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/ExperienceOrb.java b/src/main/java/net/minecraft/world/entity/ExperienceOrb.java
index 885c5a920204a31b24c7d360390eaf4177c30698..52b90ef3a145325209d3d903a2b7c9a44c332cbe 100644
--- a/src/main/java/net/minecraft/world/entity/ExperienceOrb.java
+++ b/src/main/java/net/minecraft/world/entity/ExperienceOrb.java
@@ -264,10 +264,12 @@ public class ExperienceOrb extends Entity {
         }
     }
 
+    public final int durToXp(int i) { return durabilityToXp(i); } // Paper OBFHELPER
     private int durabilityToXp(int repairAmount) {
         return repairAmount / 2;
     }
 
+    public final int xpToDur(int i) { return xpToDurability(i); } // Paper OBFHELPER
     private int xpToDurability(int experienceAmount) {
         return experienceAmount * 2;
     }
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 045f937f0b7acd73469b65897bea2ca9036acf22..c82e1b6e3ec98530099fd6452fdaaefebfd99b33 100644
--- a/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
+++ b/src/main/java/net/minecraft/world/item/enchantment/EnchantmentHelper.java
@@ -269,8 +269,8 @@ public class EnchantmentHelper {
         return getItemEnchantmentLevel(Enchantments.CHANNELING, stack) > 0;
     }
 
-    @Nullable
-    public static Entry<EquipmentSlot, ItemStack> getRandomItemWith(Enchantment enchantment, LivingEntity entity) {
+    public static @javax.annotation.Nonnull ItemStack getRandomEquippedItemWithEnchant(Enchantment enchantment, LivingEntity entityliving) { Entry<EquipmentSlot, ItemStack> entry = getRandomItemWith(enchantment, entityliving); return entry != null ? entry.getValue() : ItemStack.NULL_ITEM; } // Paper - OBFHELPER
+    @Nullable public static Entry<EquipmentSlot, ItemStack> getRandomItemWith(Enchantment enchantment, LivingEntity entity) {
         return getRandomItemWith(enchantment, entity, (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 8a5bf0b83c1e65f07e14da0e053a64c34976b91a..efdcb8dac8db15c4bbaed84a7861ce98339e516a 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftPlayer.java
@@ -58,11 +58,14 @@ 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.entity.SignBlockEntity;
 import net.minecraft.world.level.saveddata.maps.MapDecoration;
@@ -1176,8 +1179,37 @@ public class CraftPlayer extends CraftHumanEntity implements Player {
         return GameMode.getByValue(getHandle().gameMode.getGameModeForPlayer().getId());
     }
 
+    // Paper start
     @Override
-    public void giveExp(int exp) {
+    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.xpToDur(amount), itemstack.getDamageValue());
+            org.bukkit.event.player.PlayerItemMendEvent event = org.bukkit.craftbukkit.event.CraftEventFactory.callPlayerItemMendEvent(handle, orb, itemstack, i);
+            i = event.getRepairAmount();
+            orb.removed = true;
+            if (!event.isCancelled()) {
+                amount -= orb.durToXp(i);
+                itemstack.setDamageValue(itemstack.getDamageValue() - i);
+            }
+        }
+        return amount;
+    }
+
+    @Override
+    public void giveExp(int exp, boolean applyMending) {
+        if (applyMending) {
+            exp = this.applyMending(exp);
+        }
+        // Paper end
         getHandle().giveExperiencePoints(exp);
     }