Merge remote-tracking branch 'upstream/master' into client-logger

51 files changed, 1762 insertions, 1610 deletions

diff --git a/MediaBrowser.Controller/Entities/AggregateFolder.cs b/MediaBrowser.Controller/Entities/AggregateFolder.cs
index 6ebea5f44..9589f5245 100644
--- a/MediaBrowser.Controller/Entities/AggregateFolder.cs
+++ b/MediaBrowser.Controller/Entities/AggregateFolder.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 using System.Collections.Concurrent;
@@ -16,30 +18,23 @@ namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
     /// Specialized folder that can have items added to it's children by external entities.
-    /// Used for our RootFolder so plug-ins can add items.
+    /// Used for our RootFolder so plugins can add items.
     /// </summary>
     public class AggregateFolder : Folder
     {
-        public AggregateFolder()
-        {
-            PhysicalLocationsList = Array.Empty<string>();
-        }
-
-        [JsonIgnore]
-        public override bool IsPhysicalRoot => true;
-
-        public override bool CanDelete()
-        {
-            return false;
-        }
-
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
+        private readonly object _childIdsLock = new object();
 
         /// <summary>
         /// The _virtual children.
         /// </summary>
         private readonly ConcurrentBag<BaseItem> _virtualChildren = new ConcurrentBag<BaseItem>();
+        private bool _requiresRefresh;
+        private Guid[] _childrenIds = null;
+
+        public AggregateFolder()
+        {
+            PhysicalLocationsList = Array.Empty<string>();
+        }
 
         /// <summary>
         /// Gets the virtual children.
@@ -48,18 +43,26 @@ namespace MediaBrowser.Controller.Entities
         public ConcurrentBag<BaseItem> VirtualChildren => _virtualChildren;
 
         [JsonIgnore]
+        public override bool IsPhysicalRoot => true;
+
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        [JsonIgnore]
         public override string[] PhysicalLocations => PhysicalLocationsList;
 
         public string[] PhysicalLocationsList { get; set; }
 
+        public override bool CanDelete()
+        {
+            return false;
+        }
+
         protected override FileSystemMetadata[] GetFileSystemChildren(IDirectoryService directoryService)
         {
             return CreateResolveArgs(directoryService, true).FileSystemChildren;
         }
 
-        private Guid[] _childrenIds = null;
-        private readonly object _childIdsLock = new object();
-
         protected override List<BaseItem> LoadChildren()
         {
             lock (_childIdsLock)
@@ -83,7 +86,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private bool _requiresRefresh;
         public override bool RequiresRefresh()
         {
             var changed = base.RequiresRefresh() || _requiresRefresh;
@@ -103,11 +105,11 @@ namespace MediaBrowser.Controller.Entities
             return changed;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
             ClearCache();
 
-            var changed = base.BeforeMetadataRefresh(replaceAllMetdata) || _requiresRefresh;
+            var changed = base.BeforeMetadataRefresh(replaceAllMetadata) || _requiresRefresh;
             _requiresRefresh = false;
             return changed;
         }
@@ -120,8 +122,7 @@ namespace MediaBrowser.Controller.Entities
 
             var args = new ItemResolveArgs(ConfigurationManager.ApplicationPaths, directoryService)
             {
-                FileInfo = FileSystem.GetDirectoryInfo(path),
-                Path = path
+                FileInfo = FileSystem.GetDirectoryInfo(path)
             };
 
             // Gather child folder and files
@@ -153,11 +154,11 @@ namespace MediaBrowser.Controller.Entities
             return base.GetNonCachedChildren(directoryService).Concat(_virtualChildren);
         }
 
-        protected override async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             ClearCache();
 
-            await base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService)
+            await base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken)
                 .ConfigureAwait(false);
 
             ClearCache();
@@ -167,7 +168,7 @@ namespace MediaBrowser.Controller.Entities
         /// Adds the virtual child.
         /// </summary>
         /// <param name="child">The child.</param>
-        /// <exception cref="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throws if child is null.</exception>
         public void AddVirtualChild(BaseItem child)
         {
             if (child == null)
@@ -183,7 +184,7 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="id">The id.</param>
         /// <returns>BaseItem.</returns>
-        /// <exception cref="ArgumentNullException">id</exception>
+        /// <exception cref="ArgumentNullException">The id is empty.</exception>
         public BaseItem FindVirtualChild(Guid id)
         {
             if (id.Equals(Guid.Empty))
diff --git a/MediaBrowser.Controller/Entities/Audio/Audio.cs b/MediaBrowser.Controller/Entities/Audio/Audio.cs
index 8220464b3..536668e50 100644
--- a/MediaBrowser.Controller/Entities/Audio/Audio.cs
+++ b/MediaBrowser.Controller/Entities/Audio/Audio.cs
@@ -1,7 +1,10 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA1724, CA1826, CS1591
 
 using System;
 using System.Collections.Generic;
+using System.Globalization;
 using System.Linq;
 using System.Text.Json.Serialization;
 using Jellyfin.Data.Enums;
@@ -22,6 +25,12 @@ namespace MediaBrowser.Controller.Entities.Audio
         IHasLookupInfo<SongInfo>,
         IHasMediaSources
     {
+        public Audio()
+        {
+            Artists = Array.Empty<string>();
+            AlbumArtists = Array.Empty<string>();
+        }
+
         /// <inheritdoc />
         [JsonIgnore]
         public IReadOnlyList<string> Artists { get; set; }
@@ -30,22 +39,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public IReadOnlyList<string> AlbumArtists { get; set; }
 
-        public Audio()
-        {
-            Artists = Array.Empty<string>();
-            AlbumArtists = Array.Empty<string>();
-        }
-
-        public override double GetDefaultPrimaryImageAspectRatio()
-        {
-            return 1;
-        }
-
         [JsonIgnore]
         public override bool SupportsPlayedStatus => true;
 
         [JsonIgnore]
-        public override bool SupportsPeople => false;
+        public override bool SupportsPeople => true;
 
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
@@ -59,11 +57,6 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override Folder LatestItemsIndexContainer => AlbumEntity;
 
-        public override bool CanDownload()
-        {
-            return IsFileProtocol;
-        }
-
         [JsonIgnore]
         public MusicAlbum AlbumEntity => FindParent<MusicAlbum>();
 
@@ -74,25 +67,35 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override string MediaType => Model.Entities.MediaType.Audio;
 
+        public override double GetDefaultPrimaryImageAspectRatio()
+        {
+            return 1;
+        }
+
+        public override bool CanDownload()
+        {
+            return IsFileProtocol;
+        }
+
         /// <summary>
         /// Creates the name of the sort.
         /// </summary>
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("0000 - ") : "")
-                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ") : "") + Name;
+            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty)
+                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty) + Name;
         }
 
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
 
-            var songKey = IndexNumber.HasValue ? IndexNumber.Value.ToString("0000") : string.Empty;
+            var songKey = IndexNumber.HasValue ? IndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) : string.Empty;
 
             if (ParentIndexNumber.HasValue)
             {
-                songKey = ParentIndexNumber.Value.ToString("0000") + "-" + songKey;
+                songKey = ParentIndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) + "-" + songKey;
             }
 
             songKey += Name;
diff --git a/MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs b/MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs
index 20fad4cb0..1625c748a 100644
--- a/MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs
+++ b/MediaBrowser.Controller/Entities/Audio/IHasAlbumArtist.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Collections.Generic;
diff --git a/MediaBrowser.Controller/Entities/Audio/IHasMusicGenres.cs b/MediaBrowser.Controller/Entities/Audio/IHasMusicGenres.cs
index ac4dd1688..c2dae5a2d 100644
--- a/MediaBrowser.Controller/Entities/Audio/IHasMusicGenres.cs
+++ b/MediaBrowser.Controller/Entities/Audio/IHasMusicGenres.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 namespace MediaBrowser.Controller.Entities.Audio
 {
diff --git a/MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs b/MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs
index 9a33ad9d7..03d1f3304 100644
--- a/MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs
+++ b/MediaBrowser.Controller/Entities/Audio/MusicAlbum.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1721, CA1826, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -21,18 +23,18 @@ namespace MediaBrowser.Controller.Entities.Audio
     /// </summary>
     public class MusicAlbum : Folder, IHasAlbumArtist, IHasArtist, IHasMusicGenres, IHasLookupInfo<AlbumInfo>, IMetadataContainer
     {
-        /// <inheritdoc />
-        public IReadOnlyList<string> AlbumArtists { get; set; }
-
-        /// <inheritdoc />
-        public IReadOnlyList<string> Artists { get; set; }
-
         public MusicAlbum()
         {
             Artists = Array.Empty<string>();
             AlbumArtists = Array.Empty<string>();
         }
 
+        /// <inheritdoc />
+        public IReadOnlyList<string> AlbumArtists { get; set; }
+
+        /// <inheritdoc />
+        public IReadOnlyList<string> Artists { get; set; }
+
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
 
@@ -42,6 +44,25 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public MusicArtist MusicArtist => GetMusicArtist(new DtoOptions(true));
 
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        [JsonIgnore]
+        public override bool SupportsCumulativeRunTimeTicks => true;
+
+        [JsonIgnore]
+        public string AlbumArtist => AlbumArtists.FirstOrDefault();
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        /// <summary>
+        /// Gets the tracks.
+        /// </summary>
+        /// <value>The tracks.</value>
+        [JsonIgnore]
+        public IEnumerable<Audio> Tracks => GetRecursiveChildren(i => i is Audio).Cast<Audio>();
+
         public MusicArtist GetMusicArtist(DtoOptions options)
         {
             var parents = GetParents();
@@ -62,25 +83,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return null;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
-
-        [JsonIgnore]
-        public override bool SupportsCumulativeRunTimeTicks => true;
-
-        [JsonIgnore]
-        public string AlbumArtist => AlbumArtists.FirstOrDefault();
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        /// <summary>
-        /// Gets the tracks.
-        /// </summary>
-        /// <value>The tracks.</value>
-        [JsonIgnore]
-        public IEnumerable<Audio> Tracks => GetRecursiveChildren(i => i is Audio).Cast<Audio>();
-
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             return Tracks;
diff --git a/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs b/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
index 8a9bb12c7..f30f8ce7f 100644
--- a/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
+++ b/MediaBrowser.Controller/Entities/Audio/MusicArtist.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -6,9 +8,9 @@ using System.Linq;
 using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
+using Diacritics.Extensions;
 using Jellyfin.Data.Entities;
 using Jellyfin.Data.Enums;
-using MediaBrowser.Controller.Extensions;
 using MediaBrowser.Controller.Providers;
 using MediaBrowser.Model.Entities;
 using Microsoft.Extensions.Logging;
@@ -42,6 +44,36 @@ namespace MediaBrowser.Controller.Entities.Audio
         [JsonIgnore]
         public override bool SupportsPlayedStatus => false;
 
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override IEnumerable<BaseItem> Children
+        {
+            get
+            {
+                if (IsAccessedByName)
+                {
+                    return new List<BaseItem>();
+                }
+
+                return base.Children;
+            }
+        }
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        public static string GetPath(string name)
+        {
+            return GetPath(name, true);
+        }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             return 1;
@@ -63,20 +95,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override IEnumerable<BaseItem> Children
-        {
-            get
-            {
-                if (IsAccessedByName)
-                {
-                    return new List<BaseItem>();
-                }
-
-                return base.Children;
-            }
-        }
-
         public override int GetChildCount(User user)
         {
             return IsAccessedByName ? 0 : base.GetChildCount(user);
@@ -92,7 +110,7 @@ namespace MediaBrowser.Controller.Entities.Audio
             return base.IsSaveLocalMetadataEnabled();
         }
 
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             if (IsAccessedByName)
             {
@@ -100,7 +118,7 @@ namespace MediaBrowser.Controller.Entities.Audio
                 return Task.CompletedTask;
             }
 
-            return base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService);
+            return base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken);
         }
 
         public override List<string> GetUserDataKeys()
@@ -112,14 +130,6 @@ namespace MediaBrowser.Controller.Entities.Audio
         }
 
         /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
-        /// <summary>
         /// Gets the user data key.
         /// </summary>
         /// <param name="item">The item.</param>
@@ -165,14 +175,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return info;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        public static string GetPath(string name)
-        {
-            return GetPath(name, true);
-        }
-
         public static string GetPath(string name, bool normalizeName)
         {
             // Trim the period at the end because windows will have a hard time with that
@@ -206,9 +208,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Option to replace metadata.</param>
+        /// <returns>True if metadata changed.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (IsAccessedByName)
             {
diff --git a/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs b/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
index f0c076108..dc6fcc55a 100644
--- a/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
+++ b/MediaBrowser.Controller/Entities/Audio/MusicGenre.cs
@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities.Audio
@@ -13,19 +15,6 @@ namespace MediaBrowser.Controller.Entities.Audio
     /// </summary>
     public class MusicGenre : BaseItem, IItemByName
     {
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
-
-            list.Insert(0, GetType().Name + "-" + (Name ?? string.Empty).RemoveDiacritics());
-            return list;
-        }
-
-        public override string CreatePresentationUniqueKey()
-        {
-            return GetUserDataKeys()[0];
-        }
-
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
 
@@ -36,13 +25,29 @@ namespace MediaBrowser.Controller.Entities.Audio
         public override bool IsDisplayedAsFolder => true;
 
         /// <summary>
-        /// Returns the folder containing the item.
+        /// Gets the folder containing the item.
         /// If the item is a folder, it returns the folder itself.
         /// </summary>
         /// <value>The containing folder path.</value>
         [JsonIgnore]
         public override string ContainingFolderPath => Path;
 
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            list.Insert(0, GetType().Name + "-" + (Name ?? string.Empty).RemoveDiacritics());
+            return list;
+        }
+
+        public override string CreatePresentationUniqueKey()
+        {
+            return GetUserDataKeys()[0];
+        }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             return 1;
@@ -58,9 +63,6 @@ namespace MediaBrowser.Controller.Entities.Audio
             return true;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public IList<BaseItem> GetTaggedItems(InternalItemsQuery query)
         {
             query.GenreIds = new[] { Id };
@@ -104,9 +106,11 @@ namespace MediaBrowser.Controller.Entities.Audio
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Option to replace metadata.</param>
+        /// <returns>True if metadata changed.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))
diff --git a/MediaBrowser.Controller/Entities/AudioBook.cs b/MediaBrowser.Controller/Entities/AudioBook.cs
index f4bd851e1..782481fbc 100644
--- a/MediaBrowser.Controller/Entities/AudioBook.cs
+++ b/MediaBrowser.Controller/Entities/AudioBook.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1724, CS1591
 
 using System;
 using System.Text.Json.Serialization;
diff --git a/MediaBrowser.Controller/Entities/BaseItem.cs b/MediaBrowser.Controller/Entities/BaseItem.cs
index 53d45261e..838a9f2f8 100644
--- a/MediaBrowser.Controller/Entities/BaseItem.cs
+++ b/MediaBrowser.Controller/Entities/BaseItem.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CS1591, SA1401
 
 using System;
 using System.Collections.Generic;
@@ -9,13 +11,15 @@ using System.Text;
 using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
+using Diacritics.Extensions;
 using Jellyfin.Data.Entities;
 using Jellyfin.Data.Enums;
+using Jellyfin.Extensions;
 using MediaBrowser.Common.Extensions;
 using MediaBrowser.Controller.Channels;
 using MediaBrowser.Controller.Configuration;
 using MediaBrowser.Controller.Dto;
-using MediaBrowser.Controller.Extensions;
+using MediaBrowser.Controller.Entities.Audio;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Persistence;
 using MediaBrowser.Controller.Providers;
@@ -38,6 +42,14 @@ namespace MediaBrowser.Controller.Entities
     public abstract class BaseItem : IHasProviderIds, IHasLookupInfo<ItemLookupInfo>, IEquatable<BaseItem>
     {
         /// <summary>
+        /// The trailer folder name.
+        /// </summary>
+        public const string TrailersFolderName = "trailers";
+        public const string ThemeSongsFolderName = "theme-music";
+        public const string ThemeSongFileName = "theme";
+        public const string ThemeVideosFolderName = "backdrops";
+
+        /// <summary>
         /// The supported image extensions.
         /// </summary>
         public static readonly string[] SupportedImageExtensions
@@ -58,6 +70,47 @@ namespace MediaBrowser.Controller.Entities
             ".ttml"
         };
 
+        /// <summary>
+        /// Extra types that should be counted and displayed as "Special Features" in the UI.
+        /// </summary>
+        public static readonly IReadOnlyCollection<ExtraType> DisplayExtraTypes = new HashSet<ExtraType>
+        {
+            Model.Entities.ExtraType.Unknown,
+            Model.Entities.ExtraType.BehindTheScenes,
+            Model.Entities.ExtraType.Clip,
+            Model.Entities.ExtraType.DeletedScene,
+            Model.Entities.ExtraType.Interview,
+            Model.Entities.ExtraType.Sample,
+            Model.Entities.ExtraType.Scene
+        };
+
+        public static readonly char[] SlugReplaceChars = { '?', '/', '&' };
+
+        /// <summary>
+        /// The supported extra folder names and types. See <see cref="Emby.Naming.Common.NamingOptions" />.
+        /// </summary>
+        public static readonly Dictionary<string, ExtraType> AllExtrasTypesFolderNames = new Dictionary<string, ExtraType>(StringComparer.OrdinalIgnoreCase)
+        {
+            ["extras"] = MediaBrowser.Model.Entities.ExtraType.Unknown,
+            ["behind the scenes"] = MediaBrowser.Model.Entities.ExtraType.BehindTheScenes,
+            ["deleted scenes"] = MediaBrowser.Model.Entities.ExtraType.DeletedScene,
+            ["interviews"] = MediaBrowser.Model.Entities.ExtraType.Interview,
+            ["scenes"] = MediaBrowser.Model.Entities.ExtraType.Scene,
+            ["samples"] = MediaBrowser.Model.Entities.ExtraType.Sample,
+            ["shorts"] = MediaBrowser.Model.Entities.ExtraType.Clip,
+            ["featurettes"] = MediaBrowser.Model.Entities.ExtraType.Clip
+        };
+
+        private string _sortName;
+        private Guid[] _themeSongIds;
+        private Guid[] _themeVideoIds;
+
+        private string _forcedSortName;
+
+        private string _name;
+
+        public const char SlugChar = '-';
+
         protected BaseItem()
         {
             Tags = Array.Empty<string>();
@@ -71,50 +124,15 @@ namespace MediaBrowser.Controller.Entities
             ExtraIds = Array.Empty<Guid>();
         }
 
-        public static readonly char[] SlugReplaceChars = { '?', '/', '&' };
-        public static char SlugChar = '-';
-
-        /// <summary>
-        /// The trailer folder name.
-        /// </summary>
-        public const string TrailerFolderName = "trailers";
-        public const string ThemeSongsFolderName = "theme-music";
-        public const string ThemeSongFilename = "theme";
-        public const string ThemeVideosFolderName = "backdrops";
-        public const string ExtrasFolderName = "extras";
-        public const string BehindTheScenesFolderName = "behind the scenes";
-        public const string DeletedScenesFolderName = "deleted scenes";
-        public const string InterviewFolderName = "interviews";
-        public const string SceneFolderName = "scenes";
-        public const string SampleFolderName = "samples";
-        public const string ShortsFolderName = "shorts";
-        public const string FeaturettesFolderName = "featurettes";
-
-        public static readonly string[] AllExtrasTypesFolderNames = {
-            ExtrasFolderName,
-            BehindTheScenesFolderName,
-            DeletedScenesFolderName,
-            InterviewFolderName,
-            SceneFolderName,
-            SampleFolderName,
-            ShortsFolderName,
-            FeaturettesFolderName
-        };
-
         [JsonIgnore]
         public Guid[] ThemeSongIds
         {
             get
             {
-                if (_themeSongIds == null)
-                {
-                    _themeSongIds = GetExtras()
-                        .Where(extra => extra.ExtraType == Model.Entities.ExtraType.ThemeSong)
-                        .Select(song => song.Id)
-                        .ToArray();
-                }
-
-                return _themeSongIds;
+                return _themeSongIds ??= GetExtras()
+                    .Where(extra => extra.ExtraType == Model.Entities.ExtraType.ThemeSong)
+                    .Select(song => song.Id)
+                    .ToArray();
             }
 
             private set
@@ -128,15 +146,10 @@ namespace MediaBrowser.Controller.Entities
         {
             get
             {
-                if (_themeVideoIds == null)
-                {
-                    _themeVideoIds = GetExtras()
-                        .Where(extra => extra.ExtraType == Model.Entities.ExtraType.ThemeVideo)
-                        .Select(song => song.Id)
-                        .ToArray();
-                }
-
-                return _themeVideoIds;
+                return _themeVideoIds ??= GetExtras()
+                    .Where(extra => extra.ExtraType == Model.Entities.ExtraType.ThemeVideo)
+                    .Select(song => song.Id)
+                    .ToArray();
             }
 
             private set
@@ -185,7 +198,7 @@ namespace MediaBrowser.Controller.Entities
         public virtual bool AlwaysScanInternalMetadataPath => false;
 
         /// <summary>
-        /// Gets a value indicating whether this instance is in mixed folder.
+        /// Gets or sets 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>
         [JsonIgnore]
@@ -200,8 +213,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual bool SupportsRemoteImageDownloading => true;
 
-        private string _name;
-
         /// <summary>
         /// Gets or sets the name.
         /// </summary>
@@ -252,7 +263,7 @@ namespace MediaBrowser.Controller.Entities
         public ProgramAudio? Audio { get; set; }
 
         /// <summary>
-        /// Return the id that should be used to key display prefs for this item.
+        /// Gets 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>
@@ -288,7 +299,7 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// Returns the folder containing the item.
+        /// Gets the folder containing the item.
         /// If the item is a folder, it returns the folder itself.
         /// </summary>
         [JsonIgnore]
@@ -313,8 +324,11 @@ namespace MediaBrowser.Controller.Entities
         public string ServiceName { get; set; }
 
