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;

namespace ErsatzTV.Scanner.Core.Metadata;

public class OtherVideoFolderScanner : LocalFolderScanner, IOtherVideoFolderScanner
{
    private readonly IClient _client;
    private readonly ILibraryRepository _libraryRepository;
    private readonly ILocalFileSystem _localFileSystem;
    private readonly ILocalMetadataProvider _localMetadataProvider;
    private readonly ILocalSubtitlesProvider _localSubtitlesProvider;
    private readonly ILocalChaptersProvider _localChaptersProvider;
    private readonly ILogger<OtherVideoFolderScanner> _logger;
    private readonly IMediaItemRepository _mediaItemRepository;
    private readonly IMediator _mediator;
    private readonly IOtherVideoRepository _otherVideoRepository;

    public OtherVideoFolderScanner(
        ILocalFileSystem localFileSystem,
        ILocalStatisticsProvider localStatisticsProvider,
        ILocalMetadataProvider localMetadataProvider,
        ILocalSubtitlesProvider localSubtitlesProvider,
        ILocalChaptersProvider localChaptersProvider,
        IMetadataRepository metadataRepository,
        IImageCache imageCache,
        IMediator mediator,
        IOtherVideoRepository otherVideoRepository,
        ILibraryRepository libraryRepository,
        IMediaItemRepository mediaItemRepository,
        IFFmpegPngService ffmpegPngService,
        ITempFilePool tempFilePool,
        IClient client,
        ILogger<OtherVideoFolderScanner> logger) : base(
        localFileSystem,
        localStatisticsProvider,
        metadataRepository,
        mediaItemRepository,
        imageCache,
        ffmpegPngService,
        tempFilePool,
        client,
        logger)
    {
        _localFileSystem = localFileSystem;
        _localMetadataProvider = localMetadataProvider;
        _localSubtitlesProvider = localSubtitlesProvider;
        _localChaptersProvider = localChaptersProvider;
        _mediator = mediator;
        _otherVideoRepository = otherVideoRepository;
        _libraryRepository = libraryRepository;
        _mediaItemRepository = mediaItemRepository;
        _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 allFolders = new System.Collections.Generic.HashSet<string>();
            var folderQueue = new Queue<string>();

            ImmutableHashSet<string> allTrashedItems = await _mediaItemRepository.GetAllTrashedItems(libraryPath);

            string normalizedLibraryPath = libraryPath.Path.TrimEnd(
                Path.DirectorySeparatorChar,
                Path.AltDirectorySeparatorChar);
            if (libraryPath.Path != normalizedLibraryPath)
            {
                _logger.LogDebug(
                    "Normalizing library path from {Original} to {Normalized}",
                    libraryPath.Path,
                    normalizedLibraryPath);
                await _libraryRepository.UpdatePath(libraryPath, normalizedLibraryPath);
            }

            if (ShouldIncludeFolder(libraryPath.Path) && allFolders.Add(libraryPath.Path))
            {
                _logger.LogDebug("Adding folder to scanner queue: {Folder}", libraryPath.Path);
                folderQueue.Enqueue(libraryPath.Path);
            }

            foreach (string folder in _localFileSystem.ListSubdirectories(libraryPath.Path)
                         .Filter(ShouldIncludeFolder)
                         .Filter(allFolders.Add)
                         .OrderBy(identity))
            {
                _logger.LogDebug("Adding folder to scanner queue: {Folder}", folder);
                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 otherVideoFolder = folderQueue.Dequeue();
                Option<int> maybeParentFolder =
                    await _libraryRepository.GetParentFolderId(libraryPath, otherVideoFolder);

                foldersCompleted++;

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

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

                foreach (string subdirectory in _localFileSystem.ListSubdirectories(otherVideoFolder)
                             .Filter(ShouldIncludeFolder)
                             .Filter(allFolders.Add)
                             .OrderBy(identity))
                {
                    _logger.LogDebug("Adding folder to scanner queue: {Folder}", subdirectory);
                    folderQueue.Enqueue(subdirectory);
                }

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

                if (knownFolder.Etag == etag)
                {
                    if (allFiles.Any(allTrashedItems.Contains))
                    {
                        _logger.LogDebug(
                            "Previously trashed items are now present in folder {Folder}",
                            otherVideoFolder);
                    }
                    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}",
                        otherVideoFolder);
                }

                var hasErrors = false;

                foreach (string file in allFiles.OrderBy(identity))
                {
                    _logger.LogDebug("Processing other video file {File}", file);

