jellyfin/MediaBrowser.Controller/Entities/BaseItem.cs

using MediaBrowser.Common.Extensions;
using MediaBrowser.Common.IO;
using MediaBrowser.Controller.Channels;
using MediaBrowser.Controller.Collections;
using MediaBrowser.Controller.Configuration;
using MediaBrowser.Controller.Drawing;
using MediaBrowser.Controller.Library;
using MediaBrowser.Controller.LiveTv;
using MediaBrowser.Controller.Localization;
using MediaBrowser.Controller.Persistence;
using MediaBrowser.Controller.Providers;
using MediaBrowser.Model.Configuration;
using MediaBrowser.Model.Dto;
using MediaBrowser.Model.Entities;
using MediaBrowser.Model.Library;
using MediaBrowser.Model.Logging;
using MediaBrowser.Model.Users;
using System;
using System.Collections.Generic;
using System.Globalization;
using System.IO;
using System.Linq;
using System.Runtime.Serialization;
using System.Threading;
using System.Threading.Tasks;
using CommonIO;

namespace MediaBrowser.Controller.Entities
{
    /// <summary>
    /// Class BaseItem
    /// </summary>
    public abstract class BaseItem : IHasProviderIds, ILibraryItem, IHasImages, IHasUserData, IHasMetadata, IHasLookupInfo<ItemLookupInfo>
    {
        protected BaseItem()
        {
            Genres = new List<string>();
            Studios = new List<string>();
            ProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
            LockedFields = new List<MetadataFields>();
            ImageInfos = new List<ItemImageInfo>();
        }

        /// <summary>
        /// The supported image extensions
        /// </summary>
        public static readonly string[] SupportedImageExtensions = { ".png", ".jpg", ".jpeg" };

        public static readonly List<string> SupportedImageExtensionsList = SupportedImageExtensions.ToList();

        /// <summary>
        /// The trailer folder name
        /// </summary>
        public static string TrailerFolderName = "trailers";
        public static string ThemeSongsFolderName = "theme-music";
        public static string ThemeSongFilename = "theme";
        public static string ThemeVideosFolderName = "backdrops";

        public string PreferredMetadataCountryCode { get; set; }
        public string PreferredMetadataLanguage { get; set; }

        public List<ItemImageInfo> ImageInfos { get; set; }

        /// <summary>
        /// Gets or sets the channel identifier.
        /// </summary>
        /// <value>The channel identifier.</value>
        [IgnoreDataMember]
        public string ChannelId { get; set; }

        [IgnoreDataMember]
        public virtual bool SupportsAddingToPlaylist
        {
            get
            {
                return false;
            }
        }

        [IgnoreDataMember]
        public virtual bool AlwaysScanInternalMetadataPath
        {
            get { return false; }
        }

        /// <summary>
        /// Gets a value indicating whether this instance is in mixed folder.
        /// </summary>
        /// <value><c>true</c> if this instance is in mixed folder; otherwise, <c>false</c>.</value>
        public bool IsInMixedFolder { get; set; }

        [IgnoreDataMember]
        public virtual bool SupportsRemoteImageDownloading
        {
            get
            {
                return true;
            }
        }

        private string _name;
        /// <summary>
        /// Gets or sets the name.
        /// </summary>
        /// <value>The name.</value>
        public string Name
        {
            get
            {
                return _name;
            }
            set
            {
                _name = value;

                // lazy load this again
                _sortName = null;
            }
        }

        /// <summary>
        /// Gets or sets the id.
        /// </summary>
        /// <value>The id.</value>
        public Guid Id { get; set; }

        /// <summary>
        /// Gets or sets a value indicating whether this instance is hd.
        /// </summary>
        /// <value><c>true</c> if this instance is hd; otherwise, <c>false</c>.</value>
        public bool? IsHD { get; set; }

        /// <summary>
        /// Return the id that should be used to key display prefs for this item.
        /// Default is based on the type for everything except actual generic folders.
        /// </summary>
        /// <value>The display prefs id.</value>
        [IgnoreDataMember]
        public virtual Guid DisplayPreferencesId
        {
            get
            {
                var thisType = GetType();
                return thisType == typeof(Folder) ? Id : thisType.FullName.GetMD5();
            }
        }

        /// <summary>
        /// Gets or sets the path.
        /// </summary>
        /// <value>The path.</value>
        public virtual string Path { get; set; }

        [IgnoreDataMember]
        public bool IsOffline { get; set; }

        /// <summary>
        /// Returns the folder containing the item.
        /// If the item is a folder, it returns the folder itself
        /// </summary>
        [IgnoreDataMember]
        public virtual string ContainingFolderPath
        {
            get
            {
                if (IsFolder)
                {
                    return Path;
                }

                return System.IO.Path.GetDirectoryName(Path);
            }
        }

        /// <summary>
        /// Id of the program.
        /// </summary>
        [IgnoreDataMember]
        public string ExternalId
        {
            get { return this.GetProviderId("ProviderExternalId"); }
            set
            {
                this.SetProviderId("ProviderExternalId", value);
            }
        }

        /// <summary>
        /// Gets or sets the etag.
        /// </summary>
        /// <value>The etag.</value>
        [IgnoreDataMember]
        public string ExternalEtag { get; set; }

        [IgnoreDataMember]
        public virtual bool IsHidden
        {
            get
            {
                return false;
            }
        }

        public virtual bool IsHiddenFromUser(User user)
        {
            return false;
        }

        [IgnoreDataMember]
        public virtual bool IsOwnedItem
        {
            get
            {
                // Local trailer, special feature, theme video, etc.
                // An item that belongs to another item but is not part of the Parent-Child tree
                return !IsFolder && ParentId == Guid.Empty && LocationType == LocationType.FileSystem;
            }
        }

        /// <summary>
        /// Gets or sets the type of the location.
        /// </summary>
        /// <value>The type of the location.</value>
        [IgnoreDataMember]
        public virtual LocationType LocationType
        {
            get
            {
                if (IsOffline)
                {
                    return LocationType.Offline;
                }

                if (string.IsNullOrWhiteSpace(Path))
                {
                    return LocationType.Virtual;
                }

                return FileSystem.IsPathFile(Path) ? LocationType.FileSystem : LocationType.Remote;
            }
        }

