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/entity/EntityExperienceOrb.java b/src/main/java/net/minecraft/world/entity/EntityExperienceOrb.java
index e3dfb018b06c0139594ddbb88fab2ca8d43ab12f..3387a19044b3ee2a1ef549c328c8bc354a5b6d23 100644
--- a/src/main/java/net/minecraft/world/entity/EntityExperienceOrb.java
+++ b/src/main/java/net/minecraft/world/entity/EntityExperienceOrb.java
@@ -265,10 +265,12 @@ 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/net/minecraft/world/item/enchantment/EnchantmentManager.java b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentManager.java
index d313b02f41e4f4a90676cbb37afce4e92dd4d664..72afbf8f537770540e90a2880ea81de137ea10f5 100644
--- a/src/main/java/net/minecraft/world/item/enchantment/EnchantmentManager.java
+++ b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentManager.java
@@ -269,8 +269,8 @@ 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/org/bukkit/craftbukkit/entity/CraftPlayer.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
index cf9ae60db30ef09bb4c89935a42632e562b6d61e..4766a78a0562e5ae6e7d4850bd7b5d71425c3a0c 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -58,13 +58,17 @@ import net.minecraft.server.level.WorldServer;
 import net.minecraft.server.network.PlayerConnection;
 import net.minecraft.server.players.WhiteListEntry;
 import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntityExperienceOrb;
 import net.minecraft.world.entity.EntityLiving;
+import net.minecraft.world.entity.EntityTypes;
 import net.minecraft.world.entity.ai.attributes.AttributeMapBase;
 import net.minecraft.world.entity.ai.attributes.AttributeModifiable;
 import net.minecraft.world.entity.ai.attributes.GenericAttributes;
 import net.minecraft.world.entity.player.EntityHuman;
 import net.minecraft.world.inventory.Container;
 import net.minecraft.world.item.EnumColor;
+import net.minecraft.world.item.enchantment.EnchantmentManager;
+import net.minecraft.world.item.enchantment.Enchantments;
 import net.minecraft.world.level.EnumGamemode;
 import net.minecraft.world.level.block.entity.TileEntitySign;
 import net.minecraft.world.level.saveddata.maps.MapIcon;
@@ -1180,8 +1184,37 @@ 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.world.item.ItemStack itemstack = EnchantmentManager.getRandomEquippedItemWithEnchant(Enchantments.MENDING, handle);
+        if (!itemstack.isEmpty() && itemstack.getItem().usesDurability()) {
+
+            EntityExperienceOrb orb = 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);
     }