using System.Globalization;
using Bugsnag;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Interfaces.Repositories.Caching;
using ErsatzTV.Core.Interfaces.Search;
using ErsatzTV.Core.Search;
using ErsatzTV.FFmpeg;
using ErsatzTV.FFmpeg.Format;
using LanguageExt.UnsafeValueAccess;
using Lucene.Net.Analysis;
using Lucene.Net.Documents;
using Lucene.Net.Index;
using Lucene.Net.Sandbox.Queries;
using Lucene.Net.Search;
using Lucene.Net.Store;
using Lucene.Net.Util;
using Microsoft.Extensions.Logging;
using Directory = System.IO.Directory;
using MediaStream = ErsatzTV.Core.Domain.MediaStream;
using Query = Lucene.Net.Search.Query;

namespace ErsatzTV.Infrastructure.Search;

public sealed class LuceneSearchIndex : ISearchIndex
{
    internal const LuceneVersion AppLuceneVersion = LuceneVersion.LUCENE_48;

    internal const string IdField = "id";
    internal const string TypeField = "type";
    internal const string TitleField = "title";
    internal const string SortTitleField = "sort_title";
    internal const string GenreField = "genre";
    internal const string TagField = "tag";
    internal const string TagFullField = "tag_full";
    internal const string PlotField = "plot";
    internal const string LibraryNameField = "library_name";
    internal const string LibraryIdField = "library_id";
    internal const string LibraryFolderIdField = "library_folder_id";
    internal const string TitleAndYearField = "title_and_year";
    internal const string JumpLetterField = "jump_letter";
    internal const string StudioField = "studio";
    internal const string LanguageField = "language";
    internal const string LanguageTagField = "language_tag";
    internal const string SubLanguageField = "sub_language";
    internal const string SubLanguageTagField = "sub_language_tag";
    internal const string StyleField = "style";
    internal const string MoodField = "mood";
    internal const string ActorField = "actor";
    internal const string ContentRatingField = "content_rating";
    internal const string DirectorField = "director";
    internal const string WriterField = "writer";
    internal const string TraktListField = "trakt_list";
    internal const string AlbumField = "album";
    internal const string ArtistField = "artist";
    internal const string StateField = "state";
    internal const string AlbumArtistField = "album_artist";
    internal const string ShowTitleField = "show_title";
    internal const string ShowGenreField = "show_genre";
    internal const string ShowTagField = "show_tag";
    internal const string ShowStudioField = "show_studio";
    internal const string ShowContentRatingField = "show_content_rating";
    internal const string MetadataKindField = "metadata_kind";
    internal const string VideoCodecField = "video_codec";
    internal const string VideoDynamicRange = "video_dynamic_range";

    internal const string MinutesField = "minutes";
    internal const string SecondsField = "seconds";
    internal const string HeightField = "height";
    internal const string WidthField = "width";
    internal const string SeasonNumberField = "season_number";
    internal const string EpisodeNumberField = "episode_number";
    internal const string AddedDateField = "added_date";
    internal const string ReleaseDateField = "release_date";
    internal const string VideoBitDepthField = "video_bit_depth";

    public const string MovieType = "movie";
    public const string ShowType = "show";
    public const string SeasonType = "season";
    public const string ArtistType = "artist";
    public const string MusicVideoType = "music_video";
    public const string EpisodeType = "episode";
    public const string OtherVideoType = "other_video";
    public const string SongType = "song";
    public const string ImageType = "image";
    private readonly string _cleanShutdownPath;

    private readonly List<CultureInfo> _cultureInfos;

    private readonly ILogger<LuceneSearchIndex> _logger;

    private FSDirectory _directory;
    private bool _initialized;
    private IndexWriter _writer;

    public LuceneSearchIndex(ILogger<LuceneSearchIndex> logger)
    {
        _logger = logger;
        _cultureInfos = CultureInfo.GetCultures(CultureTypes.NeutralCultures).ToList();
        _cleanShutdownPath = Path.Combine(FileSystemLayout.SearchIndexFolder, ".clean-shutdown");
        _initialized = false;
    }

    public Task<bool> IndexExists()
    {
        bool directoryExists = Directory.Exists(FileSystemLayout.SearchIndexFolder);
        bool fileExists = File.Exists(_cleanShutdownPath);

        return Task.FromResult(directoryExists && fileExists);
    }

    public int Version => 45;

    public async Task<bool> Initialize(
        ILocalFileSystem localFileSystem,
        IConfigElementRepository configElementRepository)
    {
        if (!_initialized)
        {
            localFileSystem.EnsureFolderExists(FileSystemLayout.SearchIndexFolder);

            if (!ValidateDirectory(FileSystemLayout.SearchIndexFolder))
            {
                _logger.LogWarning("Search index failed to initialize; will delete and recreate");
                await configElementRepository.Upsert(ConfigElementKey.SearchIndexVersion, 0);
                Directory.Delete(FileSystemLayout.SearchIndexFolder, true);
                localFileSystem.EnsureFolderExists(FileSystemLayout.SearchIndexFolder);
            }

            if (File.Exists(_cleanShutdownPath))
            {
                File.Delete(_cleanShutdownPath);
            }

