using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Threading;
using System.Threading.Tasks;
using MediaBrowser.Controller.Dto;
using MediaBrowser.Controller.Entities;
using MediaBrowser.Controller.Entities.Audio;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.Playlists;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.IO;
using MediaBrowser.Model.Playlists;
using Microsoft.Extensions.Logging;
using PlaylistsNET.Content;
using PlaylistsNET.Models;

namespace Emby.Server.Implementations.Playlists
{
    public class PlaylistManager : IPlaylistManager
    {
        private readonly ILibraryManager _libraryManager;
        private readonly IFileSystem _fileSystem;
        private readonly ILibraryMonitor _iLibraryMonitor;
        private readonly ILogger _logger;
        private readonly IUserManager _userManager;
        private readonly IProviderManager _providerManager;

        public PlaylistManager(
            ILibraryManager libraryManager,
            IFileSystem fileSystem,
            ILibraryMonitor iLibraryMonitor,
            ILoggerFactory loggerFactory,
            IUserManager userManager,
            IProviderManager providerManager)
        {
            _libraryManager = libraryManager;
            _fileSystem = fileSystem;
            _iLibraryMonitor = iLibraryMonitor;
            _logger = loggerFactory.CreateLogger(nameof(PlaylistManager));
            _userManager = userManager;
            _providerManager = providerManager;
        }

        public IEnumerable<Playlist> GetPlaylists(Guid userId)
        {
            var user = _userManager.GetUserById(userId);

            return GetPlaylistsFolder(userId).GetChildren(user, true).OfType<Playlist>();
        }

        public async Task<PlaylistCreationResult> CreatePlaylist(PlaylistCreationRequest options)
        {
            var name = options.Name;

            var folderName = _fileSystem.GetValidFilename(name);
            var parentFolder = GetPlaylistsFolder(Guid.Empty);
            if (parentFolder == null)
            {
                throw new ArgumentException();
            }

            if (string.IsNullOrEmpty(options.MediaType))
            {
                foreach (var itemId in options.ItemIdList)
                {
                    var item = _libraryManager.GetItemById(itemId);

                    if (item == null)
                    {
                        throw new ArgumentException("No item exists with the supplied Id");
                    }

                    if (!string.IsNullOrEmpty(item.MediaType))
                    {
                        options.MediaType = item.MediaType;
                    }
                    else if (item is MusicArtist || item is MusicAlbum || item is MusicGenre)
                    {
                        options.MediaType = MediaType.Audio;
                    }
                    else if (item is Genre)
                    {
                        options.MediaType = MediaType.Video;
                    }
                    else
                    {
                        if (item is Folder folder)
                        {
                            options.MediaType = folder.GetRecursiveChildren(i => !i.IsFolder && i.SupportsAddingToPlaylist)
                                .Select(i => i.MediaType)
                                .FirstOrDefault(i => !string.IsNullOrEmpty(i));
                        }
                    }

                    if (!string.IsNullOrEmpty(options.MediaType))
                    {
                        break;
                    }
                }
            }

            if (string.IsNullOrEmpty(options.MediaType))
            {
                options.MediaType = "Audio";
            }

            var user = _userManager.GetUserById(options.UserId);

            var path = Path.Combine(parentFolder.Path, folderName);
            path = GetTargetPath(path);

            _iLibraryMonitor.ReportFileSystemChangeBeginning(path);

            try
            {
                Directory.CreateDirectory(path);

                var playlist = new Playlist
                {
                    Name = name,
                    Path = path,
                    Shares = new[]
                    {
                        new Share
                        {
                            UserId = options.UserId.Equals(Guid.Empty) ? null : options.UserId.ToString("N", CultureInfo.InvariantCulture),
                            CanEdit = true
                        }
                    }
                };

                playlist.SetMediaType(options.MediaType);

                parentFolder.AddChild(playlist, CancellationToken.None);

                await playlist.RefreshMetadata(new MetadataRefreshOptions(new DirectoryService(_fileSystem)) { ForceSave = true }, CancellationToken.None)
                    .ConfigureAwait(false);

                if (options.ItemIdList.Length > 0)
                {
                    AddToPlaylistInternal(playlist.Id.ToString("N", CultureInfo.InvariantCulture), options.ItemIdList, user, new DtoOptions(false)
                    {
                        EnableImages = true
                    });
                }

