[help] with custom monster spawn function

So I am trying to write a function for a plugin called dungeonbuilder. You can create custom mobs that will spawn on a called event inside your dungeon. Currently I have figured out how to get a spider to shoot fireballs at a player using the following code

Code:

importPackage(java.lang);
importPackage(org.bukkit.inventory);
importPackage(org.bukkit);
importPackage(org.bukkit.entity);
importPackage(org.bukkit.util);
importPackage(org.bukkit.craftbukkit.entity);
 
function monster_spawn()
{
    //How do we make a monster with a ton of health?  Do negative damage to it!
    //A bit counterintuitive but very easy to do.
    monster.damage(-80);
 
    startingloc = monster.getLocation().clone();
 
    thread = new Thread(function() {
        while(true)
        {
            if(monster.isDead())
                return;
 
            if(Thread.currentThread().isInterrupted())
                return;
 
 
            sleep = (Math.random() * 2000) + 1500;
 
            try
            {Thread.currentThread().sleep(sleep);
 
           
                if(monster.getTarget() == null)
                    continue;
 
               
                    world = monster.getWorld();
                    loc = monster.getLocation();
                    fireball = world.spawn(loc, org.bukkit.entity.Fireball); //Delete this line and the line after if you dont want to spawn a fireball
                    fireball.setShooter(monster);
 
            }
            catch(e)
            {
                if(e.javaException instanceof InterruptedException)
                    return;
 
                e.javaException.printStackTrace();
                return;
            }
        }
    });
    thread.start();
    persistedObjects.put(monster.getUniqueId() + "thread", thread);
    persistedObjects.put(monster.getUniqueId() + "start", startingloc);
}
   
 
 
 
 
 
function monster_death()
{
    world = monster.getWorld();
 
 
    //Spawn an item at the monster's location when he dies
    is = new ItemStack(Material.FIRE, 1);
    world.dropItem(monster.getLocation(), is);  //Delete this line if you dont want to spawn an item when it dies
 
 
}
 
function monster_damage()
{
    world = monster.getWorld();
    //Make a ghast shrieking sound
    world.playEffect(monster.getLocation(), Effect.GHAST_SHRIEK, 0);
 
}

The spider spawns, shoot fireballs properly every 3ish seconds, drops an item when it dies, and screams like a ghast when it is harmed.

My biggest concern now is spawning these special spiders in groups. Eventually, due to friendly fire, they all turn on each other. What I need help with is two things:

1) I would like my custom mob to be immune to the fireball explosion event which I believe is referenced here http://jd.bukkit.org/doxygen/d1/d9c/EntityDamageEvent_8java_source.html
I am not sure how to listen for that event and cancel it if it occurs, if that is even how I should go about it.

2) I would also like to see if I could make the custom monster reset its target whenever it's target is not a player, thus eliminating quarrels between each other. Which I have no clue where to even start

 

1) EntityDamageByEntityEvent, check if the damager is a fireball and if the entity is the custom mob, if so, cancel the event

2) check if the target is not a player, if so, set the target to null

 

This is not java

 

Is that... JavaScript?

 

yes it ends up in a .js file

 

Well, it doesn't need to be javascript when the ending is .js. It just tells the program what data IS EXPECTED. You could store a picture in a .txt file, but programs will not except a picture in a blank text file.
This is just a little info.

 

Why is it JavaScript? The bukkit API is in Java. Explain please?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

I didn't make the plugin, I am just using the tools the dev gave me. His plugin calls the .js file to modify spawned monsters.