/**
 * An elastic line between the GraphicalMouse and the item being dragged.
 * Used on the Doll House scenes to pick up and move [DollPart]s, and other [Draggable] items.
 */
class Elastic : AbstractRole() {

    var dragging : Draggable = null

    // Private set by join(...)
    var mouseJoint: TickleMouseJoint = null

    // Temporary vector to hold the end positions of the elastic line.
    val tmp = Vector2()

    override fun begin() {
        super.begin()
        actor.hide()
    }

    override fun tick() {
        if ( dragging != null ) {
            val mainView = DollsHouseDirector.instance.mainView
            mainView.getMousePositionWorld( tmp )
        
            mouseJoint.target = tmp
            actor.position.set( tmp )

            mouseJoint.getAnchorB(tmp)
            actor.ninePatchAppearance.lineTo(tmp)

        }
    }

    fun join( role : Draggable, hand : GraphicalMouse, position : Vector2 ) {
        //actor.show()
        actor.event( "default" )
        val world = DollsHouseDirector.instance.mainView.stage.world
        role.actor.body.setAwake( true )

        val maxForce = 4 * role.mass()
        mouseJoint = TickleMouseJoint( hand.actor, role.actor, position, maxForce )
        dragging = role
    }

    fun unjoin() {
        if (dragging != null) {
            actor.hide()
            dragging = null
            mouseJoint.destroy()
            mouseJoint = null
        }
    }

}