                return new PlaylistCreationResult
                {
                    Id = playlist.Id.ToString("N", CultureInfo.InvariantCulture)
                };
            }
            finally
            {
                // Refresh handled internally
                _iLibraryMonitor.ReportFileSystemChangeComplete(path, false);
            }
        }

        private string GetTargetPath(string path)
        {
            while (Directory.Exists(path))
            {
                path += "1";
            }

            return path;
        }

        private List<BaseItem> GetPlaylistItems(IEnumerable<Guid> itemIds, string playlistMediaType, User user, DtoOptions options)
        {
            var items = itemIds.Select(i => _libraryManager.GetItemById(i)).Where(i => i != null);

            return Playlist.GetPlaylistItems(playlistMediaType, items, user, options);
        }

        public void AddToPlaylist(string playlistId, IEnumerable<Guid> itemIds, Guid userId)
        {
            var user = userId.Equals(Guid.Empty) ? null : _userManager.GetUserById(userId);

            AddToPlaylistInternal(playlistId, itemIds, user, new DtoOptions(false)
            {
                EnableImages = true
            });
        }

        private void AddToPlaylistInternal(string playlistId, IEnumerable<Guid> itemIds, User user, DtoOptions options)
        {
            // Retrieve the existing playlist
            var playlist = _libraryManager.GetItemById(playlistId) as Playlist
                ?? throw new ArgumentException("No Playlist exists with Id " + playlistId);

            // Retrieve all the items to be added to the playlist
            var items = GetPlaylistItems(itemIds, playlist.MediaType, user, options)
                .Where(i => i.SupportsAddingToPlaylist)
                .ToArray();

            // Remove duplicates from the new items to be added
            var existingIds = playlist.LinkedChildren.Select(c => c.ItemId).ToHashSet();
            var uniqueItems = items
                .Where(i => !existingIds.Contains(i.Id))
                .GroupBy(i => i.Id)
                .Select(group => group.First())
                .Select(i => LinkedChild.Create(i))
                .ToArray();

            // Log duplicates that have been ignored, if any
            int numDuplicates = items.Length - uniqueItems.Length;
            if (numDuplicates > 0)
            {
                _logger.LogWarning("Ignored adding {DuplicateCount} duplicate items to playlist {PlaylistName}.", numDuplicates, playlist.Name);
            }

            // Do nothing else if there are no items to add to the playlist
            if (uniqueItems.Length == 0)
            {
                return;
            }

            // Create a new array with the updated playlist items
            var newLinkedChildren = new LinkedChild[playlist.LinkedChildren.Length + uniqueItems.Length];
            playlist.LinkedChildren.CopyTo(newLinkedChildren, 0);
            uniqueItems.CopyTo(newLinkedChildren, playlist.LinkedChildren.Length);

            // Update the playlist in the repository
            playlist.LinkedChildren = newLinkedChildren;
            playlist.UpdateToRepository(ItemUpdateType.MetadataEdit, CancellationToken.None);

            // Update the playlist on disk
            if (playlist.IsFile)
            {
                SavePlaylistFile(playlist);
            }

            // Refresh playlist metadata
            _providerManager.QueueRefresh(
                playlist.Id,
                new MetadataRefreshOptions(new DirectoryService(_fileSystem))
                {
                    ForceSave = true
                },
                RefreshPriority.High);
        }

        public void RemoveFromPlaylist(string playlistId, IEnumerable<string> entryIds)
        {
            if (!(_libraryManager.GetItemById(playlistId) is Playlist playlist))
            {
                throw new ArgumentException("No Playlist exists with the supplied Id");
            }

            var children = playlist.GetManageableItems().ToList();

            var idList = entryIds.ToList();

            var removals = children.Where(i => idList.Contains(i.Item1.Id));

            playlist.LinkedChildren = children.Except(removals)
                .Select(i => i.Item1)
                .ToArray();

            playlist.UpdateToRepository(ItemUpdateType.MetadataEdit, CancellationToken.None);

            if (playlist.IsFile)
            {
                SavePlaylistFile(playlist);
            }

