From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Lulu13022002 <41980282+Lulu13022002@users.noreply.github.com>
Date: Sun, 16 Oct 2022 16:12:49 +0200
Subject: [PATCH] More vanilla friendly methods to update trades


diff --git a/src/main/java/net/minecraft/world/entity/npc/Villager.java b/src/main/java/net/minecraft/world/entity/npc/Villager.java
index ec46a095a26af507fdee0485f7c519c14decc95f..a62f69210ac63c44ade4f3ce9379071b93122afb 100644
--- a/src/main/java/net/minecraft/world/entity/npc/Villager.java
+++ b/src/main/java/net/minecraft/world/entity/npc/Villager.java
@@ -923,6 +923,12 @@ public class Villager extends AbstractVillager implements ReputationEventHandler
 
     @Override
     protected void updateTrades() {
+        // Paper start
+        updateTrades(TRADES_PER_LEVEL);
+    }
+
+    public boolean updateTrades(int amount) {
+        // Paper end
         VillagerData villagerdata = this.getVillagerData();
         Int2ObjectMap<VillagerTrades.ItemListing[]> int2objectmap = (Int2ObjectMap) VillagerTrades.TRADES.get(villagerdata.getProfession());
 
@@ -932,9 +938,11 @@ public class Villager extends AbstractVillager implements ReputationEventHandler
             if (avillagertrades_imerchantrecipeoption != null) {
                 MerchantOffers merchantrecipelist = this.getOffers();
 
-                this.addOffersFromItemListings(merchantrecipelist, avillagertrades_imerchantrecipeoption, 2);
+                this.addOffersFromItemListings(merchantrecipelist, avillagertrades_imerchantrecipeoption, amount); // Paper
+                return true; // Paper
             }
         }
+        return false; // Paper
     }
 
     public void gossip(ServerLevel world, Villager villager, long time) {
diff --git a/src/main/java/org/bukkit/craftbukkit/entity/CraftVillager.java b/src/main/java/org/bukkit/craftbukkit/entity/CraftVillager.java
index 11e44a81934255fd4efa418009d8bb78c785cfd5..e0c083f54434120609cd95824cab509fa6c93427 100644
--- a/src/main/java/org/bukkit/craftbukkit/entity/CraftVillager.java
+++ b/src/main/java/org/bukkit/craftbukkit/entity/CraftVillager.java
@@ -99,6 +99,34 @@ public class CraftVillager extends CraftAbstractVillager implements Villager {
     }
 
     // Paper start
+    @Override
+    public boolean increaseLevel(int amount) {
+        Preconditions.checkArgument(amount > 0, "Level earned must be positive");
+        int supposedFinalLevel = this.getVillagerLevel() + amount;
+        Preconditions.checkArgument(net.minecraft.world.entity.npc.VillagerData.MIN_VILLAGER_LEVEL <= supposedFinalLevel && supposedFinalLevel <= net.minecraft.world.entity.npc.VillagerData.MAX_VILLAGER_LEVEL,
+            "Final level reached after the donation (%d) must be between [%d, %d]".formatted(supposedFinalLevel, net.minecraft.world.entity.npc.VillagerData.MIN_VILLAGER_LEVEL, net.minecraft.world.entity.npc.VillagerData.MAX_VILLAGER_LEVEL));
+
+        it.unimi.dsi.fastutil.ints.Int2ObjectMap<net.minecraft.world.entity.npc.VillagerTrades.ItemListing[]> trades =
+            net.minecraft.world.entity.npc.VillagerTrades.TRADES.get(this.getHandle().getVillagerData().getProfession());
+
+        if (trades == null || trades.isEmpty()) {
+            this.getHandle().setVillagerData(this.getHandle().getVillagerData().setLevel(supposedFinalLevel));
+            return false;
+        }
+
+        while (amount > 0) {
+            this.getHandle().increaseMerchantCareer();
+            amount--;
+        }
+        return true;
+    }
+
+    @Override
+    public boolean addTrades(int amount) {
+        Preconditions.checkArgument(amount > 0, "Number of trades unlocked must be positive");
+        return this.getHandle().updateTrades(amount);
+    }
+
     @Override
     public int getRestocksToday() {
         return getHandle().numberOfRestocksToday;