using System.IO.Abstractions;
using ErsatzTV.Core;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Extensions;
using ErsatzTV.Core.Interfaces.Jellyfin;
using ErsatzTV.Core.Interfaces.Repositories;
using ErsatzTV.Core.Jellyfin;
using ErsatzTV.Core.Metadata;
using ErsatzTV.Scanner.Core.Interfaces;
using ErsatzTV.Scanner.Core.Metadata;
using Microsoft.Extensions.Logging;

namespace ErsatzTV.Scanner.Core.Jellyfin;

public class JellyfinMusicVideoLibraryScanner :
    MediaServerMusicVideoLibraryScanner<JellyfinConnectionParameters, JellyfinLibrary, JellyfinMusicVideo,
        JellyfinItemEtag>,
    IJellyfinMusicVideoLibraryScanner
{
    private readonly IJellyfinApiClient _jellyfinApiClient;
    private readonly IJellyfinMusicVideoRepository _jellyfinMusicVideoRepository;
    private readonly IMediaSourceRepository _mediaSourceRepository;
    private readonly IMetadataRepository _metadataRepository;
    private readonly IMusicVideoRepository _musicVideoRepository;
    private readonly IJellyfinPathReplacementService _pathReplacementService;

    public JellyfinMusicVideoLibraryScanner(
        IScannerProxy scannerProxy,
        IJellyfinApiClient jellyfinApiClient,
        IJellyfinMusicVideoRepository jellyfinMusicVideoRepository,
        IJellyfinPathReplacementService pathReplacementService,
        IMediaSourceRepository mediaSourceRepository,
        IArtistRepository artistRepository,
        IMusicVideoRepository musicVideoRepository,
        ILibraryRepository libraryRepository,
        IMetadataRepository metadataRepository,
        IFileSystem fileSystem,
        ILogger<JellyfinMusicVideoLibraryScanner> logger)
        : base(
            scannerProxy,
            fileSystem,
            artistRepository,
            libraryRepository,
            metadataRepository,
            logger)
    {
        _jellyfinApiClient = jellyfinApiClient;
        _jellyfinMusicVideoRepository = jellyfinMusicVideoRepository;
        _pathReplacementService = pathReplacementService;
        _mediaSourceRepository = mediaSourceRepository;
        _musicVideoRepository = musicVideoRepository;
        _metadataRepository = metadataRepository;
    }

    public async Task<Either<BaseError, Unit>> ScanLibrary(
        JellyfinConnectionParameters connectionParameters,
        JellyfinLibrary library,
        bool deepScan,
        CancellationToken cancellationToken)
    {
        Option<LibraryPath> maybeLibraryPath = Optional(library.Paths).Flatten().HeadOrNone();
        foreach (LibraryPath libraryPath in maybeLibraryPath)
        {
            List<JellyfinPathReplacement> pathReplacements =
                await _mediaSourceRepository.GetJellyfinPathReplacements(library.MediaSourceId);

            string GetLocalPath(JellyfinMusicVideo musicVideo) =>
                _pathReplacementService.GetReplacementJellyfinPath(
                    pathReplacements,
                    musicVideo.GetHeadVersion().MediaFiles.Head().Path,
                    false);

            return await ScanLibrary(
                _jellyfinMusicVideoRepository,
                connectionParameters,
                library,
                libraryPath,
                GetLocalPath,
                deepScan,
                cancellationToken);
        }

        return BaseError.New($"Jellyfin library {library.Id} has no library path");
    }

    protected override string MediaServerItemId(JellyfinMusicVideo musicVideo) => musicVideo.ItemId;

    protected override string MediaServerEtag(JellyfinMusicVideo musicVideo) => musicVideo.Etag;

    protected override IAsyncEnumerable<Tuple<JellyfinMusicVideo, int>> GetMusicVideoLibraryItems(
        JellyfinConnectionParameters connectionParameters,
        JellyfinLibrary library) =>
        _jellyfinApiClient.GetMusicVideoLibraryItems(
            connectionParameters.Address,
            connectionParameters.AuthorizationHeader,
            library);

    protected override async Task<Either<BaseError, MediaItemScanResult<JellyfinMusicVideo>>> UpdateMetadata(
        MediaItemScanResult<JellyfinMusicVideo> result,
        JellyfinMusicVideo incoming,
        CancellationToken cancellationToken)
    {
        if (await UpdateMetadata(result.Item, incoming.MusicVideoMetadata.Head()))
        {
            result.IsUpdated = true;
        }

        return result;
    }

    private async Task<bool> UpdateMetadata(MusicVideo musicVideo, MusicVideoMetadata incoming)
    {
        Option<MusicVideoMetadata> maybeExisting = Optional(musicVideo.MusicVideoMetadata).Flatten().HeadOrNone();
        foreach (MusicVideoMetadata existing in maybeExisting)
        {
            existing.Title = incoming.Title;
            existing.SortTitle = incoming.SortTitle;
            existing.Plot = incoming.Plot;
            existing.Year = incoming.Year;

