using System.Globalization;
using MediaBrowser.Model.Tasks;
using Microsoft.Extensions.Logging;
using MediaBrowser.Controller;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Playlists;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.IO;
using Jellyfin.Data.Entities;
using Jellyfin.Data.Enums;
using MediaBrowser.Model.Entities;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Model.Playlists;

using Jellyfin.Plugin.SmartPlaylist.Lisp;
using Jellyfin.Plugin.SmartPlaylist.Lisp.Compiler;
using Lisp_Object = Jellyfin.Plugin.SmartPlaylist.Lisp.Object;
using Lisp_Boolean = Jellyfin.Plugin.SmartPlaylist.Lisp.Boolean;


namespace Jellyfin.Plugin.SmartPlaylist.ScheduledTasks {
    public class GeneratePlaylist : IScheduledTask {

        public static readonly BaseItemKind[] AvailableFilterItems = {
            BaseItemKind.Audio,
            BaseItemKind.MusicAlbum,
            BaseItemKind.Playlist,
        };

        private readonly ILogger _logger;
        private readonly ILibraryManager _libraryManager;
        private readonly IUserManager _userManager;
        private readonly IProviderManager _providerManager;
        private readonly IFileSystem _fileSystem;
        private readonly IPlaylistManager _playlistManager;

        private readonly IStore _store;

        public GeneratePlaylist(
            ILogger<Plugin> logger,
            ILibraryManager libraryManager,
            IUserManager userManager,
            IProviderManager providerManager,
            IFileSystem fileSystem,
            IPlaylistManager playlistManager,
            IServerApplicationPaths serverApplicationPaths
        ) {
            _logger = logger;
            _libraryManager = libraryManager;
            _userManager = userManager;
            _providerManager = providerManager;
            _fileSystem = fileSystem;
            _playlistManager = playlistManager;

            _store = new Store(new SmartPlaylistFileSystem(serverApplicationPaths));
        }

        public string Category => "Library";
        public string Name => "(re)generate Smart Playlists";
        public string Description => "Generate or regenerate all Smart Playlists";
        public string Key => nameof(GeneratePlaylist);

        public IEnumerable<TaskTriggerInfo> GetDefaultTriggers() {
            return new[] {
                new TaskTriggerInfo {
                    IntervalTicks = TimeSpan.FromHours(24).Ticks,
                    Type = TaskTriggerInfo.TriggerInterval,
                }
            };
        }

        private void GetUsers() {
            foreach (var user in _userManager.Users) {
                _logger.LogInformation("User {0}", user);
                var query = new InternalItemsQuery(user) {
                    IncludeItemTypes = AvailableFilterItems,
                    Recursive = true,
                };
                foreach (BaseItem item in _libraryManager.GetItemsResult(query).Items) {
                    _logger.LogInformation("Item {0}", item);
                }
            }
        }

        private PlaylistId CreateNewPlaylist(string name, UserId userId) {
            _logger.LogDebug("Creating playlist '{0}'", name);
            var req = new PlaylistCreationRequest {
                Name = name,
                UserId = userId,
                Users = [new PlaylistUserPermissions(userId)],
                Public = false,
            };
            var playlistGuid = Guid.Parse(_playlistManager.CreatePlaylist(req).Result.Id);
            return playlistGuid;
        }

