From fdae333351a6e4f9e6b5aa4536133dee7ea35e91 Mon Sep 17 00:00:00 2001
From: AJ Ferguson <AJ-Ferguson@users.noreply.github.com>
Date: Wed, 1 May 2024 19:00:39 -0400
Subject: [PATCH] Add data components hash code to translated NBT

---
 .../java/org/geysermc/geyser/item/type/Item.java  |  4 ++++
 .../inventory/PlayerInventoryTranslator.java      |  6 ++++++
 .../org/geysermc/geyser/util/InventoryUtils.java  | 15 +++++++++++++++
 3 files changed, 25 insertions(+)

diff --git a/core/src/main/java/org/geysermc/geyser/item/type/Item.java b/core/src/main/java/org/geysermc/geyser/item/type/Item.java
index cc49f3785..bfcfb23d1 100644
--- a/core/src/main/java/org/geysermc/geyser/item/type/Item.java
+++ b/core/src/main/java/org/geysermc/geyser/item/type/Item.java
@@ -151,6 +151,10 @@ public class Item {
         if (repairCost != null) {
             builder.putInt("RepairCost", repairCost);
         }
+
+        // Prevents the client from trying to stack items with untranslated components
+        // Relies on correct hash code implementation, and some luck
+        builder.putInt("GeyserHash", components.hashCode()); // TODO: don't rely on this
     }
 
     /**
diff --git a/core/src/main/java/org/geysermc/geyser/translator/inventory/PlayerInventoryTranslator.java b/core/src/main/java/org/geysermc/geyser/translator/inventory/PlayerInventoryTranslator.java
index 7459ccf30..36752e582 100644
--- a/core/src/main/java/org/geysermc/geyser/translator/inventory/PlayerInventoryTranslator.java
+++ b/core/src/main/java/org/geysermc/geyser/translator/inventory/PlayerInventoryTranslator.java
@@ -261,6 +261,8 @@ public class PlayerInventoryTranslator extends InventoryTranslator {
                         GeyserItemStack sourceItem = inventory.getItem(sourceSlot);
                         if (playerInv.getCursor().isEmpty()) {
                             playerInv.setCursor(sourceItem.copy(0), session);
+                        } else if (!InventoryUtils.canStack(sourceItem, playerInv.getCursor())) {
+                            return rejectRequest(request);
                         }
 
                         playerInv.getCursor().add(transferAmount);
@@ -272,6 +274,8 @@ public class PlayerInventoryTranslator extends InventoryTranslator {
                         GeyserItemStack sourceItem = playerInv.getCursor();
                         if (inventory.getItem(destSlot).isEmpty()) {
                             inventory.setItem(destSlot, sourceItem.copy(0), session);
+                        } else if (!InventoryUtils.canStack(sourceItem, inventory.getItem(destSlot))) {
+                            return rejectRequest(request);
                         }
 
                         inventory.getItem(destSlot).add(transferAmount);
@@ -284,6 +288,8 @@ public class PlayerInventoryTranslator extends InventoryTranslator {
                         GeyserItemStack sourceItem = inventory.getItem(sourceSlot);
                         if (inventory.getItem(destSlot).isEmpty()) {
                             inventory.setItem(destSlot, sourceItem.copy(0), session);
+                        } else if (!InventoryUtils.canStack(sourceItem, inventory.getItem(destSlot))) {
+                            return rejectRequest(request);
                         }
 
                         inventory.getItem(destSlot).add(transferAmount);
diff --git a/core/src/main/java/org/geysermc/geyser/util/InventoryUtils.java b/core/src/main/java/org/geysermc/geyser/util/InventoryUtils.java
index 63644d5fc..64c95afdd 100644
--- a/core/src/main/java/org/geysermc/geyser/util/InventoryUtils.java
+++ b/core/src/main/java/org/geysermc/geyser/util/InventoryUtils.java
@@ -178,11 +178,26 @@ public class InventoryUtils {
     }
 
     public static boolean canStack(GeyserItemStack item1, GeyserItemStack item2) {
+        if (GeyserImpl.getInstance().getConfig().isDebugMode())
+            canStackDebug(item1, item2);
         if (item1.isEmpty() || item2.isEmpty())
             return false;
         return item1.getJavaId() == item2.getJavaId() && Objects.equals(item1.getComponents(), item2.getComponents());
     }
 
+    private static void canStackDebug(GeyserItemStack item1, GeyserItemStack item2) {
+        DataComponents components1 = item1.getComponents();
+        DataComponents components2 = item2.getComponents();
+        if (components1 != null && components2 != null) {
+            if (components1.hashCode() == components2.hashCode() && !components1.equals(components2)) {
+                GeyserImpl.getInstance().getLogger().error("DEBUG: DataComponents hash collision");
+                GeyserImpl.getInstance().getLogger().error("hash: " + components1.hashCode());
+                GeyserImpl.getInstance().getLogger().error("components1: " + components1);
+                GeyserImpl.getInstance().getLogger().error("components2: " + components2);
+            }
+        }
+    }
+
     /**
      * Checks to see if an item stack represents air or has no count.
      */