Run metadata task in a service on Android

app/lib/bloc/scan_account_dir.dart

@@ -12,7 +12,9 @@ import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/entity/file/data_source.dart';
 import 'package:nc_photos/entity/file_util.dart' as file_util;
 import 'package:nc_photos/event/event.dart';
+import 'package:nc_photos/event/native_event.dart';
 import 'package:nc_photos/exception_event.dart';
+import 'package:nc_photos/platform/k.dart' as platform_k;
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/throttler.dart';
 import 'package:nc_photos/touch_token_manager.dart';
@@ -112,6 +114,8 @@ class ScanAccountDirBloc
     _favoriteResyncedEventListener.begin();
     _prefUpdatedEventListener.begin();
     _accountPrefUpdatedEventListener.begin();
+
+    _nativeFileExifUpdatedListener?.begin();
   }
 
   static ScanAccountDirBloc of(Account account) {
@@ -164,6 +168,8 @@ class ScanAccountDirBloc
     _prefUpdatedEventListener.end();
     _accountPrefUpdatedEventListener.end();
 
+    _nativeFileExifUpdatedListener?.end();
+
     _refreshThrottler.clear();
     return super.close();
   }
@@ -304,6 +310,13 @@ class ScanAccountDirBloc
     }
   }
 
+  void _onNativeFileExifUpdated(FileExifUpdatedEvent ev) {
+    _refreshThrottler.trigger(
+      maxResponceTime: const Duration(seconds: 3),
+      maxPendingCount: 10,
+    );
+  }
+
   Future<List<File>> _queryOffline(ScanAccountDirBlocQueryBase ev) async {
     final c = KiwiContainer().resolve<DiContainer>();
     final files = <File>[];
@@ -484,6 +497,10 @@ class ScanAccountDirBloc
   late final _accountPrefUpdatedEventListener =
       AppEventListener<AccountPrefUpdatedEvent>(_onAccountPrefUpdatedEvent);
 
+  late final _nativeFileExifUpdatedListener = platform_k.isWeb
+      ? null
+      : NativeEventListener<FileExifUpdatedEvent>(_onNativeFileExifUpdated);
+
   late final _refreshThrottler = Throttler(
     onTriggered: (_) {
       add(const _ScanAccountDirBlocExternalEvent());

app/lib/event/native_event.dart

@@ -0,0 +1,67 @@
+import 'dart:async';
+import 'dart:convert';
+
+import 'package:logging/logging.dart';
+import 'package:nc_photos_plugin/nc_photos_plugin.dart';
+
+class NativeEventListener<T> {
+  NativeEventListener(this.listener);
+
+  void begin() {
+    if (_subscription != null) {
+      _log.warning("[begin] Already listening");
+      return;
+    }
+    _subscription = _mappedStream
+        .where((event) => event is T)
+        .cast<T>()
+        .listen(listener);
+  }
+
+  void end() {
+    if (_subscription == null) {
+      _log.warning("[end] Already not listening");
+      return;
+    }
+    _subscription?.cancel();
+    _subscription = null;
+  }
+
+  static late final _mappedStream =
+      NativeEvent.stream.where((event) => event is NativeEventObject).map((ev) {
+    switch (ev.event) {
+      case FileExifUpdatedEvent._id:
+        return FileExifUpdatedEvent.fromEvent(ev);
+
+      default:
+        throw ArgumentError("Invalid event: ${ev.event}");
+    }
+  });
+
+  final void Function(T) listener;
+  StreamSubscription<T>? _subscription;
+
+  final _log = Logger("native_event.NativeEventListener<${T.runtimeType}>");
+}
+
+class FileExifUpdatedEvent {
+  const FileExifUpdatedEvent(this.fileIds);
+
+  factory FileExifUpdatedEvent.fromEvent(NativeEventObject ev) {
+    assert(ev.event == _id);
+    assert(ev.data != null);
+    final dataJson = jsonDecode(ev.data!) as Map;
+    return FileExifUpdatedEvent((dataJson["fileIds"] as List).cast<int>());
+  }
+
+  NativeEventObject toEvent() => NativeEventObject(
+        _id,
+        jsonEncode({
+          "fileIds": fileIds,
+        }),
+      );
+
+  static const _id = "FileExifUpdatedEvent";
+
+  final List<int> fileIds;
+}