         /// <summary>
-        /// If this content came from an external service, the id of the content on that service.
+        /// Gets or sets the external id.
         /// </summary>
+        /// <remarks>
+        /// If this content came from an external service, the id of the content on that service.
+        /// </remarks>
         [JsonIgnore]
         public string ExternalId { get; set; }
 
@@ -331,14 +345,8 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual bool IsHidden => false;
 
-        public BaseItem GetOwner()
-        {
-            var ownerId = OwnerId;
-            return ownerId.Equals(Guid.Empty) ? null : LibraryManager.GetItemById(ownerId);
-        }
-
         /// <summary>
-        /// Gets or sets the type of the location.
+        /// Gets the type of the location.
         /// </summary>
         /// <value>The type of the location.</value>
         [JsonIgnore]
@@ -347,9 +355,9 @@ namespace MediaBrowser.Controller.Entities
             get
             {
                 // if (IsOffline)
-                //{
+                // {
                 //    return LocationType.Offline;
-                //}
+                // }
 
                 var path = Path;
                 if (string.IsNullOrEmpty(path))
@@ -382,13 +390,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        public bool IsPathProtocol(MediaProtocol protocol)
-        {
-            var current = PathProtocol;
-
-            return current.HasValue && current.Value == protocol;
-        }
-
         [JsonIgnore]
         public bool IsFileProtocol => IsPathProtocol(MediaProtocol.File);
 
@@ -426,109 +427,28 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual bool EnableAlphaNumericSorting => true;
 
-        private List<Tuple<StringBuilder, bool>> GetSortChunks(string s1)
-        {
-            var list = new List<Tuple<StringBuilder, bool>>();
-
-            int thisMarker = 0;
-
-            while (thisMarker < s1.Length)
-            {
-                char thisCh = s1[thisMarker];
+        public virtual bool IsHD => Height >= 720;
 
-                var thisChunk = new StringBuilder();
-                bool isNumeric = char.IsDigit(thisCh);
+        public bool IsShortcut { get; set; }
 
-                while (thisMarker < s1.Length && char.IsDigit(thisCh) == isNumeric)
-                {
-                    thisChunk.Append(thisCh);
-                    thisMarker++;
+        public string ShortcutPath { get; set; }
 
-                    if (thisMarker < s1.Length)
-                    {
-                        thisCh = s1[thisMarker];
-                    }
-                }
+        public int Width { get; set; }
 
-                list.Add(new Tuple<StringBuilder, bool>(thisChunk, isNumeric));
-            }
+        public int Height { get; set; }
 
-            return list;
-        }
+        public Guid[] ExtraIds { get; set; }
 
         /// <summary>
-        /// This is just a helper for convenience.
+        /// Gets the primary image path.
         /// </summary>
+        /// <remarks>
+        /// This is just a helper for convenience.
+        /// </remarks>
         /// <value>The primary image path.</value>
         [JsonIgnore]
         public string PrimaryImagePath => this.GetImagePath(ImageType.Primary);
 
-        public virtual bool CanDelete()
-        {
-            if (SourceType == SourceType.Channel)
-            {
-                return ChannelManager.CanDelete(this);
-            }
-
-            return IsFileProtocol;
-        }
-
-        public virtual bool IsAuthorizedToDelete(User user, List<Folder> allCollectionFolders)
-        {
-            if (user.HasPermission(PermissionKind.EnableContentDeletion))
-            {
-                return true;
-            }
-
-            var allowed = user.GetPreferenceValues<Guid>(PreferenceKind.EnableContentDeletionFromFolders);
-
-            if (SourceType == SourceType.Channel)
-            {
-                return allowed.Contains(ChannelId);
-            }
-            else
-            {
-                var collectionFolders = LibraryManager.GetCollectionFolders(this, allCollectionFolders);
-
-                foreach (var folder in collectionFolders)
-                {
-                    if (allowed.Contains(folder.Id))
-                    {
-                        return true;
-                    }
-                }
-            }
-
-            return false;
-        }
-
-        public bool CanDelete(User user, List<Folder> allCollectionFolders)
-        {
-            return CanDelete() && IsAuthorizedToDelete(user, allCollectionFolders);
-        }
-
-        public bool CanDelete(User user)
-        {
-            var allCollectionFolders = LibraryManager.GetUserRootFolder().Children.OfType<Folder>().ToList();
-
-            return CanDelete(user, allCollectionFolders);
-        }
-
-        public virtual bool CanDownload()
-        {
-            return false;
-        }
-
-        public virtual bool IsAuthorizedToDownload(User user)
-        {
-            return user.HasPermission(PermissionKind.EnableContentDownloading);
-        }
-
-        public bool CanDownload(User user)
-        {
-            return CanDownload() && IsAuthorizedToDownload(user);
-        }
-
         /// <summary>
         /// Gets or sets the date created.
         /// </summary>
@@ -548,38 +468,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public DateTime DateLastRefreshed { get; set; }
 
-        /// <summary>
-        /// The logger.
-        /// </summary>
-        public static ILogger<BaseItem> 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 IChannelManager ChannelManager { get; set; }
-
-        public static IMediaSourceManager MediaSourceManager { get; set; }
-
-        /// <summary>
-        /// Returns a <see cref="string" /> that represents this instance.
-        /// </summary>
-        /// <returns>A <see cref="string" /> that represents this instance.</returns>
-        public override string ToString()
-        {
-            return Name;
-        }
-
         [JsonIgnore]
         public bool IsLocked { get; set; }
 
@@ -611,223 +499,87 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private string _forcedSortName;
-
-        /// <summary>
-        /// Gets or sets the name of the forced sort.
-        /// </summary>
-        /// <value>The name of the forced sort.</value>
         [JsonIgnore]
-        public string ForcedSortName
-        {
-            get => _forcedSortName;
-            set { _forcedSortName = value; _sortName = null; }
-        }
-
-        private string _sortName;
-        private Guid[] _themeSongIds;
-        private Guid[] _themeVideoIds;
-
-        /// <summary>
-        /// Gets the name of the sort.
-        /// </summary>
-        /// <value>The name of the sort.</value>
-        [JsonIgnore]
-        public string SortName
+        public bool EnableMediaSourceDisplay
         {
             get
             {
-                if (_sortName == null)
+                if (SourceType == SourceType.Channel)
                 {
-                    if (!string.IsNullOrEmpty(ForcedSortName))
-                    {
-                        // Need the ToLower because that's what CreateSortName does
-                        _sortName = ModifySortChunks(ForcedSortName).ToLowerInvariant();
-                    }
-                    else
-                    {
-                        _sortName = CreateSortName();
-                    }
+                    return ChannelManager.EnableMediaSourceDisplay(this);
                 }
 
-                return _sortName;
+                return true;
             }
-
-            set => _sortName = value;
         }
 
-        public string GetInternalMetadataPath()
-        {
-            var basePath = ConfigurationManager.ApplicationPaths.InternalMetadataPath;
-
-            return GetInternalMetadataPath(basePath);
-        }
-
-        protected virtual string GetInternalMetadataPath(string basePath)
-        {
-            if (SourceType == SourceType.Channel)
-            {
-                return System.IO.Path.Combine(basePath, "channels", ChannelId.ToString("N", CultureInfo.InvariantCulture), Id.ToString("N", CultureInfo.InvariantCulture));
-            }
-
-            ReadOnlySpan<char> idString = Id.ToString("N", CultureInfo.InvariantCulture);
-
-            basePath = System.IO.Path.Combine(basePath, "library");
-
-            return System.IO.Path.Join(basePath, idString.Slice(0, 2), idString);
-        }
+        [JsonIgnore]
+        public Guid ParentId { get; set; }
 
         /// <summary>
-        /// Creates the name of the sort.
+        /// Gets or sets the logger.
         /// </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().ToLowerInvariant();
-
-            foreach (var removeChar in ConfigurationManager.Configuration.SortRemoveCharacters)
-            {
-                sortable = sortable.Replace(removeChar, string.Empty, StringComparison.Ordinal);
-            }
-
-            foreach (var replaceChar in ConfigurationManager.Configuration.SortReplaceCharacters)
-            {
-                sortable = sortable.Replace(replaceChar, " ", StringComparison.Ordinal);
-            }
-
-            foreach (var search in ConfigurationManager.Configuration.SortRemoveWords)
-            {
-                // Remove from beginning if a space follows
-                if (sortable.StartsWith(search + " ", StringComparison.Ordinal))
-                {
-                    sortable = sortable.Remove(0, search.Length + 1);
-                }
-
-                // Remove from middle if surrounded by spaces
-                sortable = sortable.Replace(" " + search + " ", " ", StringComparison.Ordinal);
-
-                // Remove from end if followed by a space
-                if (sortable.EndsWith(" " + search, StringComparison.Ordinal))
-                {
-                    sortable = sortable.Remove(sortable.Length - (search.Length + 1));
-                }
-            }
-
-            return ModifySortChunks(sortable);
-        }
+        public static ILogger<BaseItem> Logger { get; set; }
 
-        private string ModifySortChunks(string name)
-        {
-            var chunks = GetSortChunks(name);
+        public static ILibraryManager LibraryManager { get; set; }
 
-            var builder = new StringBuilder();
+        public static IServerConfigurationManager ConfigurationManager { get; set; }
 
-            foreach (var chunk in chunks)
-            {
-                var chunkBuilder = chunk.Item1;
+        public static IProviderManager ProviderManager { get; set; }
 
-                // This chunk is numeric
-                if (chunk.Item2)
-                {
-                    while (chunkBuilder.Length < 10)
-                    {
-                        chunkBuilder.Insert(0, '0');
-                    }
-                }
+        public static ILocalizationManager LocalizationManager { get; set; }
 
-                builder.Append(chunkBuilder);
-            }
+        public static IItemRepository ItemRepository { get; set; }
 
-            // logger.LogDebug("ModifySortChunks Start: {0} End: {1}", name, builder.ToString());
-            return builder.ToString().RemoveDiacritics();
-        }
+        public static IFileSystem FileSystem { get; set; }
 
-        [JsonIgnore]
-        public bool EnableMediaSourceDisplay
-        {
-            get
-            {
-                if (SourceType == SourceType.Channel)
-                {
-                    return ChannelManager.EnableMediaSourceDisplay(this);
-                }
+        public static IUserDataManager UserDataManager { get; set; }
 
-                return true;
-            }
-        }
+        public static IChannelManager ChannelManager { get; set; }
 
-        [JsonIgnore]
-        public Guid ParentId { get; set; }
+        public static IMediaSourceManager MediaSourceManager { get; set; }
 
         /// <summary>
-        /// Gets or sets the parent.
+        /// Gets or sets the name of the forced sort.
         /// </summary>
-        /// <value>The parent.</value>
+        /// <value>The name of the forced sort.</value>
         [JsonIgnore]
-        public Folder Parent
+        public string ForcedSortName
         {
-            get => GetParent() as Folder;
+            get => _forcedSortName;
             set
             {
-            }
-        }
-
-        public void SetParent(Folder parent)
-        {
-            ParentId = parent == null ? Guid.Empty : parent.Id;
-        }
-
-        public BaseItem GetParent()
-        {
-            var parentId = ParentId;
-            if (!parentId.Equals(Guid.Empty))
-            {
-                return LibraryManager.GetItemById(parentId);
-            }
-
-            return null;
-        }
-
-        public IEnumerable<BaseItem> GetParents()
-        {
-            var parent = GetParent();
-
-            while (parent != null)
-            {
-                yield return parent;
-
-                parent = parent.GetParent();
+                _forcedSortName = value;
+                _sortName = null;
             }
         }
 
         /// <summary>
-        /// Finds a parent of a given type.
+        /// Gets or sets the name of the sort.
         /// </summary>
-        /// <typeparam name="T"></typeparam>
-        /// <returns>``0.</returns>
-        public T FindParent<T>()
-            where T : Folder
+        /// <value>The name of the sort.</value>
+        [JsonIgnore]
+        public string SortName
         {
-            foreach (var parent in GetParents())
+            get
             {
-                var item = parent as T;
-                if (item != null)
+                if (_sortName == null)
                 {
-                    return item;
+                    if (!string.IsNullOrEmpty(ForcedSortName))
+                    {
+                        // Need the ToLower because that's what CreateSortName does
+                        _sortName = ModifySortChunks(ForcedSortName).ToLowerInvariant();
+                    }
+                    else
+                    {
+                        _sortName = CreateSortName();
+                    }
                 }
+
+                return _sortName;
             }
 
-            return null;
+            set => _sortName = value;
         }
 
         [JsonIgnore]
@@ -856,7 +608,7 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// When the item first debuted. For movies this could be premiere date, episodes would be first aired
+        /// Gets or sets the date that the item first debuted. For movies this could be premiere date, episodes would be first aired.
         /// </summary>
         /// <value>The premiere date.</value>
         [JsonIgnore]
@@ -953,7 +705,7 @@ namespace MediaBrowser.Controller.Entities
         public int? ProductionYear { get; set; }
 
         /// <summary>
-        /// If the item is part of a series, this is it's number in the series.
+        /// Gets or sets the index number. 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>
@@ -961,7 +713,7 @@ namespace MediaBrowser.Controller.Entities
         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.
+        /// Gets or sets the parent index number. 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>
         [JsonIgnore]
@@ -1013,6 +765,349 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
+        /// Gets or sets the provider ids.
+        /// </summary>
+        /// <value>The provider ids.</value>
+        [JsonIgnore]
+        public Dictionary<string, string> ProviderIds { get; set; }
+
+        [JsonIgnore]
+        public virtual Folder LatestItemsIndexContainer => null;
+
+        [JsonIgnore]
+        public string PresentationUniqueKey { get; set; }
+
+        [JsonIgnore]
+        public virtual bool EnableRememberingTrackSelections => true;
+
+        [JsonIgnore]
+        public virtual bool IsTopParent
+        {
+            get
+            {
+                if (this is BasePluginFolder || this is Channel)
+                {
+                    return true;
+                }
+
+                if (this is IHasCollectionType view)
+                {
+                    if (string.Equals(view.CollectionType, CollectionType.LiveTv, StringComparison.OrdinalIgnoreCase))
+                    {
+                        return true;
+                    }
+                }
+
+                if (GetParent() is AggregateFolder)
+                {
+                    return true;
+                }
+
+                return false;
+            }
+        }
+
+        [JsonIgnore]
+        public virtual bool SupportsAncestors => true;
+
+        [JsonIgnore]
+        public virtual bool StopRefreshIfLocalMetadataFound => true;
+
+        [JsonIgnore]
+        protected virtual bool SupportsOwnedItems => !ParentId.Equals(Guid.Empty) && IsFileProtocol;
+
+        [JsonIgnore]
+        public virtual bool SupportsPeople => false;
+
+        [JsonIgnore]
+        public virtual bool SupportsThemeMedia => false;
+
+        [JsonIgnore]
+        public virtual bool SupportsInheritedParentImages => false;
+
+        /// <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>
+        [JsonIgnore]
+        public virtual bool IsFolder => false;
+
+        [JsonIgnore]
+        public virtual bool IsDisplayedAsFolder => false;
+
+        /// <summary>
+        /// Gets or sets the remote trailers.
+        /// </summary>
+        /// <value>The remote trailers.</value>
+        public IReadOnlyList<MediaUrl> RemoteTrailers { get; set; }
+
+        public virtual bool SupportsExternalTransfer => false;
+
+        public virtual double GetDefaultPrimaryImageAspectRatio()
+        {
+            return 0;
+        }
+
+        public virtual string CreatePresentationUniqueKey()
+        {
+            return Id.ToString("N", CultureInfo.InvariantCulture);
+        }
+
+        public bool IsPathProtocol(MediaProtocol protocol)
+        {
+            var current = PathProtocol;
+
+            return current.HasValue && current.Value == protocol;
+        }
+
+        private List<Tuple<StringBuilder, bool>> GetSortChunks(string s1)
+        {
+            var list = new List<Tuple<StringBuilder, bool>>();
+
+            int thisMarker = 0;
+
+            while (thisMarker < s1.Length)
+            {
+                char thisCh = s1[thisMarker];
+
+                var thisChunk = new StringBuilder();
+                bool isNumeric = char.IsDigit(thisCh);
+
+                while (thisMarker < s1.Length && char.IsDigit(thisCh) == isNumeric)
+                {
+                    thisChunk.Append(thisCh);
+                    thisMarker++;
+
+                    if (thisMarker < s1.Length)
+                    {
+                        thisCh = s1[thisMarker];
+                    }
+                }
+
+                list.Add(new Tuple<StringBuilder, bool>(thisChunk, isNumeric));
+            }
+
+            return list;
+        }
+
+        public virtual bool CanDelete()
+        {
+            if (SourceType == SourceType.Channel)
+            {
+                return ChannelManager.CanDelete(this);
+            }
+
+            return IsFileProtocol;
+        }
+
+        public virtual bool IsAuthorizedToDelete(User user, List<Folder> allCollectionFolders)
+        {
+            if (user.HasPermission(PermissionKind.EnableContentDeletion))
+            {
+                return true;
+            }
+
+            var allowed = user.GetPreferenceValues<Guid>(PreferenceKind.EnableContentDeletionFromFolders);
+
+            if (SourceType == SourceType.Channel)
+            {
+                return allowed.Contains(ChannelId);
+            }
+            else
+            {
+                var collectionFolders = LibraryManager.GetCollectionFolders(this, allCollectionFolders);
+
+                foreach (var folder in collectionFolders)
+                {
+                    if (allowed.Contains(folder.Id))
+                    {
+                        return true;
+                    }
+                }
+            }
+
+            return false;
+        }
+
+        public BaseItem GetOwner()
+        {
+            var ownerId = OwnerId;
+            return ownerId.Equals(Guid.Empty) ? null : LibraryManager.GetItemById(ownerId);
+        }
+
+        public bool CanDelete(User user, List<Folder> allCollectionFolders)
+        {
+            return CanDelete() && IsAuthorizedToDelete(user, allCollectionFolders);
+        }
+
+        public bool CanDelete(User user)
+        {
+            var allCollectionFolders = LibraryManager.GetUserRootFolder().Children.OfType<Folder>().ToList();
+
+            return CanDelete(user, allCollectionFolders);
+        }
+
+        public virtual bool CanDownload()
+        {
+            return false;
+        }
+
+        public virtual bool IsAuthorizedToDownload(User user)
+        {
+            return user.HasPermission(PermissionKind.EnableContentDownloading);
+        }
+
+        public bool CanDownload(User user)
+        {
+            return CanDownload() && IsAuthorizedToDownload(user);
+        }
+
+        /// <summary>
+        /// Returns a <see cref="string" /> that represents this instance.
+        /// </summary>
+        /// <returns>A <see cref="string" /> that represents this instance.</returns>
+        public override string ToString()
+        {
+            return Name;
+        }
+
+        public string GetInternalMetadataPath()
+        {
+            var basePath = ConfigurationManager.ApplicationPaths.InternalMetadataPath;
+
+            return GetInternalMetadataPath(basePath);
+        }
+
+        protected virtual string GetInternalMetadataPath(string basePath)
+        {
+            if (SourceType == SourceType.Channel)
+            {
+                return System.IO.Path.Join(basePath, "channels", ChannelId.ToString("N", CultureInfo.InvariantCulture), Id.ToString("N", CultureInfo.InvariantCulture));
+            }
+
+            ReadOnlySpan<char> idString = Id.ToString("N", CultureInfo.InvariantCulture);
+
+            return System.IO.Path.Join(basePath, "library", idString.Slice(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().ToLowerInvariant();
+
+            foreach (var removeChar in ConfigurationManager.Configuration.SortRemoveCharacters)
+            {
+                sortable = sortable.Replace(removeChar, string.Empty, StringComparison.Ordinal);
+            }
+
+            foreach (var replaceChar in ConfigurationManager.Configuration.SortReplaceCharacters)
+            {
+                sortable = sortable.Replace(replaceChar, " ", StringComparison.Ordinal);
+            }
+
+            foreach (var search in ConfigurationManager.Configuration.SortRemoveWords)
+            {
+                // Remove from beginning if a space follows
+                if (sortable.StartsWith(search + " ", StringComparison.Ordinal))
+                {
+                    sortable = sortable.Remove(0, search.Length + 1);
+                }
+
+                // Remove from middle if surrounded by spaces
+                sortable = sortable.Replace(" " + search + " ", " ", StringComparison.Ordinal);
+
+                // Remove from end if followed by a space
+                if (sortable.EndsWith(" " + search, StringComparison.Ordinal))
+                {
+                    sortable = sortable.Remove(sortable.Length - (search.Length + 1));
+                }
+            }
+
+            return ModifySortChunks(sortable);
+        }
+
+        private string ModifySortChunks(string name)
+        {
+            var chunks = GetSortChunks(name);
+
+            var builder = new StringBuilder();
+
+            foreach (var chunk in chunks)
+            {
+                var chunkBuilder = chunk.Item1;
+
+                // This chunk is numeric
+                if (chunk.Item2)
+                {
+                    while (chunkBuilder.Length < 10)
+                    {
+                        chunkBuilder.Insert(0, '0');
+                    }
+                }
+
+                builder.Append(chunkBuilder);
+            }
+
+            // logger.LogDebug("ModifySortChunks Start: {0} End: {1}", name, builder.ToString());
+            return builder.ToString().RemoveDiacritics();
+        }
+
+        public BaseItem GetParent()
+        {
+            var parentId = ParentId;
+            if (!parentId.Equals(Guid.Empty))
+            {
+                return LibraryManager.GetItemById(parentId);
+            }
+
+            return null;
+        }
+
+        public IEnumerable<BaseItem> GetParents()
+        {
+            var parent = GetParent();
+
+            while (parent != null)
+            {
+                yield return parent;
+
+                parent = parent.GetParent();
+            }
+        }
+
+        /// <summary>
+        /// Finds a parent of a given type.
+        /// </summary>
+        /// <typeparam name="T">Type of parent.</typeparam>
+        /// <returns>``0.</returns>
+        public T FindParent<T>()
+            where T : Folder
+        {
+            foreach (var parent in GetParents())
+            {
+                if (parent is T item)
+                {
+                    return item;
+                }
+            }
+
+            return null;
+        }
+
+        /// <summary>
         /// Gets the play access.
         /// </summary>
         /// <param name="user">The user.</param>
@@ -1025,9 +1120,9 @@ namespace MediaBrowser.Controller.Entities
             }
 
