using Bugsnag;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.Interfaces.FFmpeg;
using ErsatzTV.Core.Interfaces.Images;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.MediaSources;
using ErsatzTV.Core.Metadata;
using ErsatzTV.Scanner.Core.Interfaces.FFmpeg;
using ErsatzTV.Scanner.Core.Interfaces.Metadata;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Scanner.Core.Metadata;

public class TelevisionFolderScanner : LocalFolderScanner, ITelevisionFolderScanner
{
    private readonly IClient _client;
    private readonly ILibraryRepository _libraryRepository;
    private readonly ILocalFileSystem _localFileSystem;
    private readonly ILocalMetadataProvider _localMetadataProvider;
    private readonly ILocalSubtitlesProvider _localSubtitlesProvider;
    private readonly ILogger<TelevisionFolderScanner> _logger;
    private readonly IMediator _mediator;
    private readonly IMetadataRepository _metadataRepository;
    private readonly ITelevisionRepository _televisionRepository;

    public TelevisionFolderScanner(
        ILocalFileSystem localFileSystem,
        ITelevisionRepository televisionRepository,
        ILocalStatisticsProvider localStatisticsProvider,
        ILocalMetadataProvider localMetadataProvider,
        ILocalSubtitlesProvider localSubtitlesProvider,
        IMetadataRepository metadataRepository,
        IImageCache imageCache,
        ILibraryRepository libraryRepository,
        IMediaItemRepository mediaItemRepository,
        IMediator mediator,
        IFFmpegPngService ffmpegPngService,
        ITempFilePool tempFilePool,
        IClient client,
        ILogger<TelevisionFolderScanner> logger) : base(
        localFileSystem,
        localStatisticsProvider,
        metadataRepository,
        mediaItemRepository,
        imageCache,
        ffmpegPngService,
        tempFilePool,
        client,
        logger)
    {
        _localFileSystem = localFileSystem;
        _televisionRepository = televisionRepository;
        _localMetadataProvider = localMetadataProvider;
        _localSubtitlesProvider = localSubtitlesProvider;
        _metadataRepository = metadataRepository;
        _libraryRepository = libraryRepository;
        _mediator = mediator;
        _client = client;
        _logger = logger;
    }

    public async Task<Either<BaseError, Unit>> ScanFolder(
        LibraryPath libraryPath,
        string ffmpegPath,
        string ffprobePath,
        decimal progressMin,
        decimal progressMax,
        CancellationToken cancellationToken)
    {
        try
        {
            decimal progressSpread = progressMax - progressMin;

            var allShowFolders = _localFileSystem.ListSubdirectories(libraryPath.Path)
                .Filter(ShouldIncludeFolder)
                .OrderBy(identity)
                .ToList();

            foreach (string showFolder in allShowFolders)
            {
                if (cancellationToken.IsCancellationRequested)
                {
                    return new ScanCanceled();
                }

                decimal percentCompletion = (decimal)allShowFolders.IndexOf(showFolder) / allShowFolders.Count;
                await _mediator.Publish(
                    new ScannerProgressUpdate(
                        libraryPath.LibraryId,
                        null,
                        progressMin + percentCompletion * progressSpread,
                        Array.Empty<int>(),
                        Array.Empty<int>()),
                    cancellationToken);

                Either<BaseError, MediaItemScanResult<Show>> maybeShow =
                    await FindOrCreateShow(libraryPath.Id, showFolder)
                        .BindT(show => UpdateMetadataForShow(show, showFolder))
                        .BindT(show => UpdateArtworkForShow(show, showFolder, ArtworkKind.Poster, cancellationToken))
                        .BindT(show => UpdateArtworkForShow(show, showFolder, ArtworkKind.FanArt, cancellationToken))
                        .BindT(
                            show => UpdateArtworkForShow(show, showFolder, ArtworkKind.Thumbnail, cancellationToken));

                foreach (BaseError error in maybeShow.LeftToSeq())
                {
                    _logger.LogWarning(
                        "Error processing show in folder {Folder}: {Error}",
                        showFolder,
                        error.Value);
                }

                foreach (MediaItemScanResult<Show> result in maybeShow.RightToSeq())
                {
                    // add show to search index right away
                    if (result.IsAdded || result.IsUpdated)
                    {
                        await _mediator.Publish(
                            new ScannerProgressUpdate(
                                libraryPath.LibraryId,
                                null,
                                null,
                                new[] { result.Item.Id },
                                Array.Empty<int>()),
                            cancellationToken);
                    }

