ErsatzTV/ErsatzTV.Application/Channels/Commands/RefreshChannelDataHandler.cs

using System.Globalization;
using System.Xml;
using ErsatzTV.Application.Configuration;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Core.Emby;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Jellyfin;
using ErsatzTV.Core.Streaming;
using ErsatzTV.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Microsoft.IO;
using Newtonsoft.Json;
using Scriban;
using Scriban.Runtime;
using WebMarkupMin.Core;

namespace ErsatzTV.Application.Channels;

public class RefreshChannelDataHandler : IRequestHandler<RefreshChannelData>
{
    private readonly IConfigElementRepository _configElementRepository;
    private readonly IDbContextFactory<TvContext> _dbContextFactory;
    private readonly ILocalFileSystem _localFileSystem;
    private readonly ILogger<RefreshChannelDataHandler> _logger;
    private readonly RecyclableMemoryStreamManager _recyclableMemoryStreamManager;

    public RefreshChannelDataHandler(
        RecyclableMemoryStreamManager recyclableMemoryStreamManager,
        IDbContextFactory<TvContext> dbContextFactory,
        ILocalFileSystem localFileSystem,
        IConfigElementRepository configElementRepository,
        ILogger<RefreshChannelDataHandler> logger)
    {
        _recyclableMemoryStreamManager = recyclableMemoryStreamManager;
        _dbContextFactory = dbContextFactory;
        _localFileSystem = localFileSystem;
        _configElementRepository = configElementRepository;
        _logger = logger;
    }

    public async Task Handle(RefreshChannelData request, CancellationToken cancellationToken)
    {
        _logger.LogDebug("Refreshing channel data (XMLTV) for channel {Channel}", request.ChannelNumber);

        _localFileSystem.EnsureFolderExists(FileSystemLayout.ChannelGuideCacheFolder);

        string movieTemplateFileName = GetMovieTemplateFileName();
        string episodeTemplateFileName = GetEpisodeTemplateFileName();
        string musicVideoTemplateFileName = GetMusicVideoTemplateFileName();
        string songTemplateFileName = GetSongTemplateFileName();
        string otherVideoTemplateFileName = GetOtherVideoTemplateFileName();
        if (movieTemplateFileName is null || episodeTemplateFileName is null || musicVideoTemplateFileName is null ||
            songTemplateFileName is null || otherVideoTemplateFileName is null)
        {
            return;
        }

        var minifier = new XmlMinifier(
            new XmlMinificationSettings
            {
                MinifyWhitespace = true,
                RemoveXmlComments = true,
                CollapseTagsWithoutContent = true
            });

        var templateContext = new XmlTemplateContext();

        string movieText = await File.ReadAllTextAsync(movieTemplateFileName, cancellationToken);
        var movieTemplate = Template.Parse(movieText, movieTemplateFileName);

        string episodeText = await File.ReadAllTextAsync(episodeTemplateFileName, cancellationToken);
        var episodeTemplate = Template.Parse(episodeText, episodeTemplateFileName);

        string musicVideoText = await File.ReadAllTextAsync(musicVideoTemplateFileName, cancellationToken);
        var musicVideoTemplate = Template.Parse(musicVideoText, musicVideoTemplateFileName);

        string songText = await File.ReadAllTextAsync(songTemplateFileName, cancellationToken);
        var songTemplate = Template.Parse(songText, songTemplateFileName);

        string otherVideoText = await File.ReadAllTextAsync(otherVideoTemplateFileName, cancellationToken);
        var otherVideoTemplate = Template.Parse(otherVideoText, otherVideoTemplateFileName);

        await using TvContext dbContext = await _dbContextFactory.CreateDbContextAsync(cancellationToken);

        List<Playout> playouts = await dbContext.Playouts
            .AsNoTracking()
            .Filter(pi => pi.Channel.Number == request.ChannelNumber)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Episode).EpisodeMetadata)
            .ThenInclude(em => em.Guids)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Episode).Season)
            .ThenInclude(s => s.Show)
            .ThenInclude(s => s.ShowMetadata)
            .ThenInclude(sm => sm.Artwork)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Episode).Season)
            .ThenInclude(s => s.Show)
            .ThenInclude(s => s.ShowMetadata)
            .ThenInclude(sm => sm.Genres)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Episode).Season)
            .ThenInclude(s => s.Show)
            .ThenInclude(s => s.ShowMetadata)
            .ThenInclude(sm => sm.Guids)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Movie).MovieMetadata)
            .ThenInclude(mm => mm.Artwork)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Movie).MovieMetadata)
            .ThenInclude(mm => mm.Genres)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Movie).MovieMetadata)
            .ThenInclude(mm => mm.Guids)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).MusicVideoMetadata)
            .ThenInclude(mm => mm.Artwork)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).MusicVideoMetadata)
            .ThenInclude(mvm => mvm.Genres)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).MusicVideoMetadata)
            .ThenInclude(mvm => mvm.Studios)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).MusicVideoMetadata)
            .ThenInclude(mvm => mvm.Directors)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).MusicVideoMetadata)
            .ThenInclude(mvm => mvm.Artists)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as MusicVideo).Artist)
            .ThenInclude(a => a.ArtistMetadata)
            .ThenInclude(am => am.Genres)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as OtherVideo).OtherVideoMetadata)
            .ThenInclude(vm => vm.Artwork)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Song).SongMetadata)
            .ThenInclude(vm => vm.Artwork)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Song).SongMetadata)
            .ThenInclude(sm => sm.Genres)
            .Include(p => p.Items)
            .ThenInclude(i => i.MediaItem)
            .ThenInclude(i => (i as Song).SongMetadata)
            .ThenInclude(sm => sm.Studios)
            .ToListAsync(cancellationToken);

