Renew IPC mechanism

Penumbra.GameData/Enums/ChangedItemType.cs

@@ -0,0 +1,40 @@
+using System;
+using Lumina.Excel.GeneratedSheets;
+using Action = Lumina.Excel.GeneratedSheets.Action;
+
+namespace Penumbra.GameData.Enums
+{
+    public enum ChangedItemType
+    {
+        None,
+        Item,
+        Action,
+        Customization,
+    }
+
+    public static class ChangedItemExtensions
+    {
+        public static (ChangedItemType, uint) ChangedItemToTypeAndId( object? item )
+        {
+            return item switch
+            {
+                null     => ( ChangedItemType.None, 0 ),
+                Item i   => ( ChangedItemType.Item, i.RowId ),
+                Action a => ( ChangedItemType.Action, a.RowId ),
+                _        => ( ChangedItemType.Customization, 0 ),
+            };
+        }
+
+        public static object? GetObject( this ChangedItemType type, uint id )
+        {
+            return type switch
+            {
+                ChangedItemType.None          => null,
+                ChangedItemType.Item          => ObjectIdentification.DataManager?.GetExcelSheet< Item >()?.GetRow( id ),
+                ChangedItemType.Action        => ObjectIdentification.DataManager?.GetExcelSheet< Action >()?.GetRow( id ),
+                ChangedItemType.Customization => null,
+                _                             => throw new ArgumentOutOfRangeException( nameof( type ), type, null )
+            };
+        }
+    }
+}