                    Either<BaseError, Unit> scanResult = await ScanSeasons(
                        libraryPath,
                        ffmpegPath,
                        ffprobePath,
                        result.Item,
                        showFolder,
                        cancellationToken);

                    foreach (ScanCanceled error in scanResult.LeftToSeq().OfType<ScanCanceled>())
                    {
                        return error;
                    }
                }
            }

            foreach (string path in await _televisionRepository.FindEpisodePaths(libraryPath))
            {
                if (!_localFileSystem.FileExists(path))
                {
                    _logger.LogInformation("Flagging missing episode at {Path}", path);

                    List<int> episodeIds = await FlagFileNotFound(libraryPath, path);
                    await _mediator.Publish(
                        new ScannerProgressUpdate(
                            libraryPath.LibraryId,
                            null,
                            null,
                            episodeIds.ToArray(),
                            Array.Empty<int>()),
                        cancellationToken);
                }
                else if (Path.GetFileName(path).StartsWith("._"))
                {
                    _logger.LogInformation("Removing dot underscore file at {Path}", path);
                    await _televisionRepository.DeleteByPath(libraryPath, path);
                }
            }

            await _libraryRepository.CleanEtagsForLibraryPath(libraryPath);

            await _televisionRepository.DeleteEmptySeasons(libraryPath);
            List<int> ids = await _televisionRepository.DeleteEmptyShows(libraryPath);
            await _mediator.Publish(
                new ScannerProgressUpdate(
                    libraryPath.LibraryId,
                    null,
                    null,
                    Array.Empty<int>(),
                    ids.ToArray()),
                cancellationToken);

            return Unit.Default;
        }
        catch (Exception ex) when (ex is TaskCanceledException or OperationCanceledException)
        {
            return new ScanCanceled();
        }
    }

    private async Task<Either<BaseError, MediaItemScanResult<Show>>> FindOrCreateShow(
        int libraryPathId,
        string showFolder)
    {
        ShowMetadata metadata = await _localMetadataProvider.GetMetadataForShow(showFolder);
        Option<Show> maybeShow = await _televisionRepository.GetShowByMetadata(libraryPathId, metadata);

        foreach (Show show in maybeShow)
        {
            return new MediaItemScanResult<Show>(show);
        }

        return await _televisionRepository.AddShow(libraryPathId, metadata);
    }

    private async Task<Either<BaseError, Unit>> ScanSeasons(
        LibraryPath libraryPath,
        string ffmpegPath,
        string ffprobePath,
        Show show,
        string showFolder,
        CancellationToken cancellationToken)
    {
        foreach (string seasonFolder in _localFileSystem.ListSubdirectories(showFolder).Filter(ShouldIncludeFolder)
                     .OrderBy(identity))
        {
            if (cancellationToken.IsCancellationRequested)
            {
                return new ScanCanceled();
            }

            string etag = FolderEtag.CalculateWithSubfolders(seasonFolder, _localFileSystem);
            Option<LibraryFolder> knownFolder = libraryPath.LibraryFolders
                .Filter(f => f.Path == seasonFolder)
                .HeadOrNone();

            // skip folder if etag matches
            if (await knownFolder.Map(f => f.Etag ?? string.Empty).IfNoneAsync(string.Empty) == etag)
            {
                continue;
            }

            Option<int> maybeSeasonNumber = SeasonNumberForFolder(seasonFolder);
            foreach (int seasonNumber in maybeSeasonNumber)
            {
                Either<BaseError, Season> maybeSeason = await _televisionRepository
                    .GetOrAddSeason(show, libraryPath.Id, seasonNumber)
                    .BindT(EnsureMetadataExists)
                    .BindT(season => UpdatePoster(season, seasonFolder, cancellationToken));

                foreach (BaseError error in maybeSeason.LeftToSeq())
                {
                    _logger.LogWarning(
                        "Error processing season in folder {Folder}: {Error}",
                        seasonFolder,
                        error.Value);
                }

                foreach (Season season in maybeSeason.RightToSeq())
                {
                    Either<BaseError, Unit> scanResult = await ScanEpisodes(
                        libraryPath,
                        ffmpegPath,
                        ffprobePath,
                        season,
                        seasonFolder,
                        cancellationToken);

                    foreach (ScanCanceled error in scanResult.LeftToSeq().OfType<ScanCanceled>())
                    {
                        return error;
                    }

                    await _libraryRepository.SetEtag(libraryPath, knownFolder, seasonFolder, etag);

                    season.Show = show;

                    await _mediator.Publish(
                        new ScannerProgressUpdate(
                            libraryPath.LibraryId,
                            null,
                            null,
                            new[] { season.Id },
                            Array.Empty<int>()),
                        cancellationToken);
                }
            }
        }

