Merge pull request #17044 from Shadowghost/version-model-and-handling

Fixes for multi version handling

5 files changed, 367 insertions, 18 deletions

diff --git a/Emby.Server.Implementations/Dto/DtoService.cs b/Emby.Server.Implementations/Dto/DtoService.cs
index 831419f380..5c76c4014a 100644
--- a/Emby.Server.Implementations/Dto/DtoService.cs
+++ b/Emby.Server.Implementations/Dto/DtoService.cs
@@ -169,9 +169,13 @@ namespace Emby.Server.Implementations.Dto
 
             // Batch-fetch user data for all items
             Dictionary<Guid, UserItemData>? userDataBatch = null;
+            IReadOnlyDictionary<Guid, VersionResumeData>? resumeDataBatch = null;
             if (user is not null && options.EnableUserData)
             {
                 userDataBatch = _userDataRepository.GetUserDataBatch(accessibleItems, user);
+
+                // For items with alternate versions, the most recently played version drives resume.
+                resumeDataBatch = _userDataRepository.GetResumeUserDataBatch(accessibleItems, user);
             }
 
             // Pre-compute collection folders once to avoid N+1 queries in CanDelete
@@ -250,7 +254,8 @@ namespace Emby.Server.Implementations.Dto
                     allCollectionFolders,
                     childCountBatch,
                     playedCountBatch,
-                    artistsBatch);
+                    artistsBatch,
+                    resumeDataBatch?.GetValueOrDefault(item.Id));
 
                 if (item is LiveTvChannel tvChannel)
                 {
@@ -311,7 +316,8 @@ namespace Emby.Server.Implementations.Dto
             List<Folder>? allCollectionFolders = null,
             Dictionary<Guid, int>? childCountBatch = null,
             Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null,
-            IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null)
+            IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null,
+            VersionResumeData? resumeData = null)
         {
             var dto = new BaseItemDto
             {
@@ -355,7 +361,8 @@ namespace Emby.Server.Implementations.Dto
                     options,
                     userData,
                     childCountBatch,
-                    playedCountBatch);
+                    playedCountBatch,
+                    resumeData);
             }
 
             if (item is IHasMediaSources
@@ -371,7 +378,7 @@ namespace Emby.Server.Implementations.Dto
                 AttachStudios(dto, item);
             }
 
-            AttachBasicFields(dto, item, owner, options, artistsBatch);
+            AttachBasicFields(dto, item, owner, options, artistsBatch, user);
 
             if (options.ContainsField(ItemFields.CanDelete))
             {
@@ -540,7 +547,8 @@ namespace Emby.Server.Implementations.Dto
             DtoOptions options,
             UserItemData? userData = null,
             Dictionary<Guid, int>? childCountBatch = null,
-            Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null)
+            Dictionary<Guid, (int Played, int Total)>? playedCountBatch = null,
+            VersionResumeData? resumeData = null)
         {
             if (item.IsFolder)
             {
@@ -602,6 +610,9 @@ namespace Emby.Server.Implementations.Dto
                         // Use pre-fetched user data
                         dto.UserData = GetUserItemDataDto(userData, item.Id);
                         item.FillUserDataDtoValues(dto.UserData, userData, dto, user, options);
+
+                        // For items with alternate versions, the most recently played version drives resume.
+                        resumeData?.ApplyTo(dto.UserData);
                     }
                     else
                     {
@@ -945,7 +956,8 @@ namespace Emby.Server.Implementations.Dto
         /// <param name="owner">The owner.</param>
         /// <param name="options">The options.</param>
         /// <param name="artistsBatch">Optional pre-fetched artist lookup shared across a batch of items.</param>
-        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null)
+        /// <param name="user">The user, for per-user values such as the accessible media source count.</param>
+        private void AttachBasicFields(BaseItemDto dto, BaseItem item, BaseItem? owner, DtoOptions options, IReadOnlyDictionary<string, MusicArtist[]>? artistsBatch = null, User? user = null)
         {
             if (options.ContainsField(ItemFields.DateCreated))
             {
@@ -1259,7 +1271,12 @@ namespace Emby.Server.Implementations.Dto
 