             // if (!user.IsParentalScheduleAllowed())
-            //{
+            // {
             //    return PlayAccess.None;
-            //}
+            // }
 
             return PlayAccess.Full;
         }
@@ -1259,7 +1354,7 @@ namespace MediaBrowser.Controller.Entities
 
             // Support plex/xbmc convention
             files.AddRange(fileSystemChildren
-                .Where(i => !i.IsDirectory && string.Equals(FileSystem.GetFileNameWithoutExtension(i), ThemeSongFilename, StringComparison.OrdinalIgnoreCase)));
+                .Where(i => !i.IsDirectory && System.IO.Path.GetFileNameWithoutExtension(i.FullName.AsSpan()).Equals(ThemeSongFileName, StringComparison.OrdinalIgnoreCase)));
 
             return LibraryManager.ResolvePaths(files, directoryService, null, new LibraryOptions())
                 .OfType<Audio.Audio>()
@@ -1318,37 +1413,24 @@ namespace MediaBrowser.Controller.Entities
 
         protected virtual BaseItem[] LoadExtras(List<FileSystemMetadata> fileSystemChildren, IDirectoryService directoryService)
         {
-            var extras = new List<Video>();
-
-            var folders = fileSystemChildren.Where(i => i.IsDirectory).ToArray();
-            foreach (var extraFolderName in AllExtrasTypesFolderNames)
-            {
-                var files = folders
-                    .Where(i => string.Equals(i.Name, extraFolderName, StringComparison.OrdinalIgnoreCase))
-                    .SelectMany(i => FileSystem.GetFiles(i.FullName));
-
-                extras.AddRange(LibraryManager.ResolvePaths(files, directoryService, null, new LibraryOptions())
+            return fileSystemChildren
+                .Where(child => child.IsDirectory && AllExtrasTypesFolderNames.ContainsKey(child.Name))
+                .SelectMany(folder => LibraryManager
+                    .ResolvePaths(FileSystem.GetFiles(folder.FullName), directoryService, null, new LibraryOptions())
                     .OfType<Video>()
-                    .Select(item =>
+                    .Select(video =>
                     {
                         // Try to retrieve it from the db. If we don't find it, use the resolved version
-                        if (LibraryManager.GetItemById(item.Id) is Video dbItem)
+                        if (LibraryManager.GetItemById(video.Id) is Video dbItem)
                         {
-                            item = dbItem;
+                            video = dbItem;
                         }
 
-                        // Use some hackery to get the extra type based on foldername
-                        item.ExtraType = Enum.TryParse(extraFolderName.Replace(" ", string.Empty), true, out ExtraType extraType)
-                            ? extraType
-                            : Model.Entities.ExtraType.Unknown;
-
-                        return item;
-
-                        // Sort them so that the list can be easily compared for changes
-                    }).OrderBy(i => i.Path));
-            }
-
-            return extras.ToArray();
+                        video.ExtraType = AllExtrasTypesFolderNames[folder.Name];
+                        return video;
+                    })
+                    .OrderBy(video => video.Path)) // Sort them so that the list can be easily compared for changes
+                .ToArray();
         }
 
         public Task RefreshMetadata(CancellationToken cancellationToken)
@@ -1415,23 +1497,55 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        [JsonIgnore]
-        protected virtual bool SupportsOwnedItems => !ParentId.Equals(Guid.Empty) && IsFileProtocol;
+        protected bool IsVisibleStandaloneInternal(User user, bool checkFolders)
+        {
+            if (!IsVisible(user))
+            {
+                return false;
+            }
 
-        [JsonIgnore]
-        public virtual bool SupportsPeople => false;
+            if (GetParents().Any(i => !i.IsVisible(user)))
+            {
+                return false;
+            }
 
-        [JsonIgnore]
-        public virtual bool SupportsThemeMedia => false;
+            if (checkFolders)
+            {
+                var topParent = GetParents().LastOrDefault() ?? this;
+
+                if (string.IsNullOrEmpty(topParent.Path))
+                {
+                    return true;
+                }
+
+                var itemCollectionFolders = LibraryManager.GetCollectionFolders(this).Select(i => i.Id).ToList();
+
+                if (itemCollectionFolders.Count > 0)
+                {
+                    var userCollectionFolders = LibraryManager.GetUserRootFolder().GetChildren(user, true).Select(i => i.Id).ToList();
+                    if (!itemCollectionFolders.Any(userCollectionFolders.Contains))
+                    {
+                        return false;
+                    }
+                }
+            }
+
+            return true;
+        }
+
+        public void SetParent(Folder parent)
+        {
+            ParentId = parent == null ? Guid.Empty : parent.Id;
+        }
 
         /// <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>
+        /// <param name="options">The metadata refresh options.</param>
+        /// <param name="fileSystemChildren">The list of filesystem children.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
+        /// <returns><c>true</c> if any items have changed, else <c>false</c>.</returns>
         protected virtual async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
             var themeSongsChanged = false;
@@ -1619,29 +1733,6 @@ namespace MediaBrowser.Controller.Entities
             return themeSongsChanged;
         }
 
-        /// <summary>
-        /// Gets or sets the provider ids.
-        /// </summary>
-        /// <value>The provider ids.</value>
-        [JsonIgnore]
-        public Dictionary<string, string> ProviderIds { get; set; }
-
-        [JsonIgnore]
-        public virtual Folder LatestItemsIndexContainer => null;
-
-        public virtual double GetDefaultPrimaryImageAspectRatio()
-        {
-            return 0;
-        }
-
-        public virtual string CreatePresentationUniqueKey()
-        {
-            return Id.ToString("N", CultureInfo.InvariantCulture);
-        }
-
-        [JsonIgnore]
-        public string PresentationUniqueKey { get; set; }
-
         public string GetPresentationUniqueKey()
         {
             return PresentationUniqueKey ?? CreatePresentationUniqueKey();
@@ -1773,7 +1864,7 @@ namespace MediaBrowser.Controller.Entities
         /// </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="ArgumentNullException">user</exception>
+        /// <exception cref="ArgumentNullException">If user is null.</exception>
         public bool IsParentalAllowed(User user)
         {
             if (user == null)
@@ -1918,7 +2009,7 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="user">The user.</param>
         /// <returns><c>true</c> if the specified user is visible; otherwise, <c>false</c>.</returns>
-        /// <exception cref="ArgumentNullException">user</exception>
+        /// <exception cref="ArgumentNullException"><paramref name="user" /> is <c>null</c>.</exception>
         public virtual bool IsVisible(User user)
         {
             if (user == null)
@@ -1939,58 +2030,9 @@ namespace MediaBrowser.Controller.Entities
             return IsVisibleStandaloneInternal(user, true);
         }
 
-        [JsonIgnore]
-        public virtual bool SupportsInheritedParentImages => false;
-
-        protected bool IsVisibleStandaloneInternal(User user, bool checkFolders)
-        {
-            if (!IsVisible(user))
-            {
-                return false;
-            }
-
-            if (GetParents().Any(i => !i.IsVisible(user)))
-            {
-                return false;
-            }
-
-            if (checkFolders)
-            {
-                var topParent = GetParents().LastOrDefault() ?? this;
-
-                if (string.IsNullOrEmpty(topParent.Path))
-                {
-                    return true;
-                }
-
-                var itemCollectionFolders = LibraryManager.GetCollectionFolders(this).Select(i => i.Id).ToList();
-
-                if (itemCollectionFolders.Count > 0)
-                {
-                    var userCollectionFolders = LibraryManager.GetUserRootFolder().GetChildren(user, true).Select(i => i.Id).ToList();
-                    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>
-        [JsonIgnore]
-        public virtual bool IsFolder => false;
-
-        [JsonIgnore]
-        public virtual bool IsDisplayedAsFolder => false;
-
         public virtual string GetClientTypeName()
         {
-            if (IsFolder && SourceType == SourceType.Channel && !(this is Channel))
+            if (IsFolder && SourceType == SourceType.Channel && this is not Channel)
             {
                 return "ChannelFolderItem";
             }
@@ -2076,14 +2118,11 @@ namespace MediaBrowser.Controller.Entities
             return null;
         }
 
-        [JsonIgnore]
-        public virtual bool EnableRememberingTrackSelections => true;
-
         /// <summary>
         /// Adds a studio to the item.
         /// </summary>
         /// <param name="name">The name.</param>
-        /// <exception cref="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throws if name is null.</exception>
         public void AddStudio(string name)
         {
             if (string.IsNullOrEmpty(name))
@@ -2119,7 +2158,7 @@ namespace MediaBrowser.Controller.Entities
         /// Adds a genre to the item.
         /// </summary>
         /// <param name="name">The name.</param>
-        /// <exception cref="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throwns if name is null.</exception>
         public void AddGenre(string name)
         {
             if (string.IsNullOrEmpty(name))
@@ -2142,8 +2181,7 @@ namespace MediaBrowser.Controller.Entities
         /// <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="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throws if user is null.</exception>
         public virtual void MarkPlayed(
             User user,
             DateTime? datePlayed,
@@ -2180,8 +2218,7 @@ namespace MediaBrowser.Controller.Entities
         /// Marks the unplayed.
         /// </summary>
         /// <param name="user">The user.</param>
-        /// <returns>Task.</returns>
-        /// <exception cref="ArgumentNullException"></exception>
+        /// <exception cref="ArgumentNullException">Throws if user is null.</exception>
         public virtual void MarkUnplayed(User user)
         {
             if (user == null)
@@ -2216,7 +2253,7 @@ namespace MediaBrowser.Controller.Entities
         /// <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="ArgumentException">Backdrops should be accessed using Item.Backdrops</exception>
+        /// <exception cref="ArgumentException">Backdrops should be accessed using Item.Backdrops.</exception>
         public bool HasImage(ImageType type, int imageIndex)
         {
             return GetImageInfo(type, imageIndex) != null;
@@ -2281,6 +2318,7 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="type">The type.</param>
         /// <param name="index">The index.</param>
+        /// <returns>A task.</returns>
         public async Task DeleteImageAsync(ImageType type, int index)
         {
             var info = GetImageInfo(type, index);
@@ -2318,13 +2356,15 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Validates that images within the item are still on the filesystem.
         /// </summary>
+        /// <param name="directoryService">The directory service to use.</param>
+        /// <returns><c>true</c> if the images validate, <c>false</c> if not.</returns>
         public bool ValidateImages(IDirectoryService directoryService)
         {
             var allFiles = ImageInfos
                 .Where(i => i.IsLocalFile)
                 .Select(i => System.IO.Path.GetDirectoryName(i.Path))
                 .Distinct(StringComparer.OrdinalIgnoreCase)
-                .SelectMany(i => directoryService.GetFilePaths(i))
+                .SelectMany(path => directoryService.GetFilePaths(path))
                 .ToList();
 
             var deletedImages = ImageInfos
@@ -2345,9 +2385,7 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="imageType">Type of the image.</param>
         /// <param name="imageIndex">Index of the image.</param>
         /// <returns>System.String.</returns>
-        /// <exception cref="InvalidOperationException">
-        /// </exception>
-        /// <exception cref="ArgumentNullException">item</exception>
+        /// <exception cref="ArgumentNullException">Item is null.</exception>
         public string GetImagePath(ImageType imageType, int imageIndex)
             => GetImageInfo(imageType, imageIndex)?.Path;
 
@@ -2383,6 +2421,17 @@ namespace MediaBrowser.Controller.Entities
                 };
             }
 
+            // Music albums usually don't have dedicated backdrops, so return one from the artist instead
+            if (GetType() == typeof(MusicAlbum) && imageType == ImageType.Backdrop)
+            {
+                var artist = FindParent<MusicArtist>();
+
+                if (artist != null)
+                {
+                    return artist.GetImages(imageType).ElementAtOrDefault(imageIndex);
+                }
+            }
+
             return GetImages(imageType)
                 .ElementAtOrDefault(imageIndex);
         }
@@ -2434,7 +2483,15 @@ namespace MediaBrowser.Controller.Entities
                 throw new ArgumentException("No image info for chapter images");
             }
 
-            return ImageInfos.Where(i => i.Type == imageType);
+            // Yield return is more performant than LINQ Where on an Array
+            for (var i = 0; i < ImageInfos.Length; i++)
+            {
+                var imageInfo = ImageInfos[i];
+                if (imageInfo.Type == imageType)
+                {
+                    yield return imageInfo;
+                }
+            }
         }
 
         /// <summary>
@@ -2443,7 +2500,7 @@ namespace MediaBrowser.Controller.Entities
         /// <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="ArgumentException">Cannot call AddImages with chapter images</exception>
+        /// <exception cref="ArgumentException">Cannot call AddImages with chapter images.</exception>
         public bool AddImages(ImageType imageType, List<FileSystemMetadata> images)
         {
             if (imageType == ImageType.Chapter)
@@ -2466,7 +2523,7 @@ namespace MediaBrowser.Controller.Entities
                 }
 
                 var existing = existingImages
-                    .FirstOrDefault(i => string.Equals(i.Path, newImage.FullName, StringComparison.OrdinalIgnoreCase));
+                    .Find(i => string.Equals(i.Path, newImage.FullName, StringComparison.OrdinalIgnoreCase));
 
                 if (existing == null)
                 {
@@ -2497,8 +2554,7 @@ namespace MediaBrowser.Controller.Entities
                 var newImagePaths = images.Select(i => i.FullName).ToList();
 
                 var deleted = existingImages
-                    .Where(i => i.IsLocalFile && !newImagePaths.Contains(i.Path, StringComparer.OrdinalIgnoreCase) && !File.Exists(i.Path))
-                    .ToList();
+                    .FindAll(i => i.IsLocalFile && !newImagePaths.Contains(i.Path.AsSpan(), StringComparison.OrdinalIgnoreCase) && !File.Exists(i.Path));
 
                 if (deleted.Count > 0)
                 {
@@ -2527,10 +2583,11 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the file system path to delete when the item is to be deleted.
         /// </summary>
-        /// <returns></returns>
+        /// <returns>The metadata for the deleted paths.</returns>
         public virtual IEnumerable<FileSystemMetadata> GetDeletePaths()
         {
-            return new[] {
+            return new[]
+            {
                 new FileSystemMetadata
                 {
                     FullName = Path,
@@ -2637,6 +2694,7 @@ namespace MediaBrowser.Controller.Entities
                 MetadataCountryCode = GetPreferredMetadataCountryCode(),
                 MetadataLanguage = GetPreferredMetadataLanguage(),
                 Name = GetNameForMetadataLookup(),
+                OriginalTitle = OriginalTitle,
                 ProviderIds = ProviderIds,
                 IndexNumber = IndexNumber,
                 ParentIndexNumber = ParentIndexNumber,
@@ -2653,7 +2711,9 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// This is called before any metadata refresh and returns true if changes were made.
         /// </summary>
-        public virtual bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Whether to replace all metadata.</param>
+        /// <returns>true if the item has change, else false.</returns>
+        public virtual bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
             _sortName = null;
 
@@ -2777,11 +2837,11 @@ namespace MediaBrowser.Controller.Entities
 
             // var parentId = Id;
             // if (!video.IsOwnedItem || video.ParentId != parentId)
-            //{
+            // {
             //    video.IsOwnedItem = true;
             //    video.ParentId = parentId;
             //    newOptions.ForceSave = true;
-            //}
+            // }
 
             if (video == null)
             {
@@ -2821,39 +2881,6 @@ namespace MediaBrowser.Controller.Entities
             return GetParents().FirstOrDefault(parent => parent.IsTopParent);
         }
 
-        [JsonIgnore]
-        public virtual bool IsTopParent
-        {
-            get
-            {
-                if (this is BasePluginFolder || this is Channel)
-                {
-                    return true;
-                }
-
-                if (this is IHasCollectionType view)
-                {
-                    if (string.Equals(view.CollectionType, CollectionType.LiveTv, StringComparison.OrdinalIgnoreCase))
-                    {
-                        return true;
-                    }
-                }
-
-                if (GetParent() is AggregateFolder)
-                {
-                    return true;
-                }
-
-                return false;
-            }
-        }
-
-        [JsonIgnore]
-        public virtual bool SupportsAncestors => true;
-
-        [JsonIgnore]
-        public virtual bool StopRefreshIfLocalMetadataFound => true;
-
         public virtual IEnumerable<Guid> GetIdsForAncestorQuery()
         {
             return new[] { Id };
@@ -2888,7 +2915,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Updates the official rating based on content and returns true or false indicating if it changed.
         /// </summary>
-        /// <returns></returns>
+        /// <param name="children">Media children.</param>
+        /// <returns><c>true</c> if the rating was updated; otherwise <c>false</c>.</returns>
         public bool UpdateRatingToItems(IList<BaseItem> children)
         {
             var currentOfficialRating = OfficialRating;
@@ -2904,7 +2932,9 @@ namespace MediaBrowser.Controller.Entities
 
             OfficialRating = ratings.FirstOrDefault() ?? currentOfficialRating;
 
-            return !string.Equals(currentOfficialRating ?? string.Empty, OfficialRating ?? string.Empty,
+            return !string.Equals(
+                currentOfficialRating ?? string.Empty,
+                OfficialRating ?? string.Empty,
                 StringComparison.OrdinalIgnoreCase);
         }
 
@@ -2919,12 +2949,6 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// Gets or sets the remote trailers.
-        /// </summary>
-        /// <value>The remote trailers.</value>
-        public IReadOnlyList<MediaUrl> RemoteTrailers { get; set; }
-
-        /// <summary>
         /// Get all extras associated with this item, sorted by <see cref="SortName"/>.
         /// </summary>
         /// <returns>An enumerable containing the items.</returns>
@@ -2961,39 +2985,11 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        public virtual bool IsHD => Height >= 720;
-
-        public bool IsShortcut { get; set; }
-
-        public string ShortcutPath { get; set; }
-
-        public int Width { get; set; }
-
-        public int Height { get; set; }
-
-        public Guid[] ExtraIds { get; set; }
-
         public virtual long GetRunTimeTicksForPlayState()
         {
             return RunTimeTicks ?? 0;
         }
 
-        /// <summary>
-        /// Extra types that should be counted and displayed as "Special Features" in the UI.
-        /// </summary>
-        public static readonly IReadOnlyCollection<ExtraType> DisplayExtraTypes = new HashSet<ExtraType>
-        {
-            Model.Entities.ExtraType.Unknown,
-            Model.Entities.ExtraType.BehindTheScenes,
-            Model.Entities.ExtraType.Clip,
-            Model.Entities.ExtraType.DeletedScene,
-            Model.Entities.ExtraType.Interview,
-            Model.Entities.ExtraType.Sample,
-            Model.Entities.ExtraType.Scene
-        };
-
-        public virtual bool SupportsExternalTransfer => false;
-
         /// <inheritdoc />
         public override bool Equals(object obj)
         {
@@ -3001,7 +2997,7 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <inheritdoc />
-        public bool Equals(BaseItem item) => Object.Equals(Id, item?.Id);
+        public bool Equals(BaseItem other) => Equals(Id, other?.Id);
 
         /// <inheritdoc />
         public override int GetHashCode() => HashCode.Combine(Id);
diff --git a/MediaBrowser.Controller/Entities/BaseItemExtensions.cs b/MediaBrowser.Controller/Entities/BaseItemExtensions.cs
index 157ed8332..33870e2fb 100644
--- a/MediaBrowser.Controller/Entities/BaseItemExtensions.cs
+++ b/MediaBrowser.Controller/Entities/BaseItemExtensions.cs
@@ -1,4 +1,3 @@
-#nullable enable
 #pragma warning disable CS1591
 
 using System;
@@ -45,7 +44,7 @@ namespace MediaBrowser.Controller.Entities
         /// <param name="file">The file.</param>
         public static void SetImagePath(this BaseItem item, ImageType imageType, string file)
         {
-            if (file.StartsWith("http", System.StringComparison.OrdinalIgnoreCase))
+            if (file.StartsWith("http", StringComparison.OrdinalIgnoreCase))
             {
                 item.SetImage(
                 new ItemImageInfo
@@ -65,6 +64,8 @@ namespace MediaBrowser.Controller.Entities
         /// </summary>
         /// <param name="source">The source object.</param>
         /// <param name="dest">The destination object.</param>
+        /// <typeparam name="T">Source type.</typeparam>
+        /// <typeparam name="TU">Destination type.</typeparam>
         public static void DeepCopy<T, TU>(this T source, TU dest)
             where T : BaseItem
             where TU : BaseItem
@@ -110,6 +111,9 @@ namespace MediaBrowser.Controller.Entities
         /// Copies all properties on newly created object. Skips properties that do not exist.
         /// </summary>
         /// <param name="source">The source object.</param>
+        /// <typeparam name="T">Source type.</typeparam>
+        /// <typeparam name="TU">Destination type.</typeparam>
+        /// <returns>Destination object.</returns>
         public static TU DeepCopy<T, TU>(this T source)
             where T : BaseItem
             where TU : BaseItem, new()
diff --git a/MediaBrowser.Controller/Entities/BasePluginFolder.cs b/MediaBrowser.Controller/Entities/BasePluginFolder.cs
index ef5a5a734..272a37df1 100644
--- a/MediaBrowser.Controller/Entities/BasePluginFolder.cs
+++ b/MediaBrowser.Controller/Entities/BasePluginFolder.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Text.Json.Serialization;
@@ -13,6 +15,12 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual string CollectionType => null;
 
