ErsatzTV/ErsatzTV.Application/Streaming/Queries/GetPlayoutItemProcessByChannelNumberHandler.cs

using CliWrap;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Domain.Filler;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.Extensions;
using ErsatzTV.Core.Interfaces.Emby;
using ErsatzTV.Core.Interfaces.FFmpeg;
using ErsatzTV.Core.Interfaces.Jellyfin;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Plex;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Scheduling;
using ErsatzTV.Infrastructure.Data;
using ErsatzTV.Infrastructure.Extensions;
using Microsoft.EntityFrameworkCore;

namespace ErsatzTV.Application.Streaming;

public class GetPlayoutItemProcessByChannelNumberHandler : FFmpegProcessHandler<GetPlayoutItemProcessByChannelNumber>
{
    private readonly IEmbyPathReplacementService _embyPathReplacementService;
    private readonly IMediaCollectionRepository _mediaCollectionRepository;
    private readonly ITelevisionRepository _televisionRepository;
    private readonly IArtistRepository _artistRepository;
    private readonly IJellyfinPathReplacementService _jellyfinPathReplacementService;
    private readonly IFFmpegProcessService _ffmpegProcessService;
    private readonly ILocalFileSystem _localFileSystem;
    private readonly IPlexPathReplacementService _plexPathReplacementService;
    private readonly ISongVideoGenerator _songVideoGenerator;

    public GetPlayoutItemProcessByChannelNumberHandler(
        IDbContextFactory<TvContext> dbContextFactory,
        IFFmpegProcessService ffmpegProcessService,
        ILocalFileSystem localFileSystem,
        IPlexPathReplacementService plexPathReplacementService,
        IJellyfinPathReplacementService jellyfinPathReplacementService,
        IEmbyPathReplacementService embyPathReplacementService,
        IMediaCollectionRepository mediaCollectionRepository,
        ITelevisionRepository televisionRepository,
        IArtistRepository artistRepository,
        ISongVideoGenerator songVideoGenerator)
        : base(dbContextFactory)
    {
        _ffmpegProcessService = ffmpegProcessService;
        _localFileSystem = localFileSystem;
        _plexPathReplacementService = plexPathReplacementService;
        _jellyfinPathReplacementService = jellyfinPathReplacementService;
        _embyPathReplacementService = embyPathReplacementService;
        _mediaCollectionRepository = mediaCollectionRepository;
        _televisionRepository = televisionRepository;
        _artistRepository = artistRepository;
        _songVideoGenerator = songVideoGenerator;
    }

    protected override async Task<Either<BaseError, PlayoutItemProcessModel>> GetProcess(
        TvContext dbContext,
        GetPlayoutItemProcessByChannelNumber request,
        Channel channel,
        string ffmpegPath,
        string ffprobePath,
        CancellationToken cancellationToken)
    {
        DateTimeOffset now = request.Now;

        Either<BaseError, PlayoutItemWithPath> maybePlayoutItem = await dbContext.PlayoutItems
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Episode).MediaVersions)
            .ThenInclude(mv => mv.MediaFiles)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Episode).MediaVersions)
            .ThenInclude(mv => mv.Streams)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Movie).MediaVersions)
            .ThenInclude(mv => mv.MediaFiles)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Movie).MediaVersions)
            .ThenInclude(mv => mv.Streams)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as MusicVideo).MediaVersions)
            .ThenInclude(mv => mv.MediaFiles)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as MusicVideo).MediaVersions)
            .ThenInclude(mv => mv.Streams)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as OtherVideo).MediaVersions)
            .ThenInclude(ov => ov.MediaFiles)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as OtherVideo).MediaVersions)
            .ThenInclude(ov => ov.Streams)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Song).MediaVersions)
            .ThenInclude(mv => mv.MediaFiles)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Song).MediaVersions)
            .ThenInclude(mv => mv.Streams)
            .Include(i => i.MediaItem)
            .ThenInclude(mi => (mi as Song).SongMetadata)
            .ThenInclude(sm => sm.Artwork)
            .Include(i => i.Watermark)
            .ForChannelAndTime(channel.Id, now)
            .Map(o => o.ToEither<BaseError>(new UnableToLocatePlayoutItem()))
            .BindT(ValidatePlayoutItemPath);

        if (maybePlayoutItem.LeftAsEnumerable().Any(e => e is UnableToLocatePlayoutItem))
        {
            maybePlayoutItem = await CheckForFallbackFiller(dbContext, channel, now);
        }

        foreach (PlayoutItemWithPath playoutItemWithPath in maybePlayoutItem.RightToSeq())
        {
            MediaVersion version = playoutItemWithPath.PlayoutItem.MediaItem.GetHeadVersion();

            string videoPath = playoutItemWithPath.Path;
            MediaVersion videoVersion = version;

            string audioPath = playoutItemWithPath.Path;
            MediaVersion audioVersion = version;

