[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> UpdateSongs(SetlistDetailsViewModel model)
{
    Console.WriteLine("UpdateSongs POST called.");
    Console.WriteLine($"Received {model.Songs.Count} songs in the form.");

    var userId = _userManager.GetUserId(User);
    var setlist = await _context.Setlists
        .Include(s => s.Songs)
        .FirstOrDefaultAsync(s => s.Id == model.SetlistId && s.UserId == userId);

    if (setlist == null)
        return NotFound();

    // Validate all durations first and store valid ones
    var parsedDurations = new Dictionary<int, TimeSpan>(); // for existing songs (Id != 0)
    var newSongDurations = new List<TimeSpan>(); // for new songs (Id == 0), same order as in model.Songs

    for (int i = 0; i < model.Songs.Count; i++)
    {
        var songVm = model.Songs[i];
        var durationInput = songVm.Duration?.Trim();
        var durationParts = durationInput?.Split(':');

        if (durationParts == null || durationParts.Length != 2 ||
            !int.TryParse(durationParts[0], out int minutes) ||
            !int.TryParse(durationParts[1], out int seconds) ||
            minutes < 0 || seconds < 0 || seconds >= 60 || minutes >= 60)
        {
            ModelState.AddModelError($"Duration-{songVm.Title}", $"Invalid duration for song '{songVm.Title}'. Use mm:ss format.");
        }
        else
        {
            var parsedDuration = new TimeSpan(0, minutes, seconds);
            if (songVm.Id != 0)
            {
                parsedDurations[songVm.Id] = parsedDuration;
            }
            else
            {
                newSongDurations.Add(parsedDuration);
            }
        }
    }

    if (!ModelState.IsValid)
    {
        model.Songs = setlist.Songs.OrderBy(s => s.Order).Select(s => new SetlistDetailsViewModel.SongItem
        {
            Id = s.Id,
            Title = s.Title,
            Duration = s.Duration.Hours > 0 ? s.Duration.ToString(@"hh\:mm\:ss") : s.Duration.ToString(@"mm\:ss"),
            BPM = s.BPM,
            Key = s.Key,
            Order = s.Order
        }).ToList();

        return View("Details", model);
    }

    // Remove deleted songs
    var postedSongIds = model.Songs.Where(s => s.Id != 0).Select(s => s.Id).ToList();
    var songsToRemove = setlist.Songs.Where(s => !postedSongIds.Contains(s.Id)).ToList();
    _context.Songs.RemoveRange(songsToRemove);

    // Add or update songs
    Console.WriteLine($"Received {model.Songs.Count} songs in the form.");
    foreach (var songVm in model.Songs)
    {
        Console.WriteLine($"Song: Id={songVm.Id}, Title='{songVm.Title}', Duration={songVm.Duration}");
    }

    int newSongIndex = 0;
    foreach (var songVm in model.Songs)
    {
        if (songVm.Id != 0)
        {
            // Update existing song
            var existingSong = setlist.Songs.FirstOrDefault(s => s.Id == songVm.Id);
            if (existingSong != null)
            {
                existingSong.Title = songVm.Title;
                existingSong.Duration = parsedDurations[songVm.Id];
                existingSong.BPM = songVm.BPM;
                existingSong.Key = songVm.Key;
                existingSong.Order = songVm.Order;
                existingSong.SetlistId = songVm.SetlistId;
            }
        }
        else
        {
            // Add new song
            if (!string.IsNullOrWhiteSpace(songVm.Title))
            {
                var newSong = new Song
                {
                    Title = songVm.Title,
                    Duration = newSongDurations[newSongIndex],
                    BPM = songVm.BPM,
                    Key = songVm.Key,
                    Order = songVm.Order,
                    UserId = userId,
                    SetlistId = setlist.Id
                };
                _context.Songs.Add(newSong);
                newSongIndex++;
            }
        }
    }

    await _context.SaveChangesAsync();

    var debugSongs = await _context.Songs.Where(s => s.SetlistId == setlist.Id).ToListAsync();
    Console.WriteLine($"Setlist has {debugSongs.Count} songs after saving.");

    return RedirectToAction("Details", new { id = setlist.Id });
}