fix: stop mobs from targeting NPCs when they are no longer targetable (#3171)

main/src/main/java/net/citizensnpcs/EventListen.java

@@ -4,6 +4,7 @@ import java.lang.reflect.Method;
 import java.util.List;
 import java.util.Objects;
 
+import net.citizensnpcs.trait.TrackTargetedByTrait;
 import org.bukkit.Bukkit;
 import org.bukkit.Location;
 import org.bukkit.Material;
@@ -12,6 +13,7 @@ import org.bukkit.entity.EntityType;
 import org.bukkit.entity.FishHook;
 import org.bukkit.entity.LivingEntity;
 import org.bukkit.entity.Minecart;
+import org.bukkit.entity.Mob;
 import org.bukkit.entity.Player;
 import org.bukkit.entity.Snowman;
 import org.bukkit.entity.Vehicle;
@@ -445,15 +447,37 @@ public class EventListen implements Listener {
 
     @EventHandler(priority = EventPriority.LOWEST)
     public void onEntityTarget(EntityTargetEvent event) {
-        NPC npc = plugin.getNPCRegistry().getNPC(event.getTarget());
+        final Entity targeted = event.getTarget();
-        if (npc == null)
+        NPC npc = plugin.getNPCRegistry().getNPC(targeted);
-            return;
+        final Entity cause = event.getEntity();
-
+        if (npc != null) {
-        final EntityTargetNPCEvent targetNPCEvent = new EntityTargetNPCEvent(event, npc);
+            final EntityTargetNPCEvent targetNPCEvent = new EntityTargetNPCEvent(event, npc);
-        targetNPCEvent.setCancelled(!npc.data().get(NPC.Metadata.TARGETABLE, !npc.isProtected()));
+            targetNPCEvent.setCancelled(!npc.data().get(NPC.Metadata.TARGETABLE, !npc.isProtected()));
-        Bukkit.getPluginManager().callEvent(targetNPCEvent);
+            Bukkit.getPluginManager().callEvent(targetNPCEvent);
-        if (targetNPCEvent.isCancelled()) {
+            if (targetNPCEvent.isCancelled()) {
-            event.setCancelled(true);
+                event.setCancelled(true);
+            } else {
+                if (event.isCancelled()) {
+                    return;
+                }
+                if (!(cause instanceof Mob)) {
+                    return;
+                }
+                final TrackTargetedByTrait beTargetedBy = npc.getOrAddTrait(TrackTargetedByTrait.class);
+                beTargetedBy.add(cause.getUniqueId());
+            }
+        } else {
+            if (cause instanceof Mob) {
+                final LivingEntity previousTarget = ((Mob) cause).getTarget();
+                if (previousTarget == null) { // normally it is impossible
+                    return;
+                }
+                final NPC previousAsNPC = plugin.getNPCRegistry().getNPC(previousTarget);
+                if (previousAsNPC != null) {
+                    final TrackTargetedByTrait beTargetedBy = previousAsNPC.getOrAddTrait(TrackTargetedByTrait.class);
+                    beTargetedBy.remove(cause.getUniqueId());
+                }
+            }
         }
     }
 

main/src/main/java/net/citizensnpcs/commands/NPCCommands.java

@@ -18,6 +18,7 @@ import java.util.Objects;
 import java.util.UUID;
 import java.util.stream.Collectors;
 
+import net.citizensnpcs.trait.TrackTargetedByTrait;
 import org.bukkit.Art;
 import org.bukkit.Bukkit;
 import org.bukkit.ChatColor;
@@ -3418,6 +3419,12 @@ public class NPCCommands {
                 NMS.addOrRemoveFromPlayerList(npc.getEntity(), false);
             }
         }
+        if (!targetable) {
+            final TrackTargetedByTrait trackTargetedByTrait = npc.getTraitNullable(TrackTargetedByTrait.class);
+            if (trackTargetedByTrait != null) { // may not be targeted by anything so prevent possible garbages
+                trackTargetedByTrait.clearTargets();
+            }
+        }
         Messaging.sendTr(sender, targetable ? Messages.TARGETABLE_SET : Messages.TARGETABLE_UNSET, npc.getName());
     }
 

main/src/main/java/net/citizensnpcs/npc/CitizensTraitFactory.java

@@ -25,6 +25,7 @@ import net.citizensnpcs.trait.Anchors;
 import net.citizensnpcs.trait.ArmorStandTrait;
 import net.citizensnpcs.trait.AttributeTrait;
 import net.citizensnpcs.trait.BatTrait;
+import net.citizensnpcs.trait.TrackTargetedByTrait;
 import net.citizensnpcs.trait.BoundingBoxTrait;
 import net.citizensnpcs.trait.ClickRedirectTrait;
 import net.citizensnpcs.trait.CommandTrait;
@@ -103,6 +104,7 @@ public class CitizensTraitFactory implements TraitFactory {
         registerTrait(TraitInfo.create(ItemFrameTrait.class));
         registerTrait(TraitInfo.create(LookClose.class));
         registerTrait(TraitInfo.create(PaintingTrait.class));
+        registerTrait(TraitInfo.create(TrackTargetedByTrait.class));
         registerTrait(TraitInfo.create(MirrorTrait.class).optInToStats());
         registerTrait(TraitInfo.create(MountTrait.class));
         registerTrait(TraitInfo.create(MobType.class).asDefaultTrait());

main/src/main/java/net/citizensnpcs/trait/TrackTargetedByTrait.java

@@ -0,0 +1,54 @@
+package net.citizensnpcs.trait;
+
+import net.citizensnpcs.api.trait.Trait;
+import net.citizensnpcs.api.trait.TraitName;
+import org.bukkit.Bukkit;
+import org.bukkit.entity.Entity;
+import org.bukkit.entity.Mob;
+
+import java.util.HashSet;
+import java.util.Set;
+import java.util.UUID;
+
+@TraitName("tracktargetedby")
+public class TrackTargetedByTrait extends Trait {
+    private Set<UUID> beTargetedBy;
+
+    public TrackTargetedByTrait() {
+        super("tracktargetedby");
+    }
+
+    @Override
+    public void onDespawn() {
+        clearTargets();
+    }
+
+    // Only for internal use
+    public void add(UUID uuid) {
+        if (beTargetedBy == null) {
+            beTargetedBy = new HashSet<>();
+        }
+        beTargetedBy.add(uuid);
+    }
+
+    // Only for internal use
+    public void remove(UUID uuid) {
+        if (beTargetedBy != null) {
+            beTargetedBy.remove(uuid);
+        }
+    }
+
+    public void clearTargets() {
+        if (beTargetedBy != null) {
+            for (UUID entityUUID : beTargetedBy) {
+                final Entity entity = Bukkit.getEntity(entityUUID);
+                if (entity instanceof Mob) {
+                    if (entity.isValid()) {
+                        ((Mob) entity).setTarget(null);
+                    }
+                }
+            }
+            beTargetedBy = null;
+        }
+    }
+}