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/server/EnchantmentManager.java b/src/main/java/net/minecraft/server/EnchantmentManager.java
index cea65c1d80a7bd303cf28a6fe2bd73d542a19557..7a4768c32c426ef3cf16904e0f565a7f8fdc753f 100644
--- a/src/main/java/net/minecraft/server/EnchantmentManager.java
+++ b/src/main/java/net/minecraft/server/EnchantmentManager.java
@@ -251,8 +251,8 @@ public class EnchantmentManager {
         return getEnchantmentLevel(Enchantments.CHANNELING, itemstack) > 0;
     }
 
-    @Nullable
-    public static Entry<EnumItemSlot, ItemStack> b(Enchantment enchantment, EntityLiving entityliving) {
+    public static @javax.annotation.Nonnull ItemStack getRandomEquippedItemWithEnchant(Enchantment enchantment, EntityLiving entityliving) { Entry<EnumItemSlot, ItemStack> entry = b(enchantment, entityliving); return entry != null ? entry.getValue() : ItemStack.NULL_ITEM; } // Paper - OBFHELPER
+    @Nullable public static Entry<EnumItemSlot, ItemStack> b(Enchantment enchantment, EntityLiving entityliving) {
         return a(enchantment, entityliving, (itemstack) -> {
             return true;
         });
diff --git a/src/main/java/net/minecraft/server/EntityExperienceOrb.java b/src/main/java/net/minecraft/server/EntityExperienceOrb.java
index e7fb982913f391bafd608c4626086cd9cab7fad7..86fb9286cfd4e0debc00e034c3a5ff33f0a1fe06 100644
--- a/src/main/java/net/minecraft/server/EntityExperienceOrb.java
+++ b/src/main/java/net/minecraft/server/EntityExperienceOrb.java
@@ -249,10 +249,12 @@ public class EntityExperienceOrb extends Entity {
         }
     }
 
+    public final int durToXp(int i) { return b(i); } // Paper OBFHELPER
     private int b(int i) {
         return i / 2;
     }
 
+    public final 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 0121f5009b31b6d9cad0e89264fb78833177d83b..c1192c646a41a906fcb09c9b4aef611b451b1e26 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -1079,8 +1079,37 @@ 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.setPositionRaw(handle.locX(), handle.locY(), 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);
     }