app/lib/l10n/app_en.arb

@@ -1167,6 +1167,10 @@
 	"@tagPickerNoTagSelectedNotification": {
 		"description": "At least 1 tag is required to create a tag collection. This error is shown when user try to create one without selecting any tags"
 	},
+	"backgroundServiceStopping": "Stopping service",
+	"@backgroundServiceStopping": {
+		"description": "The background service is stopping itself"
+	},
 
 	"errorUnauthenticated": "Unauthenticated access. Please sign-in again if the problem continues",
 	"@errorUnauthenticated": {

app/lib/l10n/untranslated-messages.txt

@@ -82,6 +82,7 @@
     "createCollectionDialogTagDescription",
     "addTagInputHint",
     "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping",
     "errorAlbumDowngrade"
   ],
 
@@ -182,6 +183,7 @@
     "createCollectionDialogTagDescription",
     "addTagInputHint",
     "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping",
     "errorAlbumDowngrade"
   ],
 
@@ -337,12 +339,18 @@
     "createCollectionDialogTagDescription",
     "addTagInputHint",
     "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping",
     "errorAlbumDowngrade"
   ],
 
   "es": [
     "rootPickerSkipConfirmationDialogContent2",
-    "helpButtonLabel"
+    "helpButtonLabel",
+    "backgroundServiceStopping"
+  ],
+
+  "fi": [
+    "backgroundServiceStopping"
   ],
 
   "fr": [
@@ -477,6 +485,7 @@
     "createCollectionDialogTagDescription",
     "addTagInputHint",
     "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping",
     "errorAlbumDowngrade"
   ],
 
@@ -499,7 +508,8 @@
     "createCollectionDialogTagLabel",
     "createCollectionDialogTagDescription",
     "addTagInputHint",
-    "tagPickerNoTagSelectedNotification"
+    "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping"
   ],
 
   "ru": [
@@ -607,6 +617,7 @@
     "createCollectionDialogTagDescription",
     "addTagInputHint",
     "tagPickerNoTagSelectedNotification",
+    "backgroundServiceStopping",
     "errorAlbumDowngrade"
   ]
 }

