Derive version-aware media source names

1 files changed, 110 insertions, 7 deletions

diff --git a/MediaBrowser.Controller/Entities/BaseItem.cs b/MediaBrowser.Controller/Entities/BaseItem.cs
index 21304768bd..c69e24f876 100644
--- a/MediaBrowser.Controller/Entities/BaseItem.cs
+++ b/MediaBrowser.Controller/Entities/BaseItem.cs
@@ -87,6 +87,10 @@ namespace MediaBrowser.Controller.Entities
             Model.Entities.ExtraType.Short
         };
 
+        // Separators the naming layer treats as version delimiters (Emby.Naming VideoFlagDelimiters),
+        // used when stripping the shared prefix from an alternate version's media source name.
+        private static readonly char[] VersionSeparators = [' ', '-', '_', '.'];
+
         private string _sortName;
 
         private string _forcedSortName;
@@ -1099,8 +1103,9 @@ namespace MediaBrowser.Controller.Entities
                 }
             }
 
-            var list = GetAllItemsForMediaSources();
-            var result = list.Select(i => GetVersionInfo(enablePathSubstitution, i.Item, i.MediaSourceType)).ToList();
+            var list = GetAllItemsForMediaSources().ToList();
+            var commonPrefix = GetCommonNamePrefix(list);
+            var result = list.Select(i => GetVersionInfo(enablePathSubstitution, i.Item, i.MediaSourceType, commonPrefix)).ToList();
 
             if (IsActiveRecording())
             {
@@ -1128,7 +1133,7 @@ namespace MediaBrowser.Controller.Entities
             return Enumerable.Empty<(BaseItem, MediaSourceType)>();
         }
 
-        private MediaSourceInfo GetVersionInfo(bool enablePathSubstitution, BaseItem item, MediaSourceType type)
+        private MediaSourceInfo GetVersionInfo(bool enablePathSubstitution, BaseItem item, MediaSourceType type, string commonPrefix = null)
         {
             ArgumentNullException.ThrowIfNull(item);
 
@@ -1141,7 +1146,7 @@ namespace MediaBrowser.Controller.Entities
                 Protocol = protocol ?? MediaProtocol.File,
                 MediaStreams = MediaSourceManager.GetMediaStreams(item.Id),
                 MediaAttachments = MediaSourceManager.GetMediaAttachments(item.Id),
-                Name = GetMediaSourceName(item),
+                Name = GetMediaSourceName(item, commonPrefix),
                 Path = enablePathSubstitution ? GetMappedPath(item, itemPath, protocol) : itemPath,
                 RunTimeTicks = item.RunTimeTicks,
                 Container = item.Container,
@@ -1220,7 +1225,7 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        internal string GetMediaSourceName(BaseItem item)
+        internal string GetMediaSourceName(BaseItem item, string commonPrefix = null)
         {
             var terms = new List<string>();
 
@@ -1228,12 +1233,31 @@ namespace MediaBrowser.Controller.Entities
             if (item.IsFileProtocol && !string.IsNullOrEmpty(path))
             {
                 var displayName = System.IO.Path.GetFileNameWithoutExtension(path);
-                if (HasLocalAlternateVersions)
+
+                // Prefer the suffix that differs from the other versions: strip the prefix shared by
+                // all sibling files. This works regardless of folder layout, so it also labels episode
+                // versions that share a season folder (e.g. "Greyscale" instead of the full
+                // "Show - S01E02 - Title - Greyscale"). The prefix is already retreated to a separator
+                // boundary (see GetCommonVersionPrefix).
+                if (!string.IsNullOrEmpty(commonPrefix)
+                    && displayName.Length > commonPrefix.Length
+                    && displayName.StartsWith(commonPrefix, StringComparison.OrdinalIgnoreCase))
+                {
+                    var name = displayName.AsSpan(commonPrefix.Length).TrimStart(VersionSeparators);
+                    if (!name.IsWhiteSpace())
+                    {
+                        terms.Add(name.ToString());
+                    }
+                }
+
+                // Fall back to the containing folder name (the common layout for movie versions, and
+                // the path taken when no common prefix could be derived).
+                if (terms.Count == 0 && HasLocalAlternateVersions)
                 {
                     var containingFolderName = System.IO.Path.GetFileName(ContainingFolderPath);
                     if (displayName.Length > containingFolderName.Length && displayName.StartsWith(containingFolderName, StringComparison.OrdinalIgnoreCase))
                     {
-                        var name = displayName.AsSpan(containingFolderName.Length).TrimStart([' ', '-']);
+                        var name = displayName.AsSpan(containingFolderName.Length).TrimStart(VersionSeparators);
                         if (!name.IsWhiteSpace())
                         {
                             terms.Add(name.ToString());
@@ -1290,6 +1314,85 @@ namespace MediaBrowser.Controller.Entities
             return string.Join('/', terms);
         }
 
