Code review

src/main/java/net/minestom/server/event/GlobalHandles.java

@@ -5,6 +5,7 @@ import net.minestom.server.event.entity.EntityTickEvent;
 import net.minestom.server.event.instance.InstanceChunkLoadEvent;
 import net.minestom.server.event.instance.InstanceTickEvent;
 import net.minestom.server.event.inventory.InventoryItemChangeEvent;
+import net.minestom.server.event.inventory.PlayerInventoryItemChangeEvent;
 import net.minestom.server.event.player.PlayerChunkLoadEvent;
 import net.minestom.server.event.player.PlayerMoveEvent;
 import net.minestom.server.event.player.PlayerPacketEvent;
@@ -25,4 +26,5 @@ public final class GlobalHandles {
     public static final ListenerHandle<PlayerChunkLoadEvent> PLAYER_CHUNK_LOAD = EventDispatcher.getHandle(PlayerChunkLoadEvent.class);
     public static final ListenerHandle<InstanceChunkLoadEvent> INSTANCE_CHUNK_LOAD = EventDispatcher.getHandle(InstanceChunkLoadEvent.class);
     public static final ListenerHandle<InventoryItemChangeEvent> INVENTORY_ITEM_CHANGE_EVENT = EventDispatcher.getHandle(InventoryItemChangeEvent.class);
+    public static final ListenerHandle<PlayerInventoryItemChangeEvent> PLAYER_INVENTORY_ITEM_CHANGE_EVENT = EventDispatcher.getHandle(PlayerInventoryItemChangeEvent.class);
 }

src/main/java/net/minestom/server/event/inventory/InventoryItemChangeEvent.java

@@ -3,7 +3,6 @@ package net.minestom.server.event.inventory;
 import net.minestom.server.event.trait.InventoryEvent;
 import net.minestom.server.inventory.AbstractInventory;
 import net.minestom.server.inventory.Inventory;
-import net.minestom.server.inventory.PlayerInventory;
 import net.minestom.server.item.ItemStack;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
@@ -11,20 +10,20 @@ import org.jetbrains.annotations.Nullable;
 /**
  * Called when {@link AbstractInventory#safeItemInsert(int, ItemStack)} is being invoked.
  * This event cannot be cancelled and items related to the change are already moved.
+ *
+ * @see PlayerInventoryItemChangeEvent
  */
 @SuppressWarnings("JavadocReference")
 public class InventoryItemChangeEvent implements InventoryEvent {
 
     private final Inventory inventory;
-    private final PlayerInventory playerInventory;
     private final int slot;
     private final ItemStack previousItem;
     private final ItemStack newItem;
 
-    public InventoryItemChangeEvent(@Nullable Inventory inventory, @Nullable PlayerInventory playerInventory,
-                                    int slot, @NotNull ItemStack previousItem, @NotNull ItemStack newItem) {
+    public InventoryItemChangeEvent(@Nullable Inventory inventory, int slot,
+                                    @NotNull ItemStack previousItem, @NotNull ItemStack newItem) {
         this.inventory = inventory;
-        this.playerInventory = playerInventory;
         this.slot = slot;
         this.previousItem = previousItem;
         this.newItem = newItem;
@@ -57,16 +56,6 @@ public class InventoryItemChangeEvent implements InventoryEvent {
         return newItem;
     }
 
-    /**
-     * Gets a player inventory in which an event has occurred.
-     * If event happened in a regular (i.e. not player) inventory, the result is null.
-     *
-     * @return null or a player inventory in which an event has occurred.
-     */
-    public @Nullable PlayerInventory getPlayerInventory() {
-        return playerInventory;
-    }
-
     @Override
     public @Nullable Inventory getInventory() {
         return inventory;

src/main/java/net/minestom/server/event/inventory/PlayerInventoryItemChangeEvent.java