            _providerManager.QueueRefresh(
                playlist.Id,
                new MetadataRefreshOptions(new DirectoryService(_fileSystem))
                {
                    ForceSave = true
                },
                RefreshPriority.High);
        }

        public void MoveItem(string playlistId, string entryId, int newIndex)
        {
            if (!(_libraryManager.GetItemById(playlistId) is Playlist playlist))
            {
                throw new ArgumentException("No Playlist exists with the supplied Id");
            }

            var children = playlist.GetManageableItems().ToList();

            var oldIndex = children.FindIndex(i => string.Equals(entryId, i.Item1.Id, StringComparison.OrdinalIgnoreCase));

            if (oldIndex == newIndex)
            {
                return;
            }

            var item = playlist.LinkedChildren[oldIndex];

            var newList = playlist.LinkedChildren.ToList();

            newList.Remove(item);

            if (newIndex >= newList.Count)
            {
                newList.Add(item);
            }
            else
            {
                newList.Insert(newIndex, item);
            }

            playlist.LinkedChildren = newList.ToArray();

            playlist.UpdateToRepository(ItemUpdateType.MetadataEdit, CancellationToken.None);

            if (playlist.IsFile)
            {
                SavePlaylistFile(playlist);
            }
        }

        private void SavePlaylistFile(Playlist item)
        {
            // this is probably best done as a metadata provider
            // saving a file over itself will require some work to prevent this from happening when not needed
            var playlistPath = item.Path;
            var extension = Path.GetExtension(playlistPath);

            if (string.Equals(".wpl", extension, StringComparison.OrdinalIgnoreCase))
            {
                var playlist = new WplPlaylist();
                foreach (var child in item.GetLinkedChildren())
                {
                    var entry = new WplPlaylistEntry()
                    {
                        Path = NormalizeItemPath(playlistPath, child.Path),
                        TrackTitle = child.Name,
                        AlbumTitle = child.Album
                    };

                    var hasAlbumArtist = child as IHasAlbumArtist;
                    if (hasAlbumArtist != null)
                    {
                        entry.AlbumArtist = hasAlbumArtist.AlbumArtists.FirstOrDefault();
                    }

                    var hasArtist = child as IHasArtist;
                    if (hasArtist != null)
                    {
                        entry.TrackArtist = hasArtist.Artists.FirstOrDefault();
                    }

                    if (child.RunTimeTicks.HasValue)
                    {
                        entry.Duration = TimeSpan.FromTicks(child.RunTimeTicks.Value);
                    }

                    playlist.PlaylistEntries.Add(entry);
                }

                string text = new WplContent().ToText(playlist);
                File.WriteAllText(playlistPath, text);
            }

            if (string.Equals(".zpl", extension, StringComparison.OrdinalIgnoreCase))
            {
                var playlist = new ZplPlaylist();
                foreach (var child in item.GetLinkedChildren())
                {
                    var entry = new ZplPlaylistEntry()
                    {
                        Path = NormalizeItemPath(playlistPath, child.Path),
                        TrackTitle = child.Name,
                        AlbumTitle = child.Album
                    };

                    var hasAlbumArtist = child as IHasAlbumArtist;
                    if (hasAlbumArtist != null)
                    {
                        entry.AlbumArtist = hasAlbumArtist.AlbumArtists.FirstOrDefault();
                    }

                    var hasArtist = child as IHasArtist;
                    if (hasArtist != null)
                    {
                        entry.TrackArtist = hasArtist.Artists.FirstOrDefault();
                    }

                    if (child.RunTimeTicks.HasValue)
                    {
                        entry.Duration = TimeSpan.FromTicks(child.RunTimeTicks.Value);
                    }
                    playlist.PlaylistEntries.Add(entry);
                }

                string text = new ZplContent().ToText(playlist);
                File.WriteAllText(playlistPath, text);
            }

            if (string.Equals(".m3u", extension, StringComparison.OrdinalIgnoreCase))
            {
                var playlist = new M3uPlaylist();
                playlist.IsExtended = true;
                foreach (var child in item.GetLinkedChildren())
                {
                    var entry = new M3uPlaylistEntry()
                    {
                        Path = NormalizeItemPath(playlistPath, child.Path),
                        Title = child.Name,
                        Album = child.Album
                    };

                    var hasAlbumArtist = child as IHasAlbumArtist;
                    if (hasAlbumArtist != null)
                    {
                        entry.AlbumArtist = hasAlbumArtist.AlbumArtists.FirstOrDefault();
                    }

                    if (child.RunTimeTicks.HasValue)
                    {
                        entry.Duration = TimeSpan.FromTicks(child.RunTimeTicks.Value);
                    }