            _directory = FSDirectory.Open(FileSystemLayout.SearchIndexFolder);
            Analyzer analyzer = SearchQueryParser.AnalyzerWrapper();
            var indexConfig = new IndexWriterConfig(AppLuceneVersion, analyzer)
                { OpenMode = OpenMode.CREATE_OR_APPEND };
            _writer = new IndexWriter(_directory, indexConfig);
            _initialized = true;
        }

        return _initialized;
    }

    public async Task<Unit> UpdateItems(
        ICachingSearchRepository searchRepository,
        IFallbackMetadataProvider fallbackMetadataProvider,
        List<MediaItem> items)
    {
        foreach (MediaItem item in items)
        {
            switch (item)
            {
                case Movie movie:
                    await UpdateMovie(searchRepository, movie);
                    break;
                case Show show:
                    await UpdateShow(searchRepository, show);
                    break;
                case Season season:
                    await UpdateSeason(searchRepository, season);
                    break;
                case Artist artist:
                    await UpdateArtist(searchRepository, artist);
                    break;
                case MusicVideo musicVideo:
                    await UpdateMusicVideo(searchRepository, musicVideo);
                    break;
                case Episode episode:
                    await UpdateEpisode(searchRepository, fallbackMetadataProvider, episode);
                    break;
                case OtherVideo otherVideo:
                    await UpdateOtherVideo(searchRepository, otherVideo);
                    break;
                case Song song:
                    await UpdateSong(searchRepository, song);
                    break;
                case Image image:
                    await UpdateImage(searchRepository, image);
                    break;
            }
        }

        return Unit.Default;
    }

    public Task<bool> RemoveItems(IEnumerable<int> ids)
    {
        foreach (int id in ids)
        {
            _writer.DeleteDocuments(new Term(IdField, id.ToString(CultureInfo.InvariantCulture)));
        }

        return Task.FromResult(true);
    }

    public Task<SearchResult> Search(IClient client, string query, int skip, int limit)
    {
        var metadata = new Dictionary<string, string>
        {
            { "searchQuery", query },
            { "skip", skip.ToString(CultureInfo.InvariantCulture) },
            { "limit", limit.ToString(CultureInfo.InvariantCulture) }
        };

        client?.Breadcrumbs?.Leave("SearchIndex.Search", BreadcrumbType.State, metadata);

        if (string.IsNullOrWhiteSpace(query.Replace("*", string.Empty).Replace("?", string.Empty)) ||
            _writer.MaxDoc == 0)
        {
            return Task.FromResult(new SearchResult(new List<SearchItem>(), 0));
        }

        using DirectoryReader reader = _writer.GetReader(true);
        var searcher = new IndexSearcher(reader);
        int hitsLimit = limit == 0 ? searcher.IndexReader.MaxDoc : skip + limit;
        Query parsedQuery = SearchQueryParser.ParseQuery(query);
        // TODO: figure out if this is actually needed
        // var filter = new DuplicateFilter(TitleAndYearField);
        var sort = new Sort(new SortField(SortTitleField, SortFieldType.STRING));
        TopFieldDocs topDocs = searcher.Search(parsedQuery, null, hitsLimit, sort, true, true);
        IEnumerable<ScoreDoc> selectedHits = topDocs.ScoreDocs.Skip(skip);

        if (limit is > 0 and < 10_000)
        {
            selectedHits = selectedHits.Take(limit);
        }

        var searchResult = new SearchResult(
            selectedHits.Map(d => ProjectToSearchItem(searcher.Doc(d.Doc))).ToList(),
            topDocs.TotalHits);

        if (limit is > 0 and < 10_000)
        {
            searchResult.PageMap = GetSearchPageMap(searcher, parsedQuery, null, sort, limit);
        }

        return Task.FromResult(searchResult);
    }

    public void Commit() => _writer.Commit();

    public void Dispose()
    {
        _writer?.Dispose();
        _directory?.Dispose();

        using (File.Create(_cleanShutdownPath))
        {
            // do nothing
        }
    }

    public async Task<Unit> Rebuild(
        ICachingSearchRepository searchRepository,
        IFallbackMetadataProvider fallbackMetadataProvider)
    {
        _writer.DeleteAll();
        _writer.Commit();

        await foreach (MediaItem mediaItem in searchRepository.GetAllMediaItems())
        {
            await RebuildItem(searchRepository, fallbackMetadataProvider, mediaItem);
        }