        [IgnoreDataMember]
        public virtual bool SupportsLocalMetadata
        {
            get
            {
                var locationType = LocationType;

                return locationType != LocationType.Remote && locationType != LocationType.Virtual;
            }
        }

        [IgnoreDataMember]
        public virtual string FileNameWithoutExtension
        {
            get
            {
                if (LocationType == LocationType.FileSystem)
                {
                    return System.IO.Path.GetFileNameWithoutExtension(Path);
                }

                return null;
            }
        }

        [IgnoreDataMember]
        public virtual bool EnableAlphaNumericSorting
        {
            get
            {
                return true;
            }
        }

        /// <summary>
        /// This is just a helper for convenience
        /// </summary>
        /// <value>The primary image path.</value>
        [IgnoreDataMember]
        public string PrimaryImagePath
        {
            get { return this.GetImagePath(ImageType.Primary); }
        }

        public virtual bool IsInternetMetadataEnabled()
        {
            return ConfigurationManager.Configuration.EnableInternetProviders;
        }

        public virtual bool CanDelete()
        {
            var locationType = LocationType;
            return locationType != LocationType.Remote &&
                   locationType != LocationType.Virtual;
        }

        public virtual bool IsAuthorizedToDelete(User user)
        {
            return user.Policy.EnableContentDeletion;
        }

        public bool CanDelete(User user)
        {
            return CanDelete() && IsAuthorizedToDelete(user);
        }

        public virtual bool CanDownload()
        {
            return false;
        }

        public virtual bool IsAuthorizedToDownload(User user)
        {
            return user.Policy.EnableContentDownloading;
        }

        public bool CanDownload(User user)
        {
            return CanDownload() && IsAuthorizedToDownload(user);
        }

        /// <summary>
        /// Gets or sets the date created.
        /// </summary>
        /// <value>The date created.</value>
        public DateTime DateCreated { get; set; }

        /// <summary>
        /// Gets or sets the date modified.
        /// </summary>
        /// <value>The date modified.</value>
        public DateTime DateModified { get; set; }

        public DateTime DateLastSaved { get; set; }

        [IgnoreDataMember]
        public DateTime DateLastRefreshed { get; set; }

        /// <summary>
        /// The logger
        /// </summary>
        public static ILogger Logger { get; set; }
        public static ILibraryManager LibraryManager { get; set; }
        public static IServerConfigurationManager ConfigurationManager { get; set; }
        public static IProviderManager ProviderManager { get; set; }
        public static ILocalizationManager LocalizationManager { get; set; }
        public static IItemRepository ItemRepository { get; set; }
        public static IFileSystem FileSystem { get; set; }
        public static IUserDataManager UserDataManager { get; set; }
        public static ILiveTvManager LiveTvManager { get; set; }
        public static IChannelManager ChannelManager { get; set; }
        public static ICollectionManager CollectionManager { get; set; }
        public static IImageProcessor ImageProcessor { get; set; }
        public static IMediaSourceManager MediaSourceManager { get; set; }

        /// <summary>
        /// Returns a <see cref="System.String" /> that represents this instance.
        /// </summary>
        /// <returns>A <see cref="System.String" /> that represents this instance.</returns>
        public override string ToString()
        {
            return Name;
        }

        [IgnoreDataMember]
        public bool IsLocked { get; set; }

        /// <summary>
        /// Gets or sets the locked fields.
        /// </summary>
        /// <value>The locked fields.</value>
        public List<MetadataFields> LockedFields { get; set; }

        /// <summary>
        /// Gets the type of the media.
        /// </summary>
        /// <value>The type of the media.</value>
        [IgnoreDataMember]
        public virtual string MediaType
        {
            get
            {
                return null;
            }
        }

        [IgnoreDataMember]
        public virtual IEnumerable<string> PhysicalLocations
        {
            get
            {
                var locationType = LocationType;

                if (locationType == LocationType.Remote || locationType == LocationType.Virtual)
                {
                    return new string[] { };
                }

                return new[] { Path };
            }
        }

        private string _forcedSortName;
        /// <summary>
        /// Gets or sets the name of the forced sort.
        /// </summary>
        /// <value>The name of the forced sort.</value>
        public string ForcedSortName
        {
            get { return _forcedSortName; }
            set { _forcedSortName = value; _sortName = null; }
        }

        private string _sortName;
        /// <summary>
        /// Gets the name of the sort.
        /// </summary>
        /// <value>The name of the sort.</value>
        [IgnoreDataMember]
        public string SortName
        {
            get
            {
                if (!string.IsNullOrWhiteSpace(ForcedSortName))
                {
                    return ForcedSortName;
                }

                return _sortName ?? (_sortName = CreateSortName());
            }
            set
            {
                _sortName = value;
            }
        }

        public string GetInternalMetadataPath()
        {
            var basePath = ConfigurationManager.ApplicationPaths.InternalMetadataPath;

            return GetInternalMetadataPath(basePath);
        }

        protected virtual string GetInternalMetadataPath(string basePath)
        {
            var idString = Id.ToString("N");

            if (ConfigurationManager.Configuration.EnableLibraryMetadataSubFolder)
            {
                basePath = System.IO.Path.Combine(basePath, "library");
            }

            return System.IO.Path.Combine(basePath, idString.Substring(0, 2), idString);
        }

        /// <summary>
        /// Creates the name of the sort.
        /// </summary>
        /// <returns>System.String.</returns>
        protected virtual string CreateSortName()
        {
            if (Name == null) return null; //some items may not have name filled in properly

            if (!EnableAlphaNumericSorting)
            {
                return Name.TrimStart();
            }

            var sortable = Name.Trim().ToLower();
            sortable = ConfigurationManager.Configuration.SortRemoveCharacters.Aggregate(sortable, (current, search) => current.Replace(search.ToLower(), string.Empty));

            sortable = ConfigurationManager.Configuration.SortReplaceCharacters.Aggregate(sortable, (current, search) => current.Replace(search.ToLower(), " "));

            foreach (var search in ConfigurationManager.Configuration.SortRemoveWords)
            {
                var searchLower = search.ToLower();
                // Remove from beginning if a space follows
                if (sortable.StartsWith(searchLower + " "))
                {
                    sortable = sortable.Remove(0, searchLower.Length + 1);
                }
                // Remove from middle if surrounded by spaces
                sortable = sortable.Replace(" " + searchLower + " ", " ");

