jellyfin/MediaBrowser.TV/Providers/EpisodeProviderFromXml.cs

using System.ComponentModel.Composition;
using System.IO;
using System.Threading.Tasks;
using MediaBrowser.Controller.Events;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.Entities;
using MediaBrowser.TV.Entities;
using MediaBrowser.TV.Metadata;

namespace MediaBrowser.TV.Providers
{
    [Export(typeof(BaseMetadataProvider))]
    public class EpisodeProviderFromXml : BaseMetadataProvider
    {
        public override bool Supports(BaseEntity item)
        {
            return item is Episode;
        }

        public override MetadataProviderPriority Priority
        {
            get { return MetadataProviderPriority.First; }
        }

        public async override Task Fetch(BaseEntity item, ItemResolveEventArgs args)
        {
            await Task.Run(() =>
            {
                string metadataFolder = Path.Combine(args.Parent.Path, "metadata");

                Episode episode = item as Episode;

                string episodeFileName = Path.GetFileName(episode.Path);

                string metadataFile = Path.Combine(metadataFolder, Path.ChangeExtension(episodeFileName, ".xml"));

                FetchMetadata(episode, args.Parent as Season, metadataFile);

            }).ConfigureAwait(false);
        }

        private void FetchMetadata(Episode item, Season season, string metadataFile)
        {
            if (season == null)
            {
                // Episode directly in Series folder
                // Need to validate it the slow way
                if (!File.Exists(metadataFile))
                {
                    return;
                }
            }
            else
            {
                if (!season.ContainsMetadataFile(metadataFile))
                {
                    return;
                }
            }

            new EpisodeXmlParser().Fetch(item, metadataFile);
        }
    }
}