+        /// <summary>
+        /// Derives the prefix shared by the supplied media source items' file names, used to strip the
+        /// common part and surface a short version label per source. Returns null when there are fewer
+        /// than two file-based sources, since there is nothing to differentiate.
+        /// </summary>
+        /// <param name="items">The media source items.</param>
+        /// <returns>The shared prefix, or null when no useful prefix exists.</returns>
+        private static string GetCommonNamePrefix(IReadOnlyList<(BaseItem Item, MediaSourceType MediaSourceType)> items)
+        {
+            var fileNames = new List<string>();
+            foreach (var (item, _) in items)
+            {
+                if (item.IsFileProtocol && !string.IsNullOrEmpty(item.Path))
+                {
+                    fileNames.Add(System.IO.Path.GetFileNameWithoutExtension(item.Path));
+                }
+            }
+
+            if (fileNames.Count < 2)
+            {
+                return null;
+            }
+
+            var prefix = GetCommonVersionPrefix(fileNames);
+            return string.IsNullOrEmpty(prefix) ? null : prefix;
+        }
+
+        /// <summary>
+        /// Computes the case-insensitive longest common prefix of the supplied version file names,
+        /// retreated to the last separator boundary. Retreating keeps the differing suffix intact:
+        /// it avoids slicing through a word every version shares (e.g. "Grey" in "Greyscale" and
+        /// "Greyish") while still trimming the common part when every version is suffixed (e.g.
+        /// "- Greyscale" / "- Colorized"). The separators mirror the version delimiters recognised by
+        /// the naming layer (Emby.Naming VideoFlagDelimiters).
+        /// </summary>
+        /// <param name="fileNames">The version file names without extension; must contain at least one entry.</param>
+        /// <returns>The shared prefix retreated to a separator boundary, or an empty string when none is shared.</returns>
+        internal static string GetCommonVersionPrefix(IReadOnlyList<string> fileNames)
+        {
+            var prefix = fileNames[0];
+            for (var i = 1; i < fileNames.Count && prefix.Length > 0; i++)
+            {
+                var name = fileNames[i];
+                var length = Math.Min(prefix.Length, name.Length);
+                var common = 0;
+                while (common < length && char.ToUpperInvariant(prefix[common]) == char.ToUpperInvariant(name[common]))
+                {
+                    common++;
+                }
+
+                prefix = prefix[..common];
+            }
+
+            // If the common prefix is itself a whole file name then one version is unlabelled (the
+            // base name); the boundary already sits at the end of that name, so don't retreat into it.
+            var prefixIsWholeName = false;
+            for (var i = 0; i < fileNames.Count; i++)
+            {
+                if (fileNames[i].Length == prefix.Length)
+                {
+                    prefixIsWholeName = true;
+                    break;
+                }
+            }
+
+            if (!prefixIsWholeName)
+            {
+                var cut = prefix.Length;
+                while (cut > 0 && Array.IndexOf(VersionSeparators, prefix[cut - 1]) < 0)
+                {
+                    cut--;
+                }
+
+                prefix = prefix[..cut];
+            }
+
+            return prefix;
+        }
+
         public Task RefreshMetadata(CancellationToken cancellationToken)
         {
             return RefreshMetadata(new MetadataRefreshOptions(new DirectoryService(FileSystem)), cancellationToken);