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 284772518ecb00d9e83a9e22480842deeba47dd0..18f061f96d5c4da2c0dbd4bce1f1a7f1ee1cd62f 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);
     }