
-    });
+  /// Runs whenever the active account stops being active (sign-out or
+  /// switch). The tray and its bookkeeping belong to that account — a tap or
+  /// inline reply there would otherwise act as the next one. A new keypair
+  /// and FCM token make pushes still addressed to the previous registration
+  /// undecryptable and undeliverable (an offline sign-out or switch could not
+  /// unregister it).
+  static Future<void> accountLeft() async {
     await _stepAsync('download files', () async {
       final dir = Directory('${(await getTemporaryDirectory()).path}/downloads');
       if (dir.existsSync()) await dir.delete(recursive: true);
     });
-
-    // Push: the tray and its bookkeeping belong to the previous account — a
-    // tap or inline reply there would otherwise act as the next one. A new
-    // keypair and FCM token make pushes still addressed to the previous
-    // registration undecryptable and undeliverable (an offline sign-out
-    // could not unregister it).
     await _stepAsync(
       'notification tray',
       NotificationService().flutterLocalNotificationsPlugin.cancelAll,
@@ -120,8 +64,35 @@ abstract final class SessionWipe {
     await _stepAsync('push nid store', NidStore().clear);
     await _stepAsync('push thread store', ChatThreadStore().clearAll);
     await _stepAsync('push keypair', const PushKeypair().clear);
-    await _stepAsync('fcm token', FirebaseMessaging.instance.deleteToken);
+    // Bounded: the next account waits for this, also without a network.
+    await _stepAsync(
+      'fcm token',
+      () => FirebaseMessaging.instance.deleteToken().timeout(
+        const Duration(seconds: 5),
+      ),
+    );
+  }
 
+  /// Wipes what outlives accounts, once the last one signed out.
+  static Future<void> deviceLeft() {
+    final wipe = _deviceLeft();
+    _running = wipe;
+    return wipe.whenComplete(() {
+      if (identical(_running, wipe)) _running = null;
+    });
+  }
+
+  static Future<void> _deviceLeft() async {
+    // SettingsCubit is deliberately left alone: its selector wraps
+    // MaterialApp, and emitting a fresh state here tore down the freshly
+    // mounted Login tree (blank screen until the next interaction).
+    await _stepAsync('shared preferences', () async {
+      await (await SharedPreferences.getInstance()).clear();
+    });
+    await _stepAsync('chat background', () async {
+      final image = File(AppPaths.chatBackgroundImage);
+      if (image.existsSync()) await image.delete();
+    });
     // Stop the periodic widget refresh job so the background isolate doesn't
     // wake up every 30 minutes only to write `loggedIn=false`. Re-registers
     // on the next successful login.