                // Remove from end if followed by a space
                if (sortable.EndsWith(" " + searchLower))
                {
                    sortable = sortable.Remove(sortable.Length - (searchLower.Length + 1));
                }
            }
            return sortable;
        }

        public Guid ParentId { get; set; }

        /// <summary>
        /// Gets or sets the parent.
        /// </summary>
        /// <value>The parent.</value>
        [IgnoreDataMember]
        public Folder Parent
        {
            get
            {
                if (ParentId != Guid.Empty)
                {
                    return LibraryManager.GetItemById(ParentId) as Folder;
                }

                return null;
            }
            set
            {

            }
        }

        public void SetParent(Folder parent)
        {
            ParentId = parent == null ? Guid.Empty : parent.Id;
        }

        [IgnoreDataMember]
        public IEnumerable<Folder> Parents
        {
            get
            {
                var parent = Parent;

                while (parent != null)
                {
                    yield return parent;

                    parent = parent.Parent;
                }
            }
        }

        /// <summary>
        /// Finds a parent of a given type
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns>``0.</returns>
        public T FindParent<T>()
            where T : Folder
        {
            return Parents.OfType<T>().FirstOrDefault();
        }

        [IgnoreDataMember]
        public virtual BaseItem DisplayParent
        {
            get { return Parent; }
        }

        /// <summary>
        /// When the item first debuted. For movies this could be premiere date, episodes would be first aired
        /// </summary>
        /// <value>The premiere date.</value>
        public DateTime? PremiereDate { get; set; }

        /// <summary>
        /// Gets or sets the end date.
        /// </summary>
        /// <value>The end date.</value>
        [IgnoreDataMember]
        public DateTime? EndDate { get; set; }

        /// <summary>
        /// Gets or sets the display type of the media.
        /// </summary>
        /// <value>The display type of the media.</value>
        public string DisplayMediaType { get; set; }

        /// <summary>
        /// Gets or sets the official rating.
        /// </summary>
        /// <value>The official rating.</value>
        public string OfficialRating { get; set; }

        /// <summary>
        /// Gets or sets the official rating description.
        /// </summary>
        /// <value>The official rating description.</value>
        public string OfficialRatingDescription { get; set; }

        /// <summary>
        /// Gets or sets the custom rating.
        /// </summary>
        /// <value>The custom rating.</value>
        //[IgnoreDataMember]
        public string CustomRating { get; set; }

        /// <summary>
        /// Gets or sets the overview.
        /// </summary>
        /// <value>The overview.</value>
        public string Overview { get; set; }

        /// <summary>
        /// Gets or sets the studios.
        /// </summary>
        /// <value>The studios.</value>
        public List<string> Studios { get; set; }

        /// <summary>
        /// Gets or sets the genres.
        /// </summary>
        /// <value>The genres.</value>
        public List<string> Genres { get; set; }

        /// <summary>
        /// Gets or sets the home page URL.
        /// </summary>
        /// <value>The home page URL.</value>
        public string HomePageUrl { get; set; }

        /// <summary>
        /// Gets or sets the community rating.
        /// </summary>
        /// <value>The community rating.</value>
        //[IgnoreDataMember]
        public float? CommunityRating { get; set; }

        /// <summary>
        /// Gets or sets the community rating vote count.
        /// </summary>
        /// <value>The community rating vote count.</value>
        public int? VoteCount { get; set; }

        /// <summary>
        /// Gets or sets the run time ticks.
        /// </summary>
        /// <value>The run time ticks.</value>
        public long? RunTimeTicks { get; set; }

        /// <summary>
        /// Gets or sets the production year.
        /// </summary>
        /// <value>The production year.</value>
        public int? ProductionYear { get; set; }

        /// <summary>
        /// If the item is part of a series, this is it's number in the series.
        /// This could be episode number, album track number, etc.
        /// </summary>
        /// <value>The index number.</value>
        //[IgnoreDataMember]
        public int? IndexNumber { get; set; }

        /// <summary>
        /// For an episode this could be the season number, or for a song this could be the disc number.
        /// </summary>
        /// <value>The parent index number.</value>
        public int? ParentIndexNumber { get; set; }

        [IgnoreDataMember]
        public virtual string OfficialRatingForComparison
        {
            get { return OfficialRating; }
        }

        [IgnoreDataMember]
        public string CustomRatingForComparison
        {
            get
            {
                if (!string.IsNullOrWhiteSpace(CustomRating))
                {
                    return CustomRating;
                }

                var parent = DisplayParent;
                if (parent != null)
                {
                    return parent.CustomRatingForComparison;
                }

                return null;
            }
        }

        /// <summary>
        /// Gets the play access.
        /// </summary>
        /// <param name="user">The user.</param>
        /// <returns>PlayAccess.</returns>
        public PlayAccess GetPlayAccess(User user)
        {
            if (!user.Policy.EnableMediaPlayback)
            {
                return PlayAccess.None;
            }

            //if (!user.IsParentalScheduleAllowed())
            //{
            //    return PlayAccess.None;
            //}

            return PlayAccess.Full;
        }

        /// <summary>
        /// Loads the theme songs.
        /// </summary>
        /// <returns>List{Audio.Audio}.</returns>
        private IEnumerable<Audio.Audio> LoadThemeSongs(List<FileSystemMetadata> fileSystemChildren, IDirectoryService directoryService)
        {
            var files = fileSystemChildren.Where(i => i.IsDirectory)
                .Where(i => string.Equals(i.Name, ThemeSongsFolderName, StringComparison.OrdinalIgnoreCase))
                .SelectMany(i => directoryService.GetFiles(i.FullName))
                .ToList();

            // Support plex/xbmc convention
            files.AddRange(fileSystemChildren
                .Where(i => !i.IsDirectory && string.Equals(FileSystem.GetFileNameWithoutExtension(i), ThemeSongFilename, StringComparison.OrdinalIgnoreCase))
                );

            return LibraryManager.ResolvePaths(files, directoryService, null)
                .OfType<Audio.Audio>()
                .Select(audio =>
            {
                // Try to retrieve it from the db. If we don't find it, use the resolved version
                var dbItem = LibraryManager.GetItemById(audio.Id) as Audio.Audio;

                if (dbItem != null)
                {
                    audio = dbItem;
                }

                audio.ExtraType = ExtraType.ThemeSong;

                return audio;