        await using RecyclableMemoryStream ms = _recyclableMemoryStreamManager.GetStream();
        await using var xml = XmlWriter.Create(
            ms,
            new XmlWriterSettings { Async = true, ConformanceLevel = ConformanceLevel.Fragment });

        int daysToBuild = await _configElementRepository
            .GetValue<int>(ConfigElementKey.XmltvDaysToBuild)
            .IfNoneAsync(2);

        DateTimeOffset finish = DateTimeOffset.UtcNow.AddDays(daysToBuild);

        foreach (Playout playout in playouts)
        {
            switch (playout.ProgramSchedulePlayoutType)
            {
                case ProgramSchedulePlayoutType.Flood:
                    var floodSorted = playouts
                        .Collect(p => p.Items)
                        .OrderBy(pi => pi.Start)
                        .Filter(pi => pi.StartOffset <= finish)
                        .ToList();
                    await WritePlayoutXml(
                        request,
                        floodSorted,
                        templateContext,
                        movieTemplate,
                        episodeTemplate,
                        musicVideoTemplate,
                        songTemplate,
                        otherVideoTemplate,
                        minifier,
                        xml);
                    break;
                case ProgramSchedulePlayoutType.Block:
                    var blockSorted = playouts
                        .Collect(p => p.Items)
                        .OrderBy(pi => pi.Start)
                        .Filter(pi => pi.StartOffset <= finish)
                        .ToList();
                    await WriteBlockPlayoutXml(
                        request,
                        blockSorted,
                        templateContext,
                        movieTemplate,
                        episodeTemplate,
                        musicVideoTemplate,
                        songTemplate,
                        otherVideoTemplate,
                        minifier,
                        xml);
                    break;
                case ProgramSchedulePlayoutType.ExternalJson:
                    var externalJsonSorted = (await CollectExternalJsonItems(playout.ExternalJsonFile))
                        .Filter(pi => pi.StartOffset <= finish)
                        .ToList();

                    await WritePlayoutXml(
                        request,
                        externalJsonSorted,
                        templateContext,
                        movieTemplate,
                        episodeTemplate,
                        musicVideoTemplate,
                        songTemplate,
                        otherVideoTemplate,
                        minifier,
                        xml);
                    break;
            }
        }

        await xml.FlushAsync();

        string tempFile = Path.GetTempFileName();
        await File.WriteAllBytesAsync(tempFile, ms.ToArray(), cancellationToken);

        string targetFile = Path.Combine(FileSystemLayout.ChannelGuideCacheFolder, $"{request.ChannelNumber}.xml");
        File.Move(tempFile, targetFile, true);
    }

    private async Task WritePlayoutXml(
        RefreshChannelData request,
        List<PlayoutItem> sorted,
        XmlTemplateContext templateContext,
        Template movieTemplate,
        Template episodeTemplate,
        Template musicVideoTemplate,
        Template songTemplate,
        Template otherVideoTemplate,
        XmlMinifier minifier,
        XmlWriter xml)
    {
        XmltvTimeZone xmltvTimeZone = await _configElementRepository
            .GetValue<XmltvTimeZone>(ConfigElementKey.XmltvTimeZone)
            .IfNoneAsync(XmltvTimeZone.Local);

        // skip all filler that isn't pre-roll
        var i = 0;
        while (i < sorted.Count && sorted[i].FillerKind != FillerKind.None &&
               sorted[i].FillerKind != FillerKind.PreRoll)
        {
            i++;
        }

        while (i < sorted.Count)
        {
            PlayoutItem startItem = sorted[i];
            int j = i;
            while (sorted[j].FillerKind != FillerKind.None && j + 1 < sorted.Count)
            {
                j++;
            }