        _writer.Commit();
        return Unit.Default;
    }

    public async Task<Unit> RebuildItems(
        ICachingSearchRepository searchRepository,
        IFallbackMetadataProvider fallbackMetadataProvider,
        IEnumerable<int> itemIds)
    {
        foreach (int id in itemIds)
        {
            foreach (MediaItem mediaItem in await searchRepository.GetItemToIndex(id))
            {
                await RebuildItem(searchRepository, fallbackMetadataProvider, mediaItem);
            }
        }

        return Unit.Default;
    }

    private bool ValidateDirectory(string folder)
    {
        try
        {
            using (var d = FSDirectory.Open(folder))
            {
                using (Analyzer analyzer = SearchQueryParser.AnalyzerWrapper())
                {
                    var indexConfig = new IndexWriterConfig(AppLuceneVersion, analyzer)
                        { OpenMode = OpenMode.CREATE_OR_APPEND };
                    using (var w = new IndexWriter(d, indexConfig))
                    {
                        using (DirectoryReader _ = w.GetReader(true))
                        {
                            return File.Exists(_cleanShutdownPath);
                        }
                    }
                }
            }
        }
        catch
        {
            return false;
        }
    }

    private async Task RebuildItem(
        ISearchRepository searchRepository,
        IFallbackMetadataProvider fallbackMetadataProvider,
        MediaItem mediaItem)
    {
        switch (mediaItem)
        {
            case Movie movie:
                await UpdateMovie(searchRepository, movie);
                break;
            case Show show:
                await UpdateShow(searchRepository, show);
                break;
            case Season season:
                await UpdateSeason(searchRepository, season);
                break;
            case Artist artist:
                await UpdateArtist(searchRepository, artist);
                break;
            case MusicVideo musicVideo:
                await UpdateMusicVideo(searchRepository, musicVideo);
                break;
            case Episode episode:
                await UpdateEpisode(searchRepository, fallbackMetadataProvider, episode);
                break;
            case OtherVideo otherVideo:
                await UpdateOtherVideo(searchRepository, otherVideo);
                break;
            case Song song:
                await UpdateSong(searchRepository, song);
                break;
            case Image image:
                await UpdateImage(searchRepository, image);
                break;
        }
    }

    private static SearchPageMap GetSearchPageMap(
        IndexSearcher searcher,
        Query query,
        DuplicateFilter filter,
        Sort sort,
        int limit)
    {
        ScoreDoc[] allDocs = searcher.Search(query, filter, int.MaxValue, sort, true, true).ScoreDocs;
        var letters = new List<char>
        {
            '#', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't',
            'u', 'v', 'w', 'x', 'y', 'z'
        };
        var map = letters.ToDictionary(letter => letter, _ => 0);

        var current = 0;
        var page = 0;
        while (current < allDocs.Length)
        {
            // walk up by page size (limit)
            page++;
            current += limit;
            if (current > allDocs.Length)
            {
                current = allDocs.Length;
            }

            char jumpLetter = searcher.Doc(allDocs[current - 1].Doc).Get(JumpLetterField, CultureInfo.InvariantCulture)
                .Head();
            foreach (char letter in letters.Where(l => letters.IndexOf(l) <= letters.IndexOf(jumpLetter)))
            {
                if (map[letter] == 0)
                {
                    map[letter] = page;
                }
            }
        }

        int max = map.Values.Max();
        foreach (char letter in letters.Where(letter => map[letter] == 0))
        {
            map[letter] = max;
        }

        return new SearchPageMap(map);
    }

    private async Task UpdateMovie(ISearchRepository searchRepository, Movie movie)
    {
        Option<MovieMetadata> maybeMetadata = movie.MovieMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            MovieMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, movie.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, MovieType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, movie.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        movie.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, movie.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                await AddLanguages(searchRepository, doc, movie.MediaVersions);

                AddStatistics(doc, movie.MediaVersions);

                if (!string.IsNullOrWhiteSpace(metadata.ContentRating))
                {
                    foreach (string contentRating in (metadata.ContentRating ?? string.Empty).Split("/")
                             .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                    {
                        doc.Add(new StringField(ContentRatingField, contentRating, Field.Store.NO));
                    }
                }

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Plot))
                {
                    doc.Add(new TextField(PlotField, metadata.Plot ?? string.Empty, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in metadata.Studios)
                {
                    doc.Add(new TextField(StudioField, studio.Name, Field.Store.NO));
                }

                foreach (Actor actor in metadata.Actors)
                {
                    doc.Add(new TextField(ActorField, actor.Name, Field.Store.NO));
                }

                foreach (Director director in metadata.Directors)
                {
                    doc.Add(new TextField(DirectorField, director.Name, Field.Store.NO));
                }

                foreach (Writer writer in metadata.Writers)
                {
                    doc.Add(new TextField(WriterField, writer.Name, Field.Store.NO));
                }