                 if (options.ContainsField(ItemFields.MediaSourceCount))
                 {
-                    var mediaSourceCount = video.MediaSourceCount;
+                    // Match the per-user filtering of the media sources: versions the user cannot
+                    // access are not selectable, so they must not count towards the badge either.
+                    var mediaSourceCount = user is null
+                        || (!video.PrimaryVersionId.HasValue && video.LinkedAlternateVersions.Length == 0 && !video.HasLocalAlternateVersions)
+                            ? video.MediaSourceCount
+                            : video.GetAllVersions().Count(v => v.Id.Equals(video.Id) || v.IsVisibleStandalone(user));
                     if (mediaSourceCount != 1)
                     {
                         dto.MediaSourceCount = mediaSourceCount;
diff --git a/Emby.Server.Implementations/Library/MediaSourceManager.cs b/Emby.Server.Implementations/Library/MediaSourceManager.cs
index c369fb0957..c64833ddaa 100644
--- a/Emby.Server.Implementations/Library/MediaSourceManager.cs
+++ b/Emby.Server.Implementations/Library/MediaSourceManager.cs
@@ -229,7 +229,11 @@ namespace Emby.Server.Implementations.Library
                 list.Add(source);
             }
 
-            return SortMediaSources(list, item.Id).ToArray();
+            var preferredId = mediaSources.Count > 0 && Guid.TryParse(mediaSources[0].Id, out var topSourceId)
+                ? topSourceId
+                : item.Id;
+
+            return SortMediaSources(list, preferredId).ToArray();
         }
 
         /// <inheritdoc />>
@@ -406,6 +410,69 @@ namespace Emby.Server.Implementations.Library
                         source.SupportsDirectStream = user.HasPermission(PermissionKind.EnablePlaybackRemuxing);
                     }
                 }
+
+                sources = SetAlternateVersionResumeStates(item, sources, user);
+            }
+
+            return sources;
+        }
+
+        /// <summary>
+        /// Populates each source's own playback position for the user and, when the queried item is a
+        /// primary, moves the most recently played version to the front so that resuming without an
+        /// explicit source selection plays the version that was last watched. A directly queried
+        /// alternate version keeps its own source first.
+        /// </summary>
+        /// <param name="item">The queried item.</param>
+        /// <param name="sources">The item's media sources.</param>
+        /// <param name="user">The user.</param>
+        /// <returns>The media sources, reordered when a version drives resume.</returns>
+        private IReadOnlyList<MediaSourceInfo> SetAlternateVersionResumeStates(BaseItem item, IReadOnlyList<MediaSourceInfo> sources, User user)
+        {
+            // For a video, multiple sources means alternate versions.
+            if (item is not Video video || sources.Count < 2)
+            {
+                return sources;
+            }
+
+            var versions = video.GetAllVersions();
+            if (versions.Count < 2)
+            {
+                return sources;
+            }
+
+            var userDataByVersion = _userDataManager.GetUserDataBatch(versions, user);
+            var dataBySourceId = new Dictionary<string, UserItemData>(versions.Count, StringComparer.OrdinalIgnoreCase);
+            foreach (var version in versions)
+            {
+                if (userDataByVersion.TryGetValue(version.Id, out var data))
+                {
+                    dataBySourceId[version.Id.ToString("N", CultureInfo.InvariantCulture)] = data;
+                }
+            }
+
+            foreach (var source in sources)
+            {
+                if (source.Id is not null
+                    && dataBySourceId.TryGetValue(source.Id, out var data)
+                    && data.PlaybackPositionTicks > 0)
+                {
+                    source.PlaybackPositionTicks = data.PlaybackPositionTicks;
+                }
+            }
+
+            // Reorder only for a resumable (in-progress) version;
+            // a completed version has no position to resume, so it must not be pulled to the front here.
+            var resumeSource = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                sources,
+                source => source.Id is not null ? dataBySourceId.GetValueOrDefault(source.Id) : null,
+                data => data.PlaybackPositionTicks > 0);
+
+            if (resumeSource is not null && !video.PrimaryVersionId.HasValue && !ReferenceEquals(sources[0], resumeSource))
+            {
+                var reordered = new List<MediaSourceInfo>(sources.Count) { resumeSource };
+                reordered.AddRange(sources.Where(s => !ReferenceEquals(s, resumeSource)));
+                return reordered;
             }
 
