using Bugsnag;
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.Interfaces.Search;
using MediatR;
using Microsoft.Extensions.Logging;
using Seq = LanguageExt.Seq;

namespace ErsatzTV.Core.Metadata;

public class MovieFolderScanner : LocalFolderScanner, IMovieFolderScanner
{
    private readonly IClient _client;
    private readonly ILibraryRepository _libraryRepository;
    private readonly ILocalFileSystem _localFileSystem;
    private readonly ILocalMetadataProvider _localMetadataProvider;
    private readonly ILocalSubtitlesProvider _localSubtitlesProvider;
    private readonly ILogger<MovieFolderScanner> _logger;
    private readonly IMediator _mediator;
    private readonly IMovieRepository _movieRepository;
    private readonly ISearchIndex _searchIndex;
    private readonly ISearchRepository _searchRepository;

    public MovieFolderScanner(
        ILocalFileSystem localFileSystem,
        IMovieRepository movieRepository,
        ILocalStatisticsProvider localStatisticsProvider,
        ILocalSubtitlesProvider localSubtitlesProvider,
        ILocalMetadataProvider localMetadataProvider,
        IMetadataRepository metadataRepository,
        IImageCache imageCache,
        ISearchIndex searchIndex,
        ISearchRepository searchRepository,
        ILibraryRepository libraryRepository,
        IMediaItemRepository mediaItemRepository,
        IMediator mediator,
        IFFmpegProcessService ffmpegProcessService,
        ITempFilePool tempFilePool,
        IClient client,
        ILogger<MovieFolderScanner> logger)
        : base(
            localFileSystem,
            localStatisticsProvider,
            metadataRepository,
            mediaItemRepository,
            imageCache,
            ffmpegProcessService,
            tempFilePool,
            client,
            logger)
    {
        _localFileSystem = localFileSystem;
        _movieRepository = movieRepository;
        _localSubtitlesProvider = localSubtitlesProvider;
        _localMetadataProvider = localMetadataProvider;
        _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,
        CancellationToken cancellationToken)
    {
        try
        {
            decimal progressSpread = progressMax - progressMin;

            var foldersCompleted = 0;

            var folderQueue = new Queue<string>();
            foreach (string folder in _localFileSystem.ListSubdirectories(libraryPath.Path)
                         .Filter(ShouldIncludeFolder)
                         .OrderBy(identity))
            {
                folderQueue.Enqueue(folder);
            }

            while (folderQueue.Count > 0)
            {
                if (cancellationToken.IsCancellationRequested)
                {
                    return new ScanCanceled();
                }

                decimal percentCompletion = (decimal)foldersCompleted / (foldersCompleted + folderQueue.Count);
                await _mediator.Publish(
                    new LibraryScanProgress(libraryPath.LibraryId, progressMin + percentCompletion * progressSpread),
                    cancellationToken);

                string movieFolder = folderQueue.Dequeue();
                foldersCompleted++;

                var filesForEtag = _localFileSystem.ListFiles(movieFolder).ToList();

                var allFiles = filesForEtag
                    .Filter(f => VideoFileExtensions.Contains(Path.GetExtension(f)))
                    .Filter(f => !Path.GetFileName(f).StartsWith("._"))
                    .Filter(
                        f => !ExtraFiles.Any(
                            e => Path.GetFileNameWithoutExtension(f).EndsWith(e, StringComparison.OrdinalIgnoreCase)))
                    .ToList();

                if (allFiles.Count == 0)
                {
                    foreach (string subdirectory in _localFileSystem.ListSubdirectories(movieFolder)
                                 .Filter(ShouldIncludeFolder)
                                 .OrderBy(identity))
                    {
                        folderQueue.Enqueue(subdirectory);
                    }

                    continue;
                }

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

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

                _logger.LogDebug(
                    "UPDATE: Etag has changed for folder {Folder}",
                    movieFolder);

                foreach (string file in allFiles.OrderBy(identity))
                {
                    // TODO: figure out how to rebuild playlists
                    Either<BaseError, MediaItemScanResult<Movie>> maybeMovie = await _movieRepository
                        .GetOrAdd(libraryPath, file)
                        .BindT(movie => UpdateStatistics(movie, ffmpegPath, ffprobePath))
                        .BindT(UpdateMetadata)
                        .BindT(movie => UpdateArtwork(movie, ArtworkKind.Poster, cancellationToken))
                        .BindT(movie => UpdateArtwork(movie, ArtworkKind.FanArt, cancellationToken))
                        .BindT(UpdateSubtitles)
                        .BindT(FlagNormal);