                foreach (TraktListItem item in movie.TraktListItems)
                {
                    doc.Add(
                        new StringField(
                            TraktListField,
                            item.TraktList.TraktId.ToString(CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, movie.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Movie = null;
                _logger.LogWarning(ex, "Error indexing movie with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task AddLanguages(
        ISearchRepository searchRepository,
        Document doc,
        ICollection<MediaVersion> mediaVersions)
    {
        var mediaCodes = mediaVersions
            .Map(mv => mv.Streams.Filter(ms => ms.MediaStreamKind == MediaStreamKind.Audio).Map(ms => ms.Language))
            .Flatten()
            .Filter(c => !string.IsNullOrWhiteSpace(c))
            .Distinct()
            .ToList();

        await AddLanguages(searchRepository, doc, mediaCodes);

        var subMediaCodes = mediaVersions
            .Map(
                mv => mv.Streams
                    .Filter(ms => ms.MediaStreamKind is MediaStreamKind.Subtitle or MediaStreamKind.ExternalSubtitle)
                    .Map(ms => ms.Language))
            .Flatten()
            .Filter(c => !string.IsNullOrWhiteSpace(c))
            .Distinct()
            .ToList();

        await AddSubLanguages(searchRepository, doc, subMediaCodes);
    }

    private async Task AddLanguages(ISearchRepository searchRepository, Document doc, List<string> mediaCodes)
    {
        foreach (string code in mediaCodes.Where(c => !string.IsNullOrWhiteSpace(c)).Distinct())
        {
            doc.Add(new TextField(LanguageTagField, code, Field.Store.NO));
        }

        var englishNames = new System.Collections.Generic.HashSet<string>();
        foreach (string code in await searchRepository.GetAllThreeLetterLanguageCodes(mediaCodes))
        {
            Option<CultureInfo> maybeCultureInfo = _cultureInfos.Find(
                ci => string.Equals(ci.ThreeLetterISOLanguageName, code, StringComparison.OrdinalIgnoreCase));
            foreach (CultureInfo cultureInfo in maybeCultureInfo)
            {
                englishNames.Add(cultureInfo.EnglishName);
            }
        }

        foreach (string englishName in englishNames)
        {
            doc.Add(new TextField(LanguageField, englishName, Field.Store.NO));
        }
    }

    private async Task AddSubLanguages(ISearchRepository searchRepository, Document doc, List<string> mediaCodes)
    {
        foreach (string code in mediaCodes.Where(c => !string.IsNullOrWhiteSpace(c)).Distinct())
        {
            doc.Add(new TextField(SubLanguageTagField, code, Field.Store.NO));
        }

        var englishNames = new System.Collections.Generic.HashSet<string>();
        foreach (string code in await searchRepository.GetAllThreeLetterLanguageCodes(mediaCodes))
        {
            Option<CultureInfo> maybeCultureInfo = _cultureInfos.Find(
                ci => string.Equals(ci.ThreeLetterISOLanguageName, code, StringComparison.OrdinalIgnoreCase));
            foreach (CultureInfo cultureInfo in maybeCultureInfo)
            {
                englishNames.Add(cultureInfo.EnglishName);
            }
        }

        foreach (string englishName in englishNames)
        {
            doc.Add(new TextField(SubLanguageField, englishName, Field.Store.NO));
        }
    }

    private async Task UpdateShow(ISearchRepository searchRepository, Show show)
    {
        Option<ShowMetadata> maybeMetadata = show.ShowMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            ShowMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, show.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, ShowType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, show.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        show.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, show.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                List<string> languages = await searchRepository.GetLanguagesForShow(show);
                await AddLanguages(searchRepository, doc, languages);

                List<string> subLanguages = await searchRepository.GetSubLanguagesForShow(show);
                await AddSubLanguages(searchRepository, doc, subLanguages);

                if (!string.IsNullOrWhiteSpace(metadata.ContentRating))
                {
                    foreach (string contentRating in (metadata.ContentRating ?? string.Empty).Split("/")
                             .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                    {
                        doc.Add(new StringField(ContentRatingField, contentRating, Field.Store.NO));
                    }
                }

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Plot))
                {
                    doc.Add(new TextField(PlotField, metadata.Plot ?? string.Empty, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in metadata.Studios)
                {
                    doc.Add(new TextField(StudioField, studio.Name, Field.Store.NO));
                }

                foreach (Actor actor in metadata.Actors)
                {
                    doc.Add(new TextField(ActorField, actor.Name, Field.Store.NO));
                }

                foreach (TraktListItem item in show.TraktListItems)
                {
                    doc.Add(
                        new StringField(
                            TraktListField,
                            item.TraktList.TraktId.ToString(CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, show.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Show = null;
                _logger.LogWarning(ex, "Error indexing show with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateSeason(ISearchRepository searchRepository, Season season)
    {
        Option<SeasonMetadata> maybeMetadata = season.SeasonMetadata.HeadOrNone();
        Option<ShowMetadata> maybeShowMetadata = season.Show.ShowMetadata.HeadOrNone();
        if (maybeMetadata.IsSome && maybeShowMetadata.IsSome)
        {
            SeasonMetadata metadata = maybeMetadata.ValueUnsafe();
            ShowMetadata showMetadata = maybeShowMetadata.ValueUnsafe();