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override bool CanDelete()
         {
             return false;
@@ -22,11 +30,5 @@ namespace MediaBrowser.Controller.Entities
         {
             return true;
         }
-
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }
diff --git a/MediaBrowser.Controller/Entities/Book.cs b/MediaBrowser.Controller/Entities/Book.cs
index 55945283c..d75beb06d 100644
--- a/MediaBrowser.Controller/Entities/Book.cs
+++ b/MediaBrowser.Controller/Entities/Book.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -10,6 +12,11 @@ namespace MediaBrowser.Controller.Entities
 {
     public class Book : BaseItem, IHasLookupInfo<BookInfo>, IHasSeries
     {
+        public Book()
+        {
+            this.RunTimeTicks = TimeSpan.TicksPerSecond;
+        }
+
         [JsonIgnore]
         public override string MediaType => Model.Entities.MediaType.Book;
 
@@ -26,11 +33,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public Guid SeriesId { get; set; }
 
-        public Book()
-        {
-            this.RunTimeTicks = TimeSpan.TicksPerSecond;
-        }
-
         public string FindSeriesSortName()
         {
             return SeriesName;
diff --git a/MediaBrowser.Controller/Entities/CollectionFolder.cs b/MediaBrowser.Controller/Entities/CollectionFolder.cs
index 76b6d39a9..7dc7f774d 100644
--- a/MediaBrowser.Controller/Entities/CollectionFolder.cs
+++ b/MediaBrowser.Controller/Entities/CollectionFolder.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -8,7 +10,7 @@ using System.Text.Json;
 using System.Text.Json.Serialization;
 using System.Threading;
 using System.Threading.Tasks;
-using MediaBrowser.Common.Json;
+using Jellyfin.Extensions.Json;
 using MediaBrowser.Controller.IO;
 using MediaBrowser.Controller.Library;
 using MediaBrowser.Controller.Providers;
@@ -27,30 +29,65 @@ namespace MediaBrowser.Controller.Entities
     public class CollectionFolder : Folder, ICollectionFolder
     {
         private static readonly JsonSerializerOptions _jsonOptions = JsonDefaults.Options;
-        public static IXmlSerializer XmlSerializer { get; set; }
-
-        public static IServerApplicationHost ApplicationHost { get; set; }
+        private static readonly Dictionary<string, LibraryOptions> _libraryOptions = new Dictionary<string, LibraryOptions>();
+        private bool _requiresRefresh;
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="CollectionFolder"/> class.
+        /// </summary>
         public CollectionFolder()
         {
             PhysicalLocationsList = Array.Empty<string>();
             PhysicalFolderIds = Array.Empty<Guid>();
         }
 
+        /// <summary>
+        /// Gets the display preferences id.
+        /// </summary>
+        /// <remarks>
+        /// Allow different display preferences for each collection folder.
+        /// </remarks>
+        /// <value>The display prefs id.</value>
+        [JsonIgnore]
+        public override Guid DisplayPreferencesId => Id;
+
+        [JsonIgnore]
+        public override string[] PhysicalLocations => PhysicalLocationsList;
+
+        public string[] PhysicalLocationsList { get; set; }
+
+        public Guid[] PhysicalFolderIds { get; set; }
+
+        public static IXmlSerializer XmlSerializer { get; set; }
+
+        public static IServerApplicationHost ApplicationHost { get; set; }
+
         [JsonIgnore]
         public override bool SupportsPlayedStatus => false;
 
         [JsonIgnore]
         public override bool SupportsInheritedParentImages => false;
 
+        public string CollectionType { get; set; }
+
+        /// <summary>
+        /// Gets the item's children.
+        /// </summary>
+        /// <remarks>
+        /// Our children are actually just references to the ones in the physical root...
+        /// </remarks>
+        /// <value>The actual children.</value>
+        [JsonIgnore]
+        public override IEnumerable<BaseItem> Children => GetActualChildren();
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override bool CanDelete()
         {
             return false;
         }
 
-        public string CollectionType { get; set; }
-
-        private static readonly Dictionary<string, LibraryOptions> LibraryOptions = new Dictionary<string, LibraryOptions>();
         public LibraryOptions GetLibraryOptions()
         {
             return GetLibraryOptions(Path);
@@ -60,9 +97,7 @@ namespace MediaBrowser.Controller.Entities
         {
             try
             {
-                var result = XmlSerializer.DeserializeFromFile(typeof(LibraryOptions), GetLibraryOptionsPath(path)) as LibraryOptions;
-
-                if (result == null)
+                if (XmlSerializer.DeserializeFromFile(typeof(LibraryOptions), GetLibraryOptionsPath(path)) is not LibraryOptions result)
                 {
                     return new LibraryOptions();
                 }
@@ -105,12 +140,12 @@ namespace MediaBrowser.Controller.Entities
 
         public static LibraryOptions GetLibraryOptions(string path)
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                if (!LibraryOptions.TryGetValue(path, out var options))
+                if (!_libraryOptions.TryGetValue(path, out var options))
                 {
                     options = LoadLibraryOptions(path);
-                    LibraryOptions[path] = options;
+                    _libraryOptions[path] = options;
                 }
 
                 return options;
@@ -119,9 +154,9 @@ namespace MediaBrowser.Controller.Entities
 
         public static void SaveLibraryOptions(string path, LibraryOptions options)
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                LibraryOptions[path] = options;
+                _libraryOptions[path] = options;
 
                 var clone = JsonSerializer.Deserialize<LibraryOptions>(JsonSerializer.SerializeToUtf8Bytes(options, _jsonOptions), _jsonOptions);
                 foreach (var mediaPath in clone.PathInfos)
@@ -138,37 +173,22 @@ namespace MediaBrowser.Controller.Entities
 
         public static void OnCollectionFolderChange()
         {
-            lock (LibraryOptions)
+            lock (_libraryOptions)
             {
-                LibraryOptions.Clear();
+                _libraryOptions.Clear();
             }
         }
 
-        /// <summary>
-        /// Allow different display preferences for each collection folder.
-        /// </summary>
-        /// <value>The display prefs id.</value>
-        [JsonIgnore]
-        public override Guid DisplayPreferencesId => Id;
-
-        [JsonIgnore]
-        public override string[] PhysicalLocations => PhysicalLocationsList;
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
         }
 
-        public string[] PhysicalLocationsList { get; set; }
-
-        public Guid[] PhysicalFolderIds { get; set; }
-
         protected override FileSystemMetadata[] GetFileSystemChildren(IDirectoryService directoryService)
         {
             return CreateResolveArgs(directoryService, true).FileSystemChildren;
         }
 
-        private bool _requiresRefresh;
         public override bool RequiresRefresh()
         {
             var changed = base.RequiresRefresh() || _requiresRefresh;
@@ -200,9 +220,9 @@ namespace MediaBrowser.Controller.Entities
             return changed;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var changed = base.BeforeMetadataRefresh(replaceAllMetdata) || _requiresRefresh;
+            var changed = base.BeforeMetadataRefresh(replaceAllMetadata) || _requiresRefresh;
             _requiresRefresh = false;
             return changed;
         }
@@ -271,7 +291,6 @@ namespace MediaBrowser.Controller.Entities
             var args = new ItemResolveArgs(ConfigurationManager.ApplicationPaths, directoryService)
             {
                 FileInfo = FileSystem.GetDirectoryInfo(path),
-                Path = path,
                 Parent = GetParent() as Folder,
                 CollectionType = CollectionType
             };
@@ -298,27 +317,20 @@ namespace MediaBrowser.Controller.Entities
 
         /// <summary>
         /// Compare our current children (presumably just read from the repo) with the current state of the file system and adjust for any changes
-        /// ***Currently does not contain logic to maintain items that are unavailable in the file system***
+        /// ***Currently does not contain logic to maintain items that are unavailable in the file system***.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
         /// <param name="refreshChildMetadata">if set to <c>true</c> [refresh child metadata].</param>
         /// <param name="refreshOptions">The refresh options.</param>
         /// <param name="directoryService">The directory service.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             return Task.CompletedTask;
         }
 
-        /// <summary>
-        /// Our children are actually just references to the ones in the physical root...
-        /// </summary>
-        /// <value>The actual children.</value>
-        [JsonIgnore]
-        public override IEnumerable<BaseItem> Children => GetActualChildren();
-
         public IEnumerable<BaseItem> GetActualChildren()
         {
             return GetPhysicalFolders(true).SelectMany(c => c.Children);
@@ -355,9 +367,7 @@ namespace MediaBrowser.Controller.Entities
 
             if (result.Count == 0)
             {
-                var folder = LibraryManager.FindByPath(path, true) as Folder;
-
-                if (folder != null)
+                if (LibraryManager.FindByPath(path, true) is Folder folder)
                 {
                     result.Add(folder);
                 }
@@ -365,8 +375,5 @@ namespace MediaBrowser.Controller.Entities
 
             return result;
         }
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }
diff --git a/MediaBrowser.Controller/Entities/Extensions.cs b/MediaBrowser.Controller/Entities/Extensions.cs
index 3a34c668c..9ce8eebe3 100644
--- a/MediaBrowser.Controller/Entities/Extensions.cs
+++ b/MediaBrowser.Controller/Entities/Extensions.cs
@@ -1,6 +1,8 @@
+#nullable disable
+
 using System;
 using System.Linq;
-using MediaBrowser.Common.Extensions;
+using Jellyfin.Extensions;
 using MediaBrowser.Model.Entities;
 
 namespace MediaBrowser.Controller.Entities
@@ -13,6 +15,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Adds the trailer URL.
         /// </summary>
+        /// <param name="item">Media item.</param>
+        /// <param name="url">Trailer URL.</param>
         public static void AddTrailerUrl(this BaseItem item, string url)
         {
             if (string.IsNullOrEmpty(url))
diff --git a/MediaBrowser.Controller/Entities/Folder.cs b/MediaBrowser.Controller/Entities/Folder.cs
index d45f8758c..18b4ec3c6 100644
--- a/MediaBrowser.Controller/Entities/Folder.cs
+++ b/MediaBrowser.Controller/Entities/Folder.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1002, CA1721, CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -35,6 +37,11 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Folder : BaseItem
     {
+        public Folder()
+        {
+            LinkedChildren = Array.Empty<LinkedChild>();
+        }
+
         public static IUserViewManager UserViewManager { get; set; }
 
         /// <summary>
@@ -48,11 +55,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public DateTime? DateLastMediaAdded { get; set; }
 
-        public Folder()
-        {
-            LinkedChildren = Array.Empty<LinkedChild>();
-        }
-
         [JsonIgnore]
         public override bool SupportsThemeMedia => true;
 
@@ -84,6 +86,87 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public virtual bool SupportsDateLastMediaAdded => false;
 
+        [JsonIgnore]
+        public override string FileNameWithoutExtension
+        {
+            get
+            {
+                if (IsFileProtocol)
+                {
+                    return System.IO.Path.GetFileName(Path);
+                }
+
+                return null;
+            }
+        }
+
+        /// <summary>
+        /// Gets the actual children.
+        /// </summary>
+        /// <value>The actual children.</value>
+        [JsonIgnore]
+        public virtual IEnumerable<BaseItem> Children => LoadChildren();
+
+        /// <summary>
+        /// Gets thread-safe access to all recursive children of this folder - without regard to user.
+        /// </summary>
+        /// <value>The recursive children.</value>
+        [JsonIgnore]
+        public IEnumerable<BaseItem> RecursiveChildren => GetRecursiveChildren();
+
+        [JsonIgnore]
+        protected virtual bool SupportsShortcutChildren => false;
+
+        protected virtual bool FilterLinkedChildrenPerUser => false;
+
+        [JsonIgnore]
+        protected override bool SupportsOwnedItems => base.SupportsOwnedItems || SupportsShortcutChildren;
+
+        [JsonIgnore]
+        public virtual bool SupportsUserDataFromChildren
+        {
+            get
+            {
+                // These are just far too slow.
+                if (this is ICollectionFolder)
+                {
+                    return false;
+                }
+
+                if (this is UserView)
+                {
+                    return false;
+                }
+
+                if (this is UserRootFolder)
+                {
+                    return false;
+                }
+
+                if (this is Channel)
+                {
+                    return false;
+                }
+
+                if (SourceType != SourceType.Library)
+                {
+                    return false;
+                }
+
+                if (this is IItemByName)
+                {
+                    if (this is not IHasDualAccess hasDualAccess || hasDualAccess.IsAccessedByName)
+                    {
+                        return false;
+                    }
+                }
+
+                return true;
+            }
+        }
+
+        public static ICollectionManager CollectionManager { get; set; }
+
         public override bool CanDelete()
         {
             if (IsRoot)
@@ -106,20 +189,6 @@ namespace MediaBrowser.Controller.Entities
             return baseResult;
         }
 
-        [JsonIgnore]
-        public override string FileNameWithoutExtension
-        {
-            get
-            {
-                if (IsFileProtocol)
-                {
-                    return System.IO.Path.GetFileName(Path);
-                }
-
-                return null;
-            }
-        }
-
         protected override bool IsAllowTagFilterEnforced()
         {
             if (this is ICollectionFolder)
@@ -135,17 +204,12 @@ namespace MediaBrowser.Controller.Entities
             return true;
         }
 
-        [JsonIgnore]
-        protected virtual bool SupportsShortcutChildren => false;
-
         /// <summary>
         /// Adds the child.
         /// </summary>
         /// <param name="item">The item.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
-        /// <returns>Task.</returns>
-        /// <exception cref="InvalidOperationException">Unable to add  + item.Name</exception>
-        public void AddChild(BaseItem item, CancellationToken cancellationToken)
+        /// <exception cref="InvalidOperationException">Unable to add  + item.Name.</exception>
+        public void AddChild(BaseItem item)
         {
             item.SetParent(this);
 
@@ -167,23 +231,9 @@ namespace MediaBrowser.Controller.Entities
             LibraryManager.CreateItem(item, this);
         }
 
-        /// <summary>
-        /// Gets the actual children.
-        /// </summary>
-        /// <value>The actual children.</value>
-        [JsonIgnore]
-        public virtual IEnumerable<BaseItem> Children => LoadChildren();
-
-        /// <summary>
-        /// thread-safe access to all recursive children of this folder - without regard to user.
-        /// </summary>
-        /// <value>The recursive children.</value>
-        [JsonIgnore]
-        public IEnumerable<BaseItem> RecursiveChildren => GetRecursiveChildren();
-
         public override bool IsVisible(User user)
         {
-            if (this is ICollectionFolder && !(this is BasePluginFolder))
+            if (this is ICollectionFolder && this is not BasePluginFolder)
             {
                 var blockedMediaFolders = user.GetPreferenceValues<Guid>(PreferenceKind.BlockedMediaFolders);
                 if (blockedMediaFolders.Length > 0)
@@ -210,6 +260,7 @@ namespace MediaBrowser.Controller.Entities
         /// Loads our children.  Validation will occur externally.
         /// We want this synchronous.
         /// </summary>
+        /// <returns>Returns children.</returns>
         protected virtual List<BaseItem> LoadChildren()
         {
             // logger.LogDebug("Loading children from {0} {1} {2}", GetType().Name, Id, Path);
@@ -224,20 +275,20 @@ namespace MediaBrowser.Controller.Entities
 
         public Task ValidateChildren(IProgress<double> progress, CancellationToken cancellationToken)
         {
-            return ValidateChildren(progress, cancellationToken, new MetadataRefreshOptions(new DirectoryService(FileSystem)));
+            return ValidateChildren(progress, new MetadataRefreshOptions(new DirectoryService(FileSystem)), cancellationToken: cancellationToken);
         }
 
         /// <summary>
         /// Validates that the children of the folder still exist.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="metadataRefreshOptions">The metadata refresh options.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        public Task ValidateChildren(IProgress<double> progress, CancellationToken cancellationToken, MetadataRefreshOptions metadataRefreshOptions, bool recursive = true)
+        public Task ValidateChildren(IProgress<double> progress, MetadataRefreshOptions metadataRefreshOptions, bool recursive = true,  CancellationToken cancellationToken = default)
         {
-            return ValidateChildrenInternal(progress, cancellationToken, recursive, true, metadataRefreshOptions, metadataRefreshOptions.DirectoryService);
+            return ValidateChildrenInternal(progress, recursive, true, metadataRefreshOptions, metadataRefreshOptions.DirectoryService, cancellationToken);
         }
 
         private Dictionary<Guid, BaseItem> GetActualChildrenDictionary()
@@ -277,13 +328,13 @@ namespace MediaBrowser.Controller.Entities
         /// Validates the children internal.
         /// </summary>
         /// <param name="progress">The progress.</param>
-        /// <param name="cancellationToken">The cancellation token.</param>
         /// <param name="recursive">if set to <c>true</c> [recursive].</param>
         /// <param name="refreshChildMetadata">if set to <c>true</c> [refresh child metadata].</param>
         /// <param name="refreshOptions">The refresh options.</param>
         /// <param name="directoryService">The directory service.</param>
+        /// <param name="cancellationToken">The cancellation token.</param>
         /// <returns>Task.</returns>
-        protected virtual async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected virtual async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             if (recursive)
             {
@@ -292,7 +343,7 @@ namespace MediaBrowser.Controller.Entities
 
             try
             {
-                await ValidateChildrenInternal2(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService).ConfigureAwait(false);
+                await ValidateChildrenInternal2(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken).ConfigureAwait(false);
             }
             finally
             {
@@ -303,7 +354,7 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        private async Task ValidateChildrenInternal2(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        private async Task ValidateChildrenInternal2(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             cancellationToken.ThrowIfCancellationRequested();
 
@@ -525,7 +576,7 @@ namespace MediaBrowser.Controller.Entities
         private Task ValidateSubFolders(IList<Folder> children, IDirectoryService directoryService, IProgress<double> progress, CancellationToken cancellationToken)
         {
             return RunTasks(
-                (folder, innerProgress) => folder.ValidateChildrenInternal(innerProgress, cancellationToken, true, false, null, directoryService),
+                (folder, innerProgress) => folder.ValidateChildrenInternal(innerProgress, true, false, null, directoryService, cancellationToken),
                 children,
                 progress,
                 cancellationToken);
@@ -594,6 +645,8 @@ namespace MediaBrowser.Controller.Entities
         /// Get the children of this folder from the actual file system.
         /// </summary>
         /// <returns>IEnumerable{BaseItem}.</returns>
+        /// <param name="directoryService">The directory service to use for operation.</param>
+        /// <returns>Returns set of base items.</returns>
         protected virtual IEnumerable<BaseItem> GetNonCachedChildren(IDirectoryService directoryService)
         {
             var collectionType = LibraryManager.GetContentType(this);
@@ -620,7 +673,7 @@ namespace MediaBrowser.Controller.Entities
         {
             if (LinkedChildren.Length > 0)
             {
-                if (!(this is ICollectionFolder))
+                if (this is not ICollectionFolder)
                 {
                     return GetChildren(user, true).Count;
                 }
@@ -677,7 +730,7 @@ namespace MediaBrowser.Controller.Entities
                 return PostFilterAndSort(items, query, true);
             }
 
-            if (!(this is UserRootFolder) && !(this is AggregateFolder) && query.ParentId == Guid.Empty)
+            if (this is not UserRootFolder && this is not AggregateFolder && query.ParentId == Guid.Empty)
             {
                 query.Parent = this;
             }
@@ -752,7 +805,7 @@ namespace MediaBrowser.Controller.Entities
         {
             if (LinkedChildren.Length > 0)
             {
-                if (!(this is ICollectionFolder))
+                if (this is not ICollectionFolder)
                 {
                     Logger.LogDebug("Query requires post-filtering due to LinkedChildren. Type: " + GetType().Name);
                     return true;
@@ -938,14 +991,18 @@ namespace MediaBrowser.Controller.Entities
             }
             else
             {
-                items = GetChildren(user, true).Where(filter);
+                // need to pass this param to the children.
+                var childQuery = new InternalItemsQuery
+                {
+                    DisplayAlbumFolders = query.DisplayAlbumFolders
+                };
+
+                items = GetChildren(user, true, childQuery).Where(filter);
             }
 
             return PostFilterAndSort(items, query, true);
         }
 
-        public static ICollectionManager CollectionManager { get; set; }
-
         protected QueryResult<BaseItem> PostFilterAndSort(IEnumerable<BaseItem> items, InternalItemsQuery query, bool enableSorting)
         {
             var user = query.User;
@@ -958,17 +1015,17 @@ namespace MediaBrowser.Controller.Entities
 
             if (!string.IsNullOrEmpty(query.NameStartsWithOrGreater))
             {
-                items = items.Where(i => string.Compare(query.NameStartsWithOrGreater, i.SortName, StringComparison.CurrentCultureIgnoreCase) < 1);
+                items = items.Where(i => string.Compare(query.NameStartsWithOrGreater, i.SortName, StringComparison.InvariantCultureIgnoreCase) < 1);
             }
 
             if (!string.IsNullOrEmpty(query.NameStartsWith))
             {
-                items = items.Where(i => i.SortName.StartsWith(query.NameStartsWith, StringComparison.OrdinalIgnoreCase));
+                items = items.Where(i => i.SortName.StartsWith(query.NameStartsWith, StringComparison.InvariantCultureIgnoreCase));
             }
 
             if (!string.IsNullOrEmpty(query.NameLessThan))
             {
-                items = items.Where(i => string.Compare(query.NameLessThan, i.SortName, StringComparison.CurrentCultureIgnoreCase) == 1);
+                items = items.Where(i => string.Compare(query.NameLessThan, i.SortName, StringComparison.InvariantCultureIgnoreCase) == 1);
             }
 
