updates

lib/playlists/playlists.dart

@@ -5,12 +5,25 @@
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:collection/collection.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:path_provider/path_provider.dart';
 
 import '../subsonic/models.dart';
 import '../subsonic/subsonic_client.dart';
 
+/// Marker stored in a playlist's `comment` to flag it as a Timbre **tag** — a
+/// playlist surfaced under the Tags UI instead of Playlists. Kept out of the
+/// visible name so tags read cleanly everywhere (including other Subsonic
+/// clients, where they still appear as ordinary playlists).
+///
+/// Classification relies on `getPlaylists` returning the `comment` field;
+/// Navidrome does. A server that omitted it would show tags as plain playlists.
+const String kTagMarker = 'timbre:tag';
+
+/// Whether [p] is a Timbre tag (vs a user-facing playlist).
+bool isTagPlaylist(Playlist p) => p.comment == kTagMarker;
+
 /// Playlists snapshot: the summaries (from `getPlaylists`) plus any full details
 /// that have been opened. Details are cached so an opened playlist keeps working
 /// offline.
@@ -185,6 +198,87 @@ class PlaylistsController extends StateNotifier<PlaylistsState> {
     }
   }
 
+  // ---- Tags ---------------------------------------------------------------
+  // A tag is just a playlist whose `comment` carries [kTagMarker]. These reuse
+  // the playlist mutations above; only creation and membership need tag-aware
+  // behaviour (marker stamping + de-duplication).
+
+  /// Create a tag named [name], or return the id of an existing tag with that
+  /// name (case-insensitive) so tags stay unique. `createPlaylist` can't set a
+  /// comment inline, so we create then stamp the marker — and if stamping fails
+  /// we delete the orphan rather than leave an unmarked playlist behind.
+  Future<String?> createTag(String name) async {
+    final client = _clientGetter();
+    if (client == null) return null;
+
+    final existing = state.playlists.firstWhereOrNull(
+      (p) => isTagPlaylist(p) && p.name.toLowerCase() == name.toLowerCase(),
+    );
+    if (existing != null) return existing.id;
+
+    final id = await create(name);
+    if (id == null) return null;
+    try {
+      await client.setPlaylistComment(id, kTagMarker);
+    } catch (_) {
+      await delete(id); // don't strand a nameless, unmarked playlist
+      return null;
+    }
+    _applyComment(id, kTagMarker);
+    await _persist();
+    return id;
+  }
+
+  /// Add [songs] to a tag, skipping any already present. Playlists allow
+  /// duplicates but a tag is a set — re-tagging a song must be idempotent, so we
+  /// load current membership first and only append the new ids.
+  Future<void> addToTag(String tagId, List<Song> songs) async {
+    if (songs.isEmpty) return;
+    final detail = await loadDetail(tagId);
+    final present = {for (final s in detail?.songs ?? const <Song>[]) s.id};
+    final fresh = songs.where((s) => !present.contains(s.id)).toList();
+    if (fresh.isEmpty) return;
+    await addTracks(tagId, fresh);
+  }
+
+  /// Patch the cached summary + detail for [id] with [comment] (used right after
+  /// stamping a new tag's marker so it partitions into the Tags view at once).
+  void _applyComment(String id, String comment) {
+    state = state.copyWith(
+      playlists: [
+        for (final p in state.playlists)
+          if (p.id == id) _withComment(p, comment) else p,
+      ],
+      details: {
+        for (final e in state.details.entries)
+          e.key: e.key == id ? _detailWithComment(e.value, comment) : e.value,
+      },
+    );
+  }
+
+  static Playlist _withComment(Playlist p, String comment) => Playlist(
+        id: p.id,
+        name: p.name,
+        songCount: p.songCount,
+        duration: p.duration,
+        owner: p.owner,
+        public: p.public,
+        coverArt: p.coverArt,
+        comment: comment,
+      );
+
+  static PlaylistDetail _detailWithComment(
+          PlaylistDetail d, String comment) =>
+      PlaylistDetail(
+        id: d.id,
+        name: d.name,
+        songCount: d.songCount,
+        duration: d.duration,
+        coverArt: d.coverArt,
+        comment: comment,
+        songs: d.songs,
+      );
+
   Future<void> rename(String id, String name) async {
     final client = _clientGetter();
     if (client == null) return;
@@ -280,6 +374,7 @@ class PlaylistsController extends StateNotifier<PlaylistsState> {
             owner: p.owner,
             public: p.public,
             coverArt: p.coverArt,
+            comment: p.comment,
           )
         else
           p,
@@ -294,6 +389,7 @@ class PlaylistsController extends StateNotifier<PlaylistsState> {
         owner: p.owner,
         public: p.public,
         coverArt: p.coverArt,
+        comment: p.comment,
       );
 
   static PlaylistDetail _renamedDetail(PlaylistDetail d, String name) =>
@@ -303,6 +399,7 @@ class PlaylistsController extends StateNotifier<PlaylistsState> {
         songCount: d.songCount,
         duration: d.duration,
         coverArt: d.coverArt,
+        comment: d.comment,
         songs: d.songs,
       );
 
@@ -313,6 +410,7 @@ class PlaylistsController extends StateNotifier<PlaylistsState> {
         songCount: songs.length,
         duration: d.duration,
         coverArt: d.coverArt,
+        comment: d.comment,
         songs: songs,
       );