From 35dd3c4f069c64fb2583632c7c49b061f68d10e1 Mon Sep 17 00:00:00 2001
From: BruceChen <hi@brucec.cn>
Date: Tue, 31 Mar 2026 01:27:27 +0800
Subject: [PATCH] Add support for ItemStackTemplate in DataTypes and Protocol18

- Implemented ReadNextItemStackTemplate method to read ItemStackTemplate data with item-first encoding.
- Updated Protocol18 to utilize ReadItemStackTemplateLabel for improved item display handling.
- Enhanced item component parsing to accommodate new structured components.
---
 .../Protocol/Handlers/DataTypes.cs            | 31 +++++++++++++++++++
 .../Protocol/Handlers/Protocol18.cs           | 11 ++++++-
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/MinecraftClient/Protocol/Handlers/DataTypes.cs b/MinecraftClient/Protocol/Handlers/DataTypes.cs
index 669ba5b3..6a0d27aa 100644
--- a/MinecraftClient/Protocol/Handlers/DataTypes.cs
+++ b/MinecraftClient/Protocol/Handlers/DataTypes.cs
@@ -411,6 +411,37 @@ namespace MinecraftClient.Protocol.Handlers
             return ReadNextNbt(cache, true);
         }
 
+        /// <summary>
+        /// Read an ItemStackTemplate (26.1+) from a cache of bytes.
+        /// Unlike ItemStack, this uses item-first encoding: item_id, count, DataComponentPatch.
+        /// ItemStackTemplate is always non-empty (no count=0 sentinel).
+        /// </summary>
+        public Item ReadNextItemStackTemplate(Queue<byte> cache, ItemPalette itemPalette)
+        {
+            var itemId = ReadNextVarInt(cache);
+            var itemCount = ReadNextVarInt(cache);
+            var item = new Item(itemPalette.FromId(itemId), itemCount, null);
+
+            var numberOfComponentsToAdd = ReadNextVarInt(cache);
+            var numberofComponentsToRemove = ReadNextVarInt(cache);
+            var structuredComponentHandler = new StructuredComponentsHandler(protocolversion, this, itemPalette);
+            var strcturedComponentsToAdd = new List<StructuredComponent>(numberOfComponentsToAdd);
+
+            for (var i = 0; i < numberOfComponentsToAdd; i++)
+            {
+                var componentTypeId = ReadNextVarInt(cache);
+                strcturedComponentsToAdd.Add(structuredComponentHandler.Parse(componentTypeId, cache));
+            }
+
+            for (var i = 0; i < numberofComponentsToRemove; i++)
+                ReadNextVarInt(cache);
+
+            if (strcturedComponentsToAdd.Count > 0)
+                item.Components = strcturedComponentsToAdd;
+
+            return item;
+        }
+
         /// <summary>
         /// Read a single item slot from a cache of bytes and remove it from the cache
         /// </summary>
diff --git a/MinecraftClient/Protocol/Handlers/Protocol18.cs b/MinecraftClient/Protocol/Handlers/Protocol18.cs
index eeabc8e0..45bde28f 100644
--- a/MinecraftClient/Protocol/Handlers/Protocol18.cs
+++ b/MinecraftClient/Protocol/Handlers/Protocol18.cs
@@ -3530,7 +3530,7 @@ namespace MinecraftClient.Protocol.Handlers
                     2 => ReadWithAnyPotionSlotDisplayLabel(packetData),
                     3 => ReadOnlyWithComponentSlotDisplayLabel(packetData),
                     4 => Item.GetTypeString(itemPalette.FromId(dataTypes.ReadNextVarInt(packetData))),
-                    5 => dataTypes.ReadNextItemSlot(packetData, itemPalette)?.GetTypeString() ?? "Empty",
+                    5 => ReadItemStackTemplateLabel(packetData),
                     6 => "#" + dataTypes.ReadNextString(packetData),
                     7 => ReadDyedSlotDisplayLabel(packetData),
                     8 => ReadSmithingTrimSlotDisplayLabel(packetData),
@@ -3612,6 +3612,15 @@ namespace MinecraftClient.Protocol.Handlers
             return label;
         }
 
+        /// <summary>
+        /// Read an ItemStackTemplate (26.1+) which encodes fields in a different order
+        /// than ItemStack: item_id (VarInt), count (VarInt), DataComponentPatch.
+        /// </summary>
+        private string ReadItemStackTemplateLabel(Queue<byte> packetData)
+        {
+            return dataTypes.ReadNextItemStackTemplate(packetData, itemPalette).GetTypeString();
+        }
+
         private void SkipOptionalCraftingRequirements(Queue<byte> packetData)
         {
             if (!dataTypes.ReadNextBool(packetData))