             // This must be the last filter
@@ -1274,10 +1331,23 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Adds the children to list.
         /// </summary>
-        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
         private void AddChildren(User user, bool includeLinkedChildren, Dictionary<Guid, BaseItem> result, bool recursive, InternalItemsQuery query)
         {
-            foreach (var child in GetEligibleChildrenForRecursiveChildren(user))
+            // If Query.AlbumFolders is set, then enforce the format as per the db in that it permits sub-folders in music albums.
+            IEnumerable<BaseItem> children = null;
+            if ((query?.DisplayAlbumFolders ?? false) && (this is MusicAlbum))
+            {
+                children = Children;
+                query = null;
+            }
+
+            // If there are not sub-folders, proceed as normal.
+            if (children == null)
+            {
+                children = GetEligibleChildrenForRecursiveChildren(user);
+            }
+
+            foreach (var child in children)
             {
                 bool? isVisibleToUser = null;
 
@@ -1317,18 +1387,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        /// <summary>
-        /// Gets allowed recursive children of an item.
-        /// </summary>
-        /// <param name="user">The user.</param>
-        /// <param name="includeLinkedChildren">if set to <c>true</c> [include linked children].</param>
-        /// <returns>IEnumerable{BaseItem}.</returns>
-        /// <exception cref="ArgumentNullException"></exception>
-        public IEnumerable<BaseItem> GetRecursiveChildren(User user, bool includeLinkedChildren = true)
-        {
-            return GetRecursiveChildren(user, null);
-        }
-
         public virtual IEnumerable<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
         {
             if (user == null)
@@ -1426,8 +1484,6 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
-        protected virtual bool FilterLinkedChildrenPerUser => false;
-
         public bool ContainsLinkedChildByItemId(Guid itemId)
         {
             var linkedChildren = LinkedChildren;
@@ -1489,7 +1545,7 @@ namespace MediaBrowser.Controller.Entities
 
                 var childOwner = child.GetOwner() ?? child;
 
-                if (childOwner != null && !(child is IItemByName))
+                if (child is not IItemByName)
                 {
                     var childProtocol = childOwner.PathProtocol;
                     if (!childProtocol.HasValue || childProtocol.Value != Model.MediaInfo.MediaProtocol.File)
@@ -1528,9 +1584,6 @@ namespace MediaBrowser.Controller.Entities
                 .Where(i => i.Item2 != null);
         }
 
-        [JsonIgnore]
-        protected override bool SupportsOwnedItems => base.SupportsOwnedItems || SupportsShortcutChildren;
-
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
             var changesFound = false;
@@ -1551,7 +1604,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Refreshes the linked children.
         /// </summary>
-        /// <returns><c>true</c> if XXXX, <c>false</c> otherwise</returns>
+        /// <param name="fileSystemChildren">The enumerable of file system metadata.</param>
+        /// <returns><c>true</c> if the linked children were updated, <c>false</c> otherwise.</returns>
         protected virtual bool RefreshLinkedChildren(IEnumerable<FileSystemMetadata> fileSystemChildren)
         {
             if (SupportsShortcutChildren)
@@ -1615,7 +1669,6 @@ namespace MediaBrowser.Controller.Entities
         /// <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>
         public override void MarkPlayed(
             User user,
             DateTime? datePlayed,
@@ -1657,7 +1710,6 @@ namespace MediaBrowser.Controller.Entities
         /// Marks the unplayed.
         /// </summary>
         /// <param name="user">The user.</param>
-        /// <returns>Task.</returns>
         public override void MarkUnplayed(User user)
         {
             var itemsResult = GetItemList(new InternalItemsQuery
@@ -1694,51 +1746,6 @@ namespace MediaBrowser.Controller.Entities
             return !IsPlayed(user);
         }
 
-        [JsonIgnore]
-        public virtual bool SupportsUserDataFromChildren
-        {
-            get
-            {
-                // These are just far too slow.
-                if (this is ICollectionFolder)
-                {
-                    return false;
-                }
-
-                if (this is UserView)
-                {
-                    return false;
-                }
-
-                if (this is UserRootFolder)
-                {
-                    return false;
-                }
-
-                if (this is Channel)
-                {
-                    return false;
-                }
-
-                if (SourceType != SourceType.Library)
-                {
-                    return false;
-                }
-
-                var iItemByName = this as IItemByName;
-                if (iItemByName != null)
-                {
-                    var hasDualAccess = this as IHasDualAccess;
-                    if (hasDualAccess == null || hasDualAccess.IsAccessedByName)
-                    {
-                        return false;
-                    }
-                }
-
-                return true;
-            }
-        }
-
         public override void FillUserDataDtoValues(UserItemDataDto dto, UserItemData userData, BaseItemDto itemDto, User user, DtoOptions fields)
         {
             if (!SupportsUserDataFromChildren)
@@ -1768,20 +1775,15 @@ namespace MediaBrowser.Controller.Entities
                     {
                         EnableImages = false
                     }
-                });
+                }).TotalRecordCount;
 
-                double unplayedCount = unplayedQueryResult.TotalRecordCount;
+                dto.UnplayedItemCount = unplayedQueryResult;
 
-                dto.UnplayedItemCount = unplayedQueryResult.TotalRecordCount;
-
-                if (itemDto != null && itemDto.RecursiveItemCount.HasValue)
+                if (itemDto?.RecursiveItemCount > 0)
                 {
-                    if (itemDto.RecursiveItemCount.Value > 0)
-                    {
-                        var unplayedPercentage = (unplayedCount / itemDto.RecursiveItemCount.Value) * 100;
-                        dto.PlayedPercentage = 100 - unplayedPercentage;
-                        dto.Played = dto.PlayedPercentage.Value >= 100;
-                    }
+                    var unplayedPercentage = ((double)unplayedQueryResult / itemDto.RecursiveItemCount.Value) * 100;
+                    dto.PlayedPercentage = 100 - unplayedPercentage;
+                    dto.Played = dto.PlayedPercentage.Value >= 100;
                 }
                 else
                 {
diff --git a/MediaBrowser.Controller/Entities/Genre.cs b/MediaBrowser.Controller/Entities/Genre.cs
index 74a170204..338f96204 100644
--- a/MediaBrowser.Controller/Entities/Genre.cs
+++ b/MediaBrowser.Controller/Entities/Genre.cs
@@ -1,10 +1,12 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
+using Diacritics.Extensions;
 using MediaBrowser.Controller.Entities.Audio;
-using MediaBrowser.Controller.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities
@@ -14,6 +16,23 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Genre : BaseItem, IItemByName
     {
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        [JsonIgnore]
+        public override bool IsDisplayedAsFolder => true;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -32,20 +51,6 @@ namespace MediaBrowser.Controller.Entities
             return 1;
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
-        [JsonIgnore]
-        public override bool IsDisplayedAsFolder => true;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
@@ -70,9 +75,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -106,11 +108,13 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// This is called before any metadata refresh and returns true or false indicating if changes were made.
+        /// This is called before any metadata refresh and returns true if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Whether to replace all metadata.</param>
+        /// <returns>true if the item has change, else false.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))
diff --git a/MediaBrowser.Controller/Entities/ICollectionFolder.cs b/MediaBrowser.Controller/Entities/ICollectionFolder.cs
index b84a9fa6f..89e494ebc 100644
--- a/MediaBrowser.Controller/Entities/ICollectionFolder.cs
+++ b/MediaBrowser.Controller/Entities/ICollectionFolder.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 
diff --git a/MediaBrowser.Controller/Entities/IHasAspectRatio.cs b/MediaBrowser.Controller/Entities/IHasAspectRatio.cs
index d7d007668..3aeb7468f 100644
--- a/MediaBrowser.Controller/Entities/IHasAspectRatio.cs
+++ b/MediaBrowser.Controller/Entities/IHasAspectRatio.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
diff --git a/MediaBrowser.Controller/Entities/IHasDisplayOrder.cs b/MediaBrowser.Controller/Entities/IHasDisplayOrder.cs
index 13226b234..14459624e 100644
--- a/MediaBrowser.Controller/Entities/IHasDisplayOrder.cs
+++ b/MediaBrowser.Controller/Entities/IHasDisplayOrder.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
diff --git a/MediaBrowser.Controller/Entities/IHasMediaSources.cs b/MediaBrowser.Controller/Entities/IHasMediaSources.cs
index 0f612262a..90d9bdd2d 100644
--- a/MediaBrowser.Controller/Entities/IHasMediaSources.cs
+++ b/MediaBrowser.Controller/Entities/IHasMediaSources.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -18,6 +20,8 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the media sources.
         /// </summary>
+        /// <param name="enablePathSubstitution"><c>true</c> to enable path substitution, <c>false</c> to not.</param>
+        /// <returns>A list of media sources.</returns>
         List<MediaSourceInfo> GetMediaSources(bool enablePathSubstitution);
 
         List<MediaStream> GetMediaStreams();
diff --git a/MediaBrowser.Controller/Entities/IHasProgramAttributes.cs b/MediaBrowser.Controller/Entities/IHasProgramAttributes.cs
index f747b5149..f80f7c304 100644
--- a/MediaBrowser.Controller/Entities/IHasProgramAttributes.cs
+++ b/MediaBrowser.Controller/Entities/IHasProgramAttributes.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using MediaBrowser.Model.LiveTv;
diff --git a/MediaBrowser.Controller/Entities/IHasScreenshots.cs b/MediaBrowser.Controller/Entities/IHasScreenshots.cs
index b027a0cb1..ae01c223e 100644
--- a/MediaBrowser.Controller/Entities/IHasScreenshots.cs
+++ b/MediaBrowser.Controller/Entities/IHasScreenshots.cs
@@ -1,7 +1,7 @@
 namespace MediaBrowser.Controller.Entities
 {
     /// <summary>
-    /// Interface IHasScreenshots.
+    /// The item has screenshots.
     /// </summary>
     public interface IHasScreenshots
     {
diff --git a/MediaBrowser.Controller/Entities/IHasSeries.cs b/MediaBrowser.Controller/Entities/IHasSeries.cs
index 5444f1f52..5f774bbde 100644
--- a/MediaBrowser.Controller/Entities/IHasSeries.cs
+++ b/MediaBrowser.Controller/Entities/IHasSeries.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -7,7 +9,7 @@ namespace MediaBrowser.Controller.Entities
     public interface IHasSeries
     {
         /// <summary>
-        /// Gets the name of the series.
+        /// Gets or sets the name of the series.
         /// </summary>
         /// <value>The name of the series.</value>
         string SeriesName { get; set; }
diff --git a/MediaBrowser.Controller/Entities/IHasShares.cs b/MediaBrowser.Controller/Entities/IHasShares.cs
new file mode 100644
index 000000000..dca5af873
--- /dev/null
+++ b/MediaBrowser.Controller/Entities/IHasShares.cs
@@ -0,0 +1,11 @@
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
+
+namespace MediaBrowser.Controller.Entities
+{
+    public interface IHasShares
+    {
+        Share[] Shares { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/MediaBrowser.Controller/Entities/IHasSpecialFeatures.cs b/MediaBrowser.Controller/Entities/IHasSpecialFeatures.cs
index 6a350212b..f317a02ff 100644
--- a/MediaBrowser.Controller/Entities/IHasSpecialFeatures.cs
+++ b/MediaBrowser.Controller/Entities/IHasSpecialFeatures.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
diff --git a/MediaBrowser.Controller/Entities/IHasTrailers.cs b/MediaBrowser.Controller/Entities/IHasTrailers.cs
index d1f6f2b7e..f4271678d 100644
--- a/MediaBrowser.Controller/Entities/IHasTrailers.cs
+++ b/MediaBrowser.Controller/Entities/IHasTrailers.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -37,6 +39,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailer count.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{Guid}" />.</returns>
         public static int GetTrailerCount(this IHasTrailers item)
             => item.LocalTrailerIds.Count + item.RemoteTrailerIds.Count;
@@ -44,6 +47,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailer ids.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{Guid}" />.</returns>
         public static IReadOnlyList<Guid> GetTrailerIds(this IHasTrailers item)
         {
@@ -68,6 +72,7 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// Gets the trailers.
         /// </summary>
+        /// <param name="item">Media item.</param>
         /// <returns><see cref="IReadOnlyList{BaseItem}" />.</returns>
         public static IReadOnlyList<BaseItem> GetTrailers(this IHasTrailers item)
         {
diff --git a/MediaBrowser.Controller/Entities/InternalItemsQuery.cs b/MediaBrowser.Controller/Entities/InternalItemsQuery.cs
index 270217356..0baa7725e 100644
--- a/MediaBrowser.Controller/Entities/InternalItemsQuery.cs
+++ b/MediaBrowser.Controller/Entities/InternalItemsQuery.cs
@@ -1,4 +1,4 @@
-#pragma warning disable CS1591
+#pragma warning disable CA1044, CA1819, CA2227, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -12,15 +12,64 @@ namespace MediaBrowser.Controller.Entities
 {
     public class InternalItemsQuery
     {
+        public InternalItemsQuery()
+        {
+            AlbumArtistIds = Array.Empty<Guid>();
+            AlbumIds = Array.Empty<Guid>();
+            AncestorIds = Array.Empty<Guid>();
+            ArtistIds = Array.Empty<Guid>();
+            BlockUnratedItems = Array.Empty<UnratedItem>();
+            BoxSetLibraryFolders = Array.Empty<Guid>();
+            ChannelIds = Array.Empty<Guid>();
+            ContributingArtistIds = Array.Empty<Guid>();
+            DtoOptions = new DtoOptions();
+            EnableTotalRecordCount = true;
+            ExcludeArtistIds = Array.Empty<Guid>();
+            ExcludeInheritedTags = Array.Empty<string>();
+            ExcludeItemIds = Array.Empty<Guid>();
+            ExcludeItemTypes = Array.Empty<string>();
+            ExcludeTags = Array.Empty<string>();
+            GenreIds = Array.Empty<Guid>();
+            Genres = Array.Empty<string>();
+            GroupByPresentationUniqueKey = true;
+            ImageTypes = Array.Empty<ImageType>();
+            IncludeItemTypes = Array.Empty<string>();
+            ItemIds = Array.Empty<Guid>();
+            MediaTypes = Array.Empty<string>();
+            MinSimilarityScore = 20;
+            OfficialRatings = Array.Empty<string>();
+            OrderBy = Array.Empty<ValueTuple<string, SortOrder>>();
+            PersonIds = Array.Empty<Guid>();
+            PersonTypes = Array.Empty<string>();
+            PresetViews = Array.Empty<string>();
+            SeriesStatuses = Array.Empty<SeriesStatus>();
+            SourceTypes = Array.Empty<SourceType>();
+            StudioIds = Array.Empty<Guid>();
+            Tags = Array.Empty<string>();
+            TopParentIds = Array.Empty<Guid>();
+            TrailerTypes = Array.Empty<TrailerType>();
+            VideoTypes = Array.Empty<VideoType>();
+            Years = Array.Empty<int>();
+        }
+
+        public InternalItemsQuery(User? user)
+            : this()
+        {
+            if (user != null)
+            {
+                SetUser(user);
+            }
+        }
+
         public bool Recursive { get; set; }
 
         public int? StartIndex { get; set; }
 
         public int? Limit { get; set; }
 
-        public User User { get; set; }
+        public User? User { get; set; }
 
-        public BaseItem SimilarTo { get; set; }
+        public BaseItem? SimilarTo { get; set; }
 
         public bool? IsFolder { get; set; }
 
@@ -56,23 +105,23 @@ namespace MediaBrowser.Controller.Entities
 
         public bool? CollapseBoxSetItems { get; set; }
 
-        public string NameStartsWithOrGreater { get; set; }
+        public string? NameStartsWithOrGreater { get; set; }
 
-        public string NameStartsWith { get; set; }
+        public string? NameStartsWith { get; set; }
 
-        public string NameLessThan { get; set; }
+        public string? NameLessThan { get; set; }
 
-        public string NameContains { get; set; }
+        public string? NameContains { get; set; }
 
-        public string MinSortName { get; set; }
+        public string? MinSortName { get; set; }
 
-        public string PresentationUniqueKey { get; set; }
+        public string? PresentationUniqueKey { get; set; }
 
-        public string Path { get; set; }
+        public string? Path { get; set; }
 
-        public string Name { get; set; }
+        public string? Name { get; set; }
 
-        public string Person { get; set; }
+        public string? Person { get; set; }
 
         public Guid[] PersonIds { get; set; }
 
@@ -80,7 +129,7 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid[] ExcludeItemIds { get; set; }
 
-        public string AdjacentTo { get; set; }
+        public string? AdjacentTo { get; set; }
 
         public string[] PersonTypes { get; set; }
 
@@ -180,29 +229,12 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid ParentId { get; set; }
 
-        public string ParentType { get; set; }
+        public string? ParentType { get; set; }
 
         public Guid[] AncestorIds { get; set; }
 
         public Guid[] TopParentIds { get; set; }
 
-        public BaseItem Parent
-        {
-            set
-            {
-                if (value == null)
-                {
-                    ParentId = Guid.Empty;
-                    ParentType = null;
-                }
-                else
-                {
-                    ParentId = value.Id;
-                    ParentType = value.GetType().Name;
-                }
-            }
-        }
-
         public string[] PresetViews { get; set; }
 
         public TrailerType[] TrailerTypes { get; set; }
@@ -211,9 +243,9 @@ namespace MediaBrowser.Controller.Entities
 
         public SeriesStatus[] SeriesStatuses { get; set; }
 
-        public string ExternalSeriesId { get; set; }
+        public string? ExternalSeriesId { get; set; }
 
-        public string ExternalId { get; set; }
+        public string? ExternalId { get; set; }
 
         public Guid[] AlbumIds { get; set; }
 
@@ -221,9 +253,9 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid[] ExcludeArtistIds { get; set; }
 
-        public string AncestorWithPresentationUniqueKey { get; set; }
+        public string? AncestorWithPresentationUniqueKey { get; set; }
 
-        public string SeriesPresentationUniqueKey { get; set; }
+        public string? SeriesPresentationUniqueKey { get; set; }
 
         public bool GroupByPresentationUniqueKey { get; set; }
 
@@ -233,7 +265,7 @@ namespace MediaBrowser.Controller.Entities
 
         public bool ForceDirect { get; set; }
 
-        public Dictionary<string, string> ExcludeProviderIds { get; set; }
+        public Dictionary<string, string>? ExcludeProviderIds { get; set; }
 
         public bool EnableGroupByMetadataKey { get; set; }
 
@@ -251,13 +283,13 @@ namespace MediaBrowser.Controller.Entities
 
         public int MinSimilarityScore { get; set; }
 
-        public string HasNoAudioTrackWithLanguage { get; set; }
+        public string? HasNoAudioTrackWithLanguage { get; set; }
 
-        public string HasNoInternalSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoInternalSubtitleTrackWithLanguage { get; set; }
 
-        public string HasNoExternalSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoExternalSubtitleTrackWithLanguage { get; set; }
 
-        public string HasNoSubtitleTrackWithLanguage { get; set; }
+        public string? HasNoSubtitleTrackWithLanguage { get; set; }
 
         public bool? IsDeadArtist { get; set; }
 
@@ -265,74 +297,29 @@ namespace MediaBrowser.Controller.Entities
 
         public bool? IsDeadPerson { get; set; }
 
-        public InternalItemsQuery()
-        {
-            AlbumArtistIds = Array.Empty<Guid>();
-            AlbumIds = Array.Empty<Guid>();
-            AncestorIds = Array.Empty<Guid>();
-            ArtistIds = Array.Empty<Guid>();
-            BlockUnratedItems = Array.Empty<UnratedItem>();
-            BoxSetLibraryFolders = Array.Empty<Guid>();
-            ChannelIds = Array.Empty<Guid>();
-            ContributingArtistIds = Array.Empty<Guid>();
-            DtoOptions = new DtoOptions();
-            EnableTotalRecordCount = true;
-            ExcludeArtistIds = Array.Empty<Guid>();
-            ExcludeInheritedTags = Array.Empty<string>();
-            ExcludeItemIds = Array.Empty<Guid>();
-            ExcludeItemTypes = Array.Empty<string>();
-            ExcludeProviderIds = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            ExcludeTags = Array.Empty<string>();
-            GenreIds = Array.Empty<Guid>();
-            Genres = Array.Empty<string>();
-            GroupByPresentationUniqueKey = true;
-            HasAnyProviderId = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            ImageTypes = Array.Empty<ImageType>();
-            IncludeItemTypes = Array.Empty<string>();
-            ItemIds = Array.Empty<Guid>();
-            MediaTypes = Array.Empty<string>();
-            MinSimilarityScore = 20;
-            OfficialRatings = Array.Empty<string>();
-            OrderBy = Array.Empty<ValueTuple<string, SortOrder>>();
-            PersonIds = Array.Empty<Guid>();
-            PersonTypes = Array.Empty<string>();
-            PresetViews = Array.Empty<string>();
-            SeriesStatuses = Array.Empty<SeriesStatus>();
-            SourceTypes = Array.Empty<SourceType>();
-            StudioIds = Array.Empty<Guid>();
-            Tags = Array.Empty<string>();
-            TopParentIds = Array.Empty<Guid>();
-            TrailerTypes = Array.Empty<TrailerType>();
-            VideoTypes = Array.Empty<VideoType>();
-            Years = Array.Empty<int>();
-        }
-
-        public InternalItemsQuery(User user)
-            : this()
-        {
-            SetUser(user);
-        }
+        /// <summary>
+        /// Gets or sets a value indicating whether album sub-folders should be returned if they exist.
+        /// </summary>
+        public bool? DisplayAlbumFolders { get; set; }
 
-        public void SetUser(User user)
+        public BaseItem? Parent
         {
-            if (user != null)
+            set
             {
-                MaxParentalRating = user.MaxParentalAgeRating;
-
-                if (MaxParentalRating.HasValue)
+                if (value == null)
+                {
+                    ParentId = Guid.Empty;
+                    ParentType = null;
+                }
+                else
                 {
-                    BlockUnratedItems = user.GetPreference(PreferenceKind.BlockUnratedItems)
-                        .Where(i => i != UnratedItem.Other.ToString())
-                        .Select(e => Enum.Parse<UnratedItem>(e, true)).ToArray();
+                    ParentId = value.Id;
+                    ParentType = value.GetType().Name;
                 }
-
-                ExcludeInheritedTags = user.GetPreference(PreferenceKind.BlockedTags);
-
-                User = user;
             }
         }
 
