Add track status filter and counts, album track ids and bulk track deletion

GET /tracks/users/{userId} accepts repeated status values and returns the
albums each track belongs to. GET /tracks/users/{userId}/status-counts,
GET /albums/{id}/tracks/ids and DELETE /tracks with a list of track ids
are new.

backend/Core/Musify.Application/Albums/GetAlbumTrackIds.cs

@@ -0,0 +1,35 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Albums.Responses;
+using Musify.Application.Contracts;
+using Musify.Application.Shared;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Albums
+{
+    public record GetAlbumTrackIdsQuery(long UserId, Guid AlbumId)
+        : IQuery<ErrorOr<AlbumTrackIdsResponse>>;
+
+    public class GetAlbumTrackIdsQueryHandler(IDatabase database)
+        : IQueryHandler<GetAlbumTrackIdsQuery, ErrorOr<AlbumTrackIdsResponse>>
+    {
+        public async ValueTask<ErrorOr<AlbumTrackIdsResponse>> Handle(GetAlbumTrackIdsQuery request, CancellationToken cancellationToken)
+        {
+            var found = await database.Albums.FindOwnedAsync(request.AlbumId, request.UserId, cancellationToken);
+            if (found.IsError)
+                return found.Errors;
+
+            var trackIds = await database.AlbumHasTracks
+                .AsNoTracking()
+                .Where(albumTrack => albumTrack.AlbumId == request.AlbumId
+                    && albumTrack.Track.LifeCycleStatus == LifeCycleStatus.Active)
+                .OrderBy(albumTrack => albumTrack.TrackNumber)
+                .ThenBy(albumTrack => albumTrack.Id)
+                .Select(albumTrack => albumTrack.TrackId)
+                .ToListAsync(cancellationToken);
+
+            return new AlbumTrackIdsResponse(trackIds);
+        }
+    }
+}

backend/Core/Musify.Application/Albums/Responses/AlbumTrackIdsResponse.cs

@@ -0,0 +1,4 @@
+namespace Musify.Application.Albums.Responses
+{
+    public record AlbumTrackIdsResponse(IReadOnlyList<Guid> TrackIds);
+}

backend/Core/Musify.Application/Tracks/DeleteTracks.cs

@@ -0,0 +1,60 @@
+using ErrorOr;
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Microsoft.Extensions.Logging;
+using Musify.Application.Contracts;
+using Musify.Application.Events;
+using Musify.Application.Shared;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Tracks
+{
+    public record DeleteTracksCommand(long UserId, IReadOnlyList<Guid> TrackIds)
+        : ICommand<ErrorOr<DeleteTracksResponse>>;
+
+    public class DeleteTracksCommandHandler(
+        IDatabase database,
+        IEventBus eventBus,
+        ILogger<DeleteTracksCommandHandler> logger)
+        : ICommandHandler<DeleteTracksCommand, ErrorOr<DeleteTracksResponse>>
+    {
+        public async ValueTask<ErrorOr<DeleteTracksResponse>> Handle(DeleteTracksCommand request, CancellationToken cancellationToken)
+        {
+            var requestedIds = request.TrackIds.Distinct().ToList();
+
+            var tracks = await database.Tracks
+                .Where(track => requestedIds.Contains(track.Id) && track.LifeCycleStatus == LifeCycleStatus.Active)
+                .ToListAsync(cancellationToken);
+
+            var foreign = tracks.FirstOrDefault(track => track.OwnerUserId != request.UserId);
+            if (foreign != null)
+                return AppErrors.Forbidden("Track", foreign.Id);
+
+            var deleted = new List<Guid>();
+            var failed = new List<Guid>();
+
+            foreach (var trackId in requestedIds)
+            {
+                var track = tracks.SingleOrDefault(candidate => candidate.Id == trackId);
+                if (track == null || track.Audio.IsInProgress)
+                {
+                    failed.Add(trackId);
+                    continue;
+                }
+
+                track.LifeCycleStatus = LifeCycleStatus.Removing;
+                await eventBus.PublishAsync(new DeleteTrackEvent(track.Id, request.UserId), cancellationToken);
+                deleted.Add(trackId);
+            }
+
+            if (deleted.Count > 0)
+            {
+                await database.SaveChangesAsync(cancellationToken);
+                logger.LogInformation("Marked {Count} tracks of user {UserId} as removing", deleted.Count, request.UserId);
+            }
+
+            return new DeleteTracksResponse(deleted, failed);
+        }
+    }
+}

backend/Core/Musify.Application/Tracks/GetTrackStatusCounts.cs

@@ -0,0 +1,35 @@
+using Mediator;
+using Microsoft.EntityFrameworkCore;
+using Musify.Application.Contracts;
+using Musify.Application.Tracks.Responses;
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Tracks
+{
+    public record GetTrackStatusCountsQuery(long UserId)
+        : IQuery<TrackStatusCountsResponse>;
+
+    public class GetTrackStatusCountsQueryHandler(IDatabase database)
+        : IQueryHandler<GetTrackStatusCountsQuery, TrackStatusCountsResponse>
+    {
+        public async ValueTask<TrackStatusCountsResponse> Handle(GetTrackStatusCountsQuery request, CancellationToken cancellationToken)
+        {
+            var counts = await database.Tracks
+                .AsNoTracking()
+                .Active()
+                .Where(track => track.OwnerUserId == request.UserId)
+                .GroupBy(track => track.Audio.TranscodeStatus)
+                .Select(group => new { Status = group.Key, Count = group.Count() })
+                .ToListAsync(cancellationToken);
+
+            int CountOf(ProcessingStatus status) => counts.Where(c => c.Status == status).Sum(c => c.Count);
+
+            return new TrackStatusCountsResponse(
+                counts.Sum(c => c.Count),
+                CountOf(ProcessingStatus.Pending),
+                CountOf(ProcessingStatus.Processing),
+                CountOf(ProcessingStatus.Completed),
+                CountOf(ProcessingStatus.Failed));
+        }
+    }
+}