        return Unit.Default;
    }

    private async Task<Either<BaseError, Unit>> ScanEpisodes(
        LibraryPath libraryPath,
        string ffmpegPath,
        string ffprobePath,
        Season season,
        string seasonPath,
        CancellationToken cancellationToken)
    {
        var allSeasonFiles = _localFileSystem.ListSubdirectories(seasonPath)
            .Map(_localFileSystem.ListFiles)
            .Flatten()
            .Append(_localFileSystem.ListFiles(seasonPath))
            .Filter(f => VideoFileExtensions.Contains(Path.GetExtension(f)))
            .Filter(f => !Path.GetFileName(f).StartsWith("._"))
            .OrderBy(identity)
            .ToList();

        foreach (string file in allSeasonFiles)
        {
            // TODO: figure out how to rebuild playlists
            Either<BaseError, Episode> maybeEpisode = await _televisionRepository
                .GetOrAddEpisode(season, libraryPath, file)
                .BindT(
                    episode => UpdateStatistics(new MediaItemScanResult<Episode>(episode), ffmpegPath, ffprobePath)
                        .MapT(_ => episode))
                .BindT(UpdateMetadata)
                .BindT(e => UpdateThumbnail(e, cancellationToken))
                .BindT(UpdateSubtitles)
                .BindT(e => FlagNormal(new MediaItemScanResult<Episode>(e)))
                .MapT(r => r.Item);

            foreach (BaseError error in maybeEpisode.LeftToSeq())
            {
                _logger.LogWarning("Error processing episode at {Path}: {Error}", file, error.Value);
            }

            foreach (Episode episode in maybeEpisode.RightToSeq())
            {
                await _mediator.Publish(
                    new ScannerProgressUpdate(
                        libraryPath.LibraryId,
                        null,
                        null,
                        new[] { episode.Id },
                        Array.Empty<int>()),
                    cancellationToken);
            }
        }

        // TODO: remove missing episodes?

        return Unit.Default;
    }

    private async Task<Either<BaseError, MediaItemScanResult<Show>>> UpdateMetadataForShow(
        MediaItemScanResult<Show> result,
        string showFolder)
    {
        try
        {
            Show show = result.Item;

            Option<string> maybeNfo = LocateNfoFileForShow(showFolder);
            if (maybeNfo.IsNone)
            {
                if (!Optional(show.ShowMetadata).Flatten().Any())
                {
                    _logger.LogDebug("Refreshing {Attribute} for {Path}", "Fallback Metadata", showFolder);
                    if (await _localMetadataProvider.RefreshFallbackMetadata(show, showFolder))
                    {
                        result.IsUpdated = true;
                    }
                }
            }

            foreach (string nfoFile in maybeNfo)
            {
                bool shouldUpdate = Optional(show.ShowMetadata).Flatten().HeadOrNone().Match(
                    m => m.MetadataKind == MetadataKind.Fallback ||
                         m.DateUpdated != _localFileSystem.GetLastWriteTime(nfoFile),
                    true);

                if (shouldUpdate)
                {
                    _logger.LogDebug("Refreshing {Attribute} from {Path}", "Sidecar Metadata", nfoFile);
                    if (await _localMetadataProvider.RefreshSidecarMetadata(show, nfoFile))
                    {
                        result.IsUpdated = true;
                    }
                }
            }

            return result;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private async Task<Either<BaseError, Season>> EnsureMetadataExists(Season season)
    {
        season.SeasonMetadata ??= new List<SeasonMetadata>();

        if (!season.SeasonMetadata.Any())
        {
            var metadata = new SeasonMetadata
            {
                SeasonId = season.Id,
                Season = season,
                DateAdded = DateTime.UtcNow,
                Guids = new List<MetadataGuid>(),
                Tags = new List<Tag>()
            };

            season.SeasonMetadata.Add(metadata);
            await _metadataRepository.Add(metadata);
        }

        return season;
    }

    private async Task<Either<BaseError, Episode>> UpdateMetadata(Episode episode)
    {
        try
        {
            Option<string> maybeNfo = LocateNfoFile(episode);
            if (maybeNfo.IsNone)
            {
                bool shouldUpdate = Optional(episode.EpisodeMetadata).Flatten().HeadOrNone().Match(
                    m => m.DateUpdated == SystemTime.MinValueUtc,
                    true);

                if (shouldUpdate)
                {
                    string path = episode.MediaVersions.Head().MediaFiles.Head().Path;
                    _logger.LogDebug("Refreshing {Attribute} for {Path}", "Fallback Metadata", path);
                    await _localMetadataProvider.RefreshFallbackMetadata(episode);
                }
            }

            foreach (string nfoFile in maybeNfo)
            {
                bool shouldUpdate = Optional(episode.EpisodeMetadata).Flatten().HeadOrNone().Match(
                    m => m.MetadataKind == MetadataKind.Fallback ||
                         m.DateUpdated != _localFileSystem.GetLastWriteTime(nfoFile),
                    true);