             return sources;
diff --git a/Emby.Server.Implementations/Library/UserDataManager.cs b/Emby.Server.Implementations/Library/UserDataManager.cs
index 1281f1587f..40cd2bb69c 100644
--- a/Emby.Server.Implementations/Library/UserDataManager.cs
+++ b/Emby.Server.Implementations/Library/UserDataManager.cs
@@ -247,6 +247,103 @@ namespace Emby.Server.Implementations.Library
             return result;
         }
 
+        /// <inheritdoc />
+        public VersionResumeData? GetResumeUserData(User user, BaseItem item)
+        {
+            return GetResumeUserDataBatch([item], user).GetValueOrDefault(item.Id);
+        }
+
+        /// <inheritdoc />
+        public IReadOnlyDictionary<Guid, VersionResumeData> GetResumeUserDataBatch(IReadOnlyList<BaseItem> items, User user)
+        {
+            ArgumentNullException.ThrowIfNull(user);
+
+            var result = new Dictionary<Guid, VersionResumeData>();
+
+            // Candidate primaries: a directly queried version (PrimaryVersionId set) keeps its own data.
+            // Linked alternates are already known in memory; only the local-alternate existence check
+            // would otherwise hit the database (one query per item via Video.HasLocalAlternateVersions),
+            // so collect those ids and resolve them all in a single query below.
+            List<Video>? candidates = null;
+            List<Guid>? localProbeIds = null;
+            foreach (var item in items)
+            {
+                if (item is not Video video || video.PrimaryVersionId.HasValue)
+                {
+                    continue;
+                }
+
+                (candidates ??= []).Add(video);
+
+                if (video.LinkedAlternateVersions.Length == 0)
+                {
+                    (localProbeIds ??= []).Add(video.Id);
+                }
+            }
+
+            if (candidates is null)
+            {
+                return result;
+            }
+
+            HashSet<Guid>? withLocalAlternates = null;
+            if (localProbeIds is not null)
+            {
+                using var dbContext = _repository.CreateDbContext();
+                withLocalAlternates = dbContext.LinkedChildren
+                    .Where(lc => lc.ChildType == Jellyfin.Database.Implementations.Entities.LinkedChildType.LocalAlternateVersion
+                        && localProbeIds.Contains(lc.ParentId))
+                    .Select(lc => lc.ParentId)
+                    .Distinct()
+                    .ToHashSet();
+            }
+
+            List<(Guid PrimaryId, IReadOnlyList<Video> Versions)>? versionGroups = null;
+            List<BaseItem>? allVersions = null;
+
+            foreach (var video in candidates)
+            {
+                // Only items that actually have alternate versions aggregate over them.
+                if (video.LinkedAlternateVersions.Length == 0
+                    && (withLocalAlternates is null || !withLocalAlternates.Contains(video.Id)))
+                {
+                    continue;
+                }
+
+                var versions = video.GetAllVersions();
+                if (versions.Count < 2)
+                {
+                    continue;
+                }
+
+                (versionGroups ??= []).Add((video.Id, versions));
+                (allVersions ??= []).AddRange(versions);
+            }
+
+            if (versionGroups is null)
+            {
+                return result;
+            }
+
+            var userDataByVersion = GetUserDataBatch(allVersions!.DistinctBy(i => i.Id).ToList(), user);
+
+            foreach (var (primaryId, versions) in versionGroups)
+            {
+                // Consider both in-progress and completed versions so a finished alternate still marks the primary as played.
+                var resumeVersion = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                    versions,
+                    version => userDataByVersion.GetValueOrDefault(version.Id),
+                    data => data.PlaybackPositionTicks > 0 || data.Played);
+
+                if (resumeVersion is not null)
+                {
+                    result[primaryId] = new VersionResumeData(resumeVersion.Id, userDataByVersion[resumeVersion.Id]);
+                }
+            }
+
+            return result;
+        }
+
         /// <summary>
         /// Gets the internal key.
         /// </summary>
@@ -281,6 +378,10 @@ namespace Emby.Server.Implementations.Library
             var dto = GetUserItemDataDto(userData, item.Id);
 
             item.FillUserDataDtoValues(dto, userData, itemDto, user, options);
+
+            // For an item with alternate versions, surface the most recently played version's resume point.
+            GetResumeUserData(user, item)?.ApplyTo(dto);
+
             return dto;
         }
 
