using System.Collections.Immutable;
using Bugsnag;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Errors;
using ErsatzTV.Core.Extensions;
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;
using Seq = LanguageExt.Seq;

namespace ErsatzTV.Scanner.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 IMediaItemRepository _mediaItemRepository;
    private readonly IMediator _mediator;
    private readonly IMovieRepository _movieRepository;

    public MovieFolderScanner(
        ILocalFileSystem localFileSystem,
        IMovieRepository movieRepository,
        ILocalStatisticsProvider localStatisticsProvider,
        ILocalSubtitlesProvider localSubtitlesProvider,
        ILocalMetadataProvider localMetadataProvider,
        IMetadataRepository metadataRepository,
        IImageCache imageCache,
        ILibraryRepository libraryRepository,
        IMediaItemRepository mediaItemRepository,
        IMediator mediator,
        IFFmpegPngService ffmpegPngService,
        ITempFilePool tempFilePool,
        IClient client,
        ILogger<MovieFolderScanner> logger)
        : base(
            localFileSystem,
            localStatisticsProvider,
            metadataRepository,
            mediaItemRepository,
            imageCache,
            ffmpegPngService,
            tempFilePool,
            client,
            logger)
    {
        _localFileSystem = localFileSystem;
        _movieRepository = movieRepository;
        _localSubtitlesProvider = localSubtitlesProvider;
        _localMetadataProvider = localMetadataProvider;
        _libraryRepository = libraryRepository;
        _mediaItemRepository = mediaItemRepository;
        _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
        {
            ImmutableHashSet<string> allTrashedItems = await _mediaItemRepository.GetAllTrashedItems(libraryPath);

            decimal progressSpread = progressMax - progressMin;

            var foldersCompleted = 0;

            var folderQueue = new Queue<string>();

            string normalizedLibraryPath = libraryPath.Path.TrimEnd(
                Path.DirectorySeparatorChar,
                Path.AltDirectorySeparatorChar);
            if (libraryPath.Path != normalizedLibraryPath)
            {
                await _libraryRepository.UpdatePath(libraryPath, normalizedLibraryPath);
            }

            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 ScannerProgressUpdate(
                        libraryPath.LibraryId,
                        null,
                        progressMin + percentCompletion * progressSpread,
                        Array.Empty<int>(),
                        Array.Empty<int>()),
                    cancellationToken);

                string movieFolder = folderQueue.Dequeue();
                Option<int> maybeParentFolder = await _libraryRepository.GetParentFolderId(movieFolder);
                foldersCompleted++;

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

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

                string etag = FolderEtag.Calculate(movieFolder, _localFileSystem);
                LibraryFolder knownFolder = await _libraryRepository.GetOrAddFolder(
                    libraryPath,
                    maybeParentFolder,
                    movieFolder);

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

                    // store etag for now-empty folders
                    await _libraryRepository.SetEtag(libraryPath, knownFolder, movieFolder, etag);

                    continue;
                }

                if (knownFolder.Etag == etag)
                {
                    if (allFiles.Any(allTrashedItems.Contains))
                    {
                        _logger.LogDebug("Previously trashed items are now present in folder {Folder}", movieFolder);
                    }
                    else
                    {
                        // etag matches and no trashed items are now present, continue to next folder
                        continue;
                    }
                }
                else
                {
                    _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, knownFolder, file)
                        .BindT(movie => UpdateStatistics(movie, ffmpegPath, ffprobePath))
                        .BindT(video => UpdateLibraryFolderId(video, knownFolder))
                        .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 _mediator.Publish(
                                new ScannerProgressUpdate(
                                    libraryPath.LibraryId,
                                    null,
                                    null,
                                    new[] { result.Item.Id },
                                    Array.Empty<int>()),
                                cancellationToken);
                        }

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

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

    private async Task<Either<BaseError, MediaItemScanResult<Movie>>> UpdateLibraryFolderId(
        MediaItemScanResult<Movie> video,
        LibraryFolder libraryFolder)
    {
        MediaFile mediaFile = video.Item.GetHeadVersion().MediaFiles.Head();
        if (mediaFile.LibraryFolderId != libraryFolder.Id)
        {
            await _libraryRepository.UpdateLibraryFolderId(mediaFile, libraryFolder.Id);
            video.IsUpdated = true;
        }

        return video;
    }

    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;
    }
}