            PlayoutItem displayItem = sorted[j];
            bool hasCustomTitle = !string.IsNullOrWhiteSpace(startItem.CustomTitle);

            int finishIndex = j;
            while (finishIndex + 1 < sorted.Count && (sorted[finishIndex + 1].GuideGroup == startItem.GuideGroup
                                                      || sorted[finishIndex + 1].FillerKind is FillerKind.GuideMode
                                                          or FillerKind.Tail or FillerKind.Fallback))
            {
                finishIndex++;
            }

            int customShowId = -1;
            if (displayItem.MediaItem is Episode ep)
            {
                customShowId = ep.Season.ShowId;
            }

            bool isSameCustomShow = hasCustomTitle;
            for (int x = j; x <= finishIndex; x++)
            {
                isSameCustomShow = isSameCustomShow && sorted[x].MediaItem is Episode e &&
                                   customShowId == e.Season.ShowId;
            }

            PlayoutItem finishItem = sorted[finishIndex];
            i = finishIndex;

            DateTimeOffset startTime = xmltvTimeZone switch
            {
                XmltvTimeZone.Utc => new DateTimeOffset(startItem.Start, TimeSpan.Zero),
                _ => startItem.StartOffset
            };

            DateTimeOffset stopTime = (xmltvTimeZone, displayItem.GuideFinishOffset.HasValue) switch
            {
                (XmltvTimeZone.Utc, true) => new DateTimeOffset(displayItem.GuideFinish!.Value, TimeSpan.Zero),
                (XmltvTimeZone.Utc, false) => new DateTimeOffset(finishItem.Finish, TimeSpan.Zero),
                (_, true) => displayItem.GuideFinishOffset!.Value,
                (_, false) => finishItem.FinishOffset
            };

            string start = startTime
                .ToString("yyyyMMddHHmmss zzz", CultureInfo.InvariantCulture)
                .Replace(":", string.Empty);

            string stop = stopTime
                .ToString("yyyyMMddHHmmss zzz", CultureInfo.InvariantCulture)
                .Replace(":", string.Empty);

            await WriteItemToXml(
                request,
                displayItem,
                start,
                stop,
                hasCustomTitle,
                templateContext,
                movieTemplate,
                episodeTemplate,
                musicVideoTemplate,
                songTemplate,
                otherVideoTemplate,
                minifier,
                xml);

            i++;
        }
    }

    private static async Task WriteBlockPlayoutXml(
        RefreshChannelData request,
        List<PlayoutItem> sorted,
        XmlTemplateContext templateContext,
        Template movieTemplate,
        Template episodeTemplate,
        Template musicVideoTemplate,
        Template songTemplate,
        Template otherVideoTemplate,
        XmlMinifier minifier,
        XmlWriter xml)
    {
        var groups = sorted.GroupBy(s => new { s.GuideStart, s.GuideFinish, s.GuideGroup });
        foreach (var group in groups)
        {
            DateTime groupStart = group.Key.GuideStart!.Value;
            DateTime groupFinish = group.Key.GuideFinish!.Value;
            TimeSpan groupDuration = groupFinish - groupStart;

            var itemsToInclude = group.Filter(g => g.FillerKind is FillerKind.None).ToList();
            if (itemsToInclude.Count == 0)
            {
                continue;
            }

            TimeSpan perItem = groupDuration / itemsToInclude.Count;

            DateTimeOffset currentStart = new DateTimeOffset(groupStart, TimeSpan.Zero).ToLocalTime();
            DateTimeOffset currentFinish = currentStart + perItem;

            foreach (PlayoutItem item in itemsToInclude)
            {
                string start = currentStart.ToString("yyyyMMddHHmmss zzz", CultureInfo.InvariantCulture)
                    .Replace(":", string.Empty);
                string stop = currentFinish.ToString("yyyyMMddHHmmss zzz", CultureInfo.InvariantCulture)
                    .Replace(":", string.Empty);

                await WriteItemToXml(
                    request,
                    item,
                    start,
                    stop,
                    false,
                    templateContext,
                    movieTemplate,
                    episodeTemplate,
                    musicVideoTemplate,
                    songTemplate,
                    otherVideoTemplate,
                    minifier,
                    xml);

                currentStart = currentFinish;
                currentFinish += perItem;
            }
        }
    }

    private static async Task WriteItemToXml(
        RefreshChannelData request,
        PlayoutItem displayItem,
        string start,
        string stop,
        bool hasCustomTitle,
        XmlTemplateContext templateContext,
        Template movieTemplate,
        Template episodeTemplate,
        Template musicVideoTemplate,
        Template songTemplate,
        Template otherVideoTemplate,
        XmlMinifier minifier,
        XmlWriter xml)
    {
        string title = GetTitle(displayItem);
        string subtitle = GetSubtitle(displayItem);