                // Sort them so that the list can be easily compared for changes
            }).OrderBy(i => i.Path).ToList();
        }

        /// <summary>
        /// Loads the video backdrops.
        /// </summary>
        /// <returns>List{Video}.</returns>
        private IEnumerable<Video> LoadThemeVideos(IEnumerable<FileSystemMetadata> fileSystemChildren, IDirectoryService directoryService)
        {
            var files = fileSystemChildren.Where(i => i.IsDirectory)
                .Where(i => string.Equals(i.Name, ThemeVideosFolderName, StringComparison.OrdinalIgnoreCase))
                .SelectMany(i => directoryService.GetFiles(i.FullName));

            return LibraryManager.ResolvePaths(files, directoryService, null)
                .OfType<Video>()
                .Select(item =>
            {
                // Try to retrieve it from the db. If we don't find it, use the resolved version
                var dbItem = LibraryManager.GetItemById(item.Id) as Video;

                if (dbItem != null)
                {
                    item = dbItem;
                }

                item.ExtraType = ExtraType.ThemeVideo;

                return item;

                // Sort them so that the list can be easily compared for changes
            }).OrderBy(i => i.Path).ToList();
        }

        public Task RefreshMetadata(CancellationToken cancellationToken)
        {
            return RefreshMetadata(new MetadataRefreshOptions(new DirectoryService(FileSystem)), cancellationToken);
        }

        /// <summary>
        /// Overrides the base implementation to refresh metadata for local trailers
        /// </summary>
        /// <param name="options">The options.</param>
        /// <param name="cancellationToken">The cancellation token.</param>
        /// <returns>true if a provider reports we changed</returns>
        public async Task<ItemUpdateType> RefreshMetadata(MetadataRefreshOptions options, CancellationToken cancellationToken)
        {
            var locationType = LocationType;

            var requiresSave = false;

            if (SupportsOwnedItems)
            {
                try
                {
                    var files = locationType != LocationType.Remote && locationType != LocationType.Virtual ?
                        GetFileSystemChildren(options.DirectoryService).ToList() :
                        new List<FileSystemMetadata>();

                    var ownedItemsChanged = await RefreshedOwnedItems(options, files, cancellationToken).ConfigureAwait(false);

                    if (ownedItemsChanged)
                    {
                        requiresSave = true;
                    }
                }
                catch (Exception ex)
                {
                    Logger.ErrorException("Error refreshing owned items for {0}", ex, Path ?? Name);
                }
            }

            var refreshOptions = requiresSave
                ? new MetadataRefreshOptions(options)
                {
                    ForceSave = true
                }
                : options;

            var result = await ProviderManager.RefreshSingleItem(this, refreshOptions, cancellationToken).ConfigureAwait(false);

            return result;
        }

        [IgnoreDataMember]
        protected virtual bool SupportsOwnedItems
        {
            get { return IsFolder || Parent != null; }
        }

        [IgnoreDataMember]
        public virtual bool SupportsPeople
        {
            get { return true; }
        }

        /// <summary>
        /// Refreshes owned items such as trailers, theme videos, special features, etc.
        /// Returns true or false indicating if changes were found.
        /// </summary>
        /// <param name="options"></param>
        /// <param name="fileSystemChildren"></param>
        /// <param name="cancellationToken"></param>
        /// <returns></returns>
        protected virtual async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
        {
            var themeSongsChanged = false;

            var themeVideosChanged = false;

            var localTrailersChanged = false;

            if (LocationType == LocationType.FileSystem && Parent != null)
            {
                var hasThemeMedia = this as IHasThemeMedia;
                if (hasThemeMedia != null)
                {
                    if (!IsInMixedFolder)
                    {
                        themeSongsChanged = await RefreshThemeSongs(hasThemeMedia, options, fileSystemChildren, cancellationToken).ConfigureAwait(false);

                        themeVideosChanged = await RefreshThemeVideos(hasThemeMedia, options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
                    }
                }

                var hasTrailers = this as IHasTrailers;
                if (hasTrailers != null)
                {
                    localTrailersChanged = await RefreshLocalTrailers(hasTrailers, options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
                }
            }

            return themeSongsChanged || themeVideosChanged || localTrailersChanged;
        }

        protected virtual IEnumerable<FileSystemMetadata> GetFileSystemChildren(IDirectoryService directoryService)
        {
            var path = ContainingFolderPath;

            return directoryService.GetFileSystemEntries(path);
        }

        private async Task<bool> RefreshLocalTrailers(IHasTrailers item, MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
        {
            var newItems = LibraryManager.FindTrailers(this, fileSystemChildren, options.DirectoryService).ToList();

            var newItemIds = newItems.Select(i => i.Id).ToList();

            var itemsChanged = !item.LocalTrailerIds.SequenceEqual(newItemIds);

            var tasks = newItems.Select(i => i.RefreshMetadata(options, cancellationToken));

            await Task.WhenAll(tasks).ConfigureAwait(false);

            item.LocalTrailerIds = newItemIds;

            return itemsChanged;
        }

        private async Task<bool> RefreshThemeVideos(IHasThemeMedia item, MetadataRefreshOptions options, IEnumerable<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
        {
            var newThemeVideos = LoadThemeVideos(fileSystemChildren, options.DirectoryService).ToList();

            var newThemeVideoIds = newThemeVideos.Select(i => i.Id).ToList();

            var themeVideosChanged = !item.ThemeVideoIds.SequenceEqual(newThemeVideoIds);

            var tasks = newThemeVideos.Select(i =>
            {
                var subOptions = new MetadataRefreshOptions(options);

                if (!i.IsThemeMedia)
                {
                    i.ExtraType = ExtraType.ThemeVideo;
                    subOptions.ForceSave = true;
                }

                return i.RefreshMetadata(subOptions, cancellationToken);
            });

            await Task.WhenAll(tasks).ConfigureAwait(false);

            item.ThemeVideoIds = newThemeVideoIds;

            return themeVideosChanged;
        }

        /// <summary>
        /// Refreshes the theme songs.
        /// </summary>
        private async Task<bool> RefreshThemeSongs(IHasThemeMedia item, MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
        {
            var newThemeSongs = LoadThemeSongs(fileSystemChildren, options.DirectoryService).ToList();
            var newThemeSongIds = newThemeSongs.Select(i => i.Id).ToList();