backend/Core/Musify.Application/Tracks/GetTracksByUserId.cs

@@ -4,6 +4,7 @@ using Microsoft.EntityFrameworkCore;
 using Musify.Application.Contracts;
 using Musify.Application.Shared;
 using Musify.Application.Tracks.Responses;
+using Musify.Domain.ValueObjects;
 
 namespace Musify.Application.Tracks
 {
@@ -11,13 +12,14 @@ namespace Musify.Application.Tracks
         long UserId,
         string? Name,
         int PageNumber,
-        int PageSize)
-        : IQuery<ErrorOr<PaginatedResponse<TrackApplicationResponse>>>;
+        int PageSize,
+        IReadOnlyList<ProcessingStatus>? Statuses = null)
+        : IQuery<ErrorOr<PaginatedResponse<UserTrackApplicationResponse>>>;
 
     public class GetTracksByUserIdQueryHandler(IDatabase database)
-        : IQueryHandler<GetTracksByUserIdQuery, ErrorOr<PaginatedResponse<TrackApplicationResponse>>>
+        : IQueryHandler<GetTracksByUserIdQuery, ErrorOr<PaginatedResponse<UserTrackApplicationResponse>>>
     {
-        public async ValueTask<ErrorOr<PaginatedResponse<TrackApplicationResponse>>> Handle(GetTracksByUserIdQuery request, CancellationToken cancellationToken)
+        public async ValueTask<ErrorOr<PaginatedResponse<UserTrackApplicationResponse>>> Handle(GetTracksByUserIdQuery request, CancellationToken cancellationToken)
         {
             var tracksQuery = database.Tracks
                 .AsNoTracking()
@@ -30,10 +32,16 @@ namespace Musify.Application.Tracks
                 tracksQuery = tracksQuery.Where(track => track.NormalizedTitle.Contains(normalizedName));
             }
 
+            if (request.Statuses is { Count: > 0 } statuses)
+            {
+                var statusList = statuses.Distinct().ToList();
+                tracksQuery = tracksQuery.Where(track => statusList.Contains(track.Audio.TranscodeStatus));
+            }
+
             return await tracksQuery
                 .OrderByDescending(track => track.CreatedAt)
                 .ThenBy(track => track.Id)
-                .SelectResponse()
+                .SelectUserResponse()
                 .ToPaginatedAsync(new PageRequest(request.PageNumber, request.PageSize), cancellationToken);
         }
     }

backend/Core/Musify.Application/Tracks/Responses/DeleteTracksResponse.cs

@@ -0,0 +1,6 @@
+namespace Musify.Application.Tracks.Responses
+{
+    public record DeleteTracksResponse(
+        IReadOnlyList<Guid> DeletedTrackIds,
+        IReadOnlyList<Guid> FailedTrackIds);
+}

backend/Core/Musify.Application/Tracks/Responses/TrackProjections.cs

@@ -21,5 +21,25 @@ namespace Musify.Application.Tracks.Responses
                 track.OwnerUserId,
                 track.Tags.Select(tag => tag.Tag).ToList(),
                 track.IsExplicit));
+
+        public static IQueryable<UserTrackApplicationResponse> SelectUserResponse(this IQueryable<Track> query) =>
+            query.Select(track => new UserTrackApplicationResponse(
+                track.Id,
+                track.Title,
+                track.Owner.Name,
+                track.Audio.TranscodeStatus,
+                track.DurationSeconds,
+                track.ListeningHistories.Count(listen => listen.IsCounted),
+                track.CreatedAt,
+                track.UpdatedAt,
+                track.OwnerUserId,
+                track.Tags.Select(tag => tag.Tag).ToList(),
+                track.IsExplicit,
+                track.AlbumTracks
+                    .Where(albumTrack => albumTrack.Album.LifeCycleStatus == LifeCycleStatus.Active)
+                    .OrderBy(albumTrack => albumTrack.AddedAt)
+                    .ThenBy(albumTrack => albumTrack.AlbumId)
+                    .Select(albumTrack => new TrackAlbumReference(albumTrack.AlbumId, albumTrack.Album.Title))
+                    .ToList()));
     }
 }

backend/Core/Musify.Application/Tracks/Responses/TrackStatusCountsResponse.cs

@@ -0,0 +1,9 @@
+namespace Musify.Application.Tracks.Responses
+{
+    public record TrackStatusCountsResponse(
+        int Total,
+        int Pending,
+        int Processing,
+        int Completed,
+        int Failed);
+}

backend/Core/Musify.Application/Tracks/Responses/UserTrackApplicationResponse.cs

@@ -0,0 +1,20 @@
+using Musify.Domain.ValueObjects;
+
+namespace Musify.Application.Tracks.Responses
+{
+    public record TrackAlbumReference(Guid Id, string Title);
+
+    public record UserTrackApplicationResponse(
+        Guid Id,
+        string Title,
+        string? Artist,
+        ProcessingStatus AudioStatus,
+        double Duration,
+        int ListensCount,
+        DateTime CreatedAt,
+        DateTime UpdatedAt,
+        long OwnerUserId,
+        IReadOnlyCollection<Genre> Tags,
+        bool IsExplicit,
+        IReadOnlyList<TrackAlbumReference> Albums);
+}