        Option<string> maybeTemplateOutput = displayItem.MediaItem switch
        {
            Movie templateMovie => await ProcessMovieTemplate(
                request,
                templateMovie,
                start,
                stop,
                hasCustomTitle,
                displayItem,
                title,
                templateContext,
                movieTemplate),
            Episode templateEpisode => await ProcessEpisodeTemplate(
                request,
                templateEpisode,
                start,
                stop,
                hasCustomTitle,
                displayItem,
                title,
                subtitle,
                templateContext,
                episodeTemplate),
            MusicVideo templateMusicVideo => await ProcessMusicVideoTemplate(
                request,
                templateMusicVideo,
                start,
                stop,
                hasCustomTitle,
                displayItem,
                title,
                subtitle,
                templateContext,
                musicVideoTemplate),
            Song templateSong => await ProcessSongTemplate(
                request,
                templateSong,
                start,
                stop,
                hasCustomTitle,
                displayItem,
                title,
                subtitle,
                templateContext,
                songTemplate),
            OtherVideo templateOtherVideo => await ProcessOtherVideoTemplate(
                request,
                templateOtherVideo,
                start,
                stop,
                hasCustomTitle,
                displayItem,
                title,
                templateContext,
                otherVideoTemplate),
            _ => Option<string>.None
        };

        foreach (string templateOutput in maybeTemplateOutput)
        {
            MarkupMinificationResult minified = minifier.Minify(templateOutput);
            await xml.WriteRawAsync(minified.MinifiedContent);
        }
    }

    private static async Task<Option<string>> ProcessMovieTemplate(
        RefreshChannelData request,
        Movie templateMovie,
        string start,
        string stop,
        bool hasCustomTitle,
        PlayoutItem displayItem,
        string title,
        XmlTemplateContext templateContext,
        Template movieTemplate)
    {
        foreach (MovieMetadata metadata in templateMovie.MovieMetadata.HeadOrNone())
        {
            metadata.Genres ??= [];
            metadata.Guids ??= [];

            string poster = Optional(metadata.Artwork).Flatten()
                .Filter(a => a.ArtworkKind == ArtworkKind.Poster)
                .HeadOrNone()
                .Match(a => GetArtworkUrl(a, ArtworkKind.Poster), () => string.Empty);

            var data = new
            {
                ProgrammeStart = start,
                ProgrammeStop = stop,
                request.ChannelNumber,
                HasCustomTitle = hasCustomTitle,
                displayItem.CustomTitle,
                MovieTitle = title,
                MovieHasPlot = !string.IsNullOrWhiteSpace(metadata.Plot),
                MoviePlot = metadata.Plot,
                MovieHasYear = metadata.Year.HasValue,
                MovieYear = metadata.Year,
                MovieGenres = metadata.Genres.Map(g => g.Name).OrderBy(n => n),
                MovieHasArtwork = !string.IsNullOrWhiteSpace(poster),
                MovieArtworkUrl = poster,
                MovieHasContentRating = !string.IsNullOrWhiteSpace(metadata.ContentRating),
                MovieContentRating = metadata.ContentRating,
                MovieGuids = metadata.Guids.Map(g => g.Guid)
            };

            var scriptObject = new ScriptObject();
            scriptObject.Import(data);
            templateContext.PushGlobal(scriptObject);

            return await movieTemplate.RenderAsync(templateContext);
        }

        return Option<string>.None;
    }

    private static async Task<Option<string>> ProcessEpisodeTemplate(
        RefreshChannelData request,
        Episode templateEpisode,
        string start,
        string stop,
        bool hasCustomTitle,
        PlayoutItem displayItem,
        string title,
        string subtitle,
        XmlTemplateContext templateContext,
        Template episodeTemplate)
    {
        foreach (EpisodeMetadata metadata in templateEpisode.EpisodeMetadata.HeadOrNone())
        {
            metadata.Genres ??= [];
            metadata.Guids ??= [];

            foreach (ShowMetadata showMetadata in Optional(
                         templateEpisode.Season?.Show?.ShowMetadata.HeadOrNone()).Flatten())
            {
                showMetadata.Genres ??= [];
                showMetadata.Guids ??= [];

                string artworkPath = GetPrioritizedArtworkPath(showMetadata);

                var data = new
                {
                    ProgrammeStart = start,
                    ProgrammeStop = stop,
                    request.ChannelNumber,
                    HasCustomTitle = hasCustomTitle,
                    displayItem.CustomTitle,
                    ShowTitle = title,
                    EpisodeHasTitle = !string.IsNullOrWhiteSpace(subtitle),
                    EpisodeTitle = subtitle,
                    EpisodeHasPlot = !string.IsNullOrWhiteSpace(metadata.Plot),
                    EpisodePlot = metadata.Plot,
                    ShowHasYear = showMetadata.Year.HasValue,
                    ShowYear = showMetadata.Year,
                    ShowGenres = showMetadata.Genres.Map(g => g.Name).OrderBy(n => n),
                    EpisodeHasArtwork = !string.IsNullOrWhiteSpace(artworkPath),
                    EpisodeArtworkUrl = artworkPath,
                    SeasonNumber = templateEpisode.Season?.SeasonNumber ?? 0,
                    metadata.EpisodeNumber,
                    ShowHasContentRating = !string.IsNullOrWhiteSpace(showMetadata.ContentRating),
                    ShowContentRating = showMetadata.ContentRating,
                    ShowGuids = showMetadata.Guids.Map(g => g.Guid),
                    EpisodeGuids = metadata.Guids.Map(g => g.Guid)
                };

