2 files changed, 48 insertions, 0 deletions
diff --git a/MediaBrowser.Controller/Library/IUserDataManager.cs b/MediaBrowser.Controller/Library/IUserDataManager.cs
index 0b4229c784..2ee8845346 100644
--- a/MediaBrowser.Controller/Library/IUserDataManager.cs
+++ b/MediaBrowser.Controller/Library/IUserDataManager.cs
@@ -63,6 +63,24 @@ namespace MediaBrowser.Controller.Library
         Dictionary<Guid, UserItemData> GetUserDataBatch(IReadOnlyList<BaseItem> items, User user);
 
         /// <summary>
+        /// Gets the user data that should drive resume for a multi-version item: the data of the most
+        /// recently played alternate version (including the item itself) that has a resume point.
+        /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="item">The item.</param>
+        /// <returns>The resume version's data, or <c>null</c> when the item has no versions or none has a resume point.</returns>
+        VersionResumeData? GetResumeUserData(User user, BaseItem item);
+
+        /// <summary>
+        /// Gets the resume-driving user data for multiple items in a single batch operation.
+        /// See <see cref="GetResumeUserData(User, BaseItem)"/>.
+        /// </summary>
+        /// <param name="items">The items to get resume data for.</param>
+        /// <param name="user">The user.</param>
+        /// <returns>A dictionary mapping item ids to their resume version's data; items without one are omitted.</returns>
+        IReadOnlyDictionary<Guid, VersionResumeData> GetResumeUserDataBatch(IReadOnlyList<BaseItem> items, User user);
+
+        /// <summary>
         /// Gets the user data dto.
         /// </summary>
         /// <param name="item">Item to use.</param>
diff --git a/MediaBrowser.Controller/Library/VersionResumeData.cs b/MediaBrowser.Controller/Library/VersionResumeData.cs
new file mode 100644
index 0000000000..ca8a499d97
--- /dev/null
+++ b/MediaBrowser.Controller/Library/VersionResumeData.cs
@@ -0,0 +1,30 @@
+using MediaBrowser.Controller.Entities;
+using MediaBrowser.Model.Dto;
+
+namespace MediaBrowser.Controller.Library
+{
+    /// <summary>
+    /// The user data of the alternate version that should drive resume for a multi-version item.
+    /// </summary>
+    /// <param name="UserData">The resume version's user data.</param>
+    /// <param name="RunTimeTicks">The resume version's runtime, used for the progress percentage.</param>
+    public record VersionResumeData(UserItemData UserData, long? RunTimeTicks)
+    {
+        /// <summary>
+        /// Applies the resume version's playback state to the supplied user data dto, so that an item
+        /// whose most recent progress lives on an alternate version still reports that progress.
+        /// </summary>
+        /// <param name="dto">The user data dto to update.</param>
+        public void ApplyTo(UserItemDataDto dto)
+        {
+            dto.PlaybackPositionTicks = UserData.PlaybackPositionTicks;
+            dto.Played = UserData.Played;
+            dto.LastPlayedDate = UserData.LastPlayedDate;
+
+            if (RunTimeTicks > 0 && UserData.PlaybackPositionTicks > 0)
+            {
+                dto.PlayedPercentage = 100.0 * UserData.PlaybackPositionTicks / RunTimeTicks.Value;
+            }
+        }
+    }
+}