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

                    foreach (MediaItemScanResult<Movie> result in maybeMovie.RightToSeq())
                    {
                        if (result.IsAdded || result.IsUpdated)
                        {
                            await _searchIndex.RebuildItems(_searchRepository, new List<int> { result.Item.Id });
                        }

                        await _libraryRepository.SetEtag(libraryPath, knownFolder, movieFolder, etag);
                    }
                }
            }

            foreach (string path in await _movieRepository.FindMoviePaths(libraryPath))
            {
                if (!_localFileSystem.FileExists(path))
                {
                    _logger.LogInformation("Flagging missing movie at {Path}", path);
                    List<int> ids = await FlagFileNotFound(libraryPath, path);
                    await _searchIndex.RebuildItems(_searchRepository, ids);
                }
                else if (Path.GetFileName(path).StartsWith("._"))
                {
                    _logger.LogInformation("Removing dot underscore file at {Path}", path);
                    List<int> ids = await _movieRepository.DeleteByPath(libraryPath, path);
                    await _searchIndex.RemoveItems(ids);
                }
            }

            await _libraryRepository.CleanEtagsForLibraryPath(libraryPath);
            return Unit.Default;
        }
        catch (Exception ex) when (ex is TaskCanceledException or OperationCanceledException)
        {
            return new ScanCanceled();
        }
        finally
        {
            _searchIndex.Commit();
        }
    }

    private async Task<Either<BaseError, MediaItemScanResult<Movie>>> UpdateMetadata(
        MediaItemScanResult<Movie> result)
    {
        try
        {
            Movie movie = result.Item;

            Option<string> maybeNfoFile = LocateNfoFile(movie);
            if (maybeNfoFile.IsNone)
            {
                if (!Optional(movie.MovieMetadata).Flatten().Any())
                {
                    string path = movie.MediaVersions.Head().MediaFiles.Head().Path;
                    _logger.LogDebug("Refreshing {Attribute} for {Path}", "Fallback Metadata", path);
                    if (await _localMetadataProvider.RefreshFallbackMetadata(movie))
                    {
                        result.IsUpdated = true;
                    }
                }
            }

            foreach (string nfoFile in maybeNfoFile)
            {
                bool shouldUpdate = Optional(movie.MovieMetadata).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(movie, nfoFile))
                    {
                        result.IsUpdated = true;
                    }
                }
            }

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

    private async Task<Either<BaseError, MediaItemScanResult<Movie>>> UpdateArtwork(
        MediaItemScanResult<Movie> result,
        ArtworkKind artworkKind,
        CancellationToken cancellationToken)
    {
        try
        {
            Movie movie = result.Item;
            Option<string> maybeArtwork = LocateArtwork(movie, artworkKind);
            foreach (string posterFile in maybeArtwork)
            {
                MovieMetadata metadata = movie.MovieMetadata.Head();
                await RefreshArtwork(posterFile, metadata, artworkKind, None, None, cancellationToken);
            }

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

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

    private Option<string> LocateNfoFile(Movie movie)
    {
        string path = movie.MediaVersions.Head().MediaFiles.Head().Path;
        string movieAsNfo = Path.ChangeExtension(path, "nfo");
        string movieNfo = Path.Combine(Path.GetDirectoryName(path) ?? string.Empty, "movie.nfo");
        return Seq.create(movieAsNfo, movieNfo)
            .Filter(s => _localFileSystem.FileExists(s))
            .HeadOrNone();
    }

    private Option<string> LocateArtwork(Movie movie, ArtworkKind artworkKind)
    {
        string segment = artworkKind switch
        {
            ArtworkKind.Poster => "poster",
            ArtworkKind.FanArt => "fanart",
            _ => throw new ArgumentOutOfRangeException(nameof(artworkKind))
        };

        string path = movie.MediaVersions.Head().MediaFiles.Head().Path;
        string folder = Path.GetDirectoryName(path) ?? string.Empty;
        IEnumerable<string> possibleMoviePosters = ImageFileExtensions.Collect(
                ext => new[] { $"{segment}.{ext}", Path.GetFileNameWithoutExtension(path) + $"-{segment}.{ext}" })
            .Map(f => Path.Combine(folder, f));
        Option<string> result = possibleMoviePosters.Filter(p => _localFileSystem.FileExists(p)).HeadOrNone();
        if (result.IsNone && artworkKind == ArtworkKind.Poster)
        {
            IEnumerable<string> possibleFolderPosters = ImageFileExtensions.Collect(
                    ext => new[] { $"folder.{ext}" })
                .Map(f => Path.Combine(folder, f));
            result = possibleFolderPosters.Filter(p => _localFileSystem.FileExists(p)).HeadOrNone();
        }

        return result;
    }
}