Regression: album cover is gone after unsetting one for a dynamic album

app/lib/controller/collection_items_controller.dart

@@ -76,6 +76,9 @@ class CollectionItemsController {
     return _dataStreamController.stream;
   }
 
+  /// Peek the stream and return the current value
+  CollectionItemStreamData peekStream() => _dataStreamController.stream.value;
+
   /// Add list of [files] to [collection]
   Future<void> addFiles(List<FileDescriptor> files) async {
     final isInited = _isDataStreamInited;

app/lib/controller/collections_controller.dart

@@ -1,5 +1,6 @@
 import 'dart:async';
 
+import 'package:collection/collection.dart';
 import 'package:copy_with/copy_with.dart';
 import 'package:logging/logging.dart';
 import 'package:mutex/mutex.dart';
@@ -163,6 +164,9 @@ class CollectionsController {
   }) async {
     try {
       final c = await _mutex.protect(() async {
+        final found = _dataStreamController.value.data.firstWhereOrNull(
+            (ev) => ev.collection.compareIdentity(collection));
+        final item = found?.controller.peekStream();
         return await EditCollection(_c)(
           account,
           collection,
@@ -170,6 +174,7 @@ class CollectionsController {
           items: items,
           itemSort: itemSort,
           cover: cover,
+          knownItems: (item?.items.isEmpty ?? true) ? null : item!.items,
         );
       });
       _updateCollection(c, items);

app/lib/entity/album/cover_provider.dart

@@ -77,26 +77,25 @@ class AlbumAutoCoverProvider extends AlbumCoverProvider {
     );
   }
 
+  static FileDescriptor? getCoverByItems(List<AlbumItem> items) {
+    return items
+        .whereType<AlbumFileItem>()
+        .map((e) => e.file)
+        .where((element) =>
+            file_util.isSupportedFormat(element) &&
+            (element.hasPreview ?? false))
+        .sorted(compareFileDateTimeDescending)
+        .firstOrNull;
+  }
+
   @override
   String toString() => _$toString();
 
   @override
   FileDescriptor? getCover(Album album) {
     if (coverFile == null) {
-      try {
+      // use the latest file as cover
-        // use the latest file as cover
+      return getCoverByItems(AlbumStaticProvider.of(album).items);
-        return AlbumStaticProvider.of(album)
-            .items
-            .whereType<AlbumFileItem>()
-            .map((e) => e.file)
-            .where((element) =>
-                file_util.isSupportedFormat(element) &&
-                (element.hasPreview ?? false))
-            .sorted(compareFileDateTimeDescending)
-            .first;
-      } catch (_) {
-        return null;
-      }
     } else {
       return coverFile;
     }

app/lib/entity/collection/adapter.dart

@@ -57,6 +57,7 @@ abstract class CollectionAdapter {
     List<CollectionItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<CollectionItem>? knownItems,
   });
 
   /// Remove [items] from this collection and return the removed count

app/lib/entity/collection/adapter/album.dart

@@ -79,6 +79,7 @@ class CollectionAlbumAdapter implements CollectionAdapter {
     List<CollectionItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<CollectionItem>? knownItems,
   }) async {
     assert(name != null || items != null || itemSort != null || cover != null);
     final newItems = items?.run((items) => items
@@ -106,6 +107,10 @@ class CollectionAlbumAdapter implements CollectionAdapter {
       items: newItems,
       itemSort: itemSort,
       cover: cover,
+      knownItems: knownItems
+          ?.whereType<AlbumAdaptedCollectionItem>()
+          .map((e) => e.albumItem)
+          .toList(),
     );
     return collection.copyWith(
       name: name,

app/lib/entity/collection/adapter/nc_album.dart

@@ -77,6 +77,7 @@ class CollectionNcAlbumAdapter implements CollectionAdapter {
     List<CollectionItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<CollectionItem>? knownItems,
   }) async {
     assert(name != null);
     if (items != null || itemSort != null || cover != null) {

app/lib/entity/collection/adapter/read_only_adapter.dart

@@ -24,6 +24,7 @@ mixin CollectionReadOnlyAdapter implements CollectionAdapter {
     List<CollectionItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<CollectionItem>? knownItems,
   }) {
     throw UnsupportedError("Operation not supported");
   }

app/lib/use_case/album/edit_album.dart

@@ -26,6 +26,7 @@ class EditAlbum {
     List<AlbumItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<AlbumItem>? knownItems,
   }) async {
     _log.info(
         "[call] Edit album ${album.name}, name: $name, items: $items, itemSort: $itemSort, cover: $cover");
@@ -49,8 +50,9 @@ class EditAlbum {
     }
     if (cover != null) {
       if (cover.obj == null) {
+        final coverFile = _getCoverFile(knownItems);
         newAlbum = newAlbum.copyWith(
-          coverProvider: const AlbumAutoCoverProvider(),
+          coverProvider: AlbumAutoCoverProvider(coverFile: coverFile),
         );
       } else {
         newAlbum = newAlbum.copyWith(
@@ -65,5 +67,13 @@ class EditAlbum {
     return newAlbum;
   }
 
+  FileDescriptor? _getCoverFile(List<AlbumItem>? items) {
+    if (items?.isEmpty ?? true) {
+      return null;
+    } else {
+      return AlbumAutoCoverProvider.getCoverByItems(items!);
+    }
+  }
+
   final DiContainer _c;
 }

app/lib/use_case/collection/edit_collection.dart

@@ -19,6 +19,11 @@ class EditCollection {
   /// - Sort [items] (set [items] and/or [itemSort])
   /// - Set album [cover]
   ///
+  /// Optionally you may provide a list of known collection items. If
+  /// [knownItems] is not null, it may be used as a hint for the implementors
+  /// when updating the underlying collection (e.g., setting the latest item as
+  /// cover image)
+  ///
   /// \* To add files to a collection, use [AddFileToCollection] instead
   Future<Collection> call(
     Account account,
@@ -27,12 +32,14 @@ class EditCollection {
     List<CollectionItem>? items,
     CollectionItemSort? itemSort,
     OrNull<FileDescriptor>? cover,
+    List<CollectionItem>? knownItems,
   }) =>
       CollectionAdapter.of(_c, account, collection).edit(
         name: name,
         items: items,
         itemSort: itemSort,
         cover: cover,
+        knownItems: knownItems,
       );
 
   final DiContainer _c;