                var scriptObject = new ScriptObject();
                scriptObject.Import(data);
                templateContext.PushGlobal(scriptObject);

                return await episodeTemplate.RenderAsync(templateContext);
            }
        }

        return Option<string>.None;
    }

    private static async Task<Option<string>> ProcessMusicVideoTemplate(
        RefreshChannelData request,
        MusicVideo templateMusicVideo,
        string start,
        string stop,
        bool hasCustomTitle,
        PlayoutItem displayItem,
        string title,
        string subtitle,
        XmlTemplateContext templateContext,
        Template musicVideoTemplate)
    {
        foreach (MusicVideoMetadata metadata in templateMusicVideo.MusicVideoMetadata.HeadOrNone())
        {
            metadata.Genres ??= [];
            metadata.Artists ??= [];
            metadata.Studios ??= [];
            metadata.Directors ??= [];

            string artworkPath = GetPrioritizedArtworkPath(metadata);

            Option<ArtistMetadata> maybeMetadata =
                Optional(templateMusicVideo.Artist?.ArtistMetadata.HeadOrNone()).Flatten();

            var data = new
            {
                ProgrammeStart = start,
                ProgrammeStop = stop,
                request.ChannelNumber,
                HasCustomTitle = hasCustomTitle,
                displayItem.CustomTitle,
                ArtistTitle = title,
                MusicVideoTitle = subtitle,
                MusicVideoHasPlot = !string.IsNullOrWhiteSpace(metadata.Plot),
                MusicVideoPlot = metadata.Plot,
                MusicVideoHasYear = metadata.Year.HasValue,
                MusicVideoYear = metadata.Year,
                MusicVideoGenres = metadata.Genres.Map(g => g.Name).OrderBy(n => n),
                ArtistGenres = maybeMetadata.SelectMany(m => m.Genres.Map(g => g.Name)).OrderBy(n => n),
                MusicVideoHasArtwork = !string.IsNullOrWhiteSpace(artworkPath),
                MusicVideoArtworkUrl = artworkPath,
                MusicVideoHasTrack = metadata.Track.HasValue,
                MusicVideoTrack = metadata.Track,
                MusicVideoHasAlbum = !string.IsNullOrWhiteSpace(metadata.Album),
                MusicVideoAlbum = metadata.Album,
                MusicVideoHasReleaseDate = metadata.ReleaseDate.HasValue,
                MusicVideoReleaseDate = metadata.ReleaseDate,
                MusicVideoAllArtists = metadata.Artists.Map(a => a.Name),
                MusicVideoStudios = metadata.Studios.Map(s => s.Name),
                MusicVideoDirectors = metadata.Directors.Map(d => d.Name)
            };

            var scriptObject = new ScriptObject();
            scriptObject.Import(data);
            templateContext.PushGlobal(scriptObject);

            return await musicVideoTemplate.RenderAsync(templateContext);
        }

        return Option<string>.None;
    }

    private static async Task<Option<string>> ProcessSongTemplate(
        RefreshChannelData request,
        Song templateSong,
        string start,
        string stop,
        bool hasCustomTitle,
        PlayoutItem displayItem,
        string title,
        string subtitle,
        XmlTemplateContext templateContext,
        Template songTemplate)
    {
        foreach (SongMetadata metadata in templateSong.SongMetadata.HeadOrNone())
        {
            metadata.Genres ??= [];
            metadata.Studios ??= [];

            string artworkPath = GetPrioritizedArtworkPath(metadata);

            var data = new
            {
                ProgrammeStart = start,
                ProgrammeStop = stop,
                request.ChannelNumber,
                HasCustomTitle = hasCustomTitle,
                displayItem.CustomTitle,
                SongTitle = subtitle,
                SongArtists = metadata.Artists,
                SongAlbumArtists = metadata.AlbumArtists,
                SongHasYear = metadata.Year.HasValue,
                SongYear = metadata.Year,
                SongGenres = metadata.Genres.Map(g => g.Name).OrderBy(n => n),
                SongHasArtwork = !string.IsNullOrWhiteSpace(artworkPath),
                SongArtworkUrl = artworkPath,
                SongHasTrack = !string.IsNullOrWhiteSpace(metadata.Track),
                SongTrack = metadata.Track,
                SongHasComment = !string.IsNullOrWhiteSpace(metadata.Comment),
                SongComment = metadata.Comment,
                SongHasAlbum = !string.IsNullOrWhiteSpace(metadata.Album),
                SongAlbum = metadata.Album,
                SongHasReleaseDate = metadata.ReleaseDate.HasValue,
                SongReleaseDate = metadata.ReleaseDate,
                SongStudios = metadata.Studios.Map(s => s.Name)
            };

