From 72ec0195082095bf3f6043846e3450dd66f06963 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/server/EnchantmentManager.java b/src/main/java/net/minecraft/server/EnchantmentManager.java
index 1822178e8..fabc7a8dd 100644
--- a/src/main/java/net/minecraft/server/EnchantmentManager.java
+++ b/src/main/java/net/minecraft/server/EnchantmentManager.java
@@ -246,6 +246,11 @@ public class EnchantmentManager {
         return getEnchantmentLevel(Enchantments.CHANNELING, itemstack) > 0;
     }
 
+    // Paper - OBFHELPER
+    public static @Nullable ItemStack getRandomEquippedItemWithEnchant(Enchantment enchantment, EntityLiving entityliving) {
+        Entry<EnumItemSlot, ItemStack> entry = b(enchantment, entityliving);
+        return entry != null ? entry.getValue() : null;
+    }
     @Nullable
     public static Entry<EnumItemSlot, ItemStack> b(Enchantment enchantment, EntityLiving entityliving) {
         Map<EnumItemSlot, ItemStack> map = enchantment.a(entityliving);
diff --git a/src/main/java/net/minecraft/server/EntityExperienceOrb.java b/src/main/java/net/minecraft/server/EntityExperienceOrb.java
index b3edb69a9..87c6b77ce 100644
--- a/src/main/java/net/minecraft/server/EntityExperienceOrb.java
+++ b/src/main/java/net/minecraft/server/EntityExperienceOrb.java
@@ -254,10 +254,12 @@ public class EntityExperienceOrb extends Entity {
         }
     }
 
+    public int durToXp(int i) { return b(i); } // Paper OBFHELPER
     private int b(int i) {
         return i / 2;
     }
 
+    public int xpToDur(int i) { return c(i); } // Paper OBFHELPER
     private int c(int i) {
         return i * 2;
     }
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index cade504af..c82de14eb 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -1047,8 +1047,39 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         return GameMode.getByValue(getHandle().playerInteractManager.getGameMode().getId());
     }
 
+    // Paper start
     @Override
-    public void giveExp(int exp) {
+    public int applyMending(int amount) {
+        EntityPlayer handle = getHandle();
+        // Logic copied from EntityExperienceOrb and remapped to unobfuscated methods/properties
+        net.minecraft.server.ItemStack itemstack = net.minecraft.server.EnchantmentManager.getRandomEquippedItemWithEnchant(net.minecraft.server.Enchantments.MENDING, handle);
+        if (!itemstack.isEmpty() && itemstack.getItem().usesDurability()) {
+
+            net.minecraft.server.EntityExperienceOrb orb = net.minecraft.server.EntityTypes.EXPERIENCE_ORB.create(handle.world);
+            orb.value = amount;
+            orb.spawnReason = org.bukkit.entity.ExperienceOrb.SpawnReason.CUSTOM;
+            orb.locX = handle.locX;
+            orb.locY = handle.locY;
+            orb.locZ = handle.locZ;
+
+            int i = Math.min(orb.xpToDur(amount), itemstack.getDamage());
+            org.bukkit.event.player.PlayerItemMendEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerItemMendEvent(handle, orb, itemstack, i);
+            i = event.getRepairAmount();
+            orb.dead = true;
+            if (!event.isCancelled()) {
+                amount -= orb.durToXp(i);
+                itemstack.setDamage(itemstack.getDamage() - i);
+            }
+        }
+        return amount;
+    }
+
+    @Override
+    public void giveExp(int exp, boolean applyMending) {
+        if (applyMending) {
+            exp = this.applyMending(exp);
+        }
+        // Paper end
         getHandle().giveExp(exp);
     }
 
-- 
2.17.1