            try
            {
                var seasonTitle = $"{showMetadata.Title} - S{season.SeasonNumber}";
                string sortTitle = $"{showMetadata.SortTitle}_{season.SeasonNumber:0000}"
                    .ToLowerInvariant();
                string titleAndYear = $"{showMetadata.Title}_{showMetadata.Year}_{season.SeasonNumber}"
                    .ToLowerInvariant();

                var doc = new Document
                {
                    new StringField(IdField, season.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, SeasonType, Field.Store.YES),
                    new TextField(TitleField, seasonTitle, Field.Store.NO),
                    new StringField(SortTitleField, sortTitle, Field.Store.NO),
                    new TextField(LibraryNameField, season.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        season.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, titleAndYear, Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(showMetadata), Field.Store.YES),
                    new StringField(StateField, season.State.ToString(), Field.Store.NO),
                    new Int32Field(SeasonNumberField, season.SeasonNumber, Field.Store.NO),
                    new TextField(ShowTitleField, showMetadata.Title, Field.Store.NO)
                };

                // add some show fields to help filter seasons within a particular show
                foreach (Genre genre in showMetadata.Genres)
                {
                    doc.Add(new TextField(ShowGenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in showMetadata.Tags)
                {
                    doc.Add(new TextField(ShowTagField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in showMetadata.Studios)
                {
                    doc.Add(new TextField(ShowStudioField, studio.Name, Field.Store.NO));
                }

                if (!string.IsNullOrWhiteSpace(showMetadata.ContentRating))
                {
                    foreach (string contentRating in (showMetadata.ContentRating ?? string.Empty).Split("/")
                             .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                    {
                        doc.Add(new StringField(ShowContentRatingField, contentRating, Field.Store.NO));
                    }
                }

                List<string> languages = await searchRepository.GetLanguagesForSeason(season);
                await AddLanguages(searchRepository, doc, languages);

                List<string> subLanguages = await searchRepository.GetSubLanguagesForSeason(season);
                await AddSubLanguages(searchRepository, doc, subLanguages);

                if (!string.IsNullOrWhiteSpace(showMetadata.ContentRating))
                {
                    foreach (string contentRating in (showMetadata.ContentRating ?? string.Empty).Split("/")
                             .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                    {
                        doc.Add(new StringField(ContentRatingField, contentRating, Field.Store.NO));
                    }
                }

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                foreach (TraktListItem item in season.TraktListItems)
                {
                    doc.Add(
                        new StringField(
                            TraktListField,
                            item.TraktList.TraktId.ToString(CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, season.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Season = null;
                _logger.LogWarning(ex, "Error indexing season with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateArtist(ISearchRepository searchRepository, Artist artist)
    {
        Option<ArtistMetadata> maybeMetadata = artist.ArtistMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            ArtistMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, artist.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, ArtistType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, artist.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        artist.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                List<string> languages = await searchRepository.GetLanguagesForArtist(artist);
                await AddLanguages(searchRepository, doc, languages);

                List<string> subLanguages = await searchRepository.GetSubLanguagesForArtist(artist);
                await AddSubLanguages(searchRepository, doc, subLanguages);

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Style style in metadata.Styles)
                {
                    doc.Add(new TextField(StyleField, style.Name, Field.Store.NO));
                }

                foreach (Mood mood in metadata.Moods)
                {
                    doc.Add(new TextField(MoodField, mood.Name, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, artist.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Artist = null;
                _logger.LogWarning(ex, "Error indexing artist with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateMusicVideo(ISearchRepository searchRepository, MusicVideo musicVideo)
    {
        Option<MusicVideoMetadata> maybeMetadata = musicVideo.MusicVideoMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            MusicVideoMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, musicVideo.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, MusicVideoType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title ?? string.Empty, Field.Store.NO),
                    new StringField(
                        SortTitleField,
                        (metadata.SortTitle ?? string.Empty).ToLowerInvariant(),
                        Field.Store.NO),
                    new TextField(LibraryNameField, musicVideo.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        musicVideo.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, musicVideo.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                await AddLanguages(searchRepository, doc, musicVideo.MediaVersions);

                AddStatistics(doc, musicVideo.MediaVersions);