app/lib/service.dart

@@ -0,0 +1,266 @@
+import 'package:devicelocale/devicelocale.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_background_service/flutter_background_service.dart';
+import 'package:flutter_gen/gen_l10n/app_localizations.dart';
+import 'package:flutter_gen/gen_l10n/app_localizations_en.dart';
+import 'package:logging/logging.dart';
+import 'package:nc_photos/account.dart';
+import 'package:nc_photos/app_db.dart';
+import 'package:nc_photos/app_init.dart' as app_init;
+import 'package:nc_photos/app_localizations.dart';
+import 'package:nc_photos/entity/file.dart';
+import 'package:nc_photos/entity/file/data_source.dart';
+import 'package:nc_photos/entity/file_util.dart' as file_util;
+import 'package:nc_photos/event/event.dart';
+import 'package:nc_photos/event/native_event.dart';
+import 'package:nc_photos/language_util.dart' as language_util;
+import 'package:nc_photos/pref.dart';
+import 'package:nc_photos/use_case/update_missing_metadata.dart';
+import 'package:nc_photos_plugin/nc_photos_plugin.dart';
+
+/// Start the background service
+Future<void> startService() async {
+  _log.info("[startService] Starting service");
+  final service = FlutterBackgroundService();
+  await service.configure(
+    androidConfiguration: AndroidConfiguration(
+      onStart: serviceMain,
+      autoStart: false,
+      isForegroundMode: true,
+      foregroundServiceNotificationTitle:
+          L10n.global().metadataTaskProcessingNotification,
+    ),
+    iosConfiguration: IosConfiguration(
+      onForeground: () => throw UnimplementedError(),
+      onBackground: () => throw UnimplementedError(),
+    ),
+  );
+  await service.start();
+}
+
+/// Ask the background service to stop ASAP
+void stopService() {
+  _log.info("[stopService] Stopping service");
+  FlutterBackgroundService().sendData({
+    "stop": true,
+  });
+}
+
+@visibleForTesting
+void serviceMain() async {
+  _Service._shouldRun = true;
+  WidgetsFlutterBinding.ensureInitialized();
+
+  await _Service()();
+}
+
+class _Service {
+  Future<void> call() async {
+    await app_init.initAppLaunch();
+    await _L10n().init();
+
+    _log.info("[call] Service started");
+    final service = FlutterBackgroundService();
+    service.setForegroundMode(true);
+    final onCancelSubscription = service.onCancel.listen((_) {
+      _log.info("[call] User canceled");
+      _stopSelf();
+    });
+    final onDataSubscription =
+        service.onDataReceived.listen((event) => _onReceiveData(event ?? {}));
+
+    try {
+      await _doWork();
+    } catch (e, stackTrace) {
+      _log.shout("[call] Uncaught exception", e, stackTrace);
+    }
+    onCancelSubscription.cancel();
+    onDataSubscription.cancel();
+    service.stopBackgroundService();
+    _log.info("[call] Service stopped");
+  }
+
+  Future<void> _doWork() async {
+    final account = Pref().getCurrentAccount();
+    if (account == null) {
+      _log.shout("[_doWork] account == null");
+      return;
+    }
+    final accountPref = AccountPref.of(account);
+
+    final service = FlutterBackgroundService();
+    final metadataTask = _MetadataTask(service, account, accountPref);
+    _metadataTaskStateChangedListener.begin();
+    try {
+      await metadataTask();
+    } finally {
+      _metadataTaskStateChangedListener.end();
+    }
+  }
+
+  void _onReceiveData(Map<String, dynamic> data) {
+    try {
+      for (final e in data.entries) {
+        switch (e.key) {
+          case "stop":
+            _stopSelf();
+            break;
+        }
+      }
+    } catch (e, stackTrace) {
+      _log.shout("[_onReceiveData] Uncaught exception", e, stackTrace);
+    }
+  }
+
+  void _onMetadataTaskStateChanged(MetadataTaskStateChangedEvent ev) {
+    if (ev.state == _metadataTaskState) {
+      return;
+    }
+    _metadataTaskState = ev.state;
+    if (ev.state == MetadataTaskState.waitingForWifi) {
+      final service = FlutterBackgroundService();
+      service.setNotificationInfo(
+        title: _L10n.global().metadataTaskPauseNoWiFiNotification,