                if (shouldUpdate)
                {
                    _logger.LogDebug("Refreshing {Attribute} from {Path}", "Sidecar Metadata", nfoFile);
                    await _localMetadataProvider.RefreshSidecarMetadata(episode, nfoFile);
                }
            }

            return episode;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private async Task<Either<BaseError, MediaItemScanResult<Show>>> UpdateArtworkForShow(
        MediaItemScanResult<Show> result,
        string showFolder,
        ArtworkKind artworkKind,
        CancellationToken cancellationToken)
    {
        try
        {
            Show show = result.Item;
            Option<string> maybeArtwork = LocateArtworkForShow(showFolder, artworkKind);
            foreach (string artworkFile in maybeArtwork)
            {
                ShowMetadata metadata = show.ShowMetadata.Head();
                await RefreshArtwork(artworkFile, metadata, artworkKind, None, None, cancellationToken);
            }

            return result;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private async Task<Either<BaseError, Season>> UpdatePoster(
        Season season,
        string seasonFolder,
        CancellationToken cancellationToken)
    {
        try
        {
            Option<string> maybePoster = LocatePoster(season, seasonFolder);
            foreach (string posterFile in maybePoster)
            {
                SeasonMetadata metadata = season.SeasonMetadata.Head();
                await RefreshArtwork(posterFile, metadata, ArtworkKind.Poster, None, None, cancellationToken);
            }

            return season;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private async Task<Either<BaseError, Episode>> UpdateThumbnail(Episode episode, CancellationToken cancellationToken)
    {
        try
        {
            Option<string> maybeThumbnail = LocateThumbnail(episode);
            foreach (string thumbnailFile in maybeThumbnail)
            {
                foreach (EpisodeMetadata metadata in episode.EpisodeMetadata)
                {
                    await RefreshArtwork(
                        thumbnailFile,
                        metadata,
                        ArtworkKind.Thumbnail,
                        None,
                        None,
                        cancellationToken);
                }
            }

            return episode;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private async Task<Either<BaseError, Episode>> UpdateSubtitles(Episode episode)
    {
        try
        {
            await _localSubtitlesProvider.UpdateSubtitles(episode, None, true);
            return episode;
        }
        catch (Exception ex)
        {
            _client.Notify(ex);
            return BaseError.New(ex.ToString());
        }
    }

    private Option<string> LocateNfoFileForShow(string showFolder) =>
        Optional(Path.Combine(showFolder, "tvshow.nfo")).Filter(s => _localFileSystem.FileExists(s));

    private Option<string> LocateNfoFile(Episode episode)
    {
        string path = episode.MediaVersions.Head().MediaFiles.Head().Path;
        return Optional(Path.ChangeExtension(path, "nfo")).Filter(s => _localFileSystem.FileExists(s));
    }

    private Option<string> LocateArtworkForShow(string showFolder, ArtworkKind artworkKind)
    {
        string[] segments = artworkKind switch
        {
            ArtworkKind.Poster => new[] { "poster", "folder" },
            ArtworkKind.FanArt => new[] { "fanart" },
            ArtworkKind.Thumbnail => new[] { "thumb" },
            _ => throw new ArgumentOutOfRangeException(nameof(artworkKind))
        };

        return ImageFileExtensions
            .Map(ext => segments.Map(segment => $"{segment}.{ext}"))
            .Flatten()
            .Map(f => Path.Combine(showFolder, f))
            .Filter(s => _localFileSystem.FileExists(s))
            .HeadOrNone();
    }

    private Option<string> LocatePoster(Season season, string seasonFolder)
    {
        string folder = Path.GetDirectoryName(seasonFolder) ?? string.Empty;
        return ImageFileExtensions
            .Map(ext => Path.Combine(folder, $"season{season.SeasonNumber:00}-poster.{ext}"))
            .Filter(s => _localFileSystem.FileExists(s))
            .HeadOrNone();
    }

    private Option<string> LocateThumbnail(Episode episode)
    {
        string path = episode.MediaVersions.Head().MediaFiles.Head().Path;
        string folder = Path.GetDirectoryName(path) ?? string.Empty;
        return ImageFileExtensions
            .Map(ext => Path.GetFileNameWithoutExtension(path) + $"-thumb.{ext}")
            .Map(f => Path.Combine(folder, f))
            .Filter(f => _localFileSystem.FileExists(f))
            .HeadOrNone();
    }

    private static Option<int> SeasonNumberForFolder(string folder)
    {
        if (int.TryParse(folder.Split(" ").Last(), out int seasonNumber))
        {
            return seasonNumber;
        }

        if (folder.EndsWith("specials", StringComparison.OrdinalIgnoreCase))
        {
            return 0;
        }

        return None;
    }
}