        private IEnumerable<Guid> FilterPlaylistItems(IEnumerable<BaseItem> items, User user, SmartPlaylistDto smartPlaylist) {
            List<BaseItem> results = new List<BaseItem>();
            Expression expression = new Parser(StringTokenStream.generate(smartPlaylist.Program)).parse(); // parse here, so that we don't repeat the work for each item
            Executor executor = new Executor(new DefaultEnvironment());
            executor.environment.Set("user", Lisp_Object.FromBase(user));
            if (Plugin.Instance is not null) {
                executor.eval(Plugin.Instance.Configuration.InitialProgram);
            } else {
                throw new ApplicationException("Plugin Instance is not yet initialized");
            }
            foreach (var i in items) {
                executor.environment.Set("item", Lisp_Object.FromBase(i));
                var r = executor.eval(expression);
                _logger.LogTrace("Item {0} evaluated to {1}", i, r.ToString());
                if ((r is not Lisp_Boolean r_bool) || (r_bool.Value())) {
                    _logger.LogDebug("Added '{0}' to Smart Playlist {1}", i, smartPlaylist.Name);
                    results.Add(i);
                }
            }
            executor = new Executor(new DefaultEnvironment());
            executor.environment.Set("user", Lisp_Object.FromBase(user));
            executor.environment.Set("items", Lisp_Object.FromBase(results));
            results = new List<BaseItem>();
            var sort_result = executor.eval(smartPlaylist.SortProgram);
            if (sort_result is Cons sorted_items) {
                foreach (var i in sorted_items.ToList()) {
                    if (i is Lisp_Object iObject && iObject.Value() is BaseItem iBaseItem) {
                        results.Add(iBaseItem);
                        continue;
                    }
                    throw new ApplicationException($"Returned sorted list does contain unexpected items, got {i}");
                }
            } else if (sort_result == Lisp_Boolean.FALSE) {
            } else {
                throw new ApplicationException($"Did not return a list of items, returned {sort_result}");
            }
            return results.Select(x => x.Id);
        }

        private IEnumerable<BaseItem> GetAllUserMedia(User user) {
            var req = new InternalItemsQuery(user) {
                IncludeItemTypes = AvailableFilterItems,
                Recursive = true,
            };
            return _libraryManager.GetItemsResult(req).Items;
        }

        public async Task ExecuteAsync(IProgress<double> progress, CancellationToken cancellationToken) {
            _logger.LogInformation("Started regenerate Smart Playlists");
            foreach (SmartPlaylistDto dto in await _store.GetAllSmartPlaylistsAsync()) {
                var changedDto = false;
                if (dto.Playlists.Length == 0) {
                    dto.Playlists = _userManager.UsersIds.Select(x => new SmartPlaylistLinkDto {
                        UserId = x,
                        PlaylistId = CreateNewPlaylist(dto.Name, x),
                    }).ToArray();
                    changedDto = true;
                }
                foreach (SmartPlaylistLinkDto playlistLink in dto.Playlists) {
                    if (playlistLink.PlaylistId == Guid.Empty) {
                        // not initialized
                        playlistLink.PlaylistId = CreateNewPlaylist(dto.Name, playlistLink.UserId);
                        changedDto = true;
                    } else if (_playlistManager.GetPlaylists(playlistLink.UserId).Where(x => x.Id == playlistLink.PlaylistId).ToArray().Length == 0) {
                        // somehow the corresponding playlist doesnt
                        // exist anymore, did the user delete it?
                        playlistLink.PlaylistId = CreateNewPlaylist(dto.Name, playlistLink.UserId);
                        changedDto = true;
                    }
                }
                if (changedDto) {
                    _store.DeleteSmartPlaylist(dto); // delete in case the file was not the canonical one.
                    await _store.SaveSmartPlaylistAsync(dto);
                }
                var i = 0;
                foreach (SmartPlaylistLinkDto playlistLink in dto.Playlists) {
                    User? user = _userManager.GetUserById(playlistLink.UserId);
                    if (user == null) {
                        continue;
                    }
                    var insertItems = FilterPlaylistItems(GetAllUserMedia(user), user, dto).ToArray();
                    var playlist = _playlistManager.GetPlaylists(playlistLink.UserId).Where(x => x.Id == playlistLink.PlaylistId).First();
                    await ClearPlaylist(playlist);
                    await _playlistManager.AddItemToPlaylistAsync(playlist.Id, insertItems, playlistLink.UserId);
                    i += 1;
                    progress.Report(100 * ((double)i)/dto.Playlists.Count());
                }
            }
        }

        private async Task ClearPlaylist(Playlist playlist) {
            // fuck if I know
            if (_libraryManager.GetItemById(playlist.Id) is not Playlist playlist_new) {
                throw new ArgumentException("");
            }
            var existingItems = playlist_new.GetManageableItems().ToList();
            await _playlistManager.RemoveItemFromPlaylistAsync(playlist.Id.ToString(), existingItems.Select(x => x.Item1.ItemId?.ToString("N", CultureInfo.InvariantCulture)));
        }
    }
}