            var scriptObject = new ScriptObject();
            scriptObject.Import(data);
            templateContext.PushGlobal(scriptObject);

            return await songTemplate.RenderAsync(templateContext);
        }

        return Option<string>.None;
    }

    private static async Task<Option<string>> ProcessOtherVideoTemplate(
        RefreshChannelData request,
        OtherVideo templateOtherVideo,
        string start,
        string stop,
        bool hasCustomTitle,
        PlayoutItem displayItem,
        string title,
        XmlTemplateContext templateContext,
        Template otherVideoTemplate)
    {
        foreach (OtherVideoMetadata metadata in templateOtherVideo.OtherVideoMetadata.HeadOrNone())
        {
            metadata.Genres ??= [];
            metadata.Guids ??= [];

            var data = new
            {
                ProgrammeStart = start,
                ProgrammeStop = stop,
                request.ChannelNumber,
                HasCustomTitle = hasCustomTitle,
                displayItem.CustomTitle,
                OtherVideoTitle = title,
                OtherVideoHasPlot = !string.IsNullOrWhiteSpace(metadata.Plot),
                OtherVideoPlot = metadata.Plot,
                OtherVideoHasYear = metadata.Year.HasValue,
                OtherVideoYear = metadata.Year,
                OtherVideoGenres = metadata.Genres.Map(g => g.Name).OrderBy(n => n),
                OtherVideoHasContentRating = !string.IsNullOrWhiteSpace(metadata.ContentRating),
                OtherVideoContentRating = metadata.ContentRating
            };

            var scriptObject = new ScriptObject();
            scriptObject.Import(data);
            templateContext.PushGlobal(scriptObject);

            return await otherVideoTemplate.RenderAsync(templateContext);
        }

        return Option<string>.None;
    }

    private string GetMovieTemplateFileName()
    {
        string templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "movie.sbntxt");

        // fall back to default template
        if (!_localFileSystem.FileExists(templateFileName))
        {
            templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "_movie.sbntxt");
        }

        // fail if file doesn't exist
        if (!_localFileSystem.FileExists(templateFileName))
        {
            _logger.LogError(
                "Unable to generate movie XMLTV fragment without template file {File}; please restart ErsatzTV",
                templateFileName);

            return null;
        }

        return templateFileName;
    }

    private string GetEpisodeTemplateFileName()
    {
        string templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "episode.sbntxt");

        // fall back to default template
        if (!_localFileSystem.FileExists(templateFileName))
        {
            templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "_episode.sbntxt");
        }

        // fail if file doesn't exist
        if (!_localFileSystem.FileExists(templateFileName))
        {
            _logger.LogError(
                "Unable to generate episode XMLTV fragment without template file {File}; please restart ErsatzTV",
                templateFileName);

            return null;
        }

        return templateFileName;
    }

    private string GetMusicVideoTemplateFileName()
    {
        string templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "musicVideo.sbntxt");

        // fall back to default template
        if (!_localFileSystem.FileExists(templateFileName))
        {
            templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "_musicVideo.sbntxt");
        }

        // fail if file doesn't exist
        if (!_localFileSystem.FileExists(templateFileName))
        {
            _logger.LogError(
                "Unable to generate music video XMLTV fragment without template file {File}; please restart ErsatzTV",
                templateFileName);

            return null;
        }

        return templateFileName;
    }

    private string GetSongTemplateFileName()
    {
        string templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "song.sbntxt");

        // fall back to default template
        if (!_localFileSystem.FileExists(templateFileName))
        {
            templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "_song.sbntxt");
        }

        // fail if file doesn't exist
        if (!_localFileSystem.FileExists(templateFileName))
        {
            _logger.LogError(
                "Unable to generate song XMLTV fragment without template file {File}; please restart ErsatzTV",
                templateFileName);

            return null;
        }

        return templateFileName;
    }

    private string GetOtherVideoTemplateFileName()
    {
        string templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "otherVideo.sbntxt");

        // fall back to default template
        if (!_localFileSystem.FileExists(templateFileName))
        {
            templateFileName = Path.Combine(FileSystemLayout.ChannelGuideTemplatesFolder, "_otherVideo.sbntxt");
        }