-        public Dictionary<string, string> HasAnyProviderId { get; set; }
+        public Dictionary<string, string>? HasAnyProviderId { get; set; }
 
         public Guid[] AlbumArtistIds { get; set; }
 
@@ -354,8 +341,25 @@ namespace MediaBrowser.Controller.Entities
 
         public int? MinWidth { get; set; }
 
-        public string SearchTerm { get; set; }
+        public string? SearchTerm { get; set; }
+
+        public string? SeriesTimerId { get; set; }
 
-        public string SeriesTimerId { get; set; }
+        public void SetUser(User user)
+        {
+            MaxParentalRating = user.MaxParentalAgeRating;
+
+            if (MaxParentalRating.HasValue)
+            {
+                string other = UnratedItem.Other.ToString();
+                BlockUnratedItems = user.GetPreference(PreferenceKind.BlockUnratedItems)
+                    .Where(i => i != other)
+                    .Select(e => Enum.Parse<UnratedItem>(e, true)).ToArray();
+            }
+
+            ExcludeInheritedTags = user.GetPreference(PreferenceKind.BlockedTags);
+
+            User = user;
+        }
     }
 }
diff --git a/MediaBrowser.Controller/Entities/InternalPeopleQuery.cs b/MediaBrowser.Controller/Entities/InternalPeopleQuery.cs
index 5b96a5af6..3e1d89274 100644
--- a/MediaBrowser.Controller/Entities/InternalPeopleQuery.cs
+++ b/MediaBrowser.Controller/Entities/InternalPeopleQuery.cs
@@ -1,12 +1,26 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
+using System.Collections.Generic;
 using Jellyfin.Data.Entities;
 
 namespace MediaBrowser.Controller.Entities
 {
     public class InternalPeopleQuery
     {
+        public InternalPeopleQuery()
+         : this(Array.Empty<string>(), Array.Empty<string>())
+        {
+        }
+
+        public InternalPeopleQuery(IReadOnlyList<string> personTypes, IReadOnlyList<string> excludePersonTypes)
+        {
+            PersonTypes = personTypes;
+            ExcludePersonTypes = excludePersonTypes;
+        }
+
         /// <summary>
         /// Gets or sets the maximum number of items the query should return.
         /// </summary>
@@ -14,9 +28,9 @@ namespace MediaBrowser.Controller.Entities
 
         public Guid ItemId { get; set; }
 
-        public string[] PersonTypes { get; set; }
+        public IReadOnlyList<string> PersonTypes { get; }
 
-        public string[] ExcludePersonTypes { get; set; }
+        public IReadOnlyList<string> ExcludePersonTypes { get; }
 
         public int? MaxListOrder { get; set; }
 
@@ -27,11 +41,5 @@ namespace MediaBrowser.Controller.Entities
         public User User { get; set; }
 
         public bool? IsFavorite { get; set; }
-
-        public InternalPeopleQuery()
-        {
-            PersonTypes = Array.Empty<string>();
-            ExcludePersonTypes = Array.Empty<string>();
-        }
     }
 }
diff --git a/MediaBrowser.Controller/Entities/ItemImageInfo.cs b/MediaBrowser.Controller/Entities/ItemImageInfo.cs
index 570d8eec0..ea8555dbf 100644
--- a/MediaBrowser.Controller/Entities/ItemImageInfo.cs
+++ b/MediaBrowser.Controller/Entities/ItemImageInfo.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
diff --git a/MediaBrowser.Controller/Entities/LinkedChild.cs b/MediaBrowser.Controller/Entities/LinkedChild.cs
index 8e0f721e7..fd5fef3dc 100644
--- a/MediaBrowser.Controller/Entities/LinkedChild.cs
+++ b/MediaBrowser.Controller/Entities/LinkedChild.cs
@@ -1,15 +1,20 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
-using System.Collections.Generic;
 using System.Globalization;
 using System.Text.Json.Serialization;
-using MediaBrowser.Model.IO;
 
 namespace MediaBrowser.Controller.Entities
 {
     public class LinkedChild
     {
+        public LinkedChild()
+        {
+            Id = Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture);
+        }
+
         public string Path { get; set; }
 
         public LinkedChildType Type { get; set; }
@@ -20,7 +25,7 @@ namespace MediaBrowser.Controller.Entities
         public string Id { get; set; }
 
         /// <summary>
-        /// Serves as a cache.
+        /// Gets or sets the linked item id.
         /// </summary>
         public Guid? ItemId { get; set; }
 
@@ -39,41 +44,5 @@ namespace MediaBrowser.Controller.Entities
 
             return child;
         }
-
-        public LinkedChild()
-        {
-            Id = Guid.NewGuid().ToString("N", CultureInfo.InvariantCulture);
-        }
-    }
-
-    public enum LinkedChildType
-    {
-        Manual = 0,
-        Shortcut = 1
-    }
-
-    public class LinkedChildComparer : IEqualityComparer<LinkedChild>
-    {
-        private readonly IFileSystem _fileSystem;
-
-        public LinkedChildComparer(IFileSystem fileSystem)
-        {
-            _fileSystem = fileSystem;
-        }
-
-        public bool Equals(LinkedChild x, LinkedChild y)
-        {
-            if (x.Type == y.Type)
-            {
-                return _fileSystem.AreEqual(x.Path, y.Path);
-            }
-
-            return false;
-        }
-
-        public int GetHashCode(LinkedChild obj)
-        {
-            return ((obj.Path ?? string.Empty) + (obj.LibraryItemId ?? string.Empty) + obj.Type).GetHashCode();
-        }
     }
 }
diff --git a/MediaBrowser.Controller/Entities/LinkedChildComparer.cs b/MediaBrowser.Controller/Entities/LinkedChildComparer.cs
new file mode 100644
index 000000000..4e58e2942
--- /dev/null
+++ b/MediaBrowser.Controller/Entities/LinkedChildComparer.cs
@@ -0,0 +1,35 @@
+#nullable disable
+
+#pragma warning disable CS1591
+
+using System;
+using System.Collections.Generic;
+using MediaBrowser.Model.IO;
+
+namespace MediaBrowser.Controller.Entities
+{
+    public class LinkedChildComparer : IEqualityComparer<LinkedChild>
+    {
+        private readonly IFileSystem _fileSystem;
+
+        public LinkedChildComparer(IFileSystem fileSystem)
+        {
+            _fileSystem = fileSystem;
+        }
+
+        public bool Equals(LinkedChild x, LinkedChild y)
+        {
+            if (x.Type == y.Type)
+            {
+                return _fileSystem.AreEqual(x.Path, y.Path);
+            }
+
+            return false;
+        }
+
+        public int GetHashCode(LinkedChild obj)
+        {
+            return ((obj.Path ?? string.Empty) + (obj.LibraryItemId ?? string.Empty) + obj.Type).GetHashCode(StringComparison.Ordinal);
+        }
+    }
+}
\ No newline at end of file
diff --git a/MediaBrowser.Controller/Entities/LinkedChildType.cs b/MediaBrowser.Controller/Entities/LinkedChildType.cs
new file mode 100644
index 000000000..9ddb7b620
--- /dev/null
+++ b/MediaBrowser.Controller/Entities/LinkedChildType.cs
@@ -0,0 +1,18 @@
+namespace MediaBrowser.Controller.Entities
+{
+    /// <summary>
+    /// The linked child type.
+    /// </summary>
+    public enum LinkedChildType
+    {
+        /// <summary>
+        /// Manually linked child.
+        /// </summary>
+        Manual = 0,
+
+        /// <summary>
+        /// Shortcut linked child.
+        /// </summary>
+        Shortcut = 1
+    }
+}
\ No newline at end of file
diff --git a/MediaBrowser.Controller/Entities/Movies/BoxSet.cs b/MediaBrowser.Controller/Entities/Movies/BoxSet.cs
index 05e4229ca..e46f99cd5 100644
--- a/MediaBrowser.Controller/Entities/Movies/BoxSet.cs
+++ b/MediaBrowser.Controller/Entities/Movies/BoxSet.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1721, CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -47,6 +49,30 @@ namespace MediaBrowser.Controller.Entities.Movies
         /// <value>The display order.</value>
         public string DisplayOrder { get; set; }
 
+        [JsonIgnore]
+        private bool IsLegacyBoxSet
+        {
+            get
+            {
+                if (string.IsNullOrEmpty(Path))
+                {
+                    return false;
+                }
+
+                if (LinkedChildren.Length > 0)
+                {
+                    return false;
+                }
+
+                return !FileSystem.ContainsSubPath(ConfigurationManager.ApplicationPaths.DataPath, Path);
+            }
+        }
+
+        [JsonIgnore]
+        public override bool IsPreSorted => true;
+
+        public Guid[] LibraryFolderIds { get; set; }
+
         protected override bool GetBlockUnratedValue(User user)
         {
             return user.GetPreferenceValues<UnratedItem>(PreferenceKind.BlockUnratedItems).Contains(UnratedItem.Movie);
@@ -81,28 +107,6 @@ namespace MediaBrowser.Controller.Entities.Movies
             return new List<BaseItem>();
         }
 
-        [JsonIgnore]
-        private bool IsLegacyBoxSet
-        {
-            get
-            {
-                if (string.IsNullOrEmpty(Path))
-                {
-                    return false;
-                }
-
-                if (LinkedChildren.Length > 0)
-                {
-                    return false;
-                }
-
-                return !FileSystem.ContainsSubPath(ConfigurationManager.ApplicationPaths.DataPath, Path);
-            }
-        }
-
-        [JsonIgnore]
-        public override bool IsPreSorted => true;
-
         public override bool IsAuthorizedToDelete(User user, List<Folder> allCollectionFolders)
         {
             return true;
@@ -189,8 +193,6 @@ namespace MediaBrowser.Controller.Entities.Movies
             return IsVisible(user);
         }
 
-        public Guid[] LibraryFolderIds { get; set; }
-
         private Guid[] GetLibraryFolderIds(User user)
         {
             return LibraryManager.GetUserRootFolder().GetChildren(user, true)
@@ -217,8 +219,7 @@ namespace MediaBrowser.Controller.Entities.Movies
 
         private IEnumerable<BaseItem> FlattenItems(BaseItem item, List<Guid> expandedFolders)
         {
-            var boxset = item as BoxSet;
-            if (boxset != null)
+            if (item is BoxSet boxset)
             {
                 if (!expandedFolders.Contains(item.Id))
                 {
diff --git a/MediaBrowser.Controller/Entities/Movies/Movie.cs b/MediaBrowser.Controller/Entities/Movies/Movie.cs
index 8b67aaccc..b54bbf5eb 100644
--- a/MediaBrowser.Controller/Entities/Movies/Movie.cs
+++ b/MediaBrowser.Controller/Entities/Movies/Movie.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -142,9 +144,9 @@ namespace MediaBrowser.Controller.Entities.Movies
         }
 
         /// <inheritdoc />
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {
diff --git a/MediaBrowser.Controller/Entities/MusicVideo.cs b/MediaBrowser.Controller/Entities/MusicVideo.cs
index b278a0142..237ad5198 100644
--- a/MediaBrowser.Controller/Entities/MusicVideo.cs
+++ b/MediaBrowser.Controller/Entities/MusicVideo.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -11,15 +13,15 @@ namespace MediaBrowser.Controller.Entities
 {
     public class MusicVideo : Video, IHasArtist, IHasMusicGenres, IHasLookupInfo<MusicVideoInfo>
     {
-        /// <inheritdoc />
-        [JsonIgnore]
-        public IReadOnlyList<string> Artists { get; set; }
-
         public MusicVideo()
         {
             Artists = Array.Empty<string>();
         }
 
+        /// <inheritdoc />
+        [JsonIgnore]
+        public IReadOnlyList<string> Artists { get; set; }
+
         public override UnratedItem GetBlockUnratedType()
         {
             return UnratedItem.Music;
@@ -34,9 +36,9 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {
diff --git a/MediaBrowser.Controller/Entities/PeopleHelper.cs b/MediaBrowser.Controller/Entities/PeopleHelper.cs
index 1f3758a73..687ce1ec8 100644
--- a/MediaBrowser.Controller/Entities/PeopleHelper.cs
+++ b/MediaBrowser.Controller/Entities/PeopleHelper.cs
@@ -100,23 +100,5 @@ namespace MediaBrowser.Controller.Entities
                 existing.SetProviderId(id.Key, id.Value);
             }
         }
-
-        public static bool ContainsPerson(List<PersonInfo> people, string name)
-        {
-            if (string.IsNullOrEmpty(name))
-            {
-                throw new ArgumentNullException(nameof(name));
-            }
-
-            foreach (var i in people)
-            {
-                if (string.Equals(i.Name, name, StringComparison.OrdinalIgnoreCase))
-                {
-                    return true;
-                }
-            }
-
-            return false;
-        }
     }
 }
diff --git a/MediaBrowser.Controller/Entities/Person.cs b/MediaBrowser.Controller/Entities/Person.cs
index c4fcb0267..045c1b89f 100644
--- a/MediaBrowser.Controller/Entities/Person.cs
+++ b/MediaBrowser.Controller/Entities/Person.cs
@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using MediaBrowser.Controller.Providers;
 using Microsoft.Extensions.Logging;
 
@@ -14,6 +16,26 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Person : BaseItem, IItemByName, IHasLookupInfo<PersonLookupInfo>
     {
+        /// <summary>
+        /// Gets the folder containing the item.
+        /// If the item is a folder, it returns the folder itself.
+        /// </summary>
+        /// <value>The containing folder path.</value>
+        [JsonIgnore]
+        public override string ContainingFolderPath => Path;
+
+        /// <summary>
+        /// Gets a value indicating whether to enable alpha numeric sorting.
+        /// </summary>
+        [JsonIgnore]
+        public override bool EnableAlphaNumericSorting => false;
+
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
+
         public override List<string> GetUserDataKeys()
         {
             var list = base.GetUserDataKeys();
@@ -47,14 +69,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        /// <summary>
-        /// Returns the folder containing the item.
-        /// If the item is a folder, it returns the folder itself.
-        /// </summary>
-        /// <value>The containing folder path.</value>
-        [JsonIgnore]
-        public override string ContainingFolderPath => Path;
-
         public override bool CanDelete()
         {
             return false;
@@ -65,15 +79,6 @@ namespace MediaBrowser.Controller.Entities
             return true;
         }
 
-        [JsonIgnore]
-        public override bool EnableAlphaNumericSorting => false;
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -124,9 +129,11 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata"><c>true</c> to replace all metadata, <c>false</c> to not.</param>
+        /// <returns><c>true</c> if changes were made, <c>false</c> if not.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))
diff --git a/MediaBrowser.Controller/Entities/PersonInfo.cs b/MediaBrowser.Controller/Entities/PersonInfo.cs
index 4ff9b0955..2b689ae7e 100644
--- a/MediaBrowser.Controller/Entities/PersonInfo.cs
+++ b/MediaBrowser.Controller/Entities/PersonInfo.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA2227, CS1591
 
 using System;
 using System.Collections.Generic;
diff --git a/MediaBrowser.Controller/Entities/Photo.cs b/MediaBrowser.Controller/Entities/Photo.cs
index 2fc66176f..ba6ce189a 100644
--- a/MediaBrowser.Controller/Entities/Photo.cs
+++ b/MediaBrowser.Controller/Entities/Photo.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System.Text.Json.Serialization;
@@ -24,8 +26,7 @@ namespace MediaBrowser.Controller.Entities
                 var parents = GetParents();
                 foreach (var parent in parents)
                 {
-                    var photoAlbum = parent as PhotoAlbum;
-                    if (photoAlbum != null)
+                    if (parent is PhotoAlbum photoAlbum)
                     {
                         return photoAlbum;
                     }
@@ -35,6 +36,30 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
+        public string CameraMake { get; set; }
+
+        public string CameraModel { get; set; }
+
+        public string Software { get; set; }
+
+        public double? ExposureTime { get; set; }
+
+        public double? FocalLength { get; set; }
+
+        public ImageOrientation? Orientation { get; set; }
+
+        public double? Aperture { get; set; }
+
+        public double? ShutterSpeed { get; set; }
+
+        public double? Latitude { get; set; }
+
+        public double? Longitude { get; set; }
+
+        public double? Altitude { get; set; }
+
+        public int? IsoSpeedRating { get; set; }
+
         public override bool CanDownload()
         {
             return true;
@@ -68,29 +93,5 @@ namespace MediaBrowser.Controller.Entities
 
             return base.GetDefaultPrimaryImageAspectRatio();
         }
-
-        public string CameraMake { get; set; }
-
-        public string CameraModel { get; set; }
-
-        public string Software { get; set; }
-
-        public double? ExposureTime { get; set; }
-
-        public double? FocalLength { get; set; }
-
-        public ImageOrientation? Orientation { get; set; }
-
-        public double? Aperture { get; set; }
-
-        public double? ShutterSpeed { get; set; }
-
-        public double? Latitude { get; set; }
-
-        public double? Longitude { get; set; }
-
-        public double? Altitude { get; set; }
-
-        public int? IsoSpeedRating { get; set; }
     }
 }
diff --git a/MediaBrowser.Controller/Entities/Share.cs b/MediaBrowser.Controller/Entities/Share.cs
index 50f1655f3..64f446eef 100644
--- a/MediaBrowser.Controller/Entities/Share.cs
+++ b/MediaBrowser.Controller/Entities/Share.cs
@@ -1,12 +1,9 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 namespace MediaBrowser.Controller.Entities
 {
-    public interface IHasShares
-    {
-        Share[] Shares { get; set; }
-    }
-
     public class Share
     {
         public string UserId { get; set; }
diff --git a/MediaBrowser.Controller/Entities/Studio.cs b/MediaBrowser.Controller/Entities/Studio.cs
index 9018ddb75..c8feb1c94 100644
--- a/MediaBrowser.Controller/Entities/Studio.cs
+++ b/MediaBrowser.Controller/Entities/Studio.cs
@@ -1,9 +1,11 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
 using System.Collections.Generic;
 using System.Text.Json.Serialization;
-using MediaBrowser.Controller.Extensions;
+using Diacritics.Extensions;
 using Microsoft.Extensions.Logging;
 
 namespace MediaBrowser.Controller.Entities
@@ -13,21 +15,8 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Studio : BaseItem, IItemByName
     {
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
-
-            list.Insert(0, GetType().Name + "-" + (Name ?? string.Empty).RemoveDiacritics());
-            return list;
-        }
-
-        public override string CreatePresentationUniqueKey()
-        {
-            return GetUserDataKeys()[0];
-        }
-
         /// <summary>
-        /// Returns the folder containing the item.
+        /// Gets the folder containing the item.
         /// If the item is a folder, it returns the folder itself.
         /// </summary>
         /// <value>The containing folder path.</value>
@@ -40,6 +29,22 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public override bool SupportsAncestors => false;
 
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            list.Insert(0, GetType().Name + "-" + (Name ?? string.Empty).RemoveDiacritics());
+            return list;
+        }
+
+        public override string CreatePresentationUniqueKey()
+        {
+            return GetUserDataKeys()[0];
+        }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 16;
@@ -65,9 +70,6 @@ namespace MediaBrowser.Controller.Entities
             return LibraryManager.GetItemList(query);
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -103,9 +105,11 @@ namespace MediaBrowser.Controller.Entities
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata"><c>true</c> to replace all metadata, <c>false</c> to not.</param>
+        /// <returns><c>true</c> if changes were made, <c>false</c> if not.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))
diff --git a/MediaBrowser.Controller/Entities/TV/Episode.cs b/MediaBrowser.Controller/Entities/TV/Episode.cs
index 70663ef47..27c3ff81b 100644
--- a/MediaBrowser.Controller/Entities/TV/Episode.cs
+++ b/MediaBrowser.Controller/Entities/TV/Episode.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -32,7 +34,7 @@ namespace MediaBrowser.Controller.Entities.TV
         public IReadOnlyList<Guid> RemoteTrailerIds { get; set; }
 
         /// <summary>
-        /// Gets the season in which it aired.
+        /// Gets or sets the season in which it aired.
         /// </summary>
         /// <value>The aired season.</value>
         public int? AirsBeforeSeasonNumber { get; set; }
@@ -42,17 +44,11 @@ namespace MediaBrowser.Controller.Entities.TV
         public int? AirsBeforeEpisodeNumber { get; set; }
 
         /// <summary>
-        /// This is the ending episode number for double episodes.
+        /// Gets or sets the ending episode number for double episodes.
         /// </summary>
         /// <value>The index number.</value>
         public int? IndexNumberEnd { get; set; }
 
-        public string FindSeriesSortName()
-        {
-            var series = Series;
-            return series == null ? SeriesName : series.SortName;
-        }
-
         [JsonIgnore]
         protected override bool SupportsOwnedItems => IsStacked || MediaSourceCount > 1;
 
@@ -74,47 +70,8 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         protected override bool EnableDefaultVideoUserDataKeys => false;
 
-        public override double GetDefaultPrimaryImageAspectRatio()
-        {
-            // hack for tv plugins
-            if (SourceType == SourceType.Channel)
-            {
-                return 0;
-            }
-
-            return 16.0 / 9;
-        }
-
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
-
-            var series = Series;
-            if (series != null && ParentIndexNumber.HasValue && IndexNumber.HasValue)
-            {
-                var seriesUserDataKeys = series.GetUserDataKeys();
-                var take = seriesUserDataKeys.Count;
-                if (seriesUserDataKeys.Count > 1)
-                {
-                    take--;
-                }
-
-                var newList = seriesUserDataKeys.GetRange(0, take);
-                var suffix = ParentIndexNumber.Value.ToString("000", CultureInfo.InvariantCulture) + IndexNumber.Value.ToString("000", CultureInfo.InvariantCulture);
-                for (int i = 0; i < take; i++)
-                {
-                    newList[i] = newList[i] + suffix;
-                }
-
-                newList.AddRange(list);
-                list = newList;
-            }
-
-            return list;
-        }
-
         /// <summary>
-        /// This Episode's Series Instance.
+        /// Gets the Episode's Series Instance.
         /// </summary>
         /// <value>The series.</value>
         [JsonIgnore]
@@ -159,6 +116,74 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         public string SeasonName { get; set; }
 