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Album))
                {
                    doc.Add(new TextField(AlbumField, metadata.Album, Field.Store.NO));
                }

                if (!string.IsNullOrWhiteSpace(metadata.Plot))
                {
                    doc.Add(new TextField(PlotField, metadata.Plot ?? string.Empty, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in metadata.Studios)
                {
                    doc.Add(new TextField(StudioField, studio.Name, Field.Store.NO));
                }

                var artists = new System.Collections.Generic.HashSet<string>();

                if (musicVideo.Artist != null)
                {
                    foreach (ArtistMetadata artistMetadata in musicVideo.Artist.ArtistMetadata)
                    {
                        artists.Add(artistMetadata.Title);
                    }
                }

                foreach (MusicVideoArtist artist in metadata.Artists)
                {
                    artists.Add(artist.Name);
                }

                foreach (string artist in artists)
                {
                    doc.Add(new TextField(ArtistField, artist, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, musicVideo.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.MusicVideo = null;
                _logger.LogWarning(ex, "Error indexing music video with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateEpisode(
        ISearchRepository searchRepository,
        IFallbackMetadataProvider fallbackMetadataProvider,
        Episode episode)
    {
        // try to load metadata here, since episodes without metadata won't index
        if (episode.EpisodeMetadata.Count == 0)
        {
            episode.EpisodeMetadata ??= new List<EpisodeMetadata>();
            episode.EpisodeMetadata = fallbackMetadataProvider.GetFallbackMetadata(episode);
            foreach (EpisodeMetadata metadata in episode.EpisodeMetadata)
            {
                metadata.Episode = episode;
            }
        }

        foreach (EpisodeMetadata metadata in episode.EpisodeMetadata)
        {
            try
            {
                var doc = new Document
                {
                    new StringField(IdField, episode.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, EpisodeType, Field.Store.YES),
                    new TextField(LibraryNameField, episode.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        episode.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, episode.State.ToString(), Field.Store.NO),
                    new Int32Field(SeasonNumberField, episode.Season?.SeasonNumber ?? 0, Field.Store.NO),
                    new Int32Field(EpisodeNumberField, metadata.EpisodeNumber, Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                // add some show fields to help filter episodes within a particular show
                foreach (ShowMetadata showMetadata in Optional(episode.Season?.Show?.ShowMetadata).Flatten())
                {
                    doc.Add(new TextField(ShowTitleField, showMetadata.Title, Field.Store.NO));

                    foreach (Genre genre in showMetadata.Genres)
                    {
                        doc.Add(new TextField(ShowGenreField, genre.Name, Field.Store.NO));
                    }

                    foreach (Tag tag in showMetadata.Tags)
                    {
                        doc.Add(new TextField(ShowTagField, tag.Name, Field.Store.NO));
                    }

                    foreach (Studio studio in showMetadata.Studios)
                    {
                        doc.Add(new TextField(ShowStudioField, studio.Name, Field.Store.NO));
                    }

                    if (!string.IsNullOrWhiteSpace(showMetadata.ContentRating))
                    {
                        foreach (string contentRating in (showMetadata.ContentRating ?? string.Empty).Split("/")
                                 .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                        {
                            doc.Add(new StringField(ShowContentRatingField, contentRating, Field.Store.NO));
                        }
                    }
                }

                if (!string.IsNullOrWhiteSpace(metadata.Title))
                {
                    doc.Add(new TextField(TitleField, metadata.Title, Field.Store.NO));
                }

                if (!string.IsNullOrWhiteSpace(metadata.SortTitle))
                {
                    doc.Add(new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO));
                }

                await AddLanguages(searchRepository, doc, episode.MediaVersions);

                AddStatistics(doc, episode.MediaVersions);

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Plot))
                {
                    doc.Add(new TextField(PlotField, metadata.Plot ?? string.Empty, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in metadata.Studios)
                {
                    doc.Add(new TextField(StudioField, studio.Name, Field.Store.NO));
                }

                foreach (Actor actor in metadata.Actors)
                {
                    doc.Add(new TextField(ActorField, actor.Name, Field.Store.NO));
                }

                foreach (Director director in metadata.Directors)
                {
                    doc.Add(new TextField(DirectorField, director.Name, Field.Store.NO));
                }

                foreach (Writer writer in metadata.Writers)
                {
                    doc.Add(new TextField(WriterField, writer.Name, Field.Store.NO));
                }

                foreach (TraktListItem item in episode.TraktListItems)
                {
                    doc.Add(
                        new StringField(
                            TraktListField,
                            item.TraktList.TraktId.ToString(CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, episode.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Episode = null;
                _logger.LogWarning(ex, "Error indexing episode with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateOtherVideo(ISearchRepository searchRepository, OtherVideo otherVideo)
    {
        Option<OtherVideoMetadata> maybeMetadata = otherVideo.OtherVideoMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            OtherVideoMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, otherVideo.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, OtherVideoType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, otherVideo.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        otherVideo.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, otherVideo.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                await AddLanguages(searchRepository, doc, otherVideo.MediaVersions);