@@ -385,5 +486,41 @@ namespace Emby.Server.Implementations.Library
 
             return playedToCompletion;
         }
+
+        /// <inheritdoc />
+        public void ResetPlaybackStreamSelections(User user, BaseItem item)
+        {
+            ArgumentNullException.ThrowIfNull(user);
+            ArgumentNullException.ThrowIfNull(item);
+
+            using var dbContext = _repository.CreateDbContext();
+            var rows = dbContext.UserData
+                .Where(e => e.ItemId == item.Id && e.UserId == user.Id
+                            && (e.AudioStreamIndex != null || e.SubtitleStreamIndex != null))
+                .ToList();
+
+            if (rows.Count == 0)
+            {
+                return;
+            }
+
+            foreach (var row in rows)
+            {
+                row.AudioStreamIndex = null;
+                row.SubtitleStreamIndex = null;
+            }
+
+            dbContext.SaveChanges();
+
+            var cacheKey = GetCacheKey(user.InternalId, item.Id);
+            if (_cache.TryGet(cacheKey, out var cached))
+            {
+                cached.AudioStreamIndex = null;
+                cached.SubtitleStreamIndex = null;
+                _cache.AddOrUpdate(cacheKey, cached);
+            }
+
+            item.UserData = dbContext.UserData.Where(e => e.ItemId == item.Id).AsNoTracking().ToArray();
+        }
     }
 }
diff --git a/Emby.Server.Implementations/Session/SessionManager.cs b/Emby.Server.Implementations/Session/SessionManager.cs
index 19823dff37..828bdd6859 100644
--- a/Emby.Server.Implementations/Session/SessionManager.cs
+++ b/Emby.Server.Implementations/Session/SessionManager.cs
@@ -730,6 +730,31 @@ namespace Emby.Server.Implementations.Session
         }
 
         /// <summary>
+        /// Resolves the item whose user data (playback position, played status) should be updated
+        /// for a playback report. When an alternate version is played the client reports the displayed
+        /// item as <c>ItemId</c> and the played version as <c>MediaSourceId</c>.
+        /// </summary>
+        /// <param name="libraryItem">The now playing (displayed) item.</param>
+        /// <param name="mediaSourceId">The reported media source id.</param>
+        /// <returns>The item to track progress against.</returns>
+        private BaseItem GetProgressItem(BaseItem libraryItem, string mediaSourceId)
+        {
+            if (libraryItem is Video libraryVideo
+                && !string.IsNullOrEmpty(mediaSourceId)
+                && Guid.TryParse(mediaSourceId, out var mediaSourceItemId)
+                && !mediaSourceItemId.Equals(libraryVideo.Id))
+            {
+                var versionItem = libraryVideo.GetAlternateVersion(mediaSourceItemId);
+                if (versionItem is not null)
+                {
+                    return versionItem;
+                }
+            }
+
+            return libraryItem;
+        }
+
+        /// <summary>
         /// Used to report that playback has started for an item.
         /// </summary>
         /// <param name="info">The info.</param>
@@ -760,9 +785,10 @@ namespace Emby.Server.Implementations.Session
 
             if (libraryItem is not null)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    OnPlaybackStart(user, libraryItem);
+                    OnPlaybackStart(user, progressItem);
                 }
             }
 
@@ -894,9 +920,10 @@ namespace Emby.Server.Implementations.Session
             // only update saved user data on actual check-ins, not automated ones
             if (libraryItem is not null && !isAutomated)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    OnPlaybackProgress(user, libraryItem, info);
+                    OnPlaybackProgress(user, progressItem, info);
                 }
             }
 
