From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 20 Dec 2017 17:36:49 -0500
Subject: [PATCH] Ability to apply mending to XP API

This allows plugins that give players the ability to apply the experience
points to the Item Mending formula, which will repair an item instead
of giving the player experience points.

Both an API To standalone mend, and apply mending logic to .giveExp has been added.

diff --git a/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
index 6f25e9f41d93a225acaa6575954967438a6cabbf..d439e8ce87bf7da03683a336941c7673b8b166e4 100644
--- a/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
+++ b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
@@ -270,8 +270,11 @@ public class EnchantmentHelper {
         return getItemEnchantmentLevel(Enchantments.CHANNELING, stack) > 0;
     }
 
-    @Nullable
-    public static Entry<EquipmentSlot, ItemStack> getRandomItemWith(Enchantment enchantment, LivingEntity entity) {
+    @Deprecated public static @javax.annotation.Nonnull ItemStack getRandomEquippedItemWithEnchant(Enchantment enchantment, LivingEntity entityliving) {
+        Entry<EquipmentSlot, ItemStack> entry = getRandomItemWith(enchantment, entityliving);
+        return entry != null ? entry.getValue() : ItemStack.EMPTY;
+    } // Paper - OBFHELPER
+    @Nullable public static Entry<EquipmentSlot, ItemStack> getRandomItemWith(Enchantment enchantment, LivingEntity entity) {
         return getRandomItemWith(enchantment, entity, (stack) -> {
             return true;
         });
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index b894b849d0063ea54696de8d0cb8286a14c45e7b..05a427f238d48c8bb815083c21e62f8e5cb75ed0 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -61,11 +61,14 @@ import net.minecraft.server.level.ServerPlayer;
 import net.minecraft.server.network.ServerGamePacketListenerImpl;
 import net.minecraft.server.players.UserWhiteListEntry;
 import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.ExperienceOrb;
 import net.minecraft.world.entity.LivingEntity;
 import net.minecraft.world.entity.ai.attributes.AttributeInstance;
 import net.minecraft.world.entity.ai.attributes.AttributeMap;
 import net.minecraft.world.entity.ai.attributes.Attributes;
 import net.minecraft.world.inventory.AbstractContainerMenu;
+import net.minecraft.world.item.enchantment.EnchantmentHelper;
+import net.minecraft.world.item.enchantment.Enchantments;
 import net.minecraft.world.level.GameType;
 import net.minecraft.world.level.block.Blocks;
 import net.minecraft.world.level.block.entity.SignBlockEntity;
@@ -1203,8 +1206,37 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         return GameMode.getByValue(this.getHandle().gameMode.getGameModeForPlayer().getId());
     }
 
+    // Paper start
+    @Override
+    public int applyMending(int amount) {
+        ServerPlayer handle = getHandle();
+        // Logic copied from EntityExperienceOrb and remapped to unobfuscated methods/properties
+        net.minecraft.world.item.ItemStack itemstack = EnchantmentHelper.getRandomEquippedItemWithEnchant(Enchantments.MENDING, handle);
+        if (!itemstack.isEmpty() && itemstack.getItem().canBeDepleted()) {
+
+            ExperienceOrb orb = net.minecraft.world.entity.EntityType.EXPERIENCE_ORB.create(handle.level);
+            orb.value = amount;
+            orb.spawnReason = org.bukkit.entity.ExperienceOrb.SpawnReason.CUSTOM;
+            orb.setPosRaw(handle.getX(), handle.getY(), handle.getZ());
+
+            int i = Math.min(orb.xpToDurability(amount), itemstack.getDamageValue());
+            org.bukkit.event.player.PlayerItemMendEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerItemMendEvent(handle, orb, itemstack, i);
+            i = event.getRepairAmount();
+            orb.discard();
+            if (!event.isCancelled()) {
+                amount -= orb.durabilityToXp(i);
+                itemstack.setDamageValue(itemstack.getDamageValue() - i);
+            }
+        }
+        return amount;
+    }
+
     @Override
-    public void giveExp(int exp) {
+    public void giveExp(int exp, boolean applyMending) {
+        if (applyMending) {
+            exp = this.applyMending(exp);
+        }
+        // Paper end
         this.getHandle().giveExperiencePoints(exp);
     }