From 1ed60d0520e6f1a2a4a6de1e35d031c279edcfdf Mon Sep 17 00:00:00 2001
From: Patbox <39821509+Patbox@users.noreply.github.com>
Date: Wed, 18 Sep 2024 11:44:11 +0200
Subject: [PATCH] Fix some mods providing empty item stacks in item groups,
 which is not valid!

---
 gradle.properties                              |  2 +-
 .../core/mixin/item/ItemGroupMixin.java        |  2 ++
 .../item/ServerPlayNetworkHandlerMixin.java    | 18 ++++++++++++++----
 3 files changed, 17 insertions(+), 5 deletions(-)

diff --git a/gradle.properties b/gradle.properties
index 4eb28f10..89a15e26 100644
--- a/gradle.properties
+++ b/gradle.properties
@@ -13,7 +13,7 @@ fabric_version=0.102.1+1.21.1
 
 maven_group = eu.pb4
 
-mod_version = 0.9.15
+mod_version = 0.9.16
 
 minecraft_version_supported = ">=1.21-"
 
diff --git a/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ItemGroupMixin.java b/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ItemGroupMixin.java
index f3d57238..4da4679d 100644
--- a/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ItemGroupMixin.java
+++ b/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ItemGroupMixin.java
@@ -39,6 +39,8 @@ public abstract class ItemGroupMixin implements ItemGroupExtra {
         var parent = new LinkedList<>(collector.parentTabStacks);
         var search = new LinkedList<>(collector.searchTabStacks);
         PolymerImplUtils.callItemGroupEvents(id, (ItemGroup) (Object) this, parent, search, context);
+        parent.removeIf(ItemStack::isEmpty);
+        search.removeIf(ItemStack::isEmpty);
         return new PolymerItemGroupUtils.Contents(parent, search);
     }
 
diff --git a/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ServerPlayNetworkHandlerMixin.java b/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ServerPlayNetworkHandlerMixin.java
index e6d84a07..3dc46109 100644
--- a/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ServerPlayNetworkHandlerMixin.java
+++ b/polymer-core/src/main/java/eu/pb4/polymer/core/mixin/item/ServerPlayNetworkHandlerMixin.java
@@ -8,6 +8,7 @@
 import eu.pb4.polymer.core.impl.interfaces.PolymerPlayNetworkHandlerExtension;
 import eu.pb4.polymer.core.impl.networking.PolymerServerProtocol;
 import eu.pb4.polymer.networking.api.server.PolymerServerNetworking;
+import net.minecraft.entity.EquipmentSlot;
 import net.minecraft.item.BlockItem;
 import net.minecraft.item.BucketItem;
 import net.minecraft.item.Equipment;
@@ -90,10 +91,19 @@ public ServerPlayNetworkHandlerMixin(MinecraftServer server, ClientConnection co
 
         if (itemStack.getItem() instanceof PolymerItem polymerItem) {
             var data = PolymerItemUtils.getItemSafely(polymerItem, itemStack, this.player);
-            if (data.item() instanceof Equipment equipment && equipment.getSlotType().isArmorSlot()) {
-                this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(), packet.getHand() == Hand.MAIN_HAND ? 36 + this.player.getInventory().selectedSlot : 45, itemStack));
-
-                this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(), 8 - equipment.getSlotType().getEntitySlotId(), this.player.getEquippedStack(equipment.getSlotType())));
+            if (data.item() instanceof Equipment equipment) {
+                if (equipment.getSlotType().getType() == EquipmentSlot.Type.HUMANOID_ARMOR) {
+                    this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(),
+                            packet.getHand() == Hand.MAIN_HAND ? 36 + this.player.getInventory().selectedSlot : 45, itemStack));
+
+                    this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(),
+                            8 - equipment.getSlotType().getEntitySlotId(), this.player.getEquippedStack(equipment.getSlotType())));
+                } else if (equipment.getSlotType().getType() == EquipmentSlot.Type.ANIMAL_ARMOR && packet.getHand() == Hand.OFF_HAND) {
+                    this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(),
+                            45, itemStack));
+                    this.sendPacket(new ScreenHandlerSlotUpdateS2CPacket(this.player.playerScreenHandler.syncId, this.player.playerScreenHandler.nextRevision(),
+                            36 + this.player.getInventory().selectedSlot, this.player.getMainHandStack()));
+                }
             }
         }
     }