using ErsatzTV.Core.Api.LibraryBrowse;
using ErsatzTV.Core.Domain;
using ErsatzTV.Core.Emby;
using ErsatzTV.Core.Jellyfin;
using ErsatzTV.Infrastructure.Data;
using Flurl;
using Microsoft.EntityFrameworkCore;

namespace ErsatzTV.Application.LibraryBrowse;

// Shared MediaItem -> LibraryBrowseItemResponseModel projection used by both the library-browse
// search handler and the collection-items handler (#155). Keeping the per-kind hydration and the
// rooted-artwork logic in one place avoids duplicating the Blazor-vs-SPA artwork rooting rules
// (see the Artwork helper below and docs/api-conventions.md §4).
internal static class LibraryBrowseItemMapper
{
    // Hydrates an arbitrary set of media item ids (any kinds mixed) into response models. MediaItem
    // ids are globally unique across kinds, so passing the full id list to every per-kind query is
    // safe: each query only matches its own kind. Callers order/page the result themselves.
    public static async Task<List<LibraryBrowseItemResponseModel>> HydrateMediaItemsByIds(
        TvContext dbContext,
        IReadOnlyList<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        var idList = ids.Distinct().ToList();

        var results = new List<LibraryBrowseItemResponseModel>();
        results.AddRange(await GetMovies(dbContext, idList, cancellationToken));
        results.AddRange(await GetShows(dbContext, idList, cancellationToken));
        results.AddRange(await GetSeasons(dbContext, idList, cancellationToken));
        results.AddRange(await GetArtists(dbContext, idList, cancellationToken));
        results.AddRange(await GetEpisodes(dbContext, idList, cancellationToken));
        results.AddRange(await GetMusicVideos(dbContext, idList, cancellationToken));
        results.AddRange(await GetSongs(dbContext, idList, cancellationToken));
        results.AddRange(await GetOtherVideos(dbContext, idList, cancellationToken));
        results.AddRange(await GetImages(dbContext, idList, cancellationToken));
        results.AddRange(await GetRemoteStreams(dbContext, idList, cancellationToken));
        return results;
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetMovies(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.MovieMetadata
            .AsNoTracking()
            .Where(mm => ids.Contains(mm.MovieId))
            .Include(mm => mm.Artwork)
            .Include(mm => mm.Movie)
            .ThenInclude(m => m.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(mm => mm.Movie)
            .ThenInclude(m => m.MediaVersions)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(mm => mm.MovieId)
                .Select(g => g.OrderBy(mm => mm.Id).First())
                .Map(mm => new LibraryBrowseItemResponseModel(
                mm.MovieId,
                LibraryBrowseMediaType.Movie,
                mm.Title ?? string.Empty,
                mm.Movie.LibraryPath.LibraryId,
                mm.Movie.LibraryPath.Library.Name,
                Artwork(mm, ArtworkKind.Poster),
                BestDuration(mm.Movie.MediaVersions),
                1,
                null,
                CollectionType.Movie,
                null,
                null,
                null,
                null,
                mm.MovieId,
                null)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetShows(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        Dictionary<int, int> counts = await dbContext.Episodes
            .AsNoTracking()
            .Where(e => ids.Contains(e.Season.ShowId))
            .GroupBy(e => e.Season.ShowId)
            .Select(g => new { ShowId = g.Key, Count = g.Count() })
            .ToDictionaryAsync(g => g.ShowId, g => g.Count, cancellationToken);