                    playlist.PlaylistEntries.Add(entry);
                }

                string text = new M3uContent().ToText(playlist);
                File.WriteAllText(playlistPath, text);
            }

            if (string.Equals(".m3u8", extension, StringComparison.OrdinalIgnoreCase))
            {
                var playlist = new M3uPlaylist();
                playlist.IsExtended = true;
                foreach (var child in item.GetLinkedChildren())
                {
                    var entry = new M3uPlaylistEntry()
                    {
                        Path = NormalizeItemPath(playlistPath, child.Path),
                        Title = child.Name,
                        Album = child.Album
                    };

                    var hasAlbumArtist = child as IHasAlbumArtist;
                    if (hasAlbumArtist != null)
                    {
                        entry.AlbumArtist = hasAlbumArtist.AlbumArtists.FirstOrDefault();
                    }

                    if (child.RunTimeTicks.HasValue)
                    {
                        entry.Duration = TimeSpan.FromTicks(child.RunTimeTicks.Value);
                    }

                    playlist.PlaylistEntries.Add(entry);
                }

                string text = new M3u8Content().ToText(playlist);
                File.WriteAllText(playlistPath, text);
            }

            if (string.Equals(".pls", extension, StringComparison.OrdinalIgnoreCase))
            {
                var playlist = new PlsPlaylist();
                foreach (var child in item.GetLinkedChildren())
                {
                    var entry = new PlsPlaylistEntry()
                    {
                        Path = NormalizeItemPath(playlistPath, child.Path),
                        Title = child.Name
                    };

                    if (child.RunTimeTicks.HasValue)
                    {
                        entry.Length = TimeSpan.FromTicks(child.RunTimeTicks.Value);
                    }

                    playlist.PlaylistEntries.Add(entry);
                }

                string text = new PlsContent().ToText(playlist);
                File.WriteAllText(playlistPath, text);
            }
        }

        private string NormalizeItemPath(string playlistPath, string itemPath)
        {
            return MakeRelativePath(Path.GetDirectoryName(playlistPath), itemPath);
        }

        private static string MakeRelativePath(string folderPath, string fileAbsolutePath)
        {
            if (string.IsNullOrEmpty(folderPath))
            {
                throw new ArgumentException("Folder path was null or empty.", nameof(folderPath));
            }

            if (string.IsNullOrEmpty(fileAbsolutePath))
            {
                throw new ArgumentException("File absolute path was null or empty.", nameof(fileAbsolutePath));
            }

            if (!folderPath.EndsWith(Path.DirectorySeparatorChar))
            {
                folderPath = folderPath + Path.DirectorySeparatorChar;
            }

            var folderUri = new Uri(folderPath);
            var fileAbsoluteUri = new Uri(fileAbsolutePath);

            // path can't be made relative
            if (folderUri.Scheme != fileAbsoluteUri.Scheme)
            {
                return fileAbsolutePath;
            }

            var relativeUri = folderUri.MakeRelativeUri(fileAbsoluteUri);
            string relativePath = Uri.UnescapeDataString(relativeUri.ToString());

            if (fileAbsoluteUri.Scheme.Equals("file", StringComparison.CurrentCultureIgnoreCase))
            {
                relativePath = relativePath.Replace(Path.AltDirectorySeparatorChar, Path.DirectorySeparatorChar);
            }

            return relativePath;
        }

        private static string UnEscape(string content)
        {
            if (content == null) return content;
            return content.Replace("&amp;", "&").Replace("&apos;", "'").Replace("&quot;", "\"").Replace("&gt;", ">").Replace("&lt;", "<");
        }

        private static string Escape(string content)
        {
            if (content == null) return null;
            return content.Replace("&", "&amp;").Replace("'", "&apos;").Replace("\"", "&quot;").Replace(">", "&gt;").Replace("<", "&lt;");
        }

        public Folder GetPlaylistsFolder(Guid userId)
        {
            var typeName = "PlaylistsFolder";

            return _libraryManager.RootFolder.Children.OfType<Folder>().FirstOrDefault(i => string.Equals(i.GetType().Name, typeName, StringComparison.Ordinal)) ??
                _libraryManager.GetUserRootFolder().Children.OfType<Folder>().FirstOrDefault(i => string.Equals(i.GetType().Name, typeName, StringComparison.Ordinal));
        }
    }
}