Skip touch token check if etag matches

lib/bloc/scan_account_dir.dart

@@ -14,6 +14,7 @@ import 'package:nc_photos/event/event.dart';
 import 'package:nc_photos/exception_event.dart';
 import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/throttler.dart';
+import 'package:nc_photos/touch_token_manager.dart';
 import 'package:nc_photos/use_case/ls.dart';
 import 'package:nc_photos/use_case/scan_dir.dart';
 import 'package:nc_photos/use_case/scan_dir_offline.dart';
@@ -307,7 +308,7 @@ class ScanAccountDirBloc
   Stream<ScanAccountDirBlocState> _queryOnline(
       ScanAccountDirBlocQueryBase ev, List<File>? cache) async* {
     // 1st pass: scan for new files
-    final files = <File>[];
+    var files = <File>[];
     {
       final stopwatch = Stopwatch()..start();
       final fileRepo = FileRepo(FileCachedDataSource(AppDb(),
@@ -336,32 +337,56 @@ class ScanAccountDirBloc
       yield ScanAccountDirBlocLoading(files);
     }
 
-    if (_shouldCheckCache) {
-      // 2nd pass: check outdated cache
-      _shouldCheckCache = false;
-      final stopwatch = Stopwatch()..start();
-      final fileRepo = FileRepo(FileCachedDataSource(AppDb(),
-          shouldCheckCache: true,
-          forwardCacheManager: FileForwardCacheManager(AppDb())));
-      final fileRepoNoCache =
-          FileRepo(FileCachedDataSource(AppDb(), shouldCheckCache: true));
-      final newFiles = <File>[];
-      await for (final event in _queryWithFileRepo(fileRepo, ev,
-          fileRepoForShareDir: fileRepoNoCache)) {
-        if (event is ExceptionEvent) {
-          _log.shout("[_queryOnline] Exception while request (2nd pass)",
-              event.error, event.stackTrace);
-          yield ScanAccountDirBlocSuccess(files);
-          return;
-        }
-        newFiles.addAll(event);
+    try {
+      if (_shouldCheckCache) {
+        // 2nd pass: check outdated cache
+        _shouldCheckCache = false;
+        files = await _queryOnlinePass2(ev, files);
       }
-      _log.info(
-          "[_queryOnline] Elapsed time (pass2): ${stopwatch.elapsedMilliseconds}ms");
-      yield ScanAccountDirBlocSuccess(newFiles);
-    } else {
-      yield ScanAccountDirBlocSuccess(files);
+    } catch (e, stackTrace) {
+      _log.shout(
+          "[_queryOnline] Failed while _queryOnlinePass2", e, stackTrace);
     }
+    yield ScanAccountDirBlocSuccess(files);
+  }
+
+  Future<List<File>> _queryOnlinePass2(
+      ScanAccountDirBlocQueryBase ev, List<File> pass1Files) async {
+    const touchTokenManager = TouchTokenManager();
+    final fileRepo = FileRepo(FileCachedDataSource(AppDb(),
+        shouldCheckCache: true,
+        forwardCacheManager: FileForwardCacheManager(AppDb())));
+    final remoteTouchEtag =
+        await touchTokenManager.getRemoteRootEtag(fileRepo, account);
+    if (remoteTouchEtag == null) {
+      _log.info("[_queryOnlinePass2] remoteTouchEtag == null");
+      await touchTokenManager.setLocalRootEtag(account, null);
+      return pass1Files;
+    }
+    final localTouchEtag = await touchTokenManager.getLocalRootEtag(account);
+    if (remoteTouchEtag == localTouchEtag) {
+      _log.info("[_queryOnlinePass2] remoteTouchEtag matched");
+      return pass1Files;
+    }
+
+    final stopwatch = Stopwatch()..start();
+    final fileRepoNoCache =
+        FileRepo(FileCachedDataSource(AppDb(), shouldCheckCache: true));
+    final newFiles = <File>[];
+    await for (final event in _queryWithFileRepo(fileRepo, ev,
+        fileRepoForShareDir: fileRepoNoCache)) {
+      if (event is ExceptionEvent) {
+        _log.shout("[_queryOnlinePass2] Exception while request (2nd pass)",
+            event.error, event.stackTrace);
+        return pass1Files;
+      }
+      newFiles.addAll(event);
+    }
+    _log.info(
+        "[_queryOnlinePass2] Elapsed time (pass2): ${stopwatch.elapsedMilliseconds}ms");
+    _log.info("[_queryOnlinePass2] Save new touch root etag: $remoteTouchEtag");
+    await touchTokenManager.setLocalRootEtag(account, remoteTouchEtag);
+    return newFiles;
   }
 
