feat(backend): add the album use cases

Create, update, delete and list albums, plus adding and removing their tracks, mirroring the playlist handlers. Only tracks the user uploaded can go into an album, and removing one renumbers the rest so the tracklist stays 1..n.
2026-07-20 20:10:45 +02:00
parent 67805062ca
commit 69468c9dbd
10 changed files with 518 additions and 0 deletions
@@ -0,0 +1,59 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+
+namespace Musify.Application.Albums
+{
+    public record RemoveTrackFromAlbumCommand(long UserId, Guid AlbumId, Guid TrackId)
+        : ICommand<ErrorOr<Success>>;
+
+    public class RemoveTrackFromAlbumCommandHandler(
+        IDatabase database,
+        ILogger<RemoveTrackFromAlbumCommandHandler> logger)
+        : ICommandHandler<RemoveTrackFromAlbumCommand, ErrorOr<Success>>
+    {
+        public async ValueTask<ErrorOr<Success>> Handle(RemoveTrackFromAlbumCommand request, CancellationToken cancellationToken)
+        {
+            var album = await database.UserAlbums
+                .AsNoTracking()
+                .SingleOrDefaultAsync(a => a.Id == request.AlbumId, cancellationToken);
+            if (album is null)
+            {
+                logger.LogInformation("Album {AlbumId} not found", request.AlbumId);
+                return Error.NotFound();
+            }
+
+            if (album.OwnerUserId != request.UserId)
+            {
+                logger.LogWarning("User {UserId} is not the owner of album {AlbumId}", request.UserId, request.AlbumId);
+                return Error.Unauthorized();
+            }
+
+            var albumTracks = await database.AlbumHasTracks
+                .Where(albumTrack => albumTrack.AlbumId == request.AlbumId)
+                .OrderBy(albumTrack => albumTrack.TrackNumber)
+                .ToListAsync(cancellationToken);
+
+            var link = albumTracks.SingleOrDefault(albumTrack => albumTrack.TrackId == request.TrackId);
+            if (link is null)
+            {
+                logger.LogInformation("Track {TrackId} not in album {AlbumId}", request.TrackId, request.AlbumId);
+                return Error.NotFound(description: "Track is not in the album.");
+            }
+
+            database.AlbumHasTracks.Remove(link);
+
+            var trackNumber = 1;
+            foreach (var remaining in albumTracks.Where(albumTrack => albumTrack.Id != link.Id))
+                remaining.TrackNumber = trackNumber++;
+
+            await database.SaveChangesAsync(cancellationToken);
+
+            logger.LogInformation("Removed track {TrackId} from album {AlbumId}", request.TrackId, request.AlbumId);
+
+            return new Success();
+        }
+    }
+}