            var themeSongsChanged = !item.ThemeSongIds.SequenceEqual(newThemeSongIds);

            var tasks = newThemeSongs.Select(i =>
            {
                var subOptions = new MetadataRefreshOptions(options);

                if (!i.IsThemeMedia)
                {
                    i.ExtraType = ExtraType.ThemeSong;
                    subOptions.ForceSave = true;
                }

                return i.RefreshMetadata(subOptions, cancellationToken);
            });

            await Task.WhenAll(tasks).ConfigureAwait(false);

            item.ThemeSongIds = newThemeSongIds;

            return themeSongsChanged;
        }

        /// <summary>
        /// Gets or sets the provider ids.
        /// </summary>
        /// <value>The provider ids.</value>
        public Dictionary<string, string> ProviderIds { get; set; }

        [IgnoreDataMember]
        public virtual Folder LatestItemsIndexContainer
        {
            get { return null; }
        }

        private string _userDataKey;
        /// <summary>
        /// Gets the user data key.
        /// </summary>
        /// <returns>System.String.</returns>
        public string GetUserDataKey()
        {
            if (string.IsNullOrWhiteSpace(_userDataKey))
            {
                var key = CreateUserDataKey();
                _userDataKey = key;
                return key;
            }

            return _userDataKey;
        }

        protected virtual string CreateUserDataKey()
        {
            return Id.ToString();
        }

        internal virtual bool IsValidFromResolver(BaseItem newItem)
        {
            var current = this;

            return current.IsInMixedFolder == newItem.IsInMixedFolder;
        }

        public void AfterMetadataRefresh()
        {
            _sortName = null;
            _userDataKey = null;
        }

        /// <summary>
        /// Gets the preferred metadata language.
        /// </summary>
        /// <returns>System.String.</returns>
        public string GetPreferredMetadataLanguage()
        {
            string lang = PreferredMetadataLanguage;

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = Parents
                    .Select(i => i.PreferredMetadataLanguage)
                    .FirstOrDefault(i => !string.IsNullOrWhiteSpace(i));
            }

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = LibraryManager.GetCollectionFolders(this)
                    .Select(i => i.PreferredMetadataLanguage)
                    .FirstOrDefault(i => !string.IsNullOrWhiteSpace(i));
            }

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = ConfigurationManager.Configuration.PreferredMetadataLanguage;
            }

            return lang;
        }

        /// <summary>
        /// Gets the preferred metadata language.
        /// </summary>
        /// <returns>System.String.</returns>
        public string GetPreferredMetadataCountryCode()
        {
            string lang = PreferredMetadataCountryCode;

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = Parents
                    .Select(i => i.PreferredMetadataCountryCode)
                    .FirstOrDefault(i => !string.IsNullOrWhiteSpace(i));
            }

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = LibraryManager.GetCollectionFolders(this)
                    .Select(i => i.PreferredMetadataCountryCode)
                    .FirstOrDefault(i => !string.IsNullOrWhiteSpace(i));
            }

            if (string.IsNullOrWhiteSpace(lang))
            {
                lang = ConfigurationManager.Configuration.MetadataCountryCode;
            }

            return lang;
        }

        public virtual bool IsSaveLocalMetadataEnabled()
        {
            return ConfigurationManager.Configuration.SaveLocalMeta;
        }

        /// <summary>
        /// Determines if a given user has access to this item
        /// </summary>
        /// <param name="user">The user.</param>
        /// <returns><c>true</c> if [is parental allowed] [the specified user]; otherwise, <c>false</c>.</returns>
        /// <exception cref="System.ArgumentNullException">user</exception>
        public bool IsParentalAllowed(User user)
        {
            if (user == null)
            {
                throw new ArgumentNullException("user");
            }

            if (!IsVisibleViaTags(user))
            {
                return false;
            }

            var maxAllowedRating = user.Policy.MaxParentalRating;

            if (maxAllowedRating == null)
            {
                return true;
            }

            var rating = CustomRatingForComparison;

            if (string.IsNullOrWhiteSpace(rating))
            {
                rating = OfficialRatingForComparison;
            }

            if (string.IsNullOrWhiteSpace(rating))
            {
                return !GetBlockUnratedValue(user.Policy);
            }

            var value = LocalizationManager.GetRatingLevel(rating);

            // Could not determine the integer value
            if (!value.HasValue)
            {
                var isAllowed = !GetBlockUnratedValue(user.Policy);

                if (!isAllowed)
                {
                    Logger.Debug("{0} has an unrecognized parental rating of {1}.", Name, rating);
                }

                return isAllowed;
            }

            return value.Value <= maxAllowedRating.Value;
        }

        public int? GetParentalRatingValue()
        {
            var rating = CustomRatingForComparison;

            if (string.IsNullOrWhiteSpace(rating))
            {
                rating = OfficialRatingForComparison;
            }

            if (string.IsNullOrWhiteSpace(rating))
            {
                return null;
            }

            return LocalizationManager.GetRatingLevel(rating);
        }

        private bool IsVisibleViaTags(User user)
        {
            var hasTags = this as IHasTags;

            if (hasTags != null)
            {
                var policy = user.Policy;
                if (policy.BlockedTags.Any(i => hasTags.Tags.Contains(i, StringComparer.OrdinalIgnoreCase)))
                {
                    return false;
                }
            }

            return true;
        }

        protected virtual bool IsAllowTagFilterEnforced()
        {
            return true;
        }