                AddStatistics(doc, otherVideo.MediaVersions);

                if (!string.IsNullOrWhiteSpace(metadata.ContentRating))
                {
                    foreach (string contentRating in (metadata.ContentRating ?? string.Empty).Split("/")
                             .Map(x => x.Trim()).Where(x => !string.IsNullOrWhiteSpace(x)))
                    {
                        doc.Add(new StringField(ContentRatingField, contentRating, Field.Store.NO));
                    }
                }

                if (metadata.ReleaseDate.HasValue)
                {
                    doc.Add(
                        new StringField(
                            ReleaseDateField,
                            metadata.ReleaseDate.Value.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Plot))
                {
                    doc.Add(new TextField(PlotField, metadata.Plot ?? string.Empty, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Studio studio in metadata.Studios)
                {
                    doc.Add(new TextField(StudioField, studio.Name, Field.Store.NO));
                }

                foreach (Actor actor in metadata.Actors)
                {
                    doc.Add(new TextField(ActorField, actor.Name, Field.Store.NO));
                }

                foreach (Director director in metadata.Directors)
                {
                    doc.Add(new TextField(DirectorField, director.Name, Field.Store.NO));
                }

                foreach (Writer writer in metadata.Writers)
                {
                    doc.Add(new TextField(WriterField, writer.Name, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, otherVideo.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.OtherVideo = null;
                _logger.LogWarning(ex, "Error indexing other video with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateSong(ISearchRepository searchRepository, Song song)
    {
        Option<SongMetadata> maybeMetadata = song.SongMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            SongMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, song.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, SongType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, song.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        song.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, song.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                await AddLanguages(searchRepository, doc, song.MediaVersions);

                AddStatistics(doc, song.MediaVersions);

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                if (!string.IsNullOrWhiteSpace(metadata.Album))
                {
                    doc.Add(new TextField(AlbumField, metadata.Album, Field.Store.NO));
                }

                foreach (string artist in metadata.Artists)
                {
                    doc.Add(new TextField(ArtistField, artist, Field.Store.NO));
                }

                foreach (string albumArtist in metadata.AlbumArtists)
                {
                    doc.Add(new TextField(AlbumArtistField, albumArtist, Field.Store.NO));
                }

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, song.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Song = null;
                _logger.LogWarning(ex, "Error indexing song with metadata {@Metadata}", metadata);
            }
        }
    }

    private async Task UpdateImage(ISearchRepository searchRepository, Image image)
    {
        Option<ImageMetadata> maybeMetadata = image.ImageMetadata.HeadOrNone();
        if (maybeMetadata.IsSome)
        {
            ImageMetadata metadata = maybeMetadata.ValueUnsafe();

            try
            {
                var doc = new Document
                {
                    new StringField(IdField, image.Id.ToString(CultureInfo.InvariantCulture), Field.Store.YES),
                    new StringField(TypeField, ImageType, Field.Store.YES),
                    new TextField(TitleField, metadata.Title, Field.Store.NO),
                    new StringField(SortTitleField, metadata.SortTitle.ToLowerInvariant(), Field.Store.NO),
                    new TextField(LibraryNameField, image.LibraryPath.Library.Name, Field.Store.NO),
                    new StringField(
                        LibraryIdField,
                        image.LibraryPath.Library.Id.ToString(CultureInfo.InvariantCulture),
                        Field.Store.NO),
                    new StringField(TitleAndYearField, GetTitleAndYear(metadata), Field.Store.NO),
                    new StringField(JumpLetterField, GetJumpLetter(metadata), Field.Store.YES),
                    new StringField(StateField, image.State.ToString(), Field.Store.NO),
                    new TextField(MetadataKindField, metadata.MetadataKind.ToString(), Field.Store.NO)
                };

                IEnumerable<int> libraryFolderIds = image.MediaVersions
                    .SelectMany(mv => mv.MediaFiles)
                    .SelectMany(mf => Optional(mf.LibraryFolderId));

                foreach (int libraryFolderId in libraryFolderIds)
                {
                    doc.Add(
                        new StringField(
                            LibraryFolderIdField,
                            libraryFolderId.ToString(CultureInfo.InvariantCulture),
                            Field.Store.NO));
                }

                await AddLanguages(searchRepository, doc, image.MediaVersions);

                AddStatistics(doc, image.MediaVersions);

                doc.Add(
                    new StringField(
                        AddedDateField,
                        metadata.DateAdded.ToString("yyyyMMdd", CultureInfo.InvariantCulture),
                        Field.Store.NO));

                foreach (Tag tag in metadata.Tags)
                {
                    doc.Add(new TextField(TagField, tag.Name, Field.Store.NO));
                    doc.Add(new StringField(TagFullField, tag.Name, Field.Store.NO));
                }

                foreach (Genre genre in metadata.Genres)
                {
                    doc.Add(new TextField(GenreField, genre.Name, Field.Store.NO));
                }

                AddMetadataGuids(metadata, doc);