        // fail if file doesn't exist
        if (!_localFileSystem.FileExists(templateFileName))
        {
            _logger.LogError(
                "Unable to generate other video XMLTV fragment without template file {File}; please restart ErsatzTV",
                templateFileName);

            return null;
        }

        return templateFileName;
    }

    private static string GetArtworkUrl(Artwork artwork, ArtworkKind artworkKind)
    {
        string artworkPath = artwork.Path;

        int height = artworkKind switch
        {
            ArtworkKind.Thumbnail => 220,
            _ => 440
        };

        if (artworkPath.StartsWith("http://", StringComparison.OrdinalIgnoreCase) ||
            artworkPath.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
        {
            return artworkPath;
        }

        if (artworkPath.StartsWith("jellyfin://", StringComparison.OrdinalIgnoreCase))
        {
            artworkPath = JellyfinUrl.PlaceholderProxyForArtwork(artworkPath, artworkKind, height);
        }
        else if (artworkPath.StartsWith("emby://", StringComparison.OrdinalIgnoreCase))
        {
            artworkPath = EmbyUrl.PlaceholderProxyForArtwork(artworkPath, artworkKind, height);
        }
        else
        {
            string artworkFolder = artworkKind switch
            {
                ArtworkKind.Thumbnail => "thumbnails",
                _ => "posters"
            };

            artworkPath = $"{{RequestBase}}/iptv/artwork/{artworkFolder}/{artwork.Path}.jpg{{AccessTokenUri}}";
        }

        return artworkPath;
    }

    private static string GetTitle(PlayoutItem playoutItem)
    {
        if (!string.IsNullOrWhiteSpace(playoutItem.CustomTitle))
        {
            return playoutItem.CustomTitle;
        }

        return playoutItem.MediaItem switch
        {
            Movie m => m.MovieMetadata.HeadOrNone().Map(mm => mm.Title ?? string.Empty)
                .IfNone("[unknown movie]"),
            Episode e => e.Season.Show.ShowMetadata.HeadOrNone().Map(em => em.Title ?? string.Empty)
                .IfNone("[unknown show]"),
            MusicVideo mv => mv.Artist.ArtistMetadata.HeadOrNone().Map(am => am.Title ?? string.Empty)
                .IfNone("[unknown artist]"),
            OtherVideo ov => ov.OtherVideoMetadata.HeadOrNone().Map(vm => vm.Title ?? string.Empty)
                .IfNone("[unknown video]"),
            _ => "[unknown]"
        };
    }

    private static string GetSubtitle(PlayoutItem playoutItem)
    {
        if (!string.IsNullOrWhiteSpace(playoutItem.CustomTitle))
        {
            return string.Empty;
        }

        return playoutItem.MediaItem switch
        {
            Episode e => e.EpisodeMetadata.HeadOrNone().Match(
                em => em.Title ?? string.Empty,
                () => string.Empty),
            MusicVideo mv => mv.MusicVideoMetadata.HeadOrNone().Match(
                mvm => mvm.Title ?? string.Empty,
                () => string.Empty),
            Song s => s.SongMetadata.HeadOrNone().Match(
                mvm => mvm.Title ?? string.Empty,
                () => string.Empty),
            _ => string.Empty
        };
    }

    private static string GetDescription(PlayoutItem playoutItem)
    {
        if (!string.IsNullOrWhiteSpace(playoutItem.CustomTitle))
        {
            return string.Empty;
        }

        return playoutItem.MediaItem switch
        {
            Movie m => m.MovieMetadata.HeadOrNone().Map(mm => mm.Plot ?? string.Empty).IfNone(string.Empty),
            Episode e => e.EpisodeMetadata.HeadOrNone().Map(em => em.Plot ?? string.Empty)
                .IfNone(string.Empty),
            MusicVideo mv => mv.MusicVideoMetadata.HeadOrNone().Map(mvm => mvm.Plot ?? string.Empty)
                .IfNone(string.Empty),
            OtherVideo ov => ov.OtherVideoMetadata.HeadOrNone().Map(ovm => ovm.Plot ?? string.Empty)
                .IfNone(string.Empty),
            _ => string.Empty
        };
    }

    private Option<ContentRating> GetContentRating(PlayoutItem playoutItem)
    {
        try
        {
            return playoutItem.MediaItem switch
            {
                Movie m => m.MovieMetadata
                    .HeadOrNone()
                    .Match(mm => ParseContentRating(mm.ContentRating, "MPAA"), () => None),
                Episode e => e.Season.Show.ShowMetadata
                    .HeadOrNone()
                    .Match(sm => ParseContentRating(sm.ContentRating, "VCHIP"), () => None),
                _ => None
            };
        }
        catch (Exception ex)
        {
            _logger.LogWarning(ex, "Failed to get content rating for playout item {Item}", GetTitle(playoutItem));
            return None;
        }
    }

    private static Option<ContentRating> ParseContentRating(string contentRating, string system)
    {
        Option<string> maybeFirst = (contentRating ?? string.Empty).Split('/').HeadOrNone();
        return maybeFirst.Map(
            first =>
            {
                string[] split = first.Split(':');
                if (split.Length == 2)
                {
                    return split[0].Equals("us", StringComparison.OrdinalIgnoreCase)
                        ? new ContentRating(system, split[1].ToUpperInvariant())
                        : new ContentRating(None, split[1].ToUpperInvariant());
                }