+        [JsonIgnore]
+        public override bool SupportsRemoteImageDownloading
+        {
+            get
+            {
+                if (IsMissingEpisode)
+                {
+                    return false;
+                }
+
+                return true;
+            }
+        }
+
+        [JsonIgnore]
+        public bool IsMissingEpisode => LocationType == LocationType.Virtual;
+
+        [JsonIgnore]
+        public Guid SeasonId { get; set; }
+
+        [JsonIgnore]
+        public Guid SeriesId { get; set; }
+
+        public string FindSeriesSortName()
+        {
+            var series = Series;
+            return series == null ? SeriesName : series.SortName;
+        }
+
+        public override double GetDefaultPrimaryImageAspectRatio()
+        {
+            // hack for tv plugins
+            if (SourceType == SourceType.Channel)
+            {
+                return 0;
+            }
+
+            return 16.0 / 9;
+        }
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            var series = Series;
+            if (series != null && ParentIndexNumber.HasValue && IndexNumber.HasValue)
+            {
+                var seriesUserDataKeys = series.GetUserDataKeys();
+                var take = seriesUserDataKeys.Count;
+                if (seriesUserDataKeys.Count > 1)
+                {
+                    take--;
+                }
+
+                var newList = seriesUserDataKeys.GetRange(0, take);
+                var suffix = ParentIndexNumber.Value.ToString("000", CultureInfo.InvariantCulture) + IndexNumber.Value.ToString("000", CultureInfo.InvariantCulture);
+                for (int i = 0; i < take; i++)
+                {
+                    newList[i] = newList[i] + suffix;
+                }
+
+                newList.AddRange(list);
+                list = newList;
+            }
+
+            return list;
+        }
+
         public string FindSeriesPresentationUniqueKey()
         {
             var series = Series;
@@ -216,8 +241,8 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("000 - ") : "")
-                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ") : "") + Name;
+            return (ParentIndexNumber != null ? ParentIndexNumber.Value.ToString("000 - ", CultureInfo.InvariantCulture) : string.Empty)
+                    + (IndexNumber != null ? IndexNumber.Value.ToString("0000 - ", CultureInfo.InvariantCulture) : string.Empty) + Name;
         }
 
         /// <summary>
@@ -240,28 +265,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return false;
         }
 
-        [JsonIgnore]
-        public override bool SupportsRemoteImageDownloading
-        {
-            get
-            {
-                if (IsMissingEpisode)
-                {
-                    return false;
-                }
-
-                return true;
-            }
-        }
-
-        [JsonIgnore]
-        public bool IsMissingEpisode => LocationType == LocationType.Virtual;
-
-        [JsonIgnore]
-        public Guid SeasonId { get; set; }
-        [JsonIgnore]
-        public Guid SeriesId { get; set; }
-
         public Guid FindSeriesId()
         {
             var series = FindParent<Series>();
@@ -284,7 +287,8 @@ namespace MediaBrowser.Controller.Entities.TV
 
         public override IEnumerable<FileSystemMetadata> GetDeletePaths()
         {
-            return new[] {
+            return new[]
+            {
                 new FileSystemMetadata
                 {
                     FullName = Path,
@@ -316,9 +320,9 @@ namespace MediaBrowser.Controller.Entities.TV
             return id;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!IsLocked)
             {
@@ -326,7 +330,7 @@ namespace MediaBrowser.Controller.Entities.TV
                 {
                     try
                     {
-                        if (LibraryManager.FillMissingEpisodeNumbersFromPath(this, replaceAllMetdata))
+                        if (LibraryManager.FillMissingEpisodeNumbersFromPath(this, replaceAllMetadata))
                         {
                             hasChanges = true;
                         }
diff --git a/MediaBrowser.Controller/Entities/TV/Season.cs b/MediaBrowser.Controller/Entities/TV/Season.cs
index 5b8168d3d..926c7b045 100644
--- a/MediaBrowser.Controller/Entities/TV/Season.cs
+++ b/MediaBrowser.Controller/Entities/TV/Season.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -36,6 +38,50 @@ namespace MediaBrowser.Controller.Entities.TV
         [JsonIgnore]
         public override Guid DisplayParentId => SeriesId;
 
+        /// <summary>
+        /// Gets this Episode's Series Instance.
+        /// </summary>
+        /// <value>The series.</value>
+        [JsonIgnore]
+        public Series Series
+        {
+            get
+            {
+                var seriesId = SeriesId;
+                if (seriesId == Guid.Empty)
+                {
+                    seriesId = FindSeriesId();
+                }
+
+                return seriesId == Guid.Empty ? null : (LibraryManager.GetItemById(seriesId) as Series);
+            }
+        }
+
+        [JsonIgnore]
+        public string SeriesPath
+        {
+            get
+            {
+                var series = Series;
+
+                if (series != null)
+                {
+                    return series.Path;
+                }
+
+                return System.IO.Path.GetDirectoryName(Path);
+            }
+        }
+
+        [JsonIgnore]
+        public string SeriesPresentationUniqueKey { get; set; }
+
+        [JsonIgnore]
+        public string SeriesName { get; set; }
+
+        [JsonIgnore]
+        public Guid SeriesId { get; set; }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -78,41 +124,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return result;
         }
 
-        /// <summary>
-        /// This Episode's Series Instance.
-        /// </summary>
-        /// <value>The series.</value>
-        [JsonIgnore]
-        public Series Series
-        {
-            get
-            {
-                var seriesId = SeriesId;
-                if (seriesId == Guid.Empty)
-                {
-                    seriesId = FindSeriesId();
-                }
-
-                return seriesId == Guid.Empty ? null : (LibraryManager.GetItemById(seriesId) as Series);
-            }
-        }
-
-        [JsonIgnore]
-        public string SeriesPath
-        {
-            get
-            {
-                var series = Series;
-
-                if (series != null)
-                {
-                    return series.Path;
-                }
-
-                return System.IO.Path.GetDirectoryName(Path);
-            }
-        }
-
         public override string CreatePresentationUniqueKey()
         {
             if (IndexNumber.HasValue)
@@ -120,7 +131,7 @@ namespace MediaBrowser.Controller.Entities.TV
                 var series = Series;
                 if (series != null)
                 {
-                    return series.PresentationUniqueKey + "-" + (IndexNumber ?? 0).ToString("000");
+                    return series.PresentationUniqueKey + "-" + (IndexNumber ?? 0).ToString("000", CultureInfo.InvariantCulture);
                 }
             }
 
@@ -133,7 +144,7 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <returns>System.String.</returns>
         protected override string CreateSortName()
         {
-            return IndexNumber != null ? IndexNumber.Value.ToString("0000") : Name;
+            return IndexNumber != null ? IndexNumber.Value.ToString("0000", CultureInfo.InvariantCulture) : Name;
         }
 
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
@@ -155,6 +166,9 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Gets the episodes.
         /// </summary>
+        /// <param name="user">The user.</param>
+        /// <param name="options">The options to use.</param>
+        /// <returns>Set of episodes.</returns>
         public List<BaseItem> GetEpisodes(User user, DtoOptions options)
         {
             return GetEpisodes(Series, user, options);
@@ -191,15 +205,6 @@ namespace MediaBrowser.Controller.Entities.TV
             return UnratedItem.Series;
         }
 
-        [JsonIgnore]
-        public string SeriesPresentationUniqueKey { get; set; }
-
-        [JsonIgnore]
-        public string SeriesName { get; set; }
-
-        [JsonIgnore]
-        public Guid SeriesId { get; set; }
-
         public string FindSeriesPresentationUniqueKey()
         {
             var series = Series;
@@ -239,10 +244,11 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// This is called before any metadata refresh and returns true or false indicating if changes were made.
         /// </summary>
+        /// <param name="replaceAllMetadata"><c>true</c> to replace metdata, <c>false</c> to not.</param>
         /// <returns><c>true</c> if XXXX, <c>false</c> otherwise.</returns>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!IndexNumber.HasValue && !string.IsNullOrEmpty(Path))
             {
diff --git a/MediaBrowser.Controller/Entities/TV/Series.cs b/MediaBrowser.Controller/Entities/TV/Series.cs
index 9f9a2ad50..e4933e968 100644
--- a/MediaBrowser.Controller/Entities/TV/Series.cs
+++ b/MediaBrowser.Controller/Entities/TV/Series.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -57,8 +59,11 @@ namespace MediaBrowser.Controller.Entities.TV
         public IReadOnlyList<Guid> RemoteTrailerIds { get; set; }
 
         /// <summary>
-        /// airdate, dvd or absolute.
+        /// Gets or sets the display order.
         /// </summary>
+        /// <remarks>
+        /// Valid options are airdate, dvd or absolute.
+        /// </remarks>
         public string DisplayOrder { get; set; }
 
         /// <summary>
@@ -67,6 +72,9 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <value>The status.</value>
         public SeriesStatus? Status { get; set; }
 
+        [JsonIgnore]
+        public override bool StopRefreshIfLocalMetadataFound => false;
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -288,7 +296,7 @@ namespace MediaBrowser.Controller.Entities.TV
             // Refresh seasons
             foreach (var item in items)
             {
-                if (!(item is Season))
+                if (item is not Season)
                 {
                     continue;
                 }
@@ -316,20 +324,13 @@ namespace MediaBrowser.Controller.Entities.TV
 
                 cancellationToken.ThrowIfCancellationRequested();
 
-                var skipItem = false;
-
-                var episode = item as Episode;
-
-                if (episode != null
+                bool skipItem = item is Episode episode
                     && refreshOptions.MetadataRefreshMode != MetadataRefreshMode.FullRefresh
                     && !refreshOptions.ReplaceAllMetadata
                     && episode.IsMissingEpisode
                     && episode.LocationType == LocationType.Virtual
                     && episode.PremiereDate.HasValue
-                    && (DateTime.UtcNow - episode.PremiereDate.Value).TotalDays > 30)
-                {
-                    skipItem = true;
-                }
+                    && (DateTime.UtcNow - episode.PremiereDate.Value).TotalDays > 30;
 
                 if (!skipItem)
                 {
@@ -396,6 +397,10 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Filters the episodes by season.
         /// </summary>
+        /// <param name="episodes">The episodes.</param>
+        /// <param name="parentSeason">The season.</param>
+        /// <param name="includeSpecials"><c>true</c> to include special, <c>false</c> to not.</param>
+        /// <returns>The set of episodes.</returns>
         public static IEnumerable<BaseItem> FilterEpisodesBySeason(IEnumerable<BaseItem> episodes, Season parentSeason, bool includeSpecials)
         {
             var seasonNumber = parentSeason.IndexNumber;
@@ -426,6 +431,10 @@ namespace MediaBrowser.Controller.Entities.TV
         /// <summary>
         /// Filters the episodes by season.
         /// </summary>
+        /// <param name="episodes">The episodes.</param>
+        /// <param name="seasonNumber">The season.</param>
+        /// <param name="includeSpecials"><c>true</c> to include special, <c>false</c> to not.</param>
+        /// <returns>The set of episodes.</returns>
         public static IEnumerable<Episode> FilterEpisodesBySeason(IEnumerable<Episode> episodes, int seasonNumber, bool includeSpecials)
         {
             if (!includeSpecials || seasonNumber < 1)
@@ -501,8 +510,5 @@ namespace MediaBrowser.Controller.Entities.TV
 
             return list;
         }
-
-        [JsonIgnore]
-        public override bool StopRefreshIfLocalMetadataFound => false;
     }
 }
diff --git a/MediaBrowser.Controller/Entities/Trailer.cs b/MediaBrowser.Controller/Entities/Trailer.cs
index 9ae8ad708..1c558d419 100644
--- a/MediaBrowser.Controller/Entities/Trailer.cs
+++ b/MediaBrowser.Controller/Entities/Trailer.cs
@@ -1,4 +1,6 @@
-#pragma warning disable CS1591
+#nullable disable
+
+#pragma warning disable CA1819, CS1591
 
 using System;
 using System.Collections.Generic;
@@ -21,6 +23,9 @@ namespace MediaBrowser.Controller.Entities
             TrailerTypes = Array.Empty<TrailerType>();
         }
 
+        [JsonIgnore]
+        public override bool StopRefreshIfLocalMetadataFound => false;
+
         public TrailerType[] TrailerTypes { get; set; }
 
         public override double GetDefaultPrimaryImageAspectRatio()
@@ -43,9 +48,9 @@ namespace MediaBrowser.Controller.Entities
             return info;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (!ProductionYear.HasValue)
             {
@@ -95,8 +100,5 @@ namespace MediaBrowser.Controller.Entities
 
             return list;
         }
-
-        [JsonIgnore]
-        public override bool StopRefreshIfLocalMetadataFound => false;
     }
 }
diff --git a/MediaBrowser.Controller/Entities/UserItemData.cs b/MediaBrowser.Controller/Entities/UserItemData.cs
index db63c42e4..50ba9ef30 100644
--- a/MediaBrowser.Controller/Entities/UserItemData.cs
+++ b/MediaBrowser.Controller/Entities/UserItemData.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -10,6 +12,13 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class UserItemData
     {
+        public const double MinLikeValue = 6.5;
+
+        /// <summary>
+        /// The _rating.
+        /// </summary>
+        private double? _rating;
+
         /// <summary>
         /// Gets or sets the user id.
         /// </summary>
@@ -23,11 +32,6 @@ namespace MediaBrowser.Controller.Entities
         public string Key { get; set; }
 
         /// <summary>
-        /// The _rating.
-        /// </summary>
-        private double? _rating;
-
-        /// <summary>
         /// Gets or sets the users 0-10 rating.
         /// </summary>
         /// <value>The rating.</value>
@@ -91,10 +95,8 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The index of the subtitle stream.</value>
         public int? SubtitleStreamIndex { get; set; }
 
-        public const double MinLikeValue = 6.5;
-
         /// <summary>
-        /// This is an interpreted property to indicate likes or dislikes
+        /// Gets or sets a value indicating whether the item is liked or not.
         /// This should never be serialized.
         /// </summary>
         /// <value><c>null</c> if [likes] contains no value, <c>true</c> if [likes]; otherwise, <c>false</c>.</value>
diff --git a/MediaBrowser.Controller/Entities/UserRootFolder.cs b/MediaBrowser.Controller/Entities/UserRootFolder.cs
index 7f7224ae0..e547db523 100644
--- a/MediaBrowser.Controller/Entities/UserRootFolder.cs
+++ b/MediaBrowser.Controller/Entities/UserRootFolder.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -19,21 +21,15 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class UserRootFolder : Folder
     {
-        private List<Guid> _childrenIds = null;
         private readonly object _childIdsLock = new object();
-        protected override List<BaseItem> LoadChildren()
-        {
-            lock (_childIdsLock)
-            {
-                if (_childrenIds == null)
-                {
-                    var list = base.LoadChildren();
-                    _childrenIds = list.Select(i => i.Id).ToList();
-                    return list;
-                }
+        private List<Guid> _childrenIds = null;
 
-                return _childrenIds.Select(LibraryManager.GetItemById).Where(i => i != null).ToList();
-            }
+        /// <summary>
+        /// Initializes a new instance of the <see cref="UserRootFolder"/> class.
+        /// </summary>
+        public UserRootFolder()
+        {
+            IsRoot = true;
         }
 
         [JsonIgnore]
@@ -42,6 +38,12 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public override bool SupportsPlayedStatus => false;
 
+        [JsonIgnore]
+        protected override bool SupportsShortcutChildren => true;
+
+        [JsonIgnore]
+        public override bool IsPreSorted => true;
+
         private void ClearCache()
         {
             lock (_childIdsLock)
@@ -50,6 +52,21 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
+        protected override List<BaseItem> LoadChildren()
+        {
+            lock (_childIdsLock)
+            {
+                if (_childrenIds == null)
+                {
+                    var list = base.LoadChildren();
+                    _childrenIds = list.Select(i => i.Id).ToList();
+                    return list;
+                }
+
+                return _childrenIds.Select(LibraryManager.GetItemById).Where(i => i != null).ToList();
+            }
+        }
+
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
         {
             if (query.Recursive)
@@ -71,12 +88,6 @@ namespace MediaBrowser.Controller.Entities
             return GetChildren(user, true).Count;
         }
 
-        [JsonIgnore]
-        protected override bool SupportsShortcutChildren => true;
-
-        [JsonIgnore]
-        public override bool IsPreSorted => true;
-
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             var list = base.GetEligibleChildrenForRecursiveChildren(user).ToList();
@@ -85,10 +96,10 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
             ClearCache();
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             if (string.Equals("default", Name, StringComparison.OrdinalIgnoreCase))
             {
@@ -106,11 +117,11 @@ namespace MediaBrowser.Controller.Entities
             return base.GetNonCachedChildren(directoryService);
         }
 
-        protected override async Task ValidateChildrenInternal(IProgress<double> progress, CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService)
+        protected override async Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, MetadataRefreshOptions refreshOptions, IDirectoryService directoryService, CancellationToken cancellationToken)
         {
             ClearCache();
 
-            await base.ValidateChildrenInternal(progress, cancellationToken, recursive, refreshChildMetadata, refreshOptions, directoryService)
+            await base.ValidateChildrenInternal(progress, recursive, refreshChildMetadata, refreshOptions, directoryService, cancellationToken)
                 .ConfigureAwait(false);
 
             ClearCache();
diff --git a/MediaBrowser.Controller/Entities/UserView.cs b/MediaBrowser.Controller/Entities/UserView.cs
index b1da4d64c..62f3c4b55 100644
--- a/MediaBrowser.Controller/Entities/UserView.cs
+++ b/MediaBrowser.Controller/Entities/UserView.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -13,22 +15,57 @@ namespace MediaBrowser.Controller.Entities
 {
     public class UserView : Folder, IHasCollectionType
     {
-        /// <inheritdoc />
+        private static readonly string[] _viewTypesEligibleForGrouping = new string[]
+        {
+            Model.Entities.CollectionType.Movies,
+            Model.Entities.CollectionType.TvShows,
+            string.Empty
+        };
+
+        private static readonly string[] _originalFolderViewTypes = new string[]
+        {
+            Model.Entities.CollectionType.Books,
+            Model.Entities.CollectionType.MusicVideos,
+            Model.Entities.CollectionType.HomeVideos,
+            Model.Entities.CollectionType.Photos,
+            Model.Entities.CollectionType.Music,
+            Model.Entities.CollectionType.BoxSets
+        };
+
+        public static ITVSeriesManager TVSeriesManager { get; set; }
+
+        /// <summary>
+        /// Gets or sets the view type.
+        /// </summary>
         public string ViewType { get; set; }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Gets or sets the display parent id.
+        /// </summary>
         public new Guid DisplayParentId { get; set; }
 
-        /// <inheritdoc />
+        /// <summary>
+        /// Gets or sets the user id.
+        /// </summary>
         public Guid? UserId { get; set; }
 
-        public static ITVSeriesManager TVSeriesManager;
-
         /// <inheritdoc />
         [JsonIgnore]
         public string CollectionType => ViewType;
 
         /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsInheritedParentImages => false;
+
+        /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsPlayedStatus => false;
+
+        /// <inheritdoc />
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
+
+        /// <inheritdoc />
         public override IEnumerable<Guid> GetIdsForAncestorQuery()
         {
             if (!DisplayParentId.Equals(Guid.Empty))
@@ -45,17 +82,13 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        [JsonIgnore]
-        public override bool SupportsInheritedParentImages => false;
-
-        [JsonIgnore]
-        public override bool SupportsPlayedStatus => false;
-
+        /// <inheritdoc />
         public override int GetChildCount(User user)
         {
             return GetChildren(user, true).Count;
         }
 
+        /// <inheritdoc />
         protected override QueryResult<BaseItem> GetItemsInternal(InternalItemsQuery query)
         {
             var parent = this as Folder;
@@ -73,12 +106,10 @@ namespace MediaBrowser.Controller.Entities
                 .GetUserItems(parent, this, CollectionType, query);
         }
 
+        /// <inheritdoc />
         public override List<BaseItem> GetChildren(User user, bool includeLinkedChildren, InternalItemsQuery query)
         {
-            if (query == null)
-            {
-                query = new InternalItemsQuery(user);
-            }
+            query ??= new InternalItemsQuery(user);
 
             query.EnableTotalRecordCount = false;
             var result = GetItemList(query);
@@ -86,16 +117,19 @@ namespace MediaBrowser.Controller.Entities
             return result.ToList();
         }
 
+        /// <inheritdoc />
         public override bool CanDelete()
         {
             return false;
         }
 
+        /// <inheritdoc />
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
         }
 
+        /// <inheritdoc />
         public override IEnumerable<BaseItem> GetRecursiveChildren(User user, InternalItemsQuery query)
         {
             query.SetUser(user);
@@ -106,32 +140,26 @@ namespace MediaBrowser.Controller.Entities
             return GetItemList(query);
         }
 
+        /// <inheritdoc />
         protected override IEnumerable<BaseItem> GetEligibleChildrenForRecursiveChildren(User user)
         {
             return GetChildren(user, false);
         }
 
-        private static string[] UserSpecificViewTypes = new string[]
-            {
-                Model.Entities.CollectionType.Playlists
-            };
-
         public static bool IsUserSpecific(Folder folder)
         {
-            var collectionFolder = folder as ICollectionFolder;
-
-            if (collectionFolder == null)
+            if (folder is not ICollectionFolder collectionFolder)
             {
                 return false;
             }
 
