Add EntityEquipmentChangedEvent

Author: TonytheMacaroni

paper-api/src/main/java/io/papermc/paper/event/entity/EntityEquipmentChangedEvent.java

@@ -0,0 +1,77 @@
+package io.papermc.paper.event.entity;
+
+import java.util.Collections;
+import java.util.Map;
+import org.bukkit.entity.LivingEntity;
+import org.bukkit.event.HandlerList;
+import org.bukkit.event.entity.EntityEvent;
+import org.bukkit.inventory.EquipmentSlot;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.ApiStatus;
+import org.jetbrains.annotations.Unmodifiable;
+import org.jspecify.annotations.NullMarked;
+
+/**
+ * Called whenever a change to an entity's equipment has been detected. This event is called after effects from
+ * attribute modifiers and enchantments have been updated.
+ * <p>
+ * Examples of actions that can trigger this event:
+ * <ul>
+ *     <li>An entity being added to a world.</li>
+ *     <li>A player logging in.</li>
+ *     <li>The durability of an equipment item changing.</li>
+ *     <li>A dispenser equipping an item onto an entity.</li>
+ *     <li>An entity picking up an armor or weapon item from the ground.</li>
+ *     <li>A player changing their equipped armor.</li>
+ *     <li>A player changes their currently held item.</li>
+ * </ul>
+ */
+@NullMarked
+public class EntityEquipmentChangedEvent extends EntityEvent {
+
+    private static final HandlerList HANDLER_LIST = new HandlerList();
+
+    private final Map<EquipmentSlot, EquipmentChange> equipmentChanges;
+
+    @ApiStatus.Internal
+    public EntityEquipmentChangedEvent(final LivingEntity entity, final Map<EquipmentSlot, EquipmentChange> equipmentChanges) {
+        super(entity);
+
+        this.equipmentChanges = Collections.unmodifiableMap(equipmentChanges);
+    }
+
+    @Override
+    public LivingEntity getEntity() {
+        return (LivingEntity) entity;
+    }
+
+    /**
+     * Gets a map of changed slots to their respective equipment changes.
+     *
+     * @return the equipment changes map
+     */
+    @Unmodifiable
+    public Map<EquipmentSlot, EquipmentChange> getEquipmentChanges() {
+        return equipmentChanges;
+    }
+
+    @Override
+    public HandlerList getHandlers() {
+        return HANDLER_LIST;
+    }
+
+    public static HandlerList getHandlerList() {
+        return HANDLER_LIST;
+    }
+
+    /**
+     * Represents a change in equipment for a single equipment slot.
+     *
+     * @param oldItem the existing item that is being replaced
+     * @param newItem the new item that is replacing the existing item
+     */
+    public record EquipmentChange(ItemStack oldItem, ItemStack newItem) {
+
+    }
+
+}

paper-server/patches/sources/net/minecraft/world/entity/LivingEntity.java.patch

@@ -1336,20 +1336,44 @@
          Map<EquipmentSlot, ItemStack> map = this.collectEquipmentChanges();
          if (map != null) {
              this.handleHandSwap(map);
-@@ -2595,6 +_,13 @@
+@@ -2586,6 +_,7 @@
+     @Nullable
+     private Map<EquipmentSlot, ItemStack> collectEquipmentChanges() {
+         Map<EquipmentSlot, ItemStack> map = null;
++        Map<org.bukkit.inventory.EquipmentSlot, io.papermc.paper.event.entity.EntityEquipmentChangedEvent.EquipmentChange> equipmentChanges = null; // Paper - EntityEquipmentChangedEvent
+ 
+         for (EquipmentSlot equipmentSlot : EquipmentSlot.VALUES) {
+             ItemStack itemStack = switch (equipmentSlot.getType()) {
+@@ -2595,11 +_,20 @@
              };
              ItemStack itemBySlot = this.getItemBySlot(equipmentSlot);
              if (this.equipmentHasChanged(itemStack, itemBySlot)) {
-+                // Paper start - PlayerArmorChangeEvent
++                // Paper start - EntityEquipmentChangedEvent, PlayerArmorChangeEvent
++                final org.bukkit.inventory.ItemStack oldItem = CraftItemStack.asBukkitCopy(itemStack);
++                final org.bukkit.inventory.ItemStack newItem = CraftItemStack.asBukkitCopy(itemBySlot);
 +                if (this instanceof ServerPlayer && equipmentSlot.getType() == EquipmentSlot.Type.HUMANOID_ARMOR) {
-+                    final org.bukkit.inventory.ItemStack oldItem = CraftItemStack.asBukkitCopy(itemStack);
-+                    final org.bukkit.inventory.ItemStack newItem = CraftItemStack.asBukkitCopy(itemBySlot);
 +                    new com.destroystokyo.paper.event.player.PlayerArmorChangeEvent((org.bukkit.entity.Player) this.getBukkitEntity(), com.destroystokyo.paper.event.player.PlayerArmorChangeEvent.SlotType.valueOf(equipmentSlot.name()), oldItem, newItem).callEvent();
 +                }
-+                // Paper end - PlayerArmorChangeEvent
++                // Paper end - EntityEquipmentChangedEvent, PlayerArmorChangeEvent
                  if (map == null) {
                      map = Maps.newEnumMap(EquipmentSlot.class);
++                    equipmentChanges = Maps.newEnumMap(org.bukkit.inventory.EquipmentSlot.class); // Paper - EntityEquipmentChangedEvent
+                 }
+ 
+                 map.put(equipmentSlot, itemBySlot);
++                equipmentChanges.put(org.bukkit.craftbukkit.CraftEquipmentSlot.getSlot(equipmentSlot), new io.papermc.paper.event.entity.EntityEquipmentChangedEvent.EquipmentChange(oldItem, newItem)); // Paper - EntityEquipmentChangedEvent
+                 AttributeMap attributes = this.getAttributes();
+                 if (!itemStack.isEmpty()) {
+                     this.stopLocationBasedEffects(itemStack, equipmentSlot, attributes);
+@@ -2624,6 +_,8 @@
+                     }
                  }
+             }
++
++            new io.papermc.paper.event.entity.EntityEquipmentChangedEvent(this.getBukkitLivingEntity(), equipmentChanges).callEvent(); // Paper - EntityEquipmentChangedEvent
+         }
+ 
+         return map;
 @@ -2664,7 +_,7 @@
                      this.lastBodyItemStack = itemStack;
              }