+      );
+    }
+  }
+
+  void _stopSelf() {
+    _log.info("[_stopSelf] Stopping service");
+    FlutterBackgroundService().setNotificationInfo(
+      title: _L10n.global().backgroundServiceStopping,
+    );
+    _shouldRun = false;
+  }
+
+  var _metadataTaskState = MetadataTaskState.idle;
+  late final _metadataTaskStateChangedListener =
+      AppEventListener<MetadataTaskStateChangedEvent>(
+          _onMetadataTaskStateChanged);
+
+  static var _shouldRun = true;
+  static final _log = Logger("service._Service");
+}
+
+/// Access localized string out of the main isolate
+class _L10n {
+  factory _L10n() => _inst;
+
+  _L10n._();
+
+  Future<void> init() async {
+    try {
+      final locale = language_util.getSelectedLocale();
+      if (locale == null) {
+        _l10n = await _queryL10n();
+      } else {
+        _l10n = lookupAppLocalizations(locale);
+      }
+    } catch (e, stackTrace) {
+      _log.shout("[init] Uncaught exception", e, stackTrace);
+      _l10n = AppLocalizationsEn();
+    }
+  }
+
+  static AppLocalizations global() => _L10n()._l10n;
+
+  Future<AppLocalizations> _queryL10n() async {
+    try {
+      final locale = await Devicelocale.currentAsLocale;
+      return lookupAppLocalizations(locale!);
+    } on FlutterError catch (_) {
+      // unsupported locale, use default (en)
+      return AppLocalizationsEn();
+    } catch (e, stackTrace) {
+      _log.shout(
+          "[_queryL10n] Failed while lookupAppLocalizations", e, stackTrace);
+      return AppLocalizationsEn();
+    }
+  }
+
+  static late final _inst = _L10n._();
+  late AppLocalizations _l10n;
+
+  static final _log = Logger("service._L10n");
+}
+
+class _MetadataTask {
+  _MetadataTask(this.service, this.account, this.accountPref);
+
+  Future<void> call() async {
+    try {
+      await _updateMetadata();
+    } catch (e, stackTrace) {
+      _log.shout("[call] Uncaught exception", e, stackTrace);
+    }
+    if (_processedIds.isNotEmpty) {
+      NativeEvent.fire(FileExifUpdatedEvent(_processedIds).toEvent());
+      _processedIds = [];
+    }
+  }
+
+  Future<void> _updateMetadata() async {
+    final shareFolder = File(
+        path: file_util.unstripPath(account, accountPref.getShareFolderOr()));
+    bool hasScanShareFolder = false;
+    final fileRepo = FileRepo(FileCachedDataSource(AppDb()));
+    for (final r in account.roots) {
+      final dir = File(path: file_util.unstripPath(account, r));
+      hasScanShareFolder |= file_util.isOrUnderDir(shareFolder, dir);
+      final updater = UpdateMissingMetadata(fileRepo);
+      await for (final ev in updater(account, dir)) {
+        if (!_Service._shouldRun) {
+          _log.info("[_updateMetadata] Stopping task: user canceled");
+          updater.stop();
+          return;
+        }
+        if (ev is File) {
+          _onFileProcessed(ev);
+        }
+      }
+    }
+    if (!hasScanShareFolder) {
+      final shareUpdater = UpdateMissingMetadata(fileRepo);
+      await for (final ev in shareUpdater(
+        account,
+        shareFolder,
+        isRecursive: false,
+        filter: (f) => f.ownerId != account.username,
+      )) {
+        if (!_Service._shouldRun) {
+          _log.info("[_updateMetadata] Stopping task: user canceled");
+          shareUpdater.stop();
+          return;
+        }
+        if (ev is File) {
+          _onFileProcessed(ev);
+        }
+      }
+    }
+  }
+
+  void _onFileProcessed(File file) {
+    ++_count;
+    service.setNotificationInfo(
+      title: _L10n.global().metadataTaskProcessingNotification,
+      content: file.strippedPath,
+    );
+
+    _processedIds.add(file.fileId!);
+    if (_processedIds.length >= 10) {
+      NativeEvent.fire(FileExifUpdatedEvent(_processedIds).toEvent());
+      _processedIds = [];
+    }
+  }
+
+  final FlutterBackgroundService service;
+  final Account account;
+  final AccountPref accountPref;
+
+  var _count = 0;
+  var _processedIds = <int>[];
+
+  static final _log = Logger("service._MetadataTask");
+}
+
+final _log = Logger("service");