-            var supportsUserSpecific = folder as ISupportsUserSpecificView;
-            if (supportsUserSpecific != null && supportsUserSpecific.EnableUserSpecificView)
+            if (folder is ISupportsUserSpecificView supportsUserSpecific
+                && supportsUserSpecific.EnableUserSpecificView)
             {
                 return true;
             }
 
-            return UserSpecificViewTypes.Contains(collectionFolder.CollectionType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return string.Equals(Model.Entities.CollectionType.Playlists, collectionFolder.CollectionType, StringComparison.OrdinalIgnoreCase);
         }
 
         public static bool IsEligibleForGrouping(Folder folder)
@@ -140,39 +168,19 @@ namespace MediaBrowser.Controller.Entities
                     && IsEligibleForGrouping(collectionFolder.CollectionType);
         }
 
-        private static string[] ViewTypesEligibleForGrouping = new string[]
-            {
-                Model.Entities.CollectionType.Movies,
-                Model.Entities.CollectionType.TvShows,
-                string.Empty
-            };
-
         public static bool IsEligibleForGrouping(string viewType)
         {
-            return ViewTypesEligibleForGrouping.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return _viewTypesEligibleForGrouping.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
         }
 
-        private static string[] OriginalFolderViewTypes = new string[]
-            {
-                Model.Entities.CollectionType.Books,
-                Model.Entities.CollectionType.MusicVideos,
-                Model.Entities.CollectionType.HomeVideos,
-                Model.Entities.CollectionType.Photos,
-                Model.Entities.CollectionType.Music,
-                Model.Entities.CollectionType.BoxSets
-            };
-
         public static bool EnableOriginalFolder(string viewType)
         {
-            return OriginalFolderViewTypes.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
+            return _originalFolderViewTypes.Contains(viewType ?? string.Empty, StringComparer.OrdinalIgnoreCase);
         }
 
-        protected override Task ValidateChildrenInternal(IProgress<double> progress, System.Threading.CancellationToken cancellationToken, bool recursive, bool refreshChildMetadata, Providers.MetadataRefreshOptions refreshOptions, Providers.IDirectoryService directoryService)
+        protected override Task ValidateChildrenInternal(IProgress<double> progress, bool recursive, bool refreshChildMetadata, Providers.MetadataRefreshOptions refreshOptions, Providers.IDirectoryService directoryService, System.Threading.CancellationToken cancellationToken)
         {
             return Task.CompletedTask;
         }
-
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
     }
 }
diff --git a/MediaBrowser.Controller/Entities/UserViewBuilder.cs b/MediaBrowser.Controller/Entities/UserViewBuilder.cs
index 78a64d8c9..266fda767 100644
--- a/MediaBrowser.Controller/Entities/UserViewBuilder.cs
+++ b/MediaBrowser.Controller/Entities/UserViewBuilder.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -53,17 +55,17 @@ namespace MediaBrowser.Controller.Entities
             // if (query.IncludeItemTypes != null &&
             //    query.IncludeItemTypes.Length == 1 &&
             //    string.Equals(query.IncludeItemTypes[0], "Playlist", StringComparison.OrdinalIgnoreCase))
-            //{
+            // {
             //    if (!string.Equals(viewType, CollectionType.Playlists, StringComparison.OrdinalIgnoreCase))
             //    {
             //        return await FindPlaylists(queryParent, user, query).ConfigureAwait(false);
             //    }
-            //}
+            // }
 
             switch (viewType)
             {
                 case CollectionType.Folders:
-                    return GetResult(_libraryManager.GetUserRootFolder().GetChildren(user, true), queryParent, query);
+                    return GetResult(_libraryManager.GetUserRootFolder().GetChildren(user, true), query);
 
                 case CollectionType.TvShows:
                     return GetTvView(queryParent, user, query);
@@ -108,7 +110,7 @@ namespace MediaBrowser.Controller.Entities
                     return GetMovieMovies(queryParent, user, query);
 
                 case SpecialFolder.MovieCollections:
-                    return GetMovieCollections(queryParent, user, query);
+                    return GetMovieCollections(user, query);
 
                 case SpecialFolder.TvFavoriteEpisodes:
                     return GetFavoriteEpisodes(queryParent, user, query);
@@ -120,7 +122,7 @@ namespace MediaBrowser.Controller.Entities
                     {
                         if (queryParent is UserView)
                         {
-                            return GetResult(GetMediaFolders(user).OfType<Folder>().SelectMany(i => i.GetChildren(user, true)), queryParent, query);
+                            return GetResult(GetMediaFolders(user).OfType<Folder>().SelectMany(i => i.GetChildren(user, true)), query);
                         }
 
                         return queryParent.GetItems(query);
@@ -158,7 +160,7 @@ namespace MediaBrowser.Controller.Entities
                 GetUserView(SpecialFolder.MovieGenres, "Genres", "5", parent)
             };
 
-            return GetResult(list, parent, query);
+            return GetResult(list, query);
         }
 
         private QueryResult<BaseItem> GetFavoriteMovies(Folder parent, User user, InternalItemsQuery query)
@@ -205,7 +207,7 @@ namespace MediaBrowser.Controller.Entities
             return _libraryManager.GetItemsResult(query);
         }
 
-        private QueryResult<BaseItem> GetMovieCollections(Folder parent, User user, InternalItemsQuery query)
+        private QueryResult<BaseItem> GetMovieCollections(User user, InternalItemsQuery query)
         {
             query.Parent = null;
             query.IncludeItemTypes = new[] { nameof(BoxSet) };
@@ -273,9 +275,9 @@ namespace MediaBrowser.Controller.Entities
                     }
                 })
                 .Where(i => i != null)
-                .Select(i => GetUserViewWithName(i.Name, SpecialFolder.MovieGenre, i.SortName, parent));
+                .Select(i => GetUserViewWithName(SpecialFolder.MovieGenre, i.SortName, parent));
 
-            return GetResult(genres, parent, query);
+            return GetResult(genres, query);
         }
 
         private QueryResult<BaseItem> GetMovieGenreItems(Folder queryParent, Folder displayParent, User user, InternalItemsQuery query)
@@ -321,7 +323,7 @@ namespace MediaBrowser.Controller.Entities
                 GetUserView(SpecialFolder.TvGenres, "Genres", "6", parent)
             };
 
-            return GetResult(list, parent, query);
+            return GetResult(list, query);
         }
 
         private QueryResult<BaseItem> GetTvLatest(Folder parent, User user, InternalItemsQuery query)
@@ -342,12 +344,14 @@ namespace MediaBrowser.Controller.Entities
             var parentFolders = GetMediaFolders(parent, query.User, new[] { CollectionType.TvShows, string.Empty });
 
             var result = _tvSeriesManager.GetNextUp(
-            new NextUpQuery
-            {
-                Limit = query.Limit,
-                StartIndex = query.StartIndex,
-                UserId = query.User.Id
-            }, parentFolders, query.DtoOptions);
+                new NextUpQuery
+                {
+                    Limit = query.Limit,
+                    StartIndex = query.StartIndex,
+                    UserId = query.User.Id
+                },
+                parentFolders,
+                query.DtoOptions);
 
             return result;
         }
@@ -399,9 +403,9 @@ namespace MediaBrowser.Controller.Entities
                     }
                 })
                 .Where(i => i != null)
-                .Select(i => GetUserViewWithName(i.Name, SpecialFolder.TvGenre, i.SortName, parent));
+                .Select(i => GetUserViewWithName(SpecialFolder.TvGenre, i.SortName, parent));
 
-            return GetResult(genres, parent, query);
+            return GetResult(genres, query);
         }
 
         private QueryResult<BaseItem> GetTvGenreItems(Folder queryParent, Folder displayParent, User user, InternalItemsQuery query)
@@ -428,13 +432,12 @@ namespace MediaBrowser.Controller.Entities
 
         private QueryResult<BaseItem> GetResult<T>(
             IEnumerable<T> items,
-            BaseItem queryParent,
             InternalItemsQuery query)
             where T : BaseItem
         {
             items = items.Where(i => Filter(i, query.User, query, _userDataManager, _libraryManager));
 
-            return PostFilterAndSort(items, queryParent, null, query, _libraryManager, _config);
+            return PostFilterAndSort(items, null, query, _libraryManager);
         }
 
         public static bool FilterItem(BaseItem item, InternalItemsQuery query)
@@ -444,11 +447,9 @@ namespace MediaBrowser.Controller.Entities
 
         public static QueryResult<BaseItem> PostFilterAndSort(
             IEnumerable<BaseItem> items,
-            BaseItem queryParent,
             int? totalRecordLimit,
             InternalItemsQuery query,
-            ILibraryManager libraryManager,
-            IServerConfigurationManager configurationManager)
+            ILibraryManager libraryManager)
         {
             var user = query.User;
 
@@ -997,7 +998,7 @@ namespace MediaBrowser.Controller.Entities
             return new BaseItem[] { parent };
         }
 
-        private UserView GetUserViewWithName(string name, string type, string sortName, BaseItem parent)
+        private UserView GetUserViewWithName(string type, string sortName, BaseItem parent)
         {
             return _userViewManager.GetUserSubView(parent.Id, parent.Id.ToString("N", CultureInfo.InvariantCulture), type, sortName);
         }
diff --git a/MediaBrowser.Controller/Entities/Video.cs b/MediaBrowser.Controller/Entities/Video.cs
index 6320b01b8..7dd95b85c 100644
--- a/MediaBrowser.Controller/Entities/Video.cs
+++ b/MediaBrowser.Controller/Entities/Video.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -26,6 +28,14 @@ namespace MediaBrowser.Controller.Entities
         ISupportsPlaceHolders,
         IHasMediaSources
     {
+        public Video()
+        {
+            AdditionalParts = Array.Empty<string>();
+            LocalAlternateVersions = Array.Empty<string>();
+            SubtitleFiles = Array.Empty<string>();
+            LinkedAlternateVersions = Array.Empty<LinkedChild>();
+        }
+
         [JsonIgnore]
         public string PrimaryVersionId { get; set; }
 
@@ -72,30 +82,6 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        public void SetPrimaryVersionId(string id)
-        {
-            if (string.IsNullOrEmpty(id))
-            {
-                PrimaryVersionId = null;
-            }
-            else
-            {
-                PrimaryVersionId = id;
-            }
-
-            PresentationUniqueKey = CreatePresentationUniqueKey();
-        }
-
-        public override string CreatePresentationUniqueKey()
-        {
-            if (!string.IsNullOrEmpty(PrimaryVersionId))
-            {
-                return PrimaryVersionId;
-            }
-
-            return base.CreatePresentationUniqueKey();
-        }
-
         [JsonIgnore]
         public override bool SupportsThemeMedia => true;
 
@@ -149,24 +135,6 @@ namespace MediaBrowser.Controller.Entities
         /// <value>The aspect ratio.</value>
         public string AspectRatio { get; set; }
 
-        public Video()
-        {
-            AdditionalParts = Array.Empty<string>();
-            LocalAlternateVersions = Array.Empty<string>();
-            SubtitleFiles = Array.Empty<string>();
-            LinkedAlternateVersions = Array.Empty<LinkedChild>();
-        }
-
-        public override bool CanDownload()
-        {
-            if (VideoType == VideoType.Dvd || VideoType == VideoType.BluRay)
-            {
-                return false;
-            }
-
-            return IsFileProtocol;
-        }
-
         [JsonIgnore]
         public override bool SupportsAddingToPlaylist => true;
 
@@ -194,16 +162,6 @@ namespace MediaBrowser.Controller.Entities
         [JsonIgnore]
         public override bool HasLocalAlternateVersions => LocalAlternateVersions.Length > 0;
 
-        public IEnumerable<Guid> GetAdditionalPartIds()
-        {
-            return AdditionalParts.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
-        }
-
-        public IEnumerable<Guid> GetLocalAlternateVersionIds()
-        {
-            return LocalAlternateVersions.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
-        }
-
         public static ILiveTvManager LiveTvManager { get; set; }
 
         [JsonIgnore]
@@ -220,37 +178,77 @@ namespace MediaBrowser.Controller.Entities
             }
         }
 
-        protected override bool IsActiveRecording()
+        [JsonIgnore]
+        public bool IsCompleteMedia
         {
-            return LiveTvManager.GetActiveRecordingInfo(Path) != null;
+            get
+            {
+                if (SourceType == SourceType.Channel)
+                {
+                    return !Tags.Contains("livestream", StringComparer.OrdinalIgnoreCase);
+                }
+
+                return !IsActiveRecording();
+            }
         }
 
-        public override bool CanDelete()
+        [JsonIgnore]
+        protected virtual bool EnableDefaultVideoUserDataKeys => true;
+
+        [JsonIgnore]
+        public override string ContainingFolderPath
         {
-            if (IsActiveRecording())
+            get
             {
-                return false;
-            }
+                if (IsStacked)
+                {
+                    return System.IO.Path.GetDirectoryName(Path);
+                }
 
-            return base.CanDelete();
+                if (!IsPlaceHolder)
+                {
+                    if (VideoType == VideoType.BluRay || VideoType == VideoType.Dvd)
+                    {
+                        return Path;
+                    }
+                }
+
+                return base.ContainingFolderPath;
+            }
         }
 
         [JsonIgnore]
-        public bool IsCompleteMedia
+        public override string FileNameWithoutExtension
         {
             get
             {
-                if (SourceType == SourceType.Channel)
+                if (IsFileProtocol)
                 {
-                    return !Tags.Contains("livestream", StringComparer.OrdinalIgnoreCase);
+                    if (VideoType == VideoType.BluRay || VideoType == VideoType.Dvd)
+                    {
+                        return System.IO.Path.GetFileName(Path);
+                    }
+
+                    return System.IO.Path.GetFileNameWithoutExtension(Path);
                 }
 
-                return !IsActiveRecording();
+                return null;
             }
         }
 
+        /// <summary>
+        /// Gets a value indicating whether [is3 D].
+        /// </summary>
+        /// <value><c>true</c> if [is3 D]; otherwise, <c>false</c>.</value>
         [JsonIgnore]
-        protected virtual bool EnableDefaultVideoUserDataKeys => true;
+        public bool Is3D => Video3DFormat.HasValue;
+
+        /// <summary>
+        /// Gets the type of the media.
+        /// </summary>
+        /// <value>The type of the media.</value>
+        [JsonIgnore]
+        public override string MediaType => Model.Entities.MediaType.Video;
 
         public override List<string> GetUserDataKeys()
         {
@@ -291,6 +289,65 @@ namespace MediaBrowser.Controller.Entities
             return list;
         }
 
+        public void SetPrimaryVersionId(string id)
+        {
+            if (string.IsNullOrEmpty(id))
+            {
+                PrimaryVersionId = null;
+            }
+            else
+            {
+                PrimaryVersionId = id;
+            }
+
+            PresentationUniqueKey = CreatePresentationUniqueKey();
+        }
+
+        public override string CreatePresentationUniqueKey()
+        {
+            if (!string.IsNullOrEmpty(PrimaryVersionId))
+            {
+                return PrimaryVersionId;
+            }
+
+            return base.CreatePresentationUniqueKey();
+        }
+
+        public override bool CanDownload()
+        {
+            if (VideoType == VideoType.Dvd || VideoType == VideoType.BluRay)
+            {
+                return false;
+            }
+
+            return IsFileProtocol;
+        }
+
+        protected override bool IsActiveRecording()
+        {
+            return LiveTvManager.GetActiveRecordingInfo(Path) != null;
+        }
+
+        public override bool CanDelete()
+        {
+            if (IsActiveRecording())
+            {
+                return false;
+            }
+
+            return base.CanDelete();
+        }
+
+        public IEnumerable<Guid> GetAdditionalPartIds()
+        {
+            return AdditionalParts.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
+        }
+
+        public IEnumerable<Guid> GetLocalAlternateVersionIds()
+        {
+            return LocalAlternateVersions.Select(i => LibraryManager.GetNewItemId(i, typeof(Video)));
+        }
+
         private string GetUserDataKey(string providerId)
         {
             var key = providerId + "-" + ExtraType.ToString().ToLowerInvariant();
@@ -326,47 +383,6 @@ namespace MediaBrowser.Controller.Entities
                 .OrderBy(i => i.SortName);
         }
 
-        [JsonIgnore]
-        public override string ContainingFolderPath
-        {
-            get
-            {
-                if (IsStacked)
-                {
-                    return System.IO.Path.GetDirectoryName(Path);
-                }
-
-                if (!IsPlaceHolder)
-                {
-                    if (VideoType == VideoType.BluRay || VideoType == VideoType.Dvd)
-                    {
-                        return Path;
-                    }
-                }
-
-                return base.ContainingFolderPath;
-            }
-        }
-
-        [JsonIgnore]
-        public override string FileNameWithoutExtension
-        {
-            get
-            {
-                if (IsFileProtocol)
-                {
-                    if (VideoType == VideoType.BluRay || VideoType == VideoType.Dvd)
-                    {
-                        return System.IO.Path.GetFileName(Path);
-                    }
-
-                    return System.IO.Path.GetFileNameWithoutExtension(Path);
-                }
-
-                return null;
-            }
-        }
-
         internal override ItemUpdateType UpdateFromResolvedItem(BaseItem newItem)
         {
             var updateType = base.UpdateFromResolvedItem(newItem);
@@ -395,20 +411,6 @@ namespace MediaBrowser.Controller.Entities
             return updateType;
         }
 
-        /// <summary>
-        /// Gets a value indicating whether [is3 D].
-        /// </summary>
-        /// <value><c>true</c> if [is3 D]; otherwise, <c>false</c>.</value>
-        [JsonIgnore]
-        public bool Is3D => Video3DFormat.HasValue;
-
-        /// <summary>
-        /// Gets the type of the media.
-        /// </summary>
-        /// <value>The type of the media.</value>
-        [JsonIgnore]
-        public override string MediaType => Model.Entities.MediaType.Video;
-
         protected override async Task<bool> RefreshedOwnedItems(MetadataRefreshOptions options, List<FileSystemMetadata> fileSystemChildren, CancellationToken cancellationToken)
         {
             var hasChanges = await base.RefreshedOwnedItems(options, fileSystemChildren, cancellationToken).ConfigureAwait(false);
@@ -480,7 +482,8 @@ namespace MediaBrowser.Controller.Entities
         {
             if (!IsInMixedFolder)
             {
-                return new[] {
+                return new[]
+                {
                     new FileSystemMetadata
                     {
                         FullName = ContainingFolderPath,
diff --git a/MediaBrowser.Controller/Entities/Year.cs b/MediaBrowser.Controller/Entities/Year.cs
index b2e4d307a..afdaf448b 100644
--- a/MediaBrowser.Controller/Entities/Year.cs
+++ b/MediaBrowser.Controller/Entities/Year.cs
@@ -1,3 +1,5 @@
+#nullable disable
+
 #pragma warning disable CS1591
 
 using System;
@@ -13,22 +15,33 @@ namespace MediaBrowser.Controller.Entities
     /// </summary>
     public class Year : BaseItem, IItemByName
     {
-        public override List<string> GetUserDataKeys()
-        {
-            var list = base.GetUserDataKeys();
+        [JsonIgnore]
+        public override bool SupportsAncestors => false;
 
-            list.Insert(0, "Year-" + Name);
-            return list;
-        }
+        [JsonIgnore]
+        public override bool SupportsPeople => false;
 
         /// <summary>
-        /// Returns the folder containing the item.
+        /// Gets the folder containing the item.
         /// If the item is a folder, it returns the folder itself.
         /// </summary>
         /// <value>The containing folder path.</value>
         [JsonIgnore]
         public override string ContainingFolderPath => Path;
 
+        public override bool CanDelete()
+        {
+            return false;
+        }
+
+        public override List<string> GetUserDataKeys()
+        {
+            var list = base.GetUserDataKeys();
+
+            list.Insert(0, "Year-" + Name);
+            return list;
+        }
+
         public override double GetDefaultPrimaryImageAspectRatio()
         {
             double value = 2;
@@ -37,14 +50,6 @@ namespace MediaBrowser.Controller.Entities
             return value;
         }
 
-        [JsonIgnore]
-        public override bool SupportsAncestors => false;
-
-        public override bool CanDelete()
-        {
-            return false;
-        }
-
         public override bool IsSaveLocalMetadataEnabled()
         {
             return true;
@@ -52,9 +57,7 @@ namespace MediaBrowser.Controller.Entities
 
         public IList<BaseItem> GetTaggedItems(InternalItemsQuery query)
         {
-            var usCulture = new CultureInfo("en-US");
-
-            if (!int.TryParse(Name, NumberStyles.Integer, usCulture, out var year))
+            if (!int.TryParse(Name, NumberStyles.Integer, CultureInfo.InvariantCulture, out var year))
             {
                 return new List<BaseItem>();
             }
@@ -74,9 +77,6 @@ namespace MediaBrowser.Controller.Entities
             return null;
         }
 
-        [JsonIgnore]
-        public override bool SupportsPeople => false;
-
         public static string GetPath(string name)
         {
             return GetPath(name, true);
@@ -110,11 +110,13 @@ namespace MediaBrowser.Controller.Entities
         }
 
         /// <summary>
-        /// This is called before any metadata refresh and returns true or false indicating if changes were made.
+        /// This is called before any metadata refresh and returns true if changes were made.
         /// </summary>
-        public override bool BeforeMetadataRefresh(bool replaceAllMetdata)
+        /// <param name="replaceAllMetadata">Whether to replace all metadata.</param>
+        /// <returns>true if the item has change, else false.</returns>
+        public override bool BeforeMetadataRefresh(bool replaceAllMetadata)
         {
-            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetdata);
+            var hasChanges = base.BeforeMetadataRefresh(replaceAllMetadata);
 
             var newPath = GetRebasedPath();
             if (!string.Equals(Path, newPath, StringComparison.Ordinal))