@@ -956,6 +983,20 @@ namespace Emby.Server.Implementations.Session
             if (changed)
             {
                 _userDataManager.SaveUserData(user, item, data, UserDataSaveReason.PlaybackProgress, CancellationToken.None);
+
+                // A completed version marks every alternate version played and clears their resume points, so the
+                // whole movie leaves Continue Watching and reads as watched everywhere. (Per-version resume positions
+                // only persist while nothing has been completed yet.)
+                if (data.Played == true && item is Video playedVideo)
+                {
+                    playedVideo.PropagatePlayedState(user, true);
+                }
+            }
+
+            if ((!user.RememberAudioSelections && info.AudioStreamIndex.HasValue)
+                || (!user.RememberSubtitleSelections && info.SubtitleStreamIndex.HasValue))
+            {
+                _userDataManager.ResetPlaybackStreamSelections(user, item);
             }
         }
 
@@ -1087,9 +1128,10 @@ namespace Emby.Server.Implementations.Session
 
             if (libraryItem is not null)
             {
+                var progressItem = GetProgressItem(libraryItem, info.MediaSourceId);
                 foreach (var user in users)
                 {
-                    playedToCompletion = OnPlaybackStopped(user, libraryItem, info.PositionTicks, info.Failed);
+                    playedToCompletion = OnPlaybackStopped(user, progressItem, info.PositionTicks, info.Failed);
                 }
             }
 
@@ -1142,6 +1184,14 @@ namespace Emby.Server.Implementations.Session
 
             _userDataManager.SaveUserData(user, item, data, UserDataSaveReason.PlaybackFinished, CancellationToken.None);
 
+            // A completed version marks every alternate version played and clears their resume points, so the
+            // whole movie leaves Continue Watching and reads as watched everywhere. (Per-version resume positions
+            // only persist while nothing has been completed yet.)
+            if (data.Played == true && item is Video playedVideo)
+            {
+                playedVideo.PropagatePlayedState(user, true);
+            }
+
             return playedToCompletion;
         }
 
diff --git a/Emby.Server.Implementations/TV/TVSeriesManager.cs b/Emby.Server.Implementations/TV/TVSeriesManager.cs
index 535dc01a31..459ad1a17e 100644
--- a/Emby.Server.Implementations/TV/TVSeriesManager.cs
+++ b/Emby.Server.Implementations/TV/TVSeriesManager.cs
@@ -2,6 +2,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using Jellyfin.Data;
 using Jellyfin.Data.Enums;
@@ -136,11 +137,15 @@ namespace Emby.Server.Implementations.TV
 
                 if (nextEpisode is not null)
                 {
+                    // The last played date and the version that was actually played live on the version item's user data
+                    // The played state propagated to the sibling versions carries no date
+                    var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatched, user);
+                    nextEpisode = GetPreferredVersion(nextEpisode, result.LastWatched, playedVersion);
+
                     DateTime lastWatchedDate = DateTime.MinValue;
                     if (result.LastWatched is not null)
                     {
-                        var userData = _userDataManager.GetUserData(user, result.LastWatched);
-                        lastWatchedDate = userData?.LastPlayedDate ?? DateTime.MinValue.AddDays(1);
+                        lastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
                     }
 
                     nextUpList.Add((lastWatchedDate, nextEpisode));
@@ -152,11 +157,13 @@ namespace Emby.Server.Implementations.TV
 
                     if (nextPlayedEpisode is not null)
                     {
+                        var (playedVersion, lastPlayedDate) = GetMostRecentlyPlayedVersion(result.LastWatchedForRewatching, user);
+                        nextPlayedEpisode = GetPreferredVersion(nextPlayedEpisode, result.LastWatchedForRewatching, playedVersion);
+
                         DateTime rewatchLastWatchedDate = DateTime.MinValue;
                         if (result.LastWatchedForRewatching is not null)
                         {
-                            var userData = _userDataManager.GetUserData(user, result.LastWatchedForRewatching);
-                            rewatchLastWatchedDate = userData?.LastPlayedDate ?? DateTime.MinValue.AddDays(1);
+                            rewatchLastWatchedDate = lastPlayedDate ?? DateTime.MinValue.AddDays(1);
                         }
 