            Option<ChannelWatermark> maybeGlobalWatermark = await dbContext.ConfigElements
                .GetValue<int>(ConfigElementKey.FFmpegGlobalWatermarkId)
                .BindT(
                    watermarkId => dbContext.ChannelWatermarks
                        .SelectOneAsync(w => w.Id, w => w.Id == watermarkId));

            if (playoutItemWithPath.PlayoutItem.MediaItem is Song song)
            {
                (videoPath, videoVersion) = await _songVideoGenerator.GenerateSongVideo(
                    song,
                    channel,
                    Optional(playoutItemWithPath.PlayoutItem.Watermark),
                    maybeGlobalWatermark,
                    ffmpegPath,
                    ffprobePath,
                    cancellationToken);
            }

            bool saveReports = await dbContext.ConfigElements
                .GetValue<bool>(ConfigElementKey.FFmpegSaveReports)
                .Map(result => result.IfNone(false));

            Command process = await _ffmpegProcessService.ForPlayoutItem(
                ffmpegPath,
                ffprobePath,
                saveReports,
                channel,
                videoVersion,
                audioVersion,
                videoPath,
                audioPath,
                playoutItemWithPath.PlayoutItem.StartOffset,
                playoutItemWithPath.PlayoutItem.FinishOffset,
                request.StartAtZero ? playoutItemWithPath.PlayoutItem.StartOffset : now,
                Optional(playoutItemWithPath.PlayoutItem.Watermark),
                maybeGlobalWatermark,
                channel.FFmpegProfile.VaapiDriver,
                channel.FFmpegProfile.VaapiDevice,
                request.HlsRealtime,
                playoutItemWithPath.PlayoutItem.FillerKind,
                playoutItemWithPath.PlayoutItem.InPoint,
                playoutItemWithPath.PlayoutItem.OutPoint,
                request.PtsOffset,
                request.TargetFramerate);

            var result = new PlayoutItemProcessModel(
                process,
                playoutItemWithPath.PlayoutItem.FinishOffset - (request.StartAtZero ? playoutItemWithPath.PlayoutItem.StartOffset : now),
                playoutItemWithPath.PlayoutItem.FinishOffset);

            return Right<BaseError, PlayoutItemProcessModel>(result);
        }

        foreach (BaseError error in maybePlayoutItem.LeftToSeq())
        {
            Option<TimeSpan> maybeDuration = await dbContext.PlayoutItems
                        .Filter(pi => pi.Playout.ChannelId == channel.Id)
                        .Filter(pi => pi.Start > now.UtcDateTime)
                        .OrderBy(pi => pi.Start)
                        .FirstOrDefaultAsync(cancellationToken)
                        .Map(Optional)
                        .MapT(pi => pi.StartOffset - now);

            DateTimeOffset finish = maybeDuration.Match(d => now.Add(d), () => now);

            switch (error)
            {
                case UnableToLocatePlayoutItem:
                    Command offlineProcess = await _ffmpegProcessService.ForError(
                        ffmpegPath,
                        channel,
                        maybeDuration,
                        "Channel is Offline",
                        request.HlsRealtime,
                        request.PtsOffset);

                    return new PlayoutItemProcessModel(offlineProcess, maybeDuration, finish);
                case PlayoutItemDoesNotExistOnDisk:
                    Command doesNotExistProcess = await _ffmpegProcessService.ForError(
                        ffmpegPath,
                        channel,
                        maybeDuration,
                        error.Value,
                        request.HlsRealtime,
                        request.PtsOffset);

                    return new PlayoutItemProcessModel(doesNotExistProcess, maybeDuration, finish);
                default:
                    Command errorProcess = await _ffmpegProcessService.ForError(
                        ffmpegPath,
                        channel,
                        maybeDuration,
                        "Channel is Offline",
                        request.HlsRealtime,
                        request.PtsOffset);

                    return new PlayoutItemProcessModel(errorProcess, maybeDuration, finish);
            }
        }

        return BaseError.New($"Unexpected error locating playout item for channel {channel.Number}");
    }

    private async Task<Either<BaseError, PlayoutItemWithPath>> CheckForFallbackFiller(
        TvContext dbContext,
        Channel channel,
        DateTimeOffset now)
    {
        // check for channel fallback
        Option<FillerPreset> maybeFallback = await dbContext.FillerPresets
            .SelectOneAsync(w => w.Id, w => w.Id == channel.FallbackFillerId);