@@ -0,0 +1,32 @@
+package net.minestom.server.event.inventory;
+
+import net.minestom.server.entity.Player;
+import net.minestom.server.event.trait.PlayerEvent;
+import net.minestom.server.event.trait.RecursiveEvent;
+import net.minestom.server.inventory.AbstractInventory;
+import net.minestom.server.inventory.PlayerInventory;
+import net.minestom.server.item.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * Called when {@link AbstractInventory#safeItemInsert(int, ItemStack)} is being invoked on a {@link PlayerInventory}.
+ * This event cannot be cancelled and items related to the change are already moved.
+ *
+ * When this event is being called, {@link InventoryItemChangeEvent} listeners will also be triggered, so you can
+ * listen only for an ancestor event and check whether it is an instance of that class.
+ */
+@SuppressWarnings("JavadocReference")
+public class PlayerInventoryItemChangeEvent extends InventoryItemChangeEvent implements PlayerEvent, RecursiveEvent {
+
+    private final Player player;
+
+    public PlayerInventoryItemChangeEvent(@NotNull Player player, int slot, @NotNull ItemStack previousItem, @NotNull ItemStack newItem) {
+        super(null, slot, previousItem, newItem);
+        this.player = player;
+    }
+
+    @Override
+    public @NotNull Player getPlayer() {
+        return player;
+    }
+}

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

@@ -65,20 +65,23 @@ public abstract class AbstractInventory implements InventoryClickHandler, TagHan
      *
      * @throws IllegalArgumentException if the slot {@code slot} does not exist
      */
-    protected synchronized final void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
-        Check.argCondition(
-                !MathUtils.isBetween(slot, 0, getSize()),
-                "The slot {0} does not exist in this inventory",
-                slot
-        );
-        ItemStack previous = itemStacks[slot];
-        UNSAFE_itemInsert(slot, itemStack);
-        GlobalHandles.INVENTORY_ITEM_CHANGE_EVENT.call(getItemChangeEvent(slot, previous, itemStack));
+    protected final void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
+        ItemStack previous;
+        synchronized (this) {
+            Check.argCondition(
+                    !MathUtils.isBetween(slot, 0, getSize()),
+                    "The slot {0} does not exist in this inventory",
+                    slot
+            );
+            previous = itemStacks[slot];
+            UNSAFE_itemInsert(slot, itemStack);
+        }
+        callItemChangeEvent(slot, previous, itemStack);
     }
 
     protected abstract void UNSAFE_itemInsert(int slot, @NotNull ItemStack itemStack);
 
-    protected abstract InventoryItemChangeEvent getItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current);
+    protected abstract void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current);
 
     public synchronized <T> @NotNull T processItemStack(@NotNull ItemStack itemStack,
                                                         @NotNull TransactionType type,

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

@@ -3,6 +3,7 @@ package net.minestom.server.inventory;
 import net.kyori.adventure.text.Component;
 import net.minestom.server.Viewable;
 import net.minestom.server.entity.Player;
+import net.minestom.server.event.GlobalHandles;
 import net.minestom.server.event.inventory.InventoryItemChangeEvent;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickResult;
@@ -217,8 +218,8 @@ public class Inventory extends AbstractInventory implements Viewable {
     }
 
     @Override
-    protected InventoryItemChangeEvent getItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
-        return new InventoryItemChangeEvent(this, null, slot, previous, current);
+    protected void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
+        GlobalHandles.INVENTORY_ITEM_CHANGE_EVENT.call(new InventoryItemChangeEvent(this, slot, previous, current));
     }
 
     /**

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

@@ -3,7 +3,9 @@ package net.minestom.server.inventory;
 import net.minestom.server.entity.EquipmentSlot;
 import net.minestom.server.entity.Player;
 import net.minestom.server.event.EventDispatcher;
+import net.minestom.server.event.GlobalHandles;
 import net.minestom.server.event.inventory.InventoryItemChangeEvent;
+import net.minestom.server.event.inventory.PlayerInventoryItemChangeEvent;
 import net.minestom.server.event.item.EntityEquipEvent;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickResult;
@@ -179,8 +181,8 @@ public class PlayerInventory extends AbstractInventory implements EquipmentHandl
     }
 
     @Override
-    protected InventoryItemChangeEvent getItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
-        return new InventoryItemChangeEvent(null, this, slot, previous, current);
+    protected void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
+        GlobalHandles.PLAYER_INVENTORY_ITEM_CHANGE_EVENT.call(new PlayerInventoryItemChangeEvent(player, slot, previous, current));
     }
 
     /**