        /// <summary>
        /// Gets the block unrated value.
        /// </summary>
        /// <param name="config">The configuration.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
        protected virtual bool GetBlockUnratedValue(UserPolicy config)
        {
            // Don't block plain folders that are unrated. Let the media underneath get blocked
            // Special folders like series and albums will override this method.
            if (IsFolder)
            {
                return false;
            }
            if (this is IItemByName)
            {
                return false;
            }

            return config.BlockUnratedItems.Contains(UnratedItem.Other);
        }

        /// <summary>
        /// Determines if this folder should be visible to a given user.
        /// Default is just parental allowed. Can be overridden for more functionality.
        /// </summary>
        /// <param name="user">The user.</param>
        /// <returns><c>true</c> if the specified user is visible; otherwise, <c>false</c>.</returns>
        /// <exception cref="System.ArgumentNullException">user</exception>
        public virtual bool IsVisible(User user)
        {
            if (user == null)
            {
                throw new ArgumentNullException("user");
            }

            return IsParentalAllowed(user);
        }

        public virtual bool IsVisibleStandalone(User user)
        {
            return IsVisibleStandaloneInternal(user, true);
        }

        protected bool IsVisibleStandaloneInternal(User user, bool checkFolders)
        {
            if (!IsVisible(user))
            {
                return false;
            }

            if (Parents.Any(i => !i.IsVisible(user)))
            {
                return false;
            }

            if (checkFolders)
            {
                var topParent = Parents.LastOrDefault() ?? this;

                if (string.IsNullOrWhiteSpace(topParent.Path))
                {
                    return true;
                }

                var userCollectionFolders = user.RootFolder.GetChildren(user, true).Select(i => i.Id).ToList();
                var itemCollectionFolders = LibraryManager.GetCollectionFolders(this).Select(i => i.Id);

                if (!itemCollectionFolders.Any(userCollectionFolders.Contains))
                {
                    return false;
                }
            }

            return true;
        }

        /// <summary>
        /// Gets a value indicating whether this instance is folder.
        /// </summary>
        /// <value><c>true</c> if this instance is folder; otherwise, <c>false</c>.</value>
        [IgnoreDataMember]
        public virtual bool IsFolder
        {
            get
            {
                return false;
            }
        }

        public virtual string GetClientTypeName()
        {
            return GetType().Name;
        }

        /// <summary>
        /// Gets the linked child.
        /// </summary>
        /// <param name="info">The info.</param>
        /// <returns>BaseItem.</returns>
        protected BaseItem GetLinkedChild(LinkedChild info)
        {
            // First get using the cached Id
            if (info.ItemId.HasValue)
            {
                if (info.ItemId.Value == Guid.Empty)
                {
                    return null;
                }

                var itemById = LibraryManager.GetItemById(info.ItemId.Value);

                if (itemById != null)
                {
                    return itemById;
                }
            }

            var item = FindLinkedChild(info);

            // If still null, log
            if (item == null)
            {
                // Don't keep searching over and over
                info.ItemId = Guid.Empty;
            }
            else
            {
                // Cache the id for next time
                info.ItemId = item.Id;
            }

            return item;
        }

        private BaseItem FindLinkedChild(LinkedChild info)
        {
            if (!string.IsNullOrEmpty(info.Path))
            {
                var itemByPath = LibraryManager.RootFolder.FindByPath(info.Path);

                if (itemByPath == null)
                {
                    Logger.Warn("Unable to find linked item at path {0}", info.Path);
                }

                return itemByPath;
            }

            return null;
        }

        /// <summary>
        /// Adds a person to the item
        /// </summary>
        /// <param name="person">The person.</param>
        /// <exception cref="System.ArgumentNullException"></exception>
        public void AddPerson(PersonInfo person)
        {
        }

        /// <summary>
        /// Adds a studio to the item
        /// </summary>
        /// <param name="name">The name.</param>
        /// <exception cref="System.ArgumentNullException"></exception>
        public void AddStudio(string name)
        {
            if (string.IsNullOrWhiteSpace(name))
            {
                throw new ArgumentNullException("name");
            }

            if (!Studios.Contains(name, StringComparer.OrdinalIgnoreCase))
            {
                Studios.Add(name);
            }
        }

        /// <summary>
        /// Adds a genre to the item
        /// </summary>
        /// <param name="name">The name.</param>
        /// <exception cref="System.ArgumentNullException"></exception>
        public void AddGenre(string name)
        {
            if (string.IsNullOrWhiteSpace(name))
            {
                throw new ArgumentNullException("name");
            }

            if (!Genres.Contains(name, StringComparer.OrdinalIgnoreCase))
            {
                Genres.Add(name);
            }
        }

        /// <summary>
        /// Marks the played.
        /// </summary>
        /// <param name="user">The user.</param>
        /// <param name="datePlayed">The date played.</param>
        /// <param name="resetPosition">if set to <c>true</c> [reset position].</param>
        /// <returns>Task.</returns>
        /// <exception cref="System.ArgumentNullException"></exception>
        public virtual async Task MarkPlayed(User user,
            DateTime? datePlayed,
            bool resetPosition)
        {
            if (user == null)
            {
                throw new ArgumentNullException();
            }

            var key = GetUserDataKey();

            var data = UserDataManager.GetUserData(user.Id, key);

            if (datePlayed.HasValue)
            {
                // Incremenet
                data.PlayCount++;
            }

            // Ensure it's at least one
            data.PlayCount = Math.Max(data.PlayCount, 1);

            if (resetPosition)
            {
                data.PlaybackPositionTicks = 0;
            }

            data.LastPlayedDate = datePlayed ?? data.LastPlayedDate;
            data.Played = true;

            await UserDataManager.SaveUserData(user.Id, this, data, UserDataSaveReason.TogglePlayed, CancellationToken.None).ConfigureAwait(false);
        }

        /// <summary>
        /// Marks the unplayed.
        /// </summary>
        /// <param name="user">The user.</param>
        /// <returns>Task.</returns>
        /// <exception cref="System.ArgumentNullException"></exception>
        public virtual async Task MarkUnplayed(User user)
        {
            if (user == null)
            {
                throw new ArgumentNullException();
            }

            var key = GetUserDataKey();

            var data = UserDataManager.GetUserData(user.Id, key);

            //I think it is okay to do this here.
            // if this is only called when a user is manually forcing something to un-played
            // then it probably is what we want to do...
            data.PlayCount = 0;
            data.PlaybackPositionTicks = 0;
            data.LastPlayedDate = null;
            data.Played = false;

            await UserDataManager.SaveUserData(user.Id, this, data, UserDataSaveReason.TogglePlayed, CancellationToken.None).ConfigureAwait(false);
        }

        /// <summary>
        /// Do whatever refreshing is necessary when the filesystem pertaining to this item has changed.
        /// </summary>
        /// <returns>Task.</returns>
        public virtual Task ChangedExternally()
        {
            ProviderManager.QueueRefresh(Id, new MetadataRefreshOptions(FileSystem));
            return Task.FromResult(true);
        }

