Lidarr/src/NzbDrone.Core/MediaFiles/TrackImport/Specifications/AlbumUpgradeSpecification.cs

using System.Linq;
using NLog;
using NzbDrone.Core.DecisionEngine;
using NzbDrone.Core.Download;
using NzbDrone.Core.Parser.Model;
using NzbDrone.Core.Qualities;

namespace NzbDrone.Core.MediaFiles.TrackImport.Specifications
{
    public class AlbumUpgradeSpecification : IImportDecisionEngineSpecification<LocalAlbumRelease>
    {
        private readonly Logger _logger;

        public AlbumUpgradeSpecification(Logger logger)
        {
            _logger = logger;
        }

        public Decision IsSatisfiedBy(LocalAlbumRelease item, DownloadClientItem downloadClientItem)
        {
            // check if we are changing release
            var currentRelease = item.AlbumRelease.Album.Value.AlbumReleases.Value.Single(x => x.Monitored);
            var newRelease = item.AlbumRelease;

            // if we are, check we are upgrading
            if (newRelease.Id != currentRelease.Id)
            {
                var qualityComparer = new QualityModelComparer(item.AlbumRelease.Album.Value.Artist.Value.QualityProfile);

                // min quality of all new tracks
                var newMinQuality = item.LocalTracks.Select(x => x.Quality).OrderBy(x => x, qualityComparer).First();
                _logger.Debug("Min quality of new files: {0}", newMinQuality);

                // get minimum quality of existing release
                var existingQualities = currentRelease.Tracks.Value.Where(x => x.TrackFileId != 0).Select(x => x.TrackFile.Value.Quality);
                if (existingQualities.Any())
                {
                    var existingMinQuality = existingQualities.OrderBy(x => x, qualityComparer).First();
                    _logger.Debug("Min quality of existing files: {0}", existingMinQuality);
                    if (qualityComparer.Compare(existingMinQuality, newMinQuality) > 0)
                    {
                        _logger.Debug("This album isn't a quality upgrade for all tracks. Skipping {0}", item);
                        return Decision.Reject("Not an upgrade for existing album file(s)");
                    }
                }
            }

            return Decision.Accept();
        }
    }
}