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

using System.Linq;
using Musify.Domain.Entities;
using Musify.Domain.ValueObjects;

namespace Musify.Application.Tracks.Responses
{
    public record TrackApplicationResponse(
        Guid Id,
        string Title,
        string? Artist,
        TrackSource Source,
        string? ExternalId,
        ProcessingStatus AudioStatus,
        double Duration,
        int ListensCount,
        long? OwnerUserId,
        DateTime CreatedAt,
        DateTime UpdatedAt)
    {
        public static TrackApplicationResponse FromEntity(Track track, int listensCount) =>
            new(
                track.Id,
                track.Title,
                FormatArtist(track),
                track is ExternalTrack external ? external.Source : TrackSource.Local,
                (track as ExternalTrack)?.ExternalId,
                track.Audio.TranscodeStatus,
                track.DurationSeconds,
                listensCount,
                (track as LocalTrack)?.OwnerUserId,
                track.CreatedAt,
                track.UpdatedAt);

        private static string? FormatArtist(Track track) => track switch
        {
            LocalTrack local => local.Owner.Name,
            ExternalTrack { TrackArtists.Count: > 0 } external =>
                string.Join(", ", external.TrackArtists
                    .OrderBy(trackArtist => trackArtist.Position)
                    .Select(trackArtist => trackArtist.Artist.Name)),
            _ => null
        };
    }
}