class Mothership : AlienShip {

    @Attribute
    var birthPeriod = 300

    @Attribute
    var maxChildren = 10

    override fun createAnimation() : Action {
        return Delay( 0.2 ) then
            EventAction( actor, "frame1" ) then
            Delay( 0.2 ) then
            EventAction( actor, "frame2" ) then
            Delay( 0.2 ) then
            EventAction( actor, "default" )
    }

    override fun tick() {
        super.tick()
        
        if (maxChildren > 0 && Rand.oneIn( birthPeriod )) {

            maxChildren --
            actor.event( "birth" )
            val shipA = actor.createChild( "child" )
            val alienShip = shipA.role as AlienShip

            // Make the child come out from the bottom of the mothership
            shipA.direction.radians = actor.direction.radians
            shipA.moveForwards( radius * 0.3 )

            // The child moves directly away from the mother, but also adding the
            // mothers velocity.
            alienShip.velocity.setMinus( shipA.position, actor.position )
            alienShip.velocity *= 0.3
            alienShip.velocity += velocity

            // Make the child very small at first, and begin an action to scale it up
            shipA.scaleXY = actor.scaleXY * 0.1
            alienShip.scaleAction = ScaleTo( shipA, 1, actor.scaleXY, Eases.easeOut )
            alienShip.scaleAction.begin()
        }
    }

    override fun hit() {
        DrunkInvaders.instance.shake(0.5)
        super.hit()
    }
}