                         nextUpList.Add((rewatchLastWatchedDate, nextPlayedEpisode));
@@ -219,10 +226,13 @@ namespace Emby.Server.Implementations.TV
 
             if (nextEpisode is not null && !includeResumable)
             {
-                var userData = _userDataManager.GetUserData(user, nextEpisode);
-                if (userData?.PlaybackPositionTicks > 0)
+                // The resume progress may live on an alternate version
+                foreach (var version in nextEpisode.GetAllVersions())
                 {
-                    return null;
+                    if (_userDataManager.GetUserData(user, version)?.PlaybackPositionTicks > 0)
+                    {
+                        return null;
+                    }
                 }
             }
 
@@ -237,6 +247,74 @@ namespace Emby.Server.Implementations.TV
             return DetermineNextEpisode(result, user, includeSpecials, includeResumable: false, includePlayed: true);
         }
 
+        /// <summary>
+        /// Gets the version of the last watched episode that was actually played, together with its last played date.
+        /// The version that was played carries the most recent LastPlayedDate.
+        /// dates.
+        /// </summary>
+        /// <param name="lastWatched">The last watched episode (any version).</param>
+        /// <param name="user">The user.</param>
+        /// <returns>The played version and its last played date.</returns>
+        private (Video? PlayedVersion, DateTime? LastPlayedDate) GetMostRecentlyPlayedVersion(BaseItem? lastWatched, User user)
+        {
+            if (lastWatched is not Video lastWatchedVideo)
+            {
+                return (null, null);
+            }
+
+            var versions = lastWatchedVideo.GetAllVersions();
+            var userDataByVersion = _userDataManager.GetUserDataBatch(versions, user);
+
+            var playedVersion = VersionPlaybackSelector.SelectMostRecentlyPlayed(
+                versions,
+                version => userDataByVersion.GetValueOrDefault(version.Id),
+                data => data.LastPlayedDate.HasValue);
+
+            return (playedVersion, playedVersion is null ? null : userDataByVersion[playedVersion.Id].LastPlayedDate);
+        }
+
+        /// <summary>
+        /// When the last watched episode was played as an alternate version, prefer the next episode's version with the matching name,
+        /// so Next Up continues in the version the user has been watching instead of falling back to the primary.
+        /// </summary>
+        /// <param name="nextEpisode">The determined next episode (a primary).</param>
+        /// <param name="lastWatched">The last watched episode.</param>
+        /// <param name="playedVersion">The version of the last watched episode that was played.</param>
+        /// <returns>The matching version of the next episode, or the episode itself.</returns>
+        private Episode GetPreferredVersion(Episode nextEpisode, BaseItem? lastWatched, Video? playedVersion)
+        {
+            // No version preference, or the primary was played
+            if (lastWatched is not Video lastWatchedVideo
+                || playedVersion is null
+                || !playedVersion.PrimaryVersionId.HasValue)
+            {
+                return nextEpisode;
+            }
+
+            // Match by version name
+            var playedVersionId = playedVersion.Id.ToString("N", CultureInfo.InvariantCulture);
+            var playedVersionName = lastWatchedVideo.GetMediaSources(false)
+                .FirstOrDefault(source => string.Equals(source.Id, playedVersionId, StringComparison.OrdinalIgnoreCase))?.Name;
+
+            if (string.IsNullOrEmpty(playedVersionName))
+            {
+                return nextEpisode;
+            }
+
+            var matchingSource = nextEpisode.GetMediaSources(false)
+                .FirstOrDefault(source => string.Equals(source.Name, playedVersionName, StringComparison.OrdinalIgnoreCase));
+
+            if (matchingSource is not null
+                && Guid.TryParse(matchingSource.Id, out var matchingId)
+                && !matchingId.Equals(nextEpisode.Id)
+                && _libraryManager.GetItemById<Episode>(matchingId) is { } matchingVersion)
+            {
+                return matchingVersion;
+            }
+
+            return nextEpisode;
+        }
+
         private static string GetUniqueSeriesKey(Series series)
         {
             return series.GetPresentationUniqueKey();