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 27cdfbeb6cb2159075b35dd4f9e9557ec0eac7c2..e246bf034a86deba5a15e7c639f5e08213fe7eee 100644
--- a/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
+++ b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
@@ -246,8 +246,11 @@ 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 6549ffa087f9955849024fa62cfca9e91cbecf30..f1c56823e1e89251c518d9d51ab7442b30a85336 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;
@@ -1202,8 +1205,37 @@ 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);
     }