Implemented tag refresh on a playlist. Made audio file scanning truly asynchronous. Added basic playlist sorting functionality.

Harmonia.Core/Playlists/Playlist.cs

@@ -164,6 +164,8 @@ public class Playlist
 
     public void ImportTags(Song[] songs)
     {
+        List<PlaylistSong> updatedPlaylistSongs = [];
+
         foreach (Song song in songs)
         {
             PlaylistSong[] playlistSongs = [.. Songs.Where(playlistSong =>
@@ -171,10 +173,24 @@ public class Playlist
 
             foreach (PlaylistSong playlistSong in playlistSongs)
             {
-                //playlistSong.Song = song;
-                //playlistSong.Song.Update(song);
+                playlistSong.Song.Update(song);
             }
+
+            updatedPlaylistSongs.AddRange(playlistSongs);
         }
+
+        if (updatedPlaylistSongs.Count == 0)
+            return;
+
+        PlaylistUpdatedEventArgs eventArgs = new()
+        {
+            Action = PlaylistUpdateAction.Refresh,
+            Index = -1,
+            Count = updatedPlaylistSongs.Count,
+            Songs = [.. updatedPlaylistSongs]
+        };
+
+        PlaylistUpdated?.Invoke(this, eventArgs);
     }
 
     public void RemoveMissingSongs()

Harmonia.Core/Playlists/PlaylistUpdateAction.cs

@@ -17,5 +17,9 @@ public enum PlaylistUpdateAction
     /// <summary>
     /// The contents of the collection changed dramatically.
     /// </summary>
-    Reset
+    Reset,
+    /// <summary>
+    /// The tags of the songs in the collection were refreshed.
+    /// </summary>
+    Refresh
 }

Harmonia.Core/Scanner/AudioFileScanner.cs

@@ -9,22 +9,19 @@ public class AudioFileScanner(IAudioEngine audioEngine, ITagResolver tagResolver
 {
     public async Task<Song[]> GetSongsAsync(string[] fileNames, CancellationToken cancellationToken)
     {
-        List<Song> songs = [];
+        Song?[] songs = new Song?[fileNames.Length];
 
-        foreach (string fileName in fileNames)
+        await Parallel.ForEachAsync(Enumerable.Range(0, fileNames.Length), cancellationToken, async (index, token) =>
         {
+            string fileName = fileNames[index];
+
             if (string.IsNullOrWhiteSpace(fileName) || File.Exists(fileName) == false)
-                continue;
+                return;
 
-            Song? song = await GetSongAsync(fileName, cancellationToken);
+            songs[index] = await GetSongAsync(fileName, token);
+        });
 
-            if (song == null)
-                continue;
-
-            songs.Add(song);
-        }
-
-        return [.. songs];
+        return [.. songs.Where(song => song != null)!];
     }
 
     private async Task<Song> GetSongAsync(string fileName, CancellationToken cancellationToken)