        /// <summary>
        /// Gets an image
        /// </summary>
        /// <param name="type">The type.</param>
        /// <param name="imageIndex">Index of the image.</param>
        /// <returns><c>true</c> if the specified type has image; otherwise, <c>false</c>.</returns>
        /// <exception cref="System.ArgumentException">Backdrops should be accessed using Item.Backdrops</exception>
        public bool HasImage(ImageType type, int imageIndex)
        {
            return GetImageInfo(type, imageIndex) != null;
        }

        public void SetImage(ItemImageInfo image, int index)
        {
            if (image.Type == ImageType.Chapter)
            {
                throw new ArgumentException("Cannot set chapter images using SetImagePath");
            }

            var existingImage = GetImageInfo(image.Type, index);

            if (existingImage != null)
            {
                ImageInfos.Remove(existingImage);
            }

            ImageInfos.Add(image);
        }

        public void SetImagePath(ImageType type, int index, FileSystemMetadata file)
        {
            if (type == ImageType.Chapter)
            {
                throw new ArgumentException("Cannot set chapter images using SetImagePath");
            }

            var image = GetImageInfo(type, index);

            if (image == null)
            {
                ImageInfos.Add(GetImageInfo(file, type));
            }
            else
            {
                var imageInfo = GetImageInfo(file, type);

                image.Path = file.FullName;
                image.DateModified = imageInfo.DateModified;
            }
        }

        /// <summary>
        /// Deletes the image.
        /// </summary>
        /// <param name="type">The type.</param>
        /// <param name="index">The index.</param>
        /// <returns>Task.</returns>
        public Task DeleteImage(ImageType type, int index)
        {
            var info = GetImageInfo(type, index);

            if (info == null)
            {
                // Nothing to do
                return Task.FromResult(true);
            }

            // Remove it from the item
            RemoveImage(info);

            if (info.IsLocalFile)
            {
                // Delete the source file
                var currentFile = new FileInfo(info.Path);

                // Deletion will fail if the file is hidden so remove the attribute first
                if (currentFile.Exists)
                {
                    if ((currentFile.Attributes & FileAttributes.Hidden) == FileAttributes.Hidden)
                    {
                        currentFile.Attributes &= ~FileAttributes.Hidden;
                    }

                    FileSystem.DeleteFile(currentFile.FullName);
                }
            }

            return UpdateToRepository(ItemUpdateType.ImageUpdate, CancellationToken.None);
        }

        public void RemoveImage(ItemImageInfo image)
        {
            ImageInfos.Remove(image);
        }

        public virtual Task UpdateToRepository(ItemUpdateType updateReason, CancellationToken cancellationToken)
        {
            return LibraryManager.UpdateItem(this, updateReason, cancellationToken);
        }

        /// <summary>
        /// Validates that images within the item are still on the file system
        /// </summary>
        public bool ValidateImages(IDirectoryService directoryService)
        {
            var allFiles = ImageInfos
                .Where(i => i.IsLocalFile)
                .Select(i => System.IO.Path.GetDirectoryName(i.Path))
                .Distinct(StringComparer.OrdinalIgnoreCase)
                .SelectMany(directoryService.GetFiles)
                .Select(i => i.FullName)
                .ToList();

            var deletedImages = ImageInfos
                .Where(image => image.IsLocalFile && !allFiles.Contains(image.Path, StringComparer.OrdinalIgnoreCase))
                .ToList();

            if (deletedImages.Count > 0)
            {
                ImageInfos = ImageInfos.Except(deletedImages).ToList();
            }

            return deletedImages.Count > 0;
        }

        /// <summary>
        /// Gets the image path.
        /// </summary>
        /// <param name="imageType">Type of the image.</param>
        /// <param name="imageIndex">Index of the image.</param>
        /// <returns>System.String.</returns>
        /// <exception cref="System.InvalidOperationException">
        /// </exception>
        /// <exception cref="System.ArgumentNullException">item</exception>
        public string GetImagePath(ImageType imageType, int imageIndex)
        {
            var info = GetImageInfo(imageType, imageIndex);

            return info == null ? null : info.Path;
        }

        /// <summary>
        /// Gets the image information.
        /// </summary>
        /// <param name="imageType">Type of the image.</param>
        /// <param name="imageIndex">Index of the image.</param>
        /// <returns>ItemImageInfo.</returns>
        public ItemImageInfo GetImageInfo(ImageType imageType, int imageIndex)
        {
            if (imageType == ImageType.Chapter)
            {
                var chapter = ItemRepository.GetChapter(Id, imageIndex);

                if (chapter == null)
                {
                    return null;
                }

                var path = chapter.ImagePath;

                if (string.IsNullOrWhiteSpace(path))
                {
                    return null;
                }

                return new ItemImageInfo
                {
                    Path = path,
                    DateModified = FileSystem.GetLastWriteTimeUtc(path),
                    Type = imageType
                };
            }

            return GetImages(imageType)
                .ElementAtOrDefault(imageIndex);
        }

        public IEnumerable<ItemImageInfo> GetImages(ImageType imageType)
        {
            if (imageType == ImageType.Chapter)
            {
                throw new ArgumentException("No image info for chapter images");
            }

            return ImageInfos.Where(i => i.Type == imageType);
        }

        /// <summary>
        /// Adds the images.
        /// </summary>
        /// <param name="imageType">Type of the image.</param>
        /// <param name="images">The images.</param>
        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
        /// <exception cref="System.ArgumentException">Cannot call AddImages with chapter images</exception>
        public bool AddImages(ImageType imageType, List<FileSystemMetadata> images)
        {
            if (imageType == ImageType.Chapter)
            {
                throw new ArgumentException("Cannot call AddImages with chapter images");
            }

            var existingImages = GetImages(imageType)
                .ToList();

            var newImageList = new List<FileSystemMetadata>();
            var imageAdded = false;

            foreach (var newImage in images)
            {
                if (newImage == null)
                {
                    throw new ArgumentException("null image found in list");
                }

                var existing = existingImages
                    .FirstOrDefault(i => string.Equals(i.Path, newImage.FullName, StringComparison.OrdinalIgnoreCase));

                if (existing == null)
                {
                    newImageList.Add(newImage);
                    imageAdded = true;
                }
                else
                {
                    if (existing.IsLocalFile)
                    {
                        existing.DateModified = FileSystem.GetLastWriteTimeUtc(newImage);
                    }
                }
            }

            if (imageAdded || images.Count != existingImages.Count)
            {
                var newImagePaths = images.Select(i => i.FullName).ToList();

                var deleted = existingImages
                    .Where(i => i.IsLocalFile && !newImagePaths.Contains(i.Path, StringComparer.OrdinalIgnoreCase) && !FileSystem.FileExists(i.Path))
                    .ToList();