   /// Emit all files under this account

lib/pref.dart

@@ -236,6 +236,14 @@ class AccountPref {
       value,
       (key, value) => provider.setBool(key, value));
 
+  String? getTouchRootEtag() => provider.getString(PrefKey.touchRootEtag);
+  String getTouchRootEtagOr([String def = ""]) => getTouchRootEtag() ?? def;
+  Future<bool> setTouchRootEtag(String value) => _set<String>(
+      PrefKey.touchRootEtag,
+      value,
+      (key, value) => provider.setString(key, value));
+  Future<bool> removeTouchRootEtag() => _remove(PrefKey.touchRootEtag);
+
   Future<bool> _set<T>(PrefKey key, T value,
       Future<bool> Function(PrefKey key, T value) setFn) async {
     if (await setFn(key, value)) {
@@ -248,6 +256,8 @@ class AccountPref {
     }
   }
 
+  Future<bool> _remove(PrefKey key) => provider.remove(key);
+
   final PrefProvider provider;
 
   static final _insts = <String, AccountPref>{};
@@ -267,6 +277,7 @@ abstract class PrefProvider {
   List<String>? getStringList(PrefKey key);
   Future<bool> setStringList(PrefKey key, List<String> value);
 
+  Future<bool> remove(PrefKey key);
   Future<bool> clear();
 }
 
@@ -311,6 +322,9 @@ class PrefSharedPreferencesProvider extends PrefProvider {
   setStringList(PrefKey key, List<String> value) =>
       _pref.setStringList(key.toStringKey(), value);
 
+  @override
+  remove(PrefKey key) => _pref.remove(key.toStringKey());
+
   @override
   clear() => _pref.clear();
 
@@ -348,6 +362,14 @@ class PrefUniversalStorageProvider extends PrefProvider {
   @override
   setStringList(PrefKey key, List<String> value) => _set(key, value);
 
+  @override
+  remove(PrefKey key) async {
+    final newData = Map.of(_data)..remove(key.toStringKey());
+    await platform.UniversalStorage().putString(name, jsonEncode(newData));
+    _data.remove(key.toStringKey());
+    return true;
+  }
+
   @override
   clear() async {
     await platform.UniversalStorage().remove(name);
@@ -395,6 +417,12 @@ class PrefMemoryProvider extends PrefProvider {
   @override
   setStringList(PrefKey key, List<String> value) => _set(key, value);
 
+  @override
+  remove(PrefKey key) async {
+    _data.remove(key);
+    return true;
+  }
+
   @override
   clear() async {
     _data.clear();
@@ -439,6 +467,7 @@ enum PrefKey {
   shareFolder,
   hasNewSharedAlbum,
   isEnableMemoryAlbum,
+  touchRootEtag,
 }
 
 extension on PrefKey {
@@ -496,6 +525,8 @@ extension on PrefKey {
         return "hasNewSharedAlbum";
       case PrefKey.isEnableMemoryAlbum:
         return "isEnableMemoryAlbum";
+      case PrefKey.touchRootEtag:
+        return "touchRootEtag";
     }
   }
 }

lib/touch_token_manager.dart

@@ -8,6 +8,7 @@ import 'package:nc_photos/entity/file.dart';
 import 'package:nc_photos/exception.dart';
 import 'package:nc_photos/mobile/platform.dart'
     if (dart.library.html) 'package:nc_photos/web/platform.dart' as platform;
+import 'package:nc_photos/pref.dart';
 import 'package:nc_photos/remote_storage_util.dart' as remote_storage_util;
 import 'package:nc_photos/use_case/get_file_binary.dart';
 import 'package:nc_photos/use_case/put_file_binary.dart';
@@ -24,6 +25,29 @@ import 'package:nc_photos/use_case/remove.dart';
 class TouchTokenManager {
   const TouchTokenManager();
 
+  Future<String?> getRemoteRootEtag(FileRepo fileRepo, Account account) async {
+    try {
+      final touchDir = await fileRepo.listSingle(
+          account, File(path: remote_storage_util.getRemoteTouchDir(account)));
+      return touchDir.etag!;
+    } catch (_) {
+      // dir not found on server
+      return null;
+    }
+  }
+
+  Future<void> setLocalRootEtag(Account account, String? etag) async {
+    if (etag == null) {
+      await AccountPref.of(account).removeTouchRootEtag();
+    } else {
+      await AccountPref.of(account).setTouchRootEtag(etag);
+    }
+  }
+
+  Future<String?> getLocalRootEtag(Account account) async {
+    return AccountPref.of(account).getTouchRootEtag();
+  }
+
   Future<void> setRemoteToken(
       FileRepo fileRepo, Account account, File file, String? token) async {
     _log.info(