Add PlayerEnchantItemEvent (#1363)

This event is fired after a player enchants an item, allowing other mods to react to that action.

patches/net/minecraft/world/inventory/EnchantmentMenu.java.patch

@@ -45,13 +45,14 @@
 -                                    itemstack2 = itemstack.transmuteCopy(Items.ENCHANTED_BOOK);
 -                                    this.enchantSlots.setItem(0, itemstack2);
 -                                }
- 
+-
 -                                for (EnchantmentInstance enchantmentinstance : list) {
 -                                    itemstack2.enchant(enchantmentinstance.enchantment, enchantmentinstance.level);
 -                                }
 +                                // Neo: Allow items to transform themselves when enchanted, instead of relying on hardcoded transformations for Items.BOOK
 +                                itemstack2 = itemstack.getItem().applyEnchantments(itemstack, list);
 +                                this.enchantSlots.setItem(0, itemstack2);
++                                net.neoforged.neoforge.common.CommonHooks.onPlayerEnchantItem(p_39465_, itemstack2, list);
 
                                  itemstack1.consume(i, p_39465_);
                                  if (itemstack1.isEmpty()) {

src/main/java/net/neoforged/neoforge/common/CommonHooks.java

@@ -102,6 +102,7 @@
 import net.minecraft.world.inventory.AnvilMenu;
 import net.minecraft.world.inventory.ClickAction;
 import net.minecraft.world.inventory.ContainerLevelAccess;
+import net.minecraft.world.inventory.EnchantmentMenu;
 import net.minecraft.world.inventory.RecipeBookType;
 import net.minecraft.world.inventory.Slot;
 import net.minecraft.world.item.AdventureModePredicate;
@@ -120,6 +121,7 @@
 import net.minecraft.world.item.component.ItemAttributeModifiers;
 import net.minecraft.world.item.context.UseOnContext;
 import net.minecraft.world.item.enchantment.Enchantment;
+import net.minecraft.world.item.enchantment.EnchantmentInstance;
 import net.minecraft.world.item.enchantment.ItemEnchantments;
 import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.GameType;
@@ -200,6 +202,7 @@
 import net.neoforged.neoforge.event.entity.player.AnvilRepairEvent;
 import net.neoforged.neoforge.event.entity.player.AttackEntityEvent;
 import net.neoforged.neoforge.event.entity.player.CriticalHitEvent;
+import net.neoforged.neoforge.event.entity.player.PlayerEnchantItemEvent;
 import net.neoforged.neoforge.event.entity.player.PlayerEvent;
 import net.neoforged.neoforge.event.entity.player.PlayerInteractEvent;
 import net.neoforged.neoforge.event.level.BlockDropsEvent;
@@ -665,6 +668,18 @@ public static InteractionResult onPlaceItemIntoWorld(UseOnContext context) {
         return ret;
     }
 
+    /**
+     * Fires {@link PlayerEnchantItemEvent} in {@link EnchantmentMenu#clickMenuButton(Player, int)} after the enchants are
+     * applied to the item.
+     *
+     * @param player    the player who clicked the menu button
+     * @param stack     the item enchanted
+     * @param instances the specific enchantments that were applied to the item.
+     */
+    public static void onPlayerEnchantItem(Player player, ItemStack stack, List<EnchantmentInstance> instances) {
+        NeoForge.EVENT_BUS.post(new PlayerEnchantItemEvent(player, stack, instances));
+    }
+
     public static boolean onAnvilChange(AnvilMenu container, ItemStack left, ItemStack right, Container outputSlot, String name, long baseCost, Player player) {
         AnvilUpdateEvent e = new AnvilUpdateEvent(left, right, name, baseCost, player);
         if (NeoForge.EVENT_BUS.post(e).isCanceled())

src/main/java/net/neoforged/neoforge/event/entity/player/PlayerEnchantItemEvent.java

@@ -0,0 +1,42 @@
+/*
+ * Copyright (c) NeoForged and contributors
+ * SPDX-License-Identifier: LGPL-2.1-only
+ */
+
+package net.neoforged.neoforge.event.entity.player;
+
+import java.util.List;
+import net.minecraft.world.entity.player.Player;
+import net.minecraft.world.item.ItemStack;
+import net.minecraft.world.item.enchantment.EnchantmentInstance;
+import net.neoforged.neoforge.common.extensions.IItemExtension;
+
+/**
+ * This event fires when a player enchants an item, after {@link IItemExtension#applyEnchantments} has been called.
+ * <p>
+ * This event is only fired on the logical server.
+ */
+public class PlayerEnchantItemEvent extends PlayerEvent {
+    private final ItemStack enchantedItem;
+    private final List<EnchantmentInstance> enchantments;
+
+    public PlayerEnchantItemEvent(Player player, ItemStack enchantedItem, List<EnchantmentInstance> enchantments) {
+        super(player);
+        this.enchantedItem = enchantedItem;
+        this.enchantments = enchantments;
+    }
+
+    /**
+     * @return the {@link ItemStack} after it was enchanted
+     */
+    public ItemStack getEnchantedItem() {
+        return enchantedItem;
+    }
+
+    /**
+     * @return the list of {@link EnchantmentInstance}s that were applied to the item for this event firing
+     */
+    public List<EnchantmentInstance> getEnchantments() {
+        return enchantments;
+    }
+}