                ImageInfos = ImageInfos.Except(deleted).ToList();
            }

            ImageInfos.AddRange(newImageList.Select(i => GetImageInfo(i, imageType)));

            return newImageList.Count > 0;
        }

        private ItemImageInfo GetImageInfo(FileSystemMetadata file, ImageType type)
        {
            return new ItemImageInfo
            {
                Path = file.FullName,
                Type = type,
                DateModified = FileSystem.GetLastWriteTimeUtc(file)
            };
        }

        /// <summary>
        /// Gets the file system path to delete when the item is to be deleted
        /// </summary>
        /// <returns></returns>
        public virtual IEnumerable<string> GetDeletePaths()
        {
            return new[] { Path };
        }

        public bool AllowsMultipleImages(ImageType type)
        {
            return type == ImageType.Backdrop || type == ImageType.Screenshot || type == ImageType.Chapter;
        }

        public Task SwapImages(ImageType type, int index1, int index2)
        {
            if (!AllowsMultipleImages(type))
            {
                throw new ArgumentException("The change index operation is only applicable to backdrops and screenshots");
            }

            var info1 = GetImageInfo(type, index1);
            var info2 = GetImageInfo(type, index2);

            if (info1 == null || info2 == null)
            {
                // Nothing to do
                return Task.FromResult(true);
            }

            if (!info1.IsLocalFile || !info2.IsLocalFile)
            {
                // TODO: Not supported  yet
                return Task.FromResult(true);
            }

            var path1 = info1.Path;
            var path2 = info2.Path;

            FileSystem.SwapFiles(path1, path2);

            // Refresh these values
            info1.DateModified = FileSystem.GetLastWriteTimeUtc(info1.Path);
            info2.DateModified = FileSystem.GetLastWriteTimeUtc(info2.Path);

            return UpdateToRepository(ItemUpdateType.ImageUpdate, CancellationToken.None);
        }

        public virtual bool IsPlayed(User user)
        {
            var userdata = UserDataManager.GetUserData(user.Id, GetUserDataKey());

            return userdata != null && userdata.Played;
        }

        public bool IsFavoriteOrLiked(User user)
        {
            var userdata = UserDataManager.GetUserData(user.Id, GetUserDataKey());

            return userdata != null && (userdata.IsFavorite || (userdata.Likes ?? false));
        }

        public virtual bool IsUnplayed(User user)
        {
            if (user == null)
            {
                throw new ArgumentNullException("user");
            }

            var userdata = UserDataManager.GetUserData(user.Id, GetUserDataKey());

            return userdata == null || !userdata.Played;
        }

        ItemLookupInfo IHasLookupInfo<ItemLookupInfo>.GetLookupInfo()
        {
            return GetItemLookupInfo<ItemLookupInfo>();
        }

        protected T GetItemLookupInfo<T>()
            where T : ItemLookupInfo, new()
        {
            return new T
            {
                MetadataCountryCode = GetPreferredMetadataCountryCode(),
                MetadataLanguage = GetPreferredMetadataLanguage(),
                Name = Name,
                ProviderIds = ProviderIds,
                IndexNumber = IndexNumber,
                ParentIndexNumber = ParentIndexNumber,
                Year = ProductionYear
            };
        }

        /// <summary>
        /// This is called before any metadata refresh and returns true or false indicating if changes were made
        /// </summary>
        public virtual bool BeforeMetadataRefresh()
        {
            _userDataKey = null;
            _sortName = null;

            var hasChanges = false;

            if (string.IsNullOrEmpty(Name) && !string.IsNullOrEmpty(Path))
            {
                Name = FileSystem.GetFileNameWithoutExtension(Path);
                hasChanges = true;
            }

            return hasChanges;
        }

        protected static string GetMappedPath(string path, LocationType locationType)
        {
            if (locationType == LocationType.FileSystem || locationType == LocationType.Offline)
            {
                foreach (var map in ConfigurationManager.Configuration.PathSubstitutions)
                {
                    path = LibraryManager.SubstitutePath(path, map.From, map.To);
                }
            }

            return path;
        }

        public virtual void FillUserDataDtoValues(UserItemDataDto dto, UserItemData userData, User user)
        {
            if (RunTimeTicks.HasValue)
            {
                double pct = RunTimeTicks.Value;

                if (pct > 0)
                {
                    pct = userData.PlaybackPositionTicks / pct;

                    if (pct > 0)
                    {
                        dto.PlayedPercentage = 100 * pct;
                    }
                }
            }
        }

        protected Task RefreshMetadataForOwnedVideo(MetadataRefreshOptions options, string path, CancellationToken cancellationToken)
        {
            var newOptions = new MetadataRefreshOptions(options.DirectoryService)
            {
                ImageRefreshMode = options.ImageRefreshMode,
                MetadataRefreshMode = options.MetadataRefreshMode,
                ReplaceAllMetadata = options.ReplaceAllMetadata
            };

            var id = LibraryManager.GetNewItemId(path, typeof(Video));

            // Try to retrieve it from the db. If we don't find it, use the resolved version
            var video = LibraryManager.GetItemById(id) as Video;

            if (video == null)
            {
                video = LibraryManager.ResolvePath(FileSystem.GetFileSystemInfo(path)) as Video;

                newOptions.ForceSave = true;
            }

            if (video == null)
            {
                return Task.FromResult(true);
            }

            return video.RefreshMetadata(newOptions, cancellationToken);
        }

        public string GetEtag(User user)
        {
            return string.Join("|", GetEtagValues(user).ToArray()).GetMD5().ToString("N");
        }

        protected virtual List<string> GetEtagValues(User user)
        {
            return new List<string>
            {
                DateLastSaved.Ticks.ToString(CultureInfo.InvariantCulture)
            };
        }
    }
}