        return await dbContext.ShowMetadata
            .AsNoTracking()
            .Where(sm => ids.Contains(sm.ShowId))
            .Include(sm => sm.Artwork)
            .Include(sm => sm.Show)
            .ThenInclude(s => s.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(sm => sm.ShowId)
                .Select(g => g.OrderBy(sm => sm.Id).First())
                .Map(sm => new LibraryBrowseItemResponseModel(
                sm.ShowId,
                LibraryBrowseMediaType.TelevisionShow,
                sm.Title ?? string.Empty,
                sm.Show.LibraryPath.LibraryId,
                sm.Show.LibraryPath.Library.Name,
                Artwork(sm, ArtworkKind.Poster),
                null,
                counts.TryGetValue(sm.ShowId, out int count) ? count : 0,
                null,
                CollectionType.TelevisionShow,
                null,
                null,
                null,
                null,
                sm.ShowId,
                null)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetSeasons(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        Dictionary<int, int> counts = await dbContext.Episodes
            .AsNoTracking()
            .Where(e => ids.Contains(e.SeasonId))
            .GroupBy(e => e.SeasonId)
            .Select(g => new { SeasonId = g.Key, Count = g.Count() })
            .ToDictionaryAsync(g => g.SeasonId, g => g.Count, cancellationToken);

        return await dbContext.SeasonMetadata
            .AsNoTracking()
            .Where(sm => ids.Contains(sm.SeasonId))
            .Include(sm => sm.Artwork)
            .Include(sm => sm.Season)
            .ThenInclude(s => s.Show)
            .ThenInclude(s => s.ShowMetadata)
            .ThenInclude(shm => shm.Artwork)
            .Include(sm => sm.Season)
            .ThenInclude(s => s.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(sm => sm.SeasonId)
                .Select(g => g.OrderBy(sm => sm.Id).First())
                .Map(sm => new LibraryBrowseItemResponseModel(
                sm.SeasonId,
                LibraryBrowseMediaType.TelevisionSeason,
                SeasonTitle(sm),
                sm.Season.LibraryPath.LibraryId,
                sm.Season.LibraryPath.Library.Name,
                SeasonArtwork(sm),
                null,
                counts.TryGetValue(sm.SeasonId, out int count) ? count : 0,
                null,
                CollectionType.TelevisionSeason,
                null,
                null,
                null,
                null,
                sm.SeasonId,
                null)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetArtists(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        Dictionary<int, int> counts = await dbContext.MusicVideos
            .AsNoTracking()
            .Where(mv => ids.Contains(mv.ArtistId))
            .GroupBy(mv => mv.ArtistId)
            .Select(g => new { ArtistId = g.Key, Count = g.Count() })
            .ToDictionaryAsync(g => g.ArtistId, g => g.Count, cancellationToken);

        return await dbContext.ArtistMetadata
            .AsNoTracking()
            .Where(am => ids.Contains(am.ArtistId))
            .Include(am => am.Artwork)
            .Include(am => am.Artist)
            .ThenInclude(a => a.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(am => am.ArtistId)
                .Select(g => g.OrderBy(am => am.Id).First())
                .Map(am => new LibraryBrowseItemResponseModel(
                am.ArtistId,
                LibraryBrowseMediaType.Artist,
                am.Title ?? string.Empty,
                am.Artist.LibraryPath.LibraryId,
                am.Artist.LibraryPath.Library.Name,
                Artwork(am, ArtworkKind.Thumbnail),
                null,
                counts.TryGetValue(am.ArtistId, out int count) ? count : 0,
                null,
                CollectionType.Artist,
                null,
                null,
                null,
                null,
                am.ArtistId,
                null)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetEpisodes(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.EpisodeMetadata
            .AsNoTracking()
            .Where(em => ids.Contains(em.EpisodeId))
            .Include(em => em.Artwork)
            .Include(em => em.Episode)
            .ThenInclude(e => e.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(em => em.Episode)
            .ThenInclude(e => e.MediaVersions)
            .Include(em => em.Episode)
            .ThenInclude(e => e.Season)
            .ThenInclude(s => s.Show)
            .ThenInclude(sh => sh.ShowMetadata)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(em => em.EpisodeId)
                .Select(g => g.OrderBy(em => em.Id).First())
                .Map(em => new LibraryBrowseItemResponseModel(
                    em.EpisodeId,
                    LibraryBrowseMediaType.Episode,
                    em.Title ?? string.Empty,
                    em.Episode.LibraryPath.LibraryId,
                    em.Episode.LibraryPath.Library.Name,
                    ArtworkWithFallback(em, ArtworkKind.Thumbnail, ArtworkKind.Poster),
                    BestDuration(em.Episode.MediaVersions),
                    1,
                    null,
                    CollectionType.Episode,
                    null,
                    null,
                    null,
                    null,
                    em.EpisodeId,
                    null,
                    EpisodeSubtitle(em),
                    em.Episode.SeasonId)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetMusicVideos(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.MusicVideoMetadata
            .AsNoTracking()
            .Where(mvm => ids.Contains(mvm.MusicVideoId))
            .Include(mvm => mvm.Artwork)
            .Include(mvm => mvm.MusicVideo)
            .ThenInclude(mv => mv.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(mvm => mvm.MusicVideo)
            .ThenInclude(mv => mv.MediaVersions)
            .Include(mvm => mvm.MusicVideo)
            .ThenInclude(mv => mv.Artist)
            .ThenInclude(a => a.ArtistMetadata)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(mvm => mvm.MusicVideoId)
                .Select(g => g.OrderBy(mvm => mvm.Id).First())
                .Map(mvm => new LibraryBrowseItemResponseModel(
                    mvm.MusicVideoId,
                    LibraryBrowseMediaType.MusicVideo,
                    mvm.Title ?? string.Empty,
                    mvm.MusicVideo.LibraryPath.LibraryId,
                    mvm.MusicVideo.LibraryPath.Library.Name,
                    ArtworkWithFallback(mvm, ArtworkKind.Thumbnail, ArtworkKind.Poster),
                    BestDuration(mvm.MusicVideo.MediaVersions),
                    1,
                    null,
                    CollectionType.MusicVideo,
                    null,
                    null,
                    null,
                    null,
                    mvm.MusicVideoId,
                    null,
                    MusicVideoSubtitle(mvm))).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetSongs(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.SongMetadata
            .AsNoTracking()
            .Where(sm => ids.Contains(sm.SongId))
            .Include(sm => sm.Artwork)
            .Include(sm => sm.Song)
            .ThenInclude(s => s.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(sm => sm.Song)
            .ThenInclude(s => s.MediaVersions)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(sm => sm.SongId)
                .Select(g => g.OrderBy(sm => sm.Id).First())
                .Map(sm => new LibraryBrowseItemResponseModel(
                    sm.SongId,
                    LibraryBrowseMediaType.Song,
                    sm.Title ?? string.Empty,
                    sm.Song.LibraryPath.LibraryId,
                    sm.Song.LibraryPath.Library.Name,
                    ArtworkWithFallback(sm, ArtworkKind.Thumbnail, ArtworkKind.Poster),
                    BestDuration(sm.Song.MediaVersions),
                    1,
                    null,
                    CollectionType.Song,
                    null,
                    null,
                    null,
                    null,
                    sm.SongId,
                    null,
                    SongSubtitle(sm))).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetOtherVideos(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.OtherVideoMetadata
            .AsNoTracking()
            .Where(ovm => ids.Contains(ovm.OtherVideoId))
            .Include(ovm => ovm.Artwork)
            .Include(ovm => ovm.OtherVideo)
            .ThenInclude(ov => ov.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(ovm => ovm.OtherVideo)
            .ThenInclude(ov => ov.MediaVersions)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(ovm => ovm.OtherVideoId)
                .Select(g => g.OrderBy(ovm => ovm.Id).First())
                .Map(ovm => new LibraryBrowseItemResponseModel(
                    ovm.OtherVideoId,
                    LibraryBrowseMediaType.OtherVideo,
                    ovm.Title ?? string.Empty,
                    ovm.OtherVideo.LibraryPath.LibraryId,
                    ovm.OtherVideo.LibraryPath.Library.Name,
                    ArtworkWithFallback(ovm, ArtworkKind.Thumbnail, ArtworkKind.Poster),
                    BestDuration(ovm.OtherVideo.MediaVersions),
                    1,
                    null,
                    CollectionType.OtherVideo,
                    null,
                    null,
                    null,
                    null,
                    ovm.OtherVideoId,
                    null,
                    string.IsNullOrWhiteSpace(ovm.OriginalTitle) ? null : ovm.OriginalTitle)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetImages(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.ImageMetadata
            .AsNoTracking()
            .Where(im => ids.Contains(im.ImageId))
            .Include(im => im.Artwork)
            .Include(im => im.Image)
            .ThenInclude(i => i.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(im => im.Image)
            .ThenInclude(i => i.MediaVersions)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(im => im.ImageId)
                .Select(g => g.OrderBy(im => im.Id).First())
                .Map(im => new LibraryBrowseItemResponseModel(
                    im.ImageId,
                    LibraryBrowseMediaType.Image,
                    im.Title ?? string.Empty,
                    im.Image.LibraryPath.LibraryId,
                    im.Image.LibraryPath.Library.Name,
                    ArtworkWithFallback(im, ArtworkKind.Poster, ArtworkKind.Thumbnail),
                    BestDuration(im.Image.MediaVersions),
                    1,
                    null,
                    CollectionType.Image,
                    null,
                    null,
                    null,
                    null,
                    im.ImageId,
                    null,
                    string.IsNullOrWhiteSpace(im.OriginalTitle) ? null : im.OriginalTitle)).ToList());
    }

    public static async Task<List<LibraryBrowseItemResponseModel>> GetRemoteStreams(
        TvContext dbContext,
        List<int> ids,
        CancellationToken cancellationToken)
    {
        if (ids.Count == 0)
        {
            return [];
        }

        return await dbContext.RemoteStreamMetadata
            .AsNoTracking()
            .Where(rsm => ids.Contains(rsm.RemoteStreamId))
            .Include(rsm => rsm.Artwork)
            .Include(rsm => rsm.RemoteStream)
            .ThenInclude(rs => rs.LibraryPath)
            .ThenInclude(lp => lp.Library)
            .Include(rsm => rsm.RemoteStream)
            .ThenInclude(rs => rs.MediaVersions)
            .ToListAsync(cancellationToken)
            .Map(list => list
                .GroupBy(rsm => rsm.RemoteStreamId)
                .Select(g => g.OrderBy(rsm => rsm.Id).First())
                .Map(rsm => new LibraryBrowseItemResponseModel(
                    rsm.RemoteStreamId,
                    LibraryBrowseMediaType.RemoteStream,
                    rsm.Title ?? string.Empty,
                    rsm.RemoteStream.LibraryPath.LibraryId,
                    rsm.RemoteStream.LibraryPath.Library.Name,
                    ArtworkWithFallback(rsm, ArtworkKind.Thumbnail, ArtworkKind.Poster),
                    BestDuration(rsm.RemoteStream.MediaVersions),
                    1,
                    null,
                    CollectionType.RemoteStream,
                    null,
                    null,
                    null,
                    null,
                    rsm.RemoteStreamId,
                    null,
                    string.IsNullOrWhiteSpace(rsm.OriginalTitle) ? null : rsm.OriginalTitle)).ToList());
    }

    public static TimeSpan? BestDuration(IEnumerable<MediaVersion> versions)
    {
        TimeSpan duration = versions
            .Select(v => v.Duration)
            .Where(d => d > TimeSpan.Zero)
            .DefaultIfEmpty()
            .Max();
        return duration > TimeSpan.Zero ? duration : null;
    }

    // Returns a rooted, directly-usable artwork URL for the SPA's <img src>. Blazor pages rely on
    // GetPosterUrl to prefix "artwork/posters/" and resolve relative to <base href="/">, but the SPA
    // renders the value raw from under /app/, so the API must root the URL itself (issue #180).
    public static string Artwork(Metadata metadata, ArtworkKind artworkKind)
    {
        string artwork = Optional(metadata.Artwork.FirstOrDefault(a => a.ArtworkKind == artworkKind))
            .Match(a => a.Path, string.Empty);

        if (string.IsNullOrWhiteSpace(artwork))
        {
            return string.Empty;
        }

        // Absolute URLs are already usable as-is (matches Blazor's GetPosterUrl guard).
        if (artwork.StartsWith("http://", StringComparison.OrdinalIgnoreCase) ||
            artwork.StartsWith("https://", StringComparison.OrdinalIgnoreCase))
        {
            return artwork;
        }

        string folder = artworkKind is ArtworkKind.Thumbnail ? "thumbnails" : "posters";

        if (artwork.StartsWith("jellyfin://", StringComparison.OrdinalIgnoreCase))
        {
            Url url = JellyfinUrl.RelativeProxyForArtwork(artwork);
            if (artworkKind is ArtworkKind.Poster or ArtworkKind.Thumbnail)
            {
                url.SetQueryParam("fillHeight", 440);
            }

            return $"/artwork/{folder}/{url}";
        }

        if (artwork.StartsWith("emby://", StringComparison.OrdinalIgnoreCase))
        {
            Url url = EmbyUrl.RelativeProxyForArtwork(artwork);
            if (artworkKind is ArtworkKind.Poster or ArtworkKind.Thumbnail)
            {
                url.SetQueryParam("maxHeight", 440);
            }

            return $"/artwork/{folder}/{url}";
        }

        return $"/artwork/{folder}/{artwork}";
    }

    private static string ArtworkWithFallback(Metadata metadata, ArtworkKind primary, ArtworkKind fallback)
    {
        string artwork = Artwork(metadata, primary);
        return string.IsNullOrWhiteSpace(artwork) ? Artwork(metadata, fallback) : artwork;
    }

    private static string SeasonTitle(SeasonMetadata metadata)
    {
        string showTitle = metadata.Season.Show.ShowMetadata.HeadOrNone()
            .Map(sm => sm.Title ?? string.Empty)
            .IfNone(string.Empty);
        string seasonTitle = metadata.Season.SeasonNumber == 0
            ? "Specials"
            : $"Season {metadata.Season.SeasonNumber}";
        return string.IsNullOrWhiteSpace(showTitle) ? seasonTitle : $"{showTitle} - {seasonTitle}";
    }

    // Seasons often have no poster of their own; fall back to the parent show's poster (issue #180).
    private static string SeasonArtwork(SeasonMetadata metadata)
    {
        string artwork = Artwork(metadata, ArtworkKind.Poster);
        if (!string.IsNullOrWhiteSpace(artwork))
        {
            return artwork;
        }

        return metadata.Season.Show.ShowMetadata.HeadOrNone()
            .Match(sm => Artwork(sm, ArtworkKind.Poster), string.Empty);
    }

    private static string EpisodeSubtitle(EpisodeMetadata metadata)
    {
        string showTitle = metadata.Episode.Season.Show.ShowMetadata.HeadOrNone()
            .Map(sm => sm.Title ?? string.Empty)
            .IfNone(string.Empty);
        int seasonNumber = metadata.Episode.Season.SeasonNumber;
        string suffix = $"S{seasonNumber}E{metadata.EpisodeNumber}";
        return string.IsNullOrWhiteSpace(showTitle) ? suffix : $"{showTitle} - {suffix}";
    }

    private static string MusicVideoSubtitle(MusicVideoMetadata metadata)
    {
        string artist = metadata.MusicVideo.Artist.ArtistMetadata.HeadOrNone()
            .Map(am => am.Title ?? string.Empty)
            .IfNone(string.Empty);
        string album = string.IsNullOrWhiteSpace(metadata.Album) ? string.Empty : metadata.Album;
        if (!string.IsNullOrWhiteSpace(artist) && !string.IsNullOrWhiteSpace(album))
        {
            return $"{artist} - {album}";
        }

        return string.IsNullOrWhiteSpace(artist) ? album : artist;
    }

    private static string SongSubtitle(SongMetadata metadata)
    {
        string artists = string.Join(", ", metadata.Artists ?? []);
        string album = string.IsNullOrWhiteSpace(metadata.Album) ? string.Empty : metadata.Album;
        if (!string.IsNullOrWhiteSpace(artists) && !string.IsNullOrWhiteSpace(album))
        {
            return $"{artists} - {album}";
        }

        return string.IsNullOrWhiteSpace(artists) ? album : artists;
    }
}