app/lib/use_case/update_missing_metadata.dart

@@ -86,6 +86,9 @@ class UpdateMissingMetadata {
           metadata: OrNull(metadataObj),
         );
         yield file;
+
+        // slow down a bit to give some space for the main isolate
+        await Future.delayed(const Duration(milliseconds: 10));
       } catch (e, stackTrace) {
         _log.severe("[call] Failed while updating metadata: ${file.path}", e,
             stackTrace);

app/lib/widget/home_photos.dart

@@ -22,8 +22,10 @@ import 'package:nc_photos/exception_util.dart' as exception_util;
 import 'package:nc_photos/iterable_extension.dart';
 import 'package:nc_photos/k.dart' as k;
 import 'package:nc_photos/metadata_task_manager.dart';
+import 'package:nc_photos/platform/k.dart' as platform_k;
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/primitive.dart';
+import 'package:nc_photos/service.dart' as service;
 import 'package:nc_photos/share_handler.dart';
 import 'package:nc_photos/snack_bar_manager.dart';
 import 'package:nc_photos/theme.dart';
@@ -66,17 +68,14 @@ class _HomePhotosState extends State<HomePhotos>
     super.initState();
     _thumbZoomLevel = Pref().getHomePhotosZoomLevelOr(0);
     _initBloc();
-    _metadataTaskStateChangedListener.begin();
+    _web?.onInitState();
     _prefUpdatedListener.begin();
-    _filePropertyUpdatedListener.begin();
   }
 
   @override
   dispose() {
-    _metadataTaskIconController.stop();
-    _metadataTaskStateChangedListener.end();
     _prefUpdatedListener.end();
-    _filePropertyUpdatedListener.end();
+    _web?.onDispose();
     super.dispose();
   }
 
@@ -137,8 +136,7 @@ class _HomePhotosState extends State<HomePhotos>
                       controller: _scrollController,
                       slivers: [
                         _buildAppBar(context),
-                        if (_metadataTaskState != MetadataTaskState.idle)
-                          _buildMetadataTaskHeader(context),
+                        _web?.buildContent(context),
                         if (AccountPref.of(widget.account)
                                 .isEnableMemoryAlbumOr(true) &&
                             _smartAlbums.isNotEmpty)
@@ -151,7 +149,7 @@ class _HomePhotosState extends State<HomePhotos>
                             });
                           },
                         ),
-                      ],
+                      ].whereType<Widget>().toList(),
                     ),
                   ),
                 ),
@@ -260,81 +258,6 @@ class _HomePhotosState extends State<HomePhotos>
     );
   }
 
-  Widget _buildMetadataTaskHeader(BuildContext context) {
-    return SliverPersistentHeader(
-      pinned: true,
-      floating: false,
-      delegate: _MetadataTaskHeaderDelegate(
-        extent: _metadataTaskHeaderHeight,
-        builder: (context) => Container(
-          height: double.infinity,
-          color: Theme.of(context).scaffoldBackgroundColor,
-          alignment: AlignmentDirectional.centerStart,
-          child: Padding(
-            padding: const EdgeInsets.symmetric(horizontal: 8),
-            child: Row(
-              children: [
-                if (_metadataTaskState == MetadataTaskState.prcoessing)
-                  Row(
-                    mainAxisSize: MainAxisSize.min,
-                    children: [
-                      _MetadataTaskLoadingIcon(
-                        controller: _metadataTaskIconController,
-                      ),
-                      const SizedBox(width: 4),
-                      Text(
-                        L10n.global().metadataTaskProcessingNotification +
-                            _getMetadataTaskProgressString(),
-                        style: const TextStyle(fontSize: 12),
-                      ),
-                    ],
-                  )
-                else if (_metadataTaskState == MetadataTaskState.waitingForWifi)
-                  Row(
-                    mainAxisSize: MainAxisSize.min,
-                    children: [
-                      const Icon(
-                        Icons.sync_problem,
-                        size: 16,
-                      ),
-                      const SizedBox(width: 4),
-                      Text(
-                        L10n.global().metadataTaskPauseNoWiFiNotification,
-                        style: const TextStyle(fontSize: 12),
-                      ),
-                    ],
-                  ),
-                Expanded(
-                  child: Container(),
-                ),
-                Material(
-                  type: MaterialType.transparency,
-                  child: InkWell(
-                    child: Padding(
-                      padding: const EdgeInsets.symmetric(
-                          horizontal: 8, vertical: 4),
-                      child: Text(
-                        L10n.global().configButtonLabel,
-                        style: TextStyle(
-                          color: Theme.of(context).colorScheme.primary,
-                          fontSize: 12,
-                        ),
-                      ),
-                    ),
-                    onTap: () {
-                      Navigator.of(context).pushNamed(Settings.routeName,
-                          arguments: SettingsArguments(widget.account));
-                    },
-                  ),
-                ),
-              ],
-            ),
-          ),
-        ),
-      ),
-    );
-  }
-
   Widget _buildSmartAlbumList(BuildContext context) {
     return SliverToBoxAdapter(
       child: SizedBox(
@@ -487,48 +410,44 @@ class _HomePhotosState extends State<HomePhotos>
     );
   }
 