        // then check for global fallback
        if (maybeFallback.IsNone)
        {
            maybeFallback = await dbContext.ConfigElements
                .GetValue<int>(ConfigElementKey.FFmpegGlobalFallbackFillerId)
                .BindT(fillerId => dbContext.FillerPresets.SelectOneAsync(w => w.Id, w => w.Id == fillerId));
        }

        foreach (FillerPreset fallbackPreset in maybeFallback)
        {
            // turn this into a playout item

            var collectionKey = CollectionKey.ForFillerPreset(fallbackPreset);
            List<MediaItem> items = await MediaItemsForCollection.Collect(
                _mediaCollectionRepository,
                _televisionRepository,
                _artistRepository,
                collectionKey);

            // TODO: shuffle? does it really matter since we loop anyway
            MediaItem item = items[new Random().Next(items.Count)];
                
            Option<TimeSpan> maybeDuration = await dbContext.PlayoutItems
                        .Filter(pi => pi.Playout.ChannelId == channel.Id)
                        .Filter(pi => pi.Start > now.UtcDateTime)
                        .OrderBy(pi => pi.Start)
                        .FirstOrDefaultAsync()
                        .Map(Optional)
                        .MapT(pi => pi.StartOffset - now);

            MediaVersion version = item.GetHeadVersion();

            version.MediaFiles = await dbContext.MediaFiles
                .AsNoTracking()
                .Filter(mf => mf.MediaVersionId == version.Id)
                .ToListAsync();

            version.Streams = await dbContext.MediaStreams
                .AsNoTracking()
                .Filter(ms => ms.MediaVersionId == version.Id)
                .ToListAsync();

            DateTimeOffset finish = maybeDuration.Match(
                // next playout item exists
                // loop until it starts
                now.Add,
                // no next playout item exists
                // loop for 5 minutes if less than 30s, otherwise play full item
                () => version.Duration < TimeSpan.FromSeconds(30)
                    ? now.AddMinutes(5)
                    : now.Add(version.Duration));

            var playoutItem = new PlayoutItem
            {
                MediaItem = item,
                MediaItemId = item.Id,
                Start = now.UtcDateTime,
                Finish = finish.UtcDateTime,
                FillerKind = FillerKind.Fallback,
                InPoint = TimeSpan.Zero,
                OutPoint = version.Duration
            };
                
            return await ValidatePlayoutItemPath(playoutItem);
        }

        return new UnableToLocatePlayoutItem();
    }

    private async Task<Either<BaseError, PlayoutItemWithPath>> ValidatePlayoutItemPath(PlayoutItem playoutItem)
    {
        string path = await GetPlayoutItemPath(playoutItem);

        if (_localFileSystem.FileExists(path))
        {
            return new PlayoutItemWithPath(playoutItem, path);
        }

        return new PlayoutItemDoesNotExistOnDisk(path);
    }

    private async Task<string> GetPlayoutItemPath(PlayoutItem playoutItem)
    {
        MediaVersion version = playoutItem.MediaItem.GetHeadVersion();

        MediaFile file = version.MediaFiles.Head();
        string path = file.Path;
        return playoutItem.MediaItem switch
        {
            PlexMovie plexMovie => await _plexPathReplacementService.GetReplacementPlexPath(
                plexMovie.LibraryPathId,
                path),
            PlexEpisode plexEpisode => await _plexPathReplacementService.GetReplacementPlexPath(
                plexEpisode.LibraryPathId,
                path),
            JellyfinMovie jellyfinMovie => await _jellyfinPathReplacementService.GetReplacementJellyfinPath(
                jellyfinMovie.LibraryPathId,
                path),
            JellyfinEpisode jellyfinEpisode => await _jellyfinPathReplacementService.GetReplacementJellyfinPath(
                jellyfinEpisode.LibraryPathId,
                path),
            EmbyMovie embyMovie => await _embyPathReplacementService.GetReplacementEmbyPath(
                embyMovie.LibraryPathId,
                path),
            EmbyEpisode embyEpisode => await _embyPathReplacementService.GetReplacementEmbyPath(
                embyEpisode.LibraryPathId,
                path),
            _ => path
        };
    }

    private record PlayoutItemWithPath(PlayoutItem PlayoutItem, string Path);
}