tests/src/main/java/net/neoforged/neoforge/debug/enchantment/EnchantmentLevelTests.java

@@ -5,6 +5,8 @@
 
 package net.neoforged.neoforge.debug.enchantment;
 
+import java.util.Objects;
+import net.minecraft.core.BlockPos;
 import net.minecraft.core.component.DataComponents;
 import net.minecraft.core.registries.Registries;
 import net.minecraft.gametest.framework.GameTest;
@@ -14,7 +16,10 @@
 import net.minecraft.world.item.component.CustomData;
 import net.minecraft.world.item.enchantment.Enchantments;
 import net.minecraft.world.item.enchantment.ItemEnchantments;
+import net.minecraft.world.level.block.Blocks;
+import net.minecraft.world.level.block.entity.EnchantingTableBlockEntity;
 import net.neoforged.neoforge.event.enchanting.GetEnchantmentLevelEvent;
+import net.neoforged.neoforge.event.entity.player.PlayerEnchantItemEvent;
 import net.neoforged.testframework.DynamicTest;
 import net.neoforged.testframework.annotation.ForEachTest;
 import net.neoforged.testframework.annotation.TestHolder;
@@ -23,7 +28,7 @@
 
 @ForEachTest(groups = EnchantmentLevelTests.GROUP)
 public class EnchantmentLevelTests {
-    public static final String GROUP = "enchantment.level";
+    public static final String GROUP = "enchantment";
 
     @GameTest
     @EmptyTemplate
@@ -65,4 +70,35 @@ static void getEnchLevelEvent(final DynamicTest test, final RegistrationHelper r
             helper.succeed();
         });
     }
+
+    @GameTest
+    @EmptyTemplate
+    @TestHolder(description = "Tests if the PlayerEnchantedItemEvent fired.")
+    static void playerEnchantItemTest(final DynamicTest test, final RegistrationHelper reg) {
+        test.eventListeners().forge().addListener((PlayerEnchantItemEvent event) -> {
+            event.getEnchantedItem().setDamageValue(1); //change a value we can reference in our test sequence
+        });
+        final BlockPos pos = new BlockPos(1, 2, 1);
+        test.onGameTest(helper -> helper.startSequence(helper::makeMockPlayer)
+                //ensure the player has enough experience to perform an enchantment
+                .thenExecute(player -> player.experienceLevel = 30)
+                //place a table into the world to hold our container
+                .thenExecute(player -> helper.setBlock(pos, Blocks.ENCHANTING_TABLE))
+                //open the menu container on the player
+                .thenExecute(player -> player.containerMenu = Objects.requireNonNull(Objects.requireNonNull(
+                        Objects.requireNonNull(helper.getBlockEntity(pos, EnchantingTableBlockEntity.class)).getBlockState()
+                                .getMenuProvider(player.level(), helper.absolutePos(pos)))
+                        .createMenu(1, player.getInventory(), player)))
+                //simulate putting an iron sword in the first slot
+                .thenExecute(player -> player.containerMenu.setItem(0, player.containerMenu.getStateId(), new ItemStack(Items.IRON_SWORD)))
+                //simulate putting the lapis into the second slot
+                .thenExecute(player -> player.containerMenu.setItem(1, player.containerMenu.getStateId(), new ItemStack(Items.LAPIS_LAZULI)))
+                //ensure the lapis count is enough to pay for any enchanting costs
+                .thenExecute(player -> player.containerMenu.getSlot(1).getItem().setCount(64))
+                //simulate clicking the button on the screen.
+                .thenExecute(player -> player.containerMenu.clickMenuButton(player, 1))
+                //verify the event listener has set the damage value of our item to one
+                .thenWaitUntil(player -> helper.assertTrue(player.containerMenu.getSlot(0).getItem().getDamageValue() == 1, "Enchanted item damage not set by the event"))
+                .thenSucceed());
+    }
 }