-  void _onMetadataTaskStateChanged(MetadataTaskStateChangedEvent ev) {
-    if (ev.state == MetadataTaskState.idle) {
-      _metadataTaskProcessCount = 0;
-    }
-    if (ev.state != _metadataTaskState) {
-      setState(() {
-        _metadataTaskState = ev.state;
-      });
-    }
-  }
-
   void _onPrefUpdated(PrefUpdatedEvent ev) {
-    if (ev.key == PrefKey.enableExif && ev.value == true) {
-      _tryStartMetadataTask(ignoreFired: true);
+    if (ev.key == PrefKey.enableExif) {
+      if (ev.value == true) {
+        _tryStartMetadataTask(ignoreFired: true);
+      } else {
+        _stopMetadataTask();
+      }
     }
   }
 
-  void _onFilePropertyUpdated(FilePropertyUpdatedEvent ev) {
-    if (!ev.hasAnyProperties([FilePropertyUpdatedEvent.propMetadata])) {
-      return;
-    }
-    setState(() {
-      ++_metadataTaskProcessCount;
-    });
-  }
-
   void _tryStartMetadataTask({
     bool ignoreFired = false,
   }) {
     if (_bloc.state is ScanAccountDirBlocSuccess &&
         Pref().isEnableExifOr() &&
         (!_hasFiredMetadataTask.value || ignoreFired)) {
-      MetadataTaskManager().addTask(
-          MetadataTask(widget.account, AccountPref.of(widget.account)));
-      _metadataTaskProcessTotalCount = _backingFiles
+      final missingMetadataCount = _backingFiles
           .where(
               (f) => file_util.isSupportedImageFormat(f) && f.metadata == null)
           .length;
+      if (missingMetadataCount > 0) {
+        if (_web != null) {
+          _web!.startMetadataTask(missingMetadataCount);
+        } else {
+          service.startService();
+        }
+      }
+
       _hasFiredMetadataTask.value = true;
     }
   }
 
+  void _stopMetadataTask() {
+    if (_web == null) {
+      service.stopService();
+    }
+  }
+
   Future<void> _syncFavorite() async {
     if (!_hasResyncedFavorites.value) {
       final c = KiwiContainer().resolve<DiContainer>();
@@ -622,10 +541,7 @@ class _HomePhotosState extends State<HomePhotos>
     if (_itemListMaxExtent != null &&
         constraints.hasBoundedHeight &&
         _appBarExtent != null) {
-      final metadataTaskHeaderExtent =
-          _metadataTaskState == MetadataTaskState.idle
-              ? 0
-              : _metadataTaskHeaderHeight;
+      final metadataTaskHeaderExtent = _web?.getHeaderHeight() ?? 0;
       final smartAlbumListHeight =
           AccountPref.of(widget.account).isEnableMemoryAlbumOr(true) &&
                   _smartAlbums.isNotEmpty
@@ -647,15 +563,6 @@ class _HomePhotosState extends State<HomePhotos>
     }
   }
 
