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 3a09ce6d0ea51436adcae4719d3f28d1868c283c..7bc5aa35b52de0027cf58a6127a9903464ccaf47 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 bd17c008f307e27e493f6a1adda3e9ad89b2e73d..f9964ef85a7162a5aed81041accf3ae1528c5144 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -1224,8 +1224,37 @@ 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 = net.minecraft.world.item.enchantment.EnchantmentHelper
+            .getRandomEquippedItemWithEnchant(net.minecraft.world.item.enchantment.Enchantments.MENDING, handle);
+        if (!itemstack.isEmpty() && itemstack.getItem().canBeDepleted()) {
+            net.minecraft.world.entity.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);
     }