feat(mobile): show local assets (#905)

* introduce Asset as composition of AssetResponseDTO and AssetEntity

* filter out duplicate assets (that are both local and remote, take only remote for now)

* only allow remote images to be added to albums

* introduce ImmichImage to render Asset using local or remote data

* optimized deletion of local assets

* local video file playback

* allow multiple methods to wait on background service finished

* skip local assets when adding to album from home screen

* fix and optimize delete

* show gray box placeholder for local assets

* add comments

* fix bug: duplicate assets in state after onNewAssetUploaded

mobile/lib/shared/models/asset.dart

@@ -0,0 +1,117 @@
+import 'package:hive/hive.dart';
+import 'package:immich_mobile/constants/hive_box.dart';
+import 'package:openapi/api.dart';
+import 'package:photo_manager/photo_manager.dart';
+
+/// Asset (online or local)
+class Asset {
+  Asset.remote(this.remote) {
+    local = null;
+  }
+
+  Asset.local(this.local) {
+    remote = null;
+  }
+
+  late final AssetResponseDto? remote;
+  late final AssetEntity? local;
+
+  bool get isRemote => remote != null;
+  bool get isLocal => local != null;
+
+  String get deviceId =>
+      isRemote ? remote!.deviceId : Hive.box(userInfoBox).get(deviceIdKey);
+
+  String get deviceAssetId => isRemote ? remote!.deviceAssetId : local!.id;
+
+  String get id => isLocal ? local!.id : remote!.id;
+
+  double? get latitude =>
+      isLocal ? local!.latitude : remote!.exifInfo?.latitude?.toDouble();
+
+  double? get longitude =>
+      isLocal ? local!.longitude : remote!.exifInfo?.longitude?.toDouble();
+
+  DateTime get createdAt =>
+      isLocal ? local!.createDateTime : DateTime.parse(remote!.createdAt);
+
+  bool get isImage => isLocal
+      ? local!.type == AssetType.image
+      : remote!.type == AssetTypeEnum.IMAGE;
+
+  String get duration => isRemote
+      ? remote!.duration
+      : Duration(seconds: local!.duration).toString();
+
+  /// use only for tests
+  set createdAt(DateTime val) {
+    if (isRemote) {
+      remote!.createdAt = val.toIso8601String();
+    }
+  }
+
+  Map<String, dynamic> toJson() {
+    final json = <String, dynamic>{};
+    if (isLocal) {
+      json["local"] = _assetEntityToJson(local!);
+    } else {
+      json["remote"] = remote!.toJson();
+    }
+    return json;
+  }
+
+  static Asset? fromJson(dynamic value) {
+    if (value is Map) {
+      final json = value.cast<String, dynamic>();
+      final l = json["local"];
+      if (l != null) {
+        return Asset.local(_assetEntityFromJson(l));
+      } else {
+        return Asset.remote(AssetResponseDto.fromJson(json["remote"]));
+      }
+    }
+    return null;
+  }
+}
+
+Map<String, dynamic> _assetEntityToJson(AssetEntity a) {
+  final json = <String, dynamic>{};
+  json["id"] = a.id;
+  json["typeInt"] = a.typeInt;
+  json["width"] = a.width;
+  json["height"] = a.height;
+  json["duration"] = a.duration;
+  json["orientation"] = a.orientation;
+  json["isFavorite"] = a.isFavorite;
+  json["title"] = a.title;
+  json["createDateSecond"] = a.createDateSecond;
+  json["modifiedDateSecond"] = a.modifiedDateSecond;
+  json["latitude"] = a.latitude;
+  json["longitude"] = a.longitude;
+  json["mimeType"] = a.mimeType;
+  json["subtype"] = a.subtype;
+  return json;
+}
+
+AssetEntity? _assetEntityFromJson(dynamic value) {
+  if (value is Map) {
+    final json = value.cast<String, dynamic>();
+    return AssetEntity(
+      id: json["id"],
+      typeInt: json["typeInt"],
+      width: json["width"],
+      height: json["height"],
+      duration: json["duration"],
+      orientation: json["orientation"],
+      isFavorite: json["isFavorite"],
+      title: json["title"],
+      createDateSecond: json["createDateSecond"],
+      modifiedDateSecond: json["modifiedDateSecond"],
+      latitude: json["latitude"],
+      longitude: json["longitude"],
+      mimeType: json["mimeType"],
+      subtype: json["subtype"],
+    );
+  }
+  return null;
+}