                return string.IsNullOrWhiteSpace(first)
                    ? Option<ContentRating>.None
                    : new ContentRating(None, first);
            }).Flatten();
    }

    private static string GetPrioritizedArtworkPath(Metadata metadata)
    {
        Option<string> maybeArtwork = Optional(metadata.Artwork).Flatten()
            .Filter(a => a.ArtworkKind == ArtworkKind.Poster)
            .HeadOrNone()
            .Map(a => GetArtworkUrl(a, ArtworkKind.Poster));

        if (maybeArtwork.IsNone)
        {
            maybeArtwork = Optional(metadata.Artwork).Flatten()
                .Filter(a => a.ArtworkKind == ArtworkKind.Thumbnail)
                .HeadOrNone()
                .Map(a => GetArtworkUrl(a, ArtworkKind.Thumbnail));
        }

        return maybeArtwork.IfNone(string.Empty);
    }

    private async Task<List<PlayoutItem>> CollectExternalJsonItems(string path)
    {
        var result = new List<PlayoutItem>();

        if (_localFileSystem.FileExists(path))
        {
            Option<ExternalJsonChannel> maybeChannel = JsonConvert.DeserializeObject<ExternalJsonChannel>(
                await File.ReadAllTextAsync(path));

            // must deserialize channel from json
            foreach (ExternalJsonChannel channel in maybeChannel)
            {
                // TODO: null start time should log and throw

                DateTimeOffset startTime = DateTimeOffset.Parse(
                    channel.StartTime ?? string.Empty,
                    CultureInfo.InvariantCulture,
                    DateTimeStyles.AssumeUniversal).ToLocalTime();

                for (var i = 0; i < channel.Programs.Length; i++)
                {
                    ExternalJsonProgram program = channel.Programs[i];
                    int milliseconds = program.Duration;
                    DateTimeOffset nextStart = startTime + TimeSpan.FromMilliseconds(milliseconds);
                    if (program.Duration >= channel.GuideMinimumDurationSeconds * 1000)
                    {
                        result.Add(BuildPlayoutItem(startTime, program, i));
                    }

                    startTime = nextStart;
                }
            }
        }

        return result;
    }

    private static PlayoutItem BuildPlayoutItem(DateTimeOffset startTime, ExternalJsonProgram program, int count)
    {
        MediaItem mediaItem = program.Type switch
        {
            "episode" => BuildEpisode(program),
            _ => BuildMovie(program)
        };

        return new PlayoutItem
        {
            Start = startTime.UtcDateTime,
            Finish = startTime.AddMilliseconds(program.Duration).UtcDateTime,
            FillerKind = FillerKind.None,
            ChapterTitle = null,
            GuideFinish = null,
            GuideGroup = count,
            CustomTitle = null,
            InPoint = TimeSpan.Zero,
            OutPoint = TimeSpan.FromMilliseconds(program.Duration),
            MediaItem = mediaItem
        };
    }

    private static Episode BuildEpisode(ExternalJsonProgram program)
    {
        var artwork = new List<Artwork>();
        if (!string.IsNullOrWhiteSpace(program.Icon))
        {
            artwork.Add(
                new Artwork
                {
                    ArtworkKind = ArtworkKind.Thumbnail,
                    Path = program.Icon,
                    SourcePath = program.Icon
                });
        }

        return new Episode
        {
            MediaVersions =
            [
                new MediaVersion
                {
                    Duration = TimeSpan.FromMilliseconds(program.Duration)
                }
            ],
            EpisodeMetadata =
            [
                new EpisodeMetadata
                {
                    EpisodeNumber = program.Episode,
                    Title = program.Title
                }
            ],
            Season = new Season
            {
                SeasonNumber = program.Season,
                Show = new Show
                {
                    ShowMetadata =
                    [
                        new ShowMetadata
                        {
                            Title = program.ShowTitle,
                            Artwork = artwork
                        }
                    ]
                }
            }
        };
    }

    private static Movie BuildMovie(ExternalJsonProgram program)
    {
        var artwork = new List<Artwork>();
        if (!string.IsNullOrWhiteSpace(program.Icon))
        {
            artwork.Add(
                new Artwork
                {
                    ArtworkKind = ArtworkKind.Poster,
                    Path = program.Icon,
                    SourcePath = program.Icon
                });
        }

        return new Movie
        {
            MediaVersions =
            [
                new MediaVersion
                {
                    Duration = TimeSpan.FromMilliseconds(program.Duration)
                }
            ],
            MovieMetadata =
            [
                new MovieMetadata
                {
                    Title = program.Title,
                    Year = program.Year,
                    Artwork = artwork
                }
            ]
        };
    }

    private sealed record ContentRating(Option<string> System, string Value);
}