-  String _getMetadataTaskProgressString() {
-    if (_metadataTaskProcessTotalCount == 0) {
-      return "";
-    }
-    final clippedCount =
-        math.min(_metadataTaskProcessCount, _metadataTaskProcessTotalCount - 1);
-    return " ($clippedCount/$_metadataTaskProcessTotalCount)";
-  }
-
   Primitive<bool> get _hasFiredMetadataTask {
     final name = bloc_util.getInstNameForRootAwareAccount(
         "HomePhotosState.hasFiredMetadataTask", widget.account);
@@ -699,12 +606,161 @@ class _HomePhotosState extends State<HomePhotos>
   double? _appBarExtent;
   double? _itemListMaxExtent;
 
+  late final _prefUpdatedListener =
+      AppEventListener<PrefUpdatedEvent>(_onPrefUpdated);
+
+  late final _Web? _web = platform_k.isWeb ? _Web(this) : null;
+
+  static final _log = Logger("widget.home_photos._HomePhotosState");
+  static const _menuValueRefresh = 0;
+}
+
+class _Web {
+  _Web(this.state);
+
+  void onInitState() {
+    _metadataTaskStateChangedListener.begin();
+    _filePropertyUpdatedListener.begin();
+  }
+
+  void onDispose() {
+    _metadataTaskIconController.stop();
+    _metadataTaskStateChangedListener.end();
+    _filePropertyUpdatedListener.end();
+  }
+
+  Widget? buildContent(BuildContext context) {
+    if (_metadataTaskState != MetadataTaskState.idle) {
+      return _buildMetadataTaskHeader(context);
+    } else {
+      return null;
+    }
+  }
+
+  void startMetadataTask(int missingMetadataCount) {
+    MetadataTaskManager().addTask(MetadataTask(
+        state.widget.account, AccountPref.of(state.widget.account)));
+    _metadataTaskProcessTotalCount = missingMetadataCount;
+  }
+
+  double getHeaderHeight() {
+    return _metadataTaskState == MetadataTaskState.idle
+        ? 0
+        : _metadataTaskHeaderHeight;
+  }
+
+  Widget _buildMetadataTaskHeader(BuildContext context) {
+    return SliverPersistentHeader(
+      pinned: true,
+      floating: false,
+      delegate: _MetadataTaskHeaderDelegate(
+        extent: _metadataTaskHeaderHeight,
+        builder: (context) => Container(
+          height: double.infinity,
+          color: Theme.of(context).scaffoldBackgroundColor,
+          alignment: AlignmentDirectional.centerStart,
+          child: Padding(
+            padding: const EdgeInsets.symmetric(horizontal: 8),
+            child: Row(
+              children: [
+                if (_metadataTaskState == MetadataTaskState.prcoessing)
+                  Row(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      _MetadataTaskLoadingIcon(
+                        controller: _metadataTaskIconController,
+                      ),
+                      const SizedBox(width: 4),
+                      Text(
+                        L10n.global().metadataTaskProcessingNotification +
+                            _getMetadataTaskProgressString(),
+                        style: const TextStyle(fontSize: 12),
+                      ),
+                    ],
+                  )
+                else if (_metadataTaskState == MetadataTaskState.waitingForWifi)
+                  Row(
+                    mainAxisSize: MainAxisSize.min,
+                    children: [
+                      const Icon(
+                        Icons.sync_problem,
+                        size: 16,
+                      ),
+                      const SizedBox(width: 4),
+                      Text(
+                        L10n.global().metadataTaskPauseNoWiFiNotification,
+                        style: const TextStyle(fontSize: 12),
+                      ),
+                    ],
+                  ),
+                Expanded(
+                  child: Container(),
+                ),
+                Material(
+                  type: MaterialType.transparency,
+                  child: InkWell(
+                    child: Padding(
+                      padding: const EdgeInsets.symmetric(
+                          horizontal: 8, vertical: 4),
+                      child: Text(
+                        L10n.global().configButtonLabel,
+                        style: TextStyle(
+                          color: Theme.of(context).colorScheme.primary,
+                          fontSize: 12,
+                        ),
+                      ),
+                    ),
+                    onTap: () {
+                      Navigator.of(context).pushNamed(Settings.routeName,
+                          arguments: SettingsArguments(state.widget.account));
+                    },
+                  ),
+                ),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+  }
+
+  void _onMetadataTaskStateChanged(MetadataTaskStateChangedEvent ev) {
+    if (ev.state == MetadataTaskState.idle) {
+      _metadataTaskProcessCount = 0;
+    }
+    if (ev.state != _metadataTaskState) {
+      // ignore: invalid_use_of_protected_member
+      state.setState(() {
+        _metadataTaskState = ev.state;
+      });
+    }
+  }
+
+  void _onFilePropertyUpdated(FilePropertyUpdatedEvent ev) {
+    if (!ev.hasAnyProperties([FilePropertyUpdatedEvent.propMetadata])) {
+      return;
+    }
+    // ignore: invalid_use_of_protected_member
+    state.setState(() {
+      ++_metadataTaskProcessCount;
+    });
+  }
+
+  String _getMetadataTaskProgressString() {
+    if (_metadataTaskProcessTotalCount == 0) {
+      return "";
+    }
+    final clippedCount =
+        math.min(_metadataTaskProcessCount, _metadataTaskProcessTotalCount - 1);
+    return " ($clippedCount/$_metadataTaskProcessTotalCount)";
+  }
+
+  final _HomePhotosState state;
+
   late final _metadataTaskStateChangedListener =
       AppEventListener<MetadataTaskStateChangedEvent>(
           _onMetadataTaskStateChanged);
   var _metadataTaskState = MetadataTaskManager().state;
-  late final _prefUpdatedListener =
-      AppEventListener<PrefUpdatedEvent>(_onPrefUpdated);
   late final _filePropertyUpdatedListener =
       AppEventListener<FilePropertyUpdatedEvent>(_onFilePropertyUpdated);
   var _metadataTaskProcessCount = 0;
@@ -712,12 +768,9 @@ class _HomePhotosState extends State<HomePhotos>
   late final _metadataTaskIconController = AnimationController(
     upperBound: 2 * math.pi,
     duration: const Duration(seconds: 10),
-    vsync: this,
+    vsync: state,
   )..repeat();
 
