Rebased and re-commital of Piglin barter recipe addition.

src/main/java/io/github/thebusybiscuit/slimefun4/core/SlimefunRegistry.java

@@ -69,6 +69,7 @@ public class SlimefunRegistry {
     private final Set<String> tickers = new HashSet<>();
     private final Set<SlimefunItem> radioactive = new HashSet<>();
     private final Set<String> activeChunks = ConcurrentHashMap.newKeySet();
+    private final Set<ItemStack> barterDrops = new HashSet<>();
     
     private final KeyMap<GEOResource> geoResources = new KeyMap<>();
 
@@ -199,6 +200,9 @@ public class SlimefunRegistry {
         return mobDrops;
     }
 
+    public Set<ItemStack> getBarterDrops() {
+        return barterDrops;
+    }
     public Set<SlimefunItem> getRadioactiveItems() {
         return radioactive;
     }

src/main/java/io/github/thebusybiscuit/slimefun4/core/attributes/RandomMobDrop.java

@@ -2,7 +2,6 @@ package io.github.thebusybiscuit.slimefun4.core.attributes;
 
 import org.bukkit.entity.EntityType;
 import org.bukkit.entity.Player;
-import org.bukkit.event.entity.EntityDeathEvent;
 
 import io.github.thebusybiscuit.slimefun4.implementation.items.misc.BasicCircuitBoard;
 import io.github.thebusybiscuit.slimefun4.implementation.listeners.MobDropListener;
@@ -11,8 +10,8 @@ import me.mrCookieSlime.Slimefun.Objects.SlimefunItem.SlimefunItem;
 
 /**
  * This interface, when attached to a {@link SlimefunItem}, provides an easy method for adding
- * a % chance to drop for an {@link SlimefunItem} on {@link EntityDeathEvent}, this chance is 0-100
+ * a % chance to drop for an {@link SlimefunItem} on {@link entityDeathEvent} or {@link EntityItemDropEvent}, this chance is 0-100
- * and used in conjunction with the MOB_DROP {@link RecipeType}.
+ * and used in conjunction with the MOB_DROP {@link RecipeType} or the BARTER_DROP {@link RecipeType}.
  * 
  * @author dNiym
  *
@@ -26,7 +25,15 @@ public interface RandomMobDrop extends ItemAttribute {
     /**
      * Implement this method to make the object have a variable chance of being
      * added to the dropList when {@link EntityType} (specified in the recipe)
-     * is killed by the {@link Player}
+     * is killed by the {@link Player} for a MOB_DROP {@link RecipeType}.
+     * 
+     * Alternatively if the {@link RecipeType} is set to BARTER_DROP the item
+     * will then have its % chance to be dropped only by bartering with the
+     * Piglin creatures.
+     * 
+     * It is recommended that this chance is kept reasonably low to feel like
+     * a vanilla drop as a 100% chance will completely override all piglin 
+     * barter drops.  (NOTE: this feature only exists in 1.16+)
      * 
      * @return The integer chance (0-100%) {@link SlimefunItem} has to drop.
      */

src/main/java/io/github/thebusybiscuit/slimefun4/implementation/listeners/PiglinListener.java

@@ -1,16 +1,22 @@
 package io.github.thebusybiscuit.slimefun4.implementation.listeners;
 
+import java.util.Set;
+import java.util.concurrent.ThreadLocalRandom;
+
 import org.bukkit.Material;
 import org.bukkit.entity.EntityType;
+import org.bukkit.entity.Item;
 import org.bukkit.entity.Piglin;
 import org.bukkit.entity.Player;
 import org.bukkit.event.EventHandler;
 import org.bukkit.event.Listener;
+import org.bukkit.event.entity.EntityDropItemEvent;
 import org.bukkit.event.entity.EntityPickupItemEvent;
 import org.bukkit.event.player.PlayerInteractEntityEvent;
 import org.bukkit.inventory.EquipmentSlot;
 import org.bukkit.inventory.ItemStack;
 
+import io.github.thebusybiscuit.slimefun4.core.attributes.RandomMobDrop;
 import io.github.thebusybiscuit.slimefun4.implementation.SlimefunPlugin;
 import me.mrCookieSlime.Slimefun.Objects.SlimefunItem.SlimefunItem;
 
