partial implementation of target npc property

plugin/src/main/java/lol/pyr/znpcsplus/commands/property/PropertySetCommand.java

@@ -113,6 +113,10 @@ public class PropertySetCommand implements CommandHandler {
                 valueName = String.valueOf(value);
             }
         }
+        else if (type == NpcEntryImpl.class) {
+            value = context.parse(type);
+            valueName = value == null ? "NONE" : ((NpcEntryImpl) value).getId();
+        }
         else {
             value = context.parse(type);
             valueName = String.valueOf(value);

plugin/src/main/java/lol/pyr/znpcsplus/entity/properties/TargetNpcProperty.java

@@ -0,0 +1,29 @@
+package lol.pyr.znpcsplus.entity.properties;
+
+import com.github.retrooper.packetevents.protocol.entity.data.EntityData;
+import com.github.retrooper.packetevents.protocol.entity.data.EntityDataTypes;
+import lol.pyr.znpcsplus.entity.EntityPropertyImpl;
+import lol.pyr.znpcsplus.entity.PacketEntity;
+import lol.pyr.znpcsplus.npc.NpcEntryImpl;
+import org.bukkit.entity.Player;
+
+import java.util.Map;
+
+public class TargetNpcProperty extends EntityPropertyImpl<NpcEntryImpl> {
+    private final int index;
+
+    public TargetNpcProperty(String name, int index, NpcEntryImpl defaultValue) {
+        super(name, defaultValue, NpcEntryImpl.class);
+        this.index = index;
+    }
+
+    @Override
+    public void apply(Player player, PacketEntity entity, boolean isSpawned, Map<Integer, EntityData> properties) {
+        NpcEntryImpl value = entity.getProperty(this);
+        if (value == null) return;
+        if (value.getNpc().getEntity().getEntityId() == entity.getEntityId()) return;
+        if (value.getNpc().isVisibleTo(player)) {
+            properties.put(index, newEntityData(index, EntityDataTypes.INT, value.getNpc().getEntity().getEntityId()));
+        }
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/entity/serializers/TargetNpcPropertySerializer.java

@@ -0,0 +1,21 @@
+package lol.pyr.znpcsplus.entity.serializers;
+
+import lol.pyr.znpcsplus.entity.PropertySerializer;
+import lol.pyr.znpcsplus.npc.NpcEntryImpl;
+
+public class TargetNpcPropertySerializer implements PropertySerializer<NpcEntryImpl> {
+    @Override
+    public String serialize(NpcEntryImpl property) {
+        return property.getId();
+    }
+
+    @Override
+    public NpcEntryImpl deserialize(String property) {
+        return null; // TODO: find a way to do this
+    }
+
+    @Override
+    public Class<NpcEntryImpl> getTypeClass() {
+        return NpcEntryImpl.class;
+    }
+}

plugin/src/main/java/lol/pyr/znpcsplus/npc/NpcTypeRegistryImpl.java

@@ -329,7 +329,7 @@ public class NpcTypeRegistryImpl implements NpcTypeRegistry {
 
         register(builder(p, "frog", EntityTypes.FROG)
                 .setHologramOffset(-1.475)
-                .addProperties("frog_variant"));
+                .addProperties("frog_variant", "frog_target_npc"));
 
         register(builder(p, "tadpole", EntityTypes.TADPOLE)
                 .setHologramOffset(-1.675));