Fixed inventory id generation

src/main/java/net/minestom/server/entity/Player.java

@@ -799,7 +799,7 @@ public class Player extends LivingEntity {
         if (openInventory == null) {
             closeWindowPacket.windowId = 0;
         } else {
-            closeWindowPacket.windowId = openInventory.getWindowId();
+            closeWindowPacket.windowId = (byte) openInventory.getInventoryType().getWindowType();
             openInventory.removeViewer(this);
             refreshOpenInventory(null);
         }

src/main/java/net/minestom/server/inventory/Inventory.java

@@ -15,16 +15,17 @@ import java.util.Collections;
 import java.util.Set;
 import java.util.concurrent.ConcurrentHashMap;
 import java.util.concurrent.CopyOnWriteArraySet;
-import java.util.concurrent.atomic.AtomicInteger;
 
 public class Inventory implements InventoryModifier, InventoryClickHandler, Viewable {
 
-    private static AtomicInteger lastInventoryId = new AtomicInteger();
+    private static volatile byte lastInventoryId;
 
     private int id;
     private InventoryType inventoryType;
     private String title;
 
+    private int size;
+
     private int offset;
 
     private ItemStack[] itemStacks;
@@ -39,17 +40,22 @@ public class Inventory implements InventoryModifier, InventoryClickHandler, View
         this.inventoryType = inventoryType;
         this.title = title;
 
-        this.offset = inventoryType.getAdditionalSlot();
+        this.size = inventoryType.getAdditionalSlot();
 
-        this.itemStacks = new ItemStack[inventoryType.getAdditionalSlot()];
+        this.offset = size;
 
-        for (int i = 0; i < itemStacks.length; i++) {
+        this.itemStacks = new ItemStack[size];
+
+        for (int i = 0; i < size; i++) {
             itemStacks[i] = ItemStack.getAirItem();
         }
     }
 
-    private static int generateId() {
+    private static byte generateId() {
-        return lastInventoryId.incrementAndGet();
+        byte newInventoryId = ++lastInventoryId;
+        if (newInventoryId < 0)
+            newInventoryId = 1;
+        return newInventoryId;
     }
 
     public InventoryType getInventoryType() {

src/main/java/net/minestom/server/listener/WindowListener.java

@@ -7,8 +7,8 @@ import net.minestom.server.inventory.PlayerInventory;
 import net.minestom.server.item.ItemStack;
 import net.minestom.server.network.packet.client.play.ClientClickWindowPacket;
 import net.minestom.server.network.packet.client.play.ClientCloseWindow;
-import net.minestom.server.network.packet.server.play.ConfirmTransactionPacket;
 import net.minestom.server.network.packet.server.play.SetSlotPacket;
+import net.minestom.server.network.packet.server.play.WindowConfirmationPacket;
 
 public class WindowListener {
 
@@ -26,10 +26,10 @@ public class WindowListener {
 
         // System.out.println("Window id: " + windowId + " | slot: " + slot + " | button: " + button + " | mode: " + mode);
 
-        ConfirmTransactionPacket confirmTransactionPacket = new ConfirmTransactionPacket();
+        WindowConfirmationPacket windowConfirmationPacket = new WindowConfirmationPacket();
-        confirmTransactionPacket.windowId = windowId;
+        windowConfirmationPacket.windowId = windowId;
-        confirmTransactionPacket.actionNumber = actionNumber;
+        windowConfirmationPacket.actionNumber = actionNumber;
-        confirmTransactionPacket.accepted = true; // Change depending on output
+        windowConfirmationPacket.accepted = true; // Change depending on output
 
         switch (mode) {
             case 0:
@@ -83,7 +83,7 @@ public class WindowListener {
         setSlotPacket.itemStack = cursorItem;
 
         player.getPlayerConnection().sendPacket(setSlotPacket);
-        player.getPlayerConnection().sendPacket(confirmTransactionPacket);
+        player.getPlayerConnection().sendPacket(windowConfirmationPacket);
     }
 
     public static void closeWindowListener(ClientCloseWindow packet, Player player) {

src/main/java/net/minestom/server/network/packet/server/play/CloseWindowPacket.java

@@ -6,11 +6,11 @@ import net.minestom.server.network.packet.server.ServerPacketIdentifier;
 
 public class CloseWindowPacket implements ServerPacket {
 
-    public int windowId;
+    public byte windowId;
 
     @Override
     public void write(PacketWriter writer) {
-        writer.writeVarInt(windowId);
+        writer.writeByte(windowId);
     }
 
     @Override

src/main/java/net/minestom/server/network/packet/server/play/WindowConfirmationPacket.java

@@ -4,15 +4,15 @@ import net.minestom.server.network.packet.PacketWriter;
 import net.minestom.server.network.packet.server.ServerPacket;
 import net.minestom.server.network.packet.server.ServerPacketIdentifier;
 
-public class ConfirmTransactionPacket implements ServerPacket {
+public class WindowConfirmationPacket implements ServerPacket {
 
-    public int windowId;
+    public byte windowId;
     public short actionNumber;
     public boolean accepted;
 
     @Override
     public void write(PacketWriter writer) {
-        writer.writeVarInt(windowId);
+        writer.writeByte(windowId);
         writer.writeShort(actionNumber);
         writer.writeBoolean(accepted);
     }