                _writer.UpdateDocument(new Term(IdField, image.Id.ToString(CultureInfo.InvariantCulture)), doc);
            }
            catch (Exception ex)
            {
                metadata.Image = null;
                _logger.LogWarning(ex, "Error indexing image with metadata {@Metadata}", metadata);
            }
        }
    }

    private static SearchItem ProjectToSearchItem(Document doc) => new(
        doc.Get(TypeField, CultureInfo.InvariantCulture),
        Convert.ToInt32(doc.Get(IdField, CultureInfo.InvariantCulture), CultureInfo.InvariantCulture));

    private static void AddStatistics(Document doc, List<MediaVersion> mediaVersions)
    {
        foreach (MediaVersion version in mediaVersions)
        {
            doc.Add(new Int32Field(MinutesField, (int)Math.Ceiling(version.Duration.TotalMinutes), Field.Store.NO));
            doc.Add(new Int32Field(SecondsField, (int)Math.Ceiling(version.Duration.TotalSeconds), Field.Store.NO));

            if (version.Streams.Any(s => s.MediaStreamKind == MediaStreamKind.Video))
            {
                doc.Add(new Int32Field(HeightField, version.Height, Field.Store.NO));
                doc.Add(new Int32Field(WidthField, version.Width, Field.Store.NO));
            }

            foreach (MediaStream videoStream in version.Streams.Filter(s => s.MediaStreamKind == MediaStreamKind.Video))
            {
                if (!string.IsNullOrWhiteSpace(videoStream.Codec))
                {
                    doc.Add(new StringField(VideoCodecField, videoStream.Codec, Field.Store.NO));
                }

                Option<IPixelFormat> maybePixelFormat =
                    AvailablePixelFormats.ForPixelFormat(videoStream.PixelFormat, null);
                foreach (IPixelFormat pixelFormat in maybePixelFormat)
                {
                    doc.Add(new Int32Field(VideoBitDepthField, pixelFormat.BitDepth, Field.Store.NO));
                }

                if (maybePixelFormat.IsNone && videoStream.BitsPerRawSample > 0)
                {
                    doc.Add(new Int32Field(VideoBitDepthField, videoStream.BitsPerRawSample, Field.Store.NO));
                }

                var colorParams = new ColorParams(
                    videoStream.ColorRange,
                    videoStream.ColorSpace,
                    videoStream.ColorTransfer,
                    videoStream.ColorPrimaries);

                string dynamicRange = colorParams.IsHdr ? "hdr" : "sdr";

                doc.Add(new StringField(VideoDynamicRange, dynamicRange, Field.Store.NO));
            }
        }
    }

    private static void AddMetadataGuids(Core.Domain.Metadata metadata, Document doc)
    {
        foreach (MetadataGuid guid in metadata.Guids)
        {
            string[] split = (guid.Guid ?? string.Empty).Split("://");
            if (split.Length == 2 && !string.IsNullOrWhiteSpace(split[1]))
            {
                doc.Add(new StringField(split[0], split[1].ToLowerInvariant(), Field.Store.NO));
            }
        }
    }

    // this is used for filtering duplicate search results
    internal static string GetTitleAndYear(Core.Domain.Metadata metadata) =>
        metadata switch
        {
            EpisodeMetadata em =>
                $"{Title(em)}_{em.Episode.Season.Show.ShowMetadata.Head().Title}_{em.Year}_{em.Episode.Season.SeasonNumber}_{em.EpisodeNumber}_{em.Episode.State}"
                    .ToLowerInvariant(),
            OtherVideoMetadata ovm => $"{OtherVideoTitle(ovm).Replace(' ', '_')}_{ovm.Year}_{ovm.OtherVideo.State}"
                .ToLowerInvariant(),
            SongMetadata sm => $"{Title(sm)}_{sm.Year}_{sm.Song.State}".ToLowerInvariant(),
            ImageMetadata im => $"{Title(im)}_{im.Year}_{im.Image.State}".ToLowerInvariant(),
            MovieMetadata mm => $"{Title(mm)}_{mm.Year}_{mm.Movie.State}".ToLowerInvariant(),
            ArtistMetadata am => $"{Title(am)}_{am.Year}_{am.Artist.State}".ToLowerInvariant(),
            MusicVideoMetadata mvm => $"{Title(mvm)}_{mvm.Year}_{mvm.MusicVideo.State}".ToLowerInvariant(),
            SeasonMetadata sm => $"{Title(sm)}_{sm.Year}_{sm.Season.State}".ToLowerInvariant(),
            ShowMetadata sm => $"{Title(sm)}_{sm.Year}_{sm.Show.State}".ToLowerInvariant(),
            _ => $"{Title(metadata)}_{metadata.Year}".ToLowerInvariant()
        };

    private static string Title(Core.Domain.Metadata metadata) =>
        (metadata.Title ?? string.Empty).Replace(' ', '_');

    internal static string GetJumpLetter(Core.Domain.Metadata metadata)
    {
        foreach (char c in (metadata.SortTitle ?? " ").ToLowerInvariant().HeadOrNone())
        {
            return c switch
            {
                >= 'a' and <= 'z' => c.ToString(),
                _ => "#"
            };
        }

        return "#";
    }

    private static string OtherVideoTitle(OtherVideoMetadata ovm) =>
        string.IsNullOrWhiteSpace(ovm.OriginalTitle) ? ovm.Title : ovm.OriginalTitle;
}