                    Either<BaseError, MediaItemScanResult<OtherVideo>> maybeVideo = await _otherVideoRepository
                        .GetOrAdd(libraryPath, knownFolder, file)
                        .BindT(video => UpdateStatistics(video, ffmpegPath, ffprobePath))
                        .BindT(video => UpdateLibraryFolderId(video, knownFolder))
                        .BindT(UpdateMetadata)
                        .BindT(video => UpdateThumbnail(video, cancellationToken))
                        .BindT(UpdateSubtitles)
                        .BindT(UpdateChapters)
                        .BindT(FlagNormal);

                    foreach (BaseError error in maybeVideo.LeftToSeq())
                    {
                        _logger.LogWarning("Error processing other video at {Path}: {Error}", file, error.Value);
                        hasErrors = true;
                    }

                    foreach (MediaItemScanResult<OtherVideo> result in maybeVideo.RightToSeq())
                    {
                        if (result.IsAdded || result.IsUpdated)
                        {
                            await _mediator.Publish(
                                new ScannerProgressUpdate(
                                    libraryPath.LibraryId,
                                    null,
                                    null,
                                    [result.Item.Id],
                                    Array.Empty<int>()),
                                cancellationToken);
                        }
                    }
                }

                // only do this once per folder and only if all files processed successfully
                if (!hasErrors)
                {
                    await _libraryRepository.SetEtag(libraryPath, knownFolder, otherVideoFolder, etag);
                }
            }

            foreach (string path in await _otherVideoRepository.FindOtherVideoPaths(libraryPath))
            {
                if (!_localFileSystem.FileExists(path))
                {
                    _logger.LogInformation("Flagging missing other video at {Path}", path);
                    List<int> otherVideoIds = await FlagFileNotFound(libraryPath, path);
                    await _mediator.Publish(
                        new ScannerProgressUpdate(
                            libraryPath.LibraryId,
                            null,
                            null,
                            otherVideoIds.ToArray(),
                            Array.Empty<int>()),
                        cancellationToken);
                }
                else if (Path.GetFileName(path).StartsWith("._", StringComparison.OrdinalIgnoreCase))
                {
                    _logger.LogInformation("Removing dot underscore file at {Path}", path);
                    List<int> otherVideoIds = await _otherVideoRepository.DeleteByPath(libraryPath, path);
                    await _mediator.Publish(
                        new ScannerProgressUpdate(
                            libraryPath.LibraryId,
                            null,
                            null,
                            Array.Empty<int>(),
                            otherVideoIds.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<OtherVideo>>> UpdateLibraryFolderId(
        MediaItemScanResult<OtherVideo> 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<OtherVideo>>> UpdateMetadata(
        MediaItemScanResult<OtherVideo> result)
    {
        try
        {
            OtherVideo otherVideo = result.Item;
            string path = otherVideo.MediaVersions.Head().MediaFiles.Head().Path;

            Option<string> maybeNfoFile = new List<string> { Path.ChangeExtension(path, "nfo") }
                .Filter(_localFileSystem.FileExists)
                .HeadOrNone();

            if (maybeNfoFile.IsNone)
            {
                if (!Optional(otherVideo.OtherVideoMetadata).Flatten().Any())
                {
                    _logger.LogDebug("Refreshing {Attribute} for {Path}", "Fallback Metadata", path);
                    if (await _localMetadataProvider.RefreshFallbackMetadata(otherVideo))
                    {
                        result.IsUpdated = true;
                    }
                }
            }

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

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

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

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

    private async Task<Either<BaseError, MediaItemScanResult<OtherVideo>>> UpdateThumbnail(
        MediaItemScanResult<OtherVideo> result,
        CancellationToken cancellationToken)
    {
        try
        {
            OtherVideo otherVideo = result.Item;

            Option<string> maybeThumbnail = LocateThumbnail(otherVideo);
            foreach (string thumbnailFile in maybeThumbnail)
            {
                OtherVideoMetadata metadata = otherVideo.OtherVideoMetadata.Head();
                await RefreshArtwork(thumbnailFile, metadata, ArtworkKind.Thumbnail, None, None, cancellationToken);
            }

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

    private Option<string> LocateThumbnail(OtherVideo otherVideo)
    {
        string path = otherVideo.MediaVersions.Head().MediaFiles.Head().Path;
        return ImageFileExtensions
            .Map(ext => Path.ChangeExtension(path, ext))
            .Filter(f => _localFileSystem.FileExists(f))
            .HeadOrNone();
    }
}