Disallow updating album with a newer version

lib/entity/album.dart

@@ -28,6 +28,13 @@ import 'package:tuple/tuple.dart';
 
 /// Immutable object that represents an album
 class Album with EquatableMixin {
+  /// Create a new album
+  ///
+  /// If [lastUpdated] is null, the current time will be used.
+  ///
+  /// [savedVersion] should be null when creating a new album, such that it'll
+  /// be filled with the current version number automatically. You should only
+  /// pass this argument when reading album from storage
   Album({
     DateTime? lastUpdated,
     required this.name,
@@ -36,7 +43,9 @@ class Album with EquatableMixin {
     required this.sortProvider,
     this.shares,
     this.albumFile,
-  }) : lastUpdated = (lastUpdated ?? DateTime.now()).toUtc();
+    int? savedVersion,
+  })  : lastUpdated = (lastUpdated ?? DateTime.now()).toUtc(),
+        savedVersion = savedVersion ?? version;
 
   static Album? fromJson(
     JsonObj json, {
@@ -79,6 +88,17 @@ class Album with EquatableMixin {
         return null;
       }
     }
+    if (jsonVersion < 7) {
+      result = upgraderFactory?.buildV6()?.call(result);
+      if (result == null) {
+        _log.info("[fromJson] Version $jsonVersion not compatible");
+        return null;
+      }
+    }
+    if (jsonVersion > version) {
+      _log.warning(
+          "[fromJson] Reading album with newer version: $jsonVersion > $version");
+    }
     return Album(
       lastUpdated: result["lastUpdated"] == null
           ? null
@@ -96,6 +116,7 @@ class Album with EquatableMixin {
       albumFile: result["albumFile"] == null
           ? null
           : File.fromJson(result["albumFile"].cast<String, dynamic>()),
+      savedVersion: result["version"],
     );
   }
 
@@ -135,6 +156,7 @@ class Album with EquatableMixin {
       sortProvider: sortProvider ?? this.sortProvider,
       shares: shares == null ? this.shares : shares.obj,
       albumFile: albumFile == null ? this.albumFile : albumFile.obj,
+      savedVersion: savedVersion,
     );
   }
 
@@ -173,6 +195,7 @@ class Album with EquatableMixin {
         sortProvider,
         shares,
         albumFile,
+        savedVersion,
       ];
 
   final DateTime lastUpdated;
@@ -188,6 +211,11 @@ class Album with EquatableMixin {
   /// This field is typically only meaningful when returned by [AlbumRepo.get]
   final File? albumFile;
 
+  /// The original version of this class when saved
+  ///
+  /// This field only exists in runtime and are not persisted
+  final int savedVersion;
+
   /// versioning of this class, use to upgrade old persisted album
   static const version = 7;
 }

lib/exception.dart

@@ -89,3 +89,15 @@ class JobCanceledException implements Exception {
 
   final dynamic message;
 }
+
+/// Trying to downgrade an Album
+class AlbumDowngradeException implements Exception {
+  const AlbumDowngradeException([this.message]);
+
+  @override
+  toString() {
+    return "AlbumDowngradeException: $message";
+  }
+
+  final dynamic message;
+}

lib/exception_util.dart

@@ -21,6 +21,8 @@ String toUserString(dynamic exception) {
     return L10n.global().errorDisconnected;
   } else if (exception is InvalidBaseUrlException) {
     return L10n.global().errorInvalidBaseUrl;
+  } else if (exception is AlbumDowngradeException) {
+    return L10n.global().errorAlbumDowngrade;
   }
   return exception.toString();
 }

lib/l10n/app_en.arb

@@ -1099,5 +1099,9 @@
 	"errorServerError": "Server error. Please make sure the server is setup correctly",
 	"@errorServerError": {
 		"description": "HTTP 500"
+	},
+	"errorAlbumDowngrade": "Can't modify this album as it was created by a later version of this app. Please update the app and try again",
+	"@errorAlbumDowngrade": {
+		"description": "Album files are versioned. Overwriting a newer version is disallowed as it will lead to unexpected data loss"
 	}
 }

lib/l10n/untranslated-messages.txt

@@ -48,7 +48,8 @@
     "fixAllTooltip",
     "missingShareDescription",
     "extraShareDescription",
-    "defaultButtonLabel"
+    "defaultButtonLabel",
+    "errorAlbumDowngrade"
   ],
 
   "de": [
@@ -114,7 +115,8 @@
     "fixAllTooltip",
     "missingShareDescription",
     "extraShareDescription",
-    "defaultButtonLabel"
+    "defaultButtonLabel",
+    "errorAlbumDowngrade"
   ],
 
   "el": [
@@ -235,11 +237,13 @@
     "fixAllTooltip",
     "missingShareDescription",
     "extraShareDescription",
-    "defaultButtonLabel"
+    "defaultButtonLabel",
+    "errorAlbumDowngrade"
   ],
 
   "es": [
-    "settingsMapProviderTitle"
+    "settingsMapProviderTitle",
+    "errorAlbumDowngrade"
   ],
 
   "fr": [
@@ -340,7 +344,8 @@
     "fixAllTooltip",
     "missingShareDescription",
     "extraShareDescription",
-    "defaultButtonLabel"
+    "defaultButtonLabel",
+    "errorAlbumDowngrade"
   ],
 
   "ru": [
@@ -414,6 +419,7 @@
     "fixAllTooltip",
     "missingShareDescription",
     "extraShareDescription",
-    "defaultButtonLabel"
+    "defaultButtonLabel",
+    "errorAlbumDowngrade"
   ]
 }

lib/use_case/update_album.dart

@@ -5,11 +5,17 @@ import 'package:nc_photos/entity/album.dart';
 import 'package:nc_photos/entity/album/item.dart';
 import 'package:nc_photos/entity/album/provider.dart';
 import 'package:nc_photos/event/event.dart';
+import 'package:nc_photos/exception.dart';
 
 class UpdateAlbum {
   UpdateAlbum(this.albumRepo);
 
   Future<void> call(Account account, Album album) async {
+    if (album.savedVersion > Album.version) {
+      // the album is created by a newer version of this app
+      throw AlbumDowngradeException(
+          "Not allowed to downgrade album '${album.name}'");
+    }
     final provider = album.provider;
     if (provider is AlbumStaticProvider) {
       await albumRepo.update(