@@ -20,6 +26,18 @@ import me.mrCookieSlime.Slimefun.Objects.SlimefunItem.SlimefunItem;
  * @author poma123
  * 
  */
+
+/**
+ * Also {@link Listener} Listens to the EntityDropItemEvent event to inject a {@link RandomMobDrop} if its dropChance() check passes.
+ * this would only be possible if the {@link RecipeType} is of PiglinBarter type. 
+ * 
+ * @author dNiym
+ * 
+ * @see getBarterDrops
+ * @see RandomMobDrop
+ * 
+ */
+
 public class PiglinListener implements Listener {
 
     public PiglinListener(SlimefunPlugin plugin) {
@@ -38,6 +56,29 @@ public class PiglinListener implements Listener {
         }
     }
 
+    @EventHandler
+    public void onPiglinDropItem(EntityDropItemEvent e) {
+        if (e.getEntity() instanceof Piglin) {
+            Set<ItemStack> drops = SlimefunPlugin.getRegistry().getBarterDrops(); 
+            
+            /*
+             * NOTE:  Getting a new random number each iteration because multiple items could have the same
+             * % chance to drop, and if one fails all items with that number will fail.  Getting a new random number
+             * will allow multiple items with the same % chance to drop.
+             */
+            
+            for (ItemStack is : drops) {
+                SlimefunItem sfi = SlimefunItem.getByItem(is);
+                if (sfi instanceof RandomMobDrop && ((RandomMobDrop)sfi).getMobDropChance() >= ThreadLocalRandom.current().nextInt(100)) {
+                    Item drop = e.getEntity().getWorld().dropItemNaturally(((Piglin)e.getEntity()).getEyeLocation(), sfi.getItem());
+                    drop.setVelocity(e.getItemDrop().getVelocity());
+                    e.getItemDrop().remove();
+                    return;
+                } 
+            }
+        }
+    }
+    
     @EventHandler
     public void onInteractEntity(PlayerInteractEntityEvent e) {
         if (!e.getRightClicked().isValid() || e.getRightClicked().getType() != EntityType.PIGLIN) {

src/main/java/me/mrCookieSlime/Slimefun/Lists/RecipeType.java

@@ -19,6 +19,7 @@ import org.bukkit.inventory.ItemStack;
 
 import io.github.thebusybiscuit.cscorelib2.item.CustomItem;
 import io.github.thebusybiscuit.cscorelib2.recipes.MinecraftRecipe;
+import io.github.thebusybiscuit.slimefun4.api.MinecraftVersion;
 import io.github.thebusybiscuit.slimefun4.core.multiblocks.MultiBlockMachine;
 import io.github.thebusybiscuit.slimefun4.implementation.SlimefunItems;
 import io.github.thebusybiscuit.slimefun4.implementation.SlimefunPlugin;
@@ -47,6 +48,7 @@ public class RecipeType implements Keyed {
     });
 
     public static final RecipeType MOB_DROP = new RecipeType(new NamespacedKey(SlimefunPlugin.instance(), "mob_drop"), new CustomItem(Material.IRON_SWORD, "&bMob Drop"), RecipeType::registerMobDrop, "", "&rKill the specified Mob to obtain this Item");
+    public static final RecipeType BARTER_DROP = new RecipeType(new NamespacedKey(SlimefunPlugin.instance(), "barter_drop"), new CustomItem(Material.GOLD_INGOT, "&bBarter Drop"), RecipeType::registerBarterDrop, "&aBarter with piglins for a chance", "&a to obtain this item");
     
     public static final RecipeType HEATED_PRESSURE_CHAMBER = new RecipeType(new NamespacedKey(SlimefunPlugin.instance(), "heated_pressure_chamber"), SlimefunItems.HEATED_PRESSURE_CHAMBER);
     public static final RecipeType FOOD_FABRICATOR = new RecipeType(new NamespacedKey(SlimefunPlugin.instance(), "food_fabricator"), SlimefunItems.FOOD_FABRICATOR);
@@ -141,6 +143,11 @@ public class RecipeType implements Keyed {
         return key;
     }
 
+    private static void registerBarterDrop(ItemStack[] recipe, ItemStack output) {
+        if (SlimefunPlugin.getMinecraftVersion().isAtLeast(MinecraftVersion.MINECRAFT_1_16)) 
+            SlimefunPlugin.getRegistry().getBarterDrops().add(output);
+    }
+    
     private static void registerMobDrop(ItemStack[] recipe, ItemStack output) {
         String mob = ChatColor.stripColor(recipe[4].getItemMeta().getDisplayName()).toUpperCase(Locale.ROOT).replace(' ', '_');
         EntityType entity = EntityType.valueOf(mob);