            // ersatztv#177: Album/Track are scalars, so they must be copied here too — otherwise the
            // projection fix only ever reaches music videos ADDED after it, and an existing item whose
            // album/track is set (or corrected) in Jellyfin never picks it up. Same shape as the #497
            // collection bug below, one layer up.
            existing.Album = incoming.Album;
            existing.Track = incoming.Track;
            existing.ReleaseDate = incoming.ReleaseDate;
            existing.DateUpdated = DateTime.UtcNow;
            existing.MetadataKind = MetadataKind.External;

            bool updated = await _metadataRepository.Update(existing);

            // ersatztv#497: the scalar Update above marks only the metadata row Modified; it does NOT touch
            // child collections, and the repository's GetOrAdd loads them AsNoTracking — so tag/genre/studio/
            // artist edits made in Jellyfin never reached an EXISTING music video (only the Add path persisted
            // them). Reconcile the collections that BOTH the Add path persists AND GetOrAdd eager-loads:
            // Genres, Tags, Studios, Artists. (Guids are add-persisted but not eager-loaded here — reconciling
            // them would see an empty `existing` and duplicate-insert every scan; Directors are eager-loaded
            // but not add-persisted for music videos — both are deliberately out of scope.) Mirrors the
            // remove-stale + add-new idiom PlexMovieLibraryScanner.UpdateMetadata uses.
            updated = await ReconcileGenres(existing, incoming) || updated;
            updated = await ReconcileTags(existing, incoming) || updated;
            updated = await ReconcileStudios(existing, incoming) || updated;
            updated = await ReconcileArtists(existing, incoming) || updated;

            return updated;
        }

        incoming.MusicVideoId = musicVideo.Id;
        musicVideo.MusicVideoMetadata = [incoming];
        return await _metadataRepository.Add(incoming);
    }

    private async Task<bool> ReconcileGenres(MusicVideoMetadata existing, MusicVideoMetadata incoming)
    {
        existing.Genres ??= [];
        // ersatztv#500: dedup on Name — the add filter below is materialized (.ToList()) BEFORE the loop
        // mutates existing.Genres, so two identically-named incoming entries would both pass and both insert.
        // Deduping here (not just in the add loop) is safe: the remove filter only asks "is this name present".
        List<Genre> incomingGenres = (incoming.Genres ?? []).DistinctBy(g => g.Name).ToList();
        var updated = false;

        foreach (Genre genre in existing.Genres.Filter(g => incomingGenres.All(g2 => g2.Name != g.Name)).ToList())
        {
            existing.Genres.Remove(genre);
            updated = await _metadataRepository.RemoveGenre(genre) || updated;
        }

        foreach (Genre genre in incomingGenres.Filter(g => existing.Genres.All(g2 => g2.Name != g.Name)).ToList())
        {
            existing.Genres.Add(genre);
            updated = await _musicVideoRepository.AddGenre(existing, genre) || updated;
        }

        return updated;
    }

    private async Task<bool> ReconcileTags(MusicVideoMetadata existing, MusicVideoMetadata incoming)
    {
        existing.Tags ??= [];
        List<Tag> incomingTags = (incoming.Tags ?? []).DistinctBy(t => t.Name).ToList();
        var updated = false;

        foreach (Tag tag in existing.Tags.Filter(t => incomingTags.All(t2 => t2.Name != t.Name)).ToList())
        {
            existing.Tags.Remove(tag);
            updated = await _metadataRepository.RemoveTag(tag) || updated;
        }

        foreach (Tag tag in incomingTags.Filter(t => existing.Tags.All(t2 => t2.Name != t.Name)).ToList())
        {
            existing.Tags.Add(tag);
            updated = await _musicVideoRepository.AddTag(existing, tag) || updated;
        }

        return updated;
    }

    private async Task<bool> ReconcileStudios(MusicVideoMetadata existing, MusicVideoMetadata incoming)
    {
        existing.Studios ??= [];
        List<Studio> incomingStudios = (incoming.Studios ?? []).DistinctBy(s => s.Name).ToList();
        var updated = false;

        foreach (Studio studio in existing.Studios.Filter(s => incomingStudios.All(s2 => s2.Name != s.Name)).ToList())
        {
            existing.Studios.Remove(studio);
            updated = await _metadataRepository.RemoveStudio(studio) || updated;
        }

        foreach (Studio studio in incomingStudios.Filter(s => existing.Studios.All(s2 => s2.Name != s.Name)).ToList())
        {
            existing.Studios.Add(studio);
            updated = await _musicVideoRepository.AddStudio(existing, studio) || updated;
        }

        return updated;
    }

    private async Task<bool> ReconcileArtists(MusicVideoMetadata existing, MusicVideoMetadata incoming)
    {
        existing.Artists ??= [];
        List<MusicVideoArtist> incomingArtists = (incoming.Artists ?? []).DistinctBy(a => a.Name).ToList();
        var updated = false;

        foreach (MusicVideoArtist artist in existing.Artists
                     .Filter(a => incomingArtists.All(a2 => a2.Name != a.Name)).ToList())
        {
            existing.Artists.Remove(artist);
            updated = await _musicVideoRepository.RemoveArtist(artist) || updated;
        }

        foreach (MusicVideoArtist artist in incomingArtists
                     .Filter(a => existing.Artists.All(a2 => a2.Name != a.Name)).ToList())
        {
            existing.Artists.Add(artist);
            updated = await _musicVideoRepository.AddArtist(existing, artist) || updated;
        }

        return updated;
    }
}