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

using ErrorOr;
using Mediator;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Musify.Application.Albums.Responses;
using Musify.Application.Configuration;
using Musify.Application.Contracts;
using Musify.Application.Events;
using Musify.Application.Pictures;
using Musify.Application.Services;
using Musify.Application.Shared;
using Musify.Domain.ValueObjects;

namespace Musify.Application.Albums
{
    /// <summary>Replaces an album's picture with a previously uploaded image; the plain fields are untouched.</summary>
    public record UpdateAlbumPictureCommand(long UserId, Guid AlbumId, Guid PictureIntentId)
        : ICommand<ErrorOr<AlbumApplicationResponse>>;

    public class UpdateAlbumPictureCommandHandler(
        IEventBus eventBus,
        IDatabase database,
        UploadIntentValidator uploadIntentValidator,
        ILogger<UpdateAlbumPictureCommandHandler> logger,
        AlbumConfiguration albumConfiguration)
        : ICommandHandler<UpdateAlbumPictureCommand, ErrorOr<AlbumApplicationResponse>>
    {
        public async ValueTask<ErrorOr<AlbumApplicationResponse>> Handle(UpdateAlbumPictureCommand request, CancellationToken cancellationToken)
        {
            var found = await database.Albums.FindOwnedAsync(request.AlbumId, request.UserId, cancellationToken);
            if (found.IsError)
                return found.Errors;

            var album = found.Value;

            var prepared = await PictureSourceChange.PrepareAsync(
                uploadIntentValidator, request.PictureIntentId, request.UserId, UploadIntentPurpose.AlbumPicture, albumConfiguration, cancellationToken);
            if (prepared.IsError)
                return prepared.Errors;

            var picture = prepared.Value;
            album.Pictures = picture.Pictures;

            await eventBus.PublishAsync(
                new UpdateAlbumPictureSourceEvent(
                    album.Id, picture.Intent.Id, picture.Intent.Bucket, picture.Intent.Key, picture.FinalKey, picture.Sizes),
                cancellationToken);

            await database.SaveChangesAsync(cancellationToken);

            logger.LogInformation("Updated picture of album {AlbumId}", album.Id);

            return await database.Albums
                .AsNoTracking()
                .Where(a => a.Id == album.Id)
                .SelectResponse()
                .SingleAsync(cancellationToken);
        }
    }
}