-  static final _log = Logger("widget.home_photos._HomePhotosState");
-  static const _menuValueRefresh = 0;
-
   static const _metadataTaskHeaderHeight = 32.0;
 }
 

app/pubspec.lock

@@ -232,6 +232,13 @@ packages:
       url: "https://pub.dartlang.org"
     source: hosted
     version: "2.1.1"
+  devicelocale:
+    dependency: "direct main"
+    description:
+      name: devicelocale
+      url: "https://pub.dartlang.org"
+    source: hosted
+    version: "0.5.0"
   diff_match_patch:
     dependency: transitive
     description:
@@ -297,6 +304,15 @@ packages:
     description: flutter
     source: sdk
     version: "0.0.0"
+  flutter_background_service:
+    dependency: "direct main"
+    description:
+      path: "."
+      ref: "v0.2.6-nc-photos-1"
+      resolved-ref: c63c7ed595d39897db4791266e6208abd7d688e5
+      url: "https://gitlab.com/nc-photos/flutter_background_service.git"
+    source: git
+    version: "0.2.6"
   flutter_bloc:
     dependency: "direct main"
     description:

app/pubspec.yaml

@@ -32,6 +32,7 @@ dependencies:
   cached_network_image: ^3.0.0
   collection: ^1.15.0
   connectivity_plus: ^2.0.2
+  devicelocale: ^0.5.0
   device_info_plus: ^3.1.0
   draggable_scrollbar:
     git:
@@ -43,6 +44,10 @@ dependencies:
     git:
       url: https://gitlab.com/nc-photos/exifdart.git
       ref: 1.1.0
+  flutter_background_service:
+    git:
+      url: https://gitlab.com/nc-photos/flutter_background_service.git
+      ref: v0.2.6-nc-photos-1
   flutter_bloc: ^7.0.0
   flutter_map: ^0.14.0
   flutter_staggered_grid_view: