using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Threading.Tasks;
using Jellyfin.Data.Enums;
using Jellyfin.Database.Implementations.Entities;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.Movies;
using MediaBrowser.Controller.Library;
using Microsoft.Extensions.Logging;

namespace Jellyfin.Plugin.CinemaTrailers4Jellyfins.Services
{
    public class TrailerIntroProvider : IIntroProvider
    {
        private static readonly Random _rng = new();
        private readonly ILibraryManager _libraryManager;
        private readonly ILogger<TrailerIntroProvider> _logger;

        public string Name => "CinemaTrailers4Jellyfins";

        public TrailerIntroProvider(ILibraryManager libraryManager, ILogger<TrailerIntroProvider> logger)
        {
            _libraryManager = libraryManager;
            _logger = logger;
        }

        public Task<IEnumerable<IntroInfo>> GetIntros(BaseItem item, User user)
        {
            var config = Plugin.Instance?.Configuration;
            if (config == null || config.TrailersPerMovie <= 0)
                return Task.FromResult(Enumerable.Empty<IntroInfo>());

            if (item is not Movie)
                return Task.FromResult(Enumerable.Empty<IntroInfo>());

            var outputFolder = config.DownloadFolder?.TrimEnd(
                Path.DirectorySeparatorChar, Path.AltDirectorySeparatorChar);
            if (string.IsNullOrEmpty(outputFolder))
                return Task.FromResult(Enumerable.Empty<IntroInfo>());

            // Break potential recursion: don't inject intros before items that live inside
            // our output folder. This covers both the fake-movie files and their trailer
            // extras, so Wholphin can't trigger a getIntros loop on the intro item itself.
            if (item.Path?.StartsWith(outputFolder, StringComparison.OrdinalIgnoreCase) == true)
                return Task.FromResult(Enumerable.Empty<IntroInfo>());

            // Server-scoped query (no User parameter) so library visibility settings don't
            // prevent trailer discovery even when the output library is hidden from users.
            var fakeMovies = _libraryManager
                .GetItemList(new InternalItemsQuery
                {
                    IncludeItemTypes = new[] { BaseItemKind.Movie },
                    Recursive = true,
                })
                .OfType<Movie>()
                .Where(m =>
                    m.Path?.StartsWith(outputFolder, StringComparison.OrdinalIgnoreCase) == true
                    && m.LocalTrailers.Count > 0)
                .ToList();

            if (fakeMovies.Count == 0)
            {
                _logger.LogDebug(
                    "|CinemaTrailers4Jellyfins| No indexed trailers found in {Folder}. "
                    + "Ensure the output folder is added as a Jellyfin Movies library and scanned.",
                    outputFolder);
                return Task.FromResult(Enumerable.Empty<IntroInfo>());
            }

            var selected = fakeMovies
                .OrderBy(_ => _rng.Next())
                .Take(config.TrailersPerMovie)
                .Select(m =>
                {
                    var t = m.LocalTrailers.ElementAt(_rng.Next(m.LocalTrailers.Count));
                    return new IntroInfo { ItemId = t.Id, Path = t.Path };
                })
                .ToList();

            return Task.FromResult<IEnumerable<IntroInfo>>(selected);
        }
    }
}