using Bugsnag;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.FFmpeg;
using ErsatzTV.Core.Interfaces.FFmpeg;
using ErsatzTV.Core.Interfaces.Images;
using ErsatzTV.Core.Interfaces.Metadata;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Interfaces.Search;
using MediatR;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Core.Metadata;

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

    public TelevisionFolderScanner(
        ILocalFileSystem localFileSystem,
        ITelevisionRepository televisionRepository,
        ILocalStatisticsProvider localStatisticsProvider,
        ILocalMetadataProvider localMetadataProvider,
        IMetadataRepository metadataRepository,
        IImageCache imageCache,
        ISearchIndex searchIndex,
        ISearchRepository searchRepository,
        ILibraryRepository libraryRepository,
        IMediaItemRepository mediaItemRepository,
        IMediator mediator,
        IFFmpegProcessServiceFactory ffmpegProcessServiceFactory,
        ITempFilePool tempFilePool,
        IClient client,
        ILogger<TelevisionFolderScanner> logger) : base(
        localFileSystem,
        localStatisticsProvider,
        metadataRepository,
        mediaItemRepository,
        imageCache,
        ffmpegProcessServiceFactory,
        tempFilePool,
        client,
        logger)
    {
        _localFileSystem = localFileSystem;
        _televisionRepository = televisionRepository;
        _localMetadataProvider = localMetadataProvider;
        _metadataRepository = metadataRepository;
        _searchIndex = searchIndex;
        _searchRepository = searchRepository;
        _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)
    {
        decimal progressSpread = progressMax - progressMin;

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

        foreach (string showFolder in allShowFolders)
        {
            decimal percentCompletion = (decimal) allShowFolders.IndexOf(showFolder) / allShowFolders.Count;
            await _mediator.Publish(
                new LibraryScanProgress(libraryPath.LibraryId, progressMin + percentCompletion * progressSpread));

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

            await maybeShow.Match(
                async result =>
                {
                    await ScanSeasons(
                        libraryPath,
                        ffmpegPath,
                        ffprobePath,
                        result.Item,
                        showFolder);

                    if (result.IsAdded)
                    {
                        await _searchIndex.AddItems(_searchRepository, new List<MediaItem> { result.Item });
                    }
                    else if (result.IsUpdated)
                    {
                        await _searchIndex.UpdateItems(_searchRepository, new List<MediaItem> { result.Item });
                    }
                },
                error =>
                {
                    _logger.LogWarning(
                        "Error processing show in folder {Folder}: {Error}",
                        showFolder,
                        error.Value);
                    return Task.FromResult(Unit.Default);
                });
        }

        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 _searchIndex.RebuildItems(_searchRepository, episodeIds);
            }
            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 _searchIndex.RemoveItems(ids);

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

    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);
        return await maybeShow.Match(
            show => Right<BaseError, MediaItemScanResult<Show>>(new MediaItemScanResult<Show>(show)).AsTask(),
            async () => await _televisionRepository.AddShow(libraryPathId, showFolder, metadata));
    }

    private async Task<Unit> ScanSeasons(
        LibraryPath libraryPath,
        string ffmpegPath,
        string ffprobePath,
        Show show,
        string showFolder)
    {
        foreach (string seasonFolder in _localFileSystem.ListSubdirectories(showFolder).Filter(ShouldIncludeFolder)
                     .OrderBy(identity))
        {
            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);
            await maybeSeasonNumber.IfSomeAsync(
                async seasonNumber =>
                {
                    Either<BaseError, Season> maybeSeason = await _televisionRepository
                        .GetOrAddSeason(show, libraryPath.Id, seasonNumber)
                        .BindT(EnsureMetadataExists)
                        .BindT(season => UpdatePoster(season, seasonFolder));

                    await maybeSeason.Match(
                        async season =>
                        {
                            await ScanEpisodes(libraryPath, ffmpegPath, ffprobePath, season, seasonFolder);
                            await _libraryRepository.SetEtag(libraryPath, knownFolder, seasonFolder, etag);

                            season.Show = show;
                            await _searchIndex.UpdateItems(_searchRepository, new List<MediaItem> { season });
                        },
                        error =>
                        {
                            _logger.LogWarning(
                                "Error processing season in folder {Folder}: {Error}",
                                seasonFolder,
                                error.Value);
                            return Task.FromResult(Unit.Default);
                        });
                });
        }

        return Unit.Default;
    }

    private async Task<Unit> ScanEpisodes(
        LibraryPath libraryPath,
        string ffmpegPath,
        string ffprobePath,
        Season season,
        string seasonPath)
    {
        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(UpdateThumbnail)
                .BindT(e => FlagNormal(new MediaItemScanResult<Episode>(e)))
                .MapT(r => r.Item);

            await maybeEpisode.Match(
                async episode =>
                {
                    await _searchIndex.UpdateItems(_searchRepository, new List<MediaItem> { episode });
                },
                error =>
                {
                    _logger.LogWarning("Error processing episode at {Path}: {Error}", file, error.Value);
                    return Task.CompletedTask;
                });
        }

        // 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;
            await LocateNfoFileForShow(showFolder).Match(
                async nfoFile =>
                {
                    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;
                        }
                    }
                },
                async () =>
                {
                    if (!Optional(show.ShowMetadata).Flatten().Any())
                    {
                        _logger.LogDebug("Refreshing {Attribute} for {Path}", "Fallback Metadata", showFolder);
                        if (await _localMetadataProvider.RefreshFallbackMetadata(show, showFolder))
                        {
                            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>()
            };

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

        return season;
    }

    private async Task<Either<BaseError, Episode>> UpdateMetadata(Episode episode)
    {
        try
        {
            await LocateNfoFile(episode).Match(
                async nfoFile =>
                {
                    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);
                    }
                },
                async () =>
                {
                    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);
                    }
                });

            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)
    {
        try
        {
            Show show = result.Item;
            await LocateArtworkForShow(showFolder, artworkKind).IfSomeAsync(
                async artworkFile =>
                {
                    ShowMetadata metadata = show.ShowMetadata.Head();
                    await RefreshArtwork(artworkFile, metadata, artworkKind, None, None);
                });

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

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

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

    private async Task<Either<BaseError, Episode>> UpdateThumbnail(Episode episode)
    {
        try
        {
            await LocateThumbnail(episode).IfSomeAsync(
                async posterFile =>
                {
                    foreach (EpisodeMetadata metadata in episode.EpisodeMetadata)
                    {
                        await RefreshArtwork(posterFile, metadata, ArtworkKind.Thumbnail, None, None);
                    }
                });

            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;
    }
}