Entity.Pos compatibility for API break between 1.21 and 1.22

ChestPreview/ChestPreview/PreviewTargetProvider.cs

@@ -242,7 +242,7 @@ internal partial class PreviewTargetProvider(ICoreClientAPI api, Config config)
         if (player == null || playerEntity == null)
             return false;
 
-        return inventory.CanPlayerAccess(player, playerEntity.Pos);
+        return inventory.CanPlayerAccess(player, playerEntity.GetPos());
     }
 
     private bool IsContainerAllowed(Block block)

ChestPreview/ChestPreview/Rendering/CardRenderer.cs

@@ -1,6 +1,7 @@
 using Cairo;
 using ChestPreview.Configs;
 using ChestPreview.Models;
+using ChestPreview.Utils;
 using System;
 using System.Collections.Generic;
 using System.Globalization;
@@ -50,7 +51,7 @@ internal class CardRenderer(ICoreClientAPI api, Config config) : IDisposable
 
         IPlayer? player = api.World.Player;
         EntityPlayer? playerEntity = player?.Entity;
-        if (player == null || playerEntity == null || !inventory.CanPlayerAccess(player, playerEntity.Pos))
+        if (player == null || playerEntity == null || !inventory.CanPlayerAccess(player, playerEntity.GetPos()))
             return false;
 
         string targetKey = CreateTargetKey(target.BlockEntity.Pos);

ChestPreview/ChestPreview/Utils/CompatibilityUtil.cs

@@ -0,0 +1,55 @@
+using System;
+using Vintagestory.API.Common.Entities;
+
+namespace ChestPreview.Utils;
+
+/// <summary>
+/// When the mod is built for 1.21, and then you run it with 1.22, this happens when referring to Entity.Pos,
+/// which was changed from a field to a property (and that being the reason this happens):
+/// 
+/// System.MissingFieldException: Field not found: 'Vintagestory.API.Common.Entities.Entity.Pos'.
+///    at MonoMod.Core.Interop.CoreCLR.V60.InvokeCompileMethod(IntPtr functionPtr, IntPtr thisPtr, IntPtr corJitInfo, CORINFO_METHOD_INFO* methodInfo, UInt32 flags, Byte** nativeEntry, UInt32* nativeSizeOfCode)
+///    at MonoMod.Core.Platforms.Runtimes.Core60Runtime.JitHookDelegateHolder.CompileMethodHook(IntPtr jit, IntPtr corJitInfo, CORINFO_METHOD_INFO* methodInfo, UInt32 flags, Byte** nativeEntry, UInt32* nativeSizeOfCode)
+///    at ChestPreview.PreviewTargetProvider.CanAccessContainer(BlockEntity blockEntity) in E:\Code\VintageStory\ChestPreview\ChestPreview\ChestPreview\PreviewTargetProvider.cs:line 237
+///
+/// the PreviewTargetProvider.cs: around line 237 looks like this:
+/// 
+///     private bool CanAccessContainer(BlockEntity blockEntity)
+///    {
+///        if (blockEntity is not IBlockEntityContainer container || container.Inventory is not InventoryBase inventory)
+///            return false;
+///
+///        IPlayer? player = api.World.Player;
+///        EntityPlayer? playerEntity = player?.Entity;
+///        if (player == null || playerEntity == null)
+///            return false;
+///
+///        return inventory.CanPlayerAccess(player, playerEntity.Pos);
+///    }
+/// 
+/// it happens because of the last line where we refer to "playerEntity.Pos" - this field doesn't exist now, because it's a property.
+/// 
+/// This class uses reflection to refer to either the property, or the field, whichever actually exists.
+/// </summary>
+internal static class CompatibilityUtil
+{
+#if !VERSION22
+    private static Func<Entity, EntityPos>? _getPos;
+
+    private static Func<Entity, EntityPos> GetPosFunc => _getPos ??= BuildGetPos();
+
+    private static Func<Entity, EntityPos> BuildGetPos()
+    {
+        var prop = typeof(Entity).GetProperty("Pos");
+        if (prop != null)
+            return (Func<Entity, EntityPos>)Delegate.CreateDelegate(typeof(Func<Entity, EntityPos>), prop.GetGetMethod()!);
+
+        var field = typeof(Entity).GetField("Pos")!;
+        return entity => (EntityPos)field.GetValue(entity)!;
+    }
+
+    public static EntityPos GetPos(this Entity entity) => GetPosFunc(entity);
+#else
+    public static EntityPos GetPos(this Entity entity) => entity.Pos;
+#endif
+}