/**
    The ship is not allowed to go beyond the dome
    Droplets fall down from the top of the dome.
*/
class Dome : ActionRole() {

    @Attribute
    var rainPeriod = 3.0

    // Used to test if ships/cargo are outside of an ellipse bounded by this rectangle.
    val rect = Rect()

    override fun begin() {
        Play.instance.dome = this

        // Make rect a bit SMALLER than the true rectangle, by the radius of cargo/ship (ish)
        // Therefore [isOutside] will be closer to perfect.
        // Without this margin, ships/cargo will explode when their CENTERS are outside of the dome.
        rect.set( actor.appearance.worldRect())
        val margin = 30
        rect.left += margin
        rect.right -= margin
        rect.top -= margin

        prepareDrip()
    }

    fun prepareDrip() {

        if (rainPeriod > 0) {
            val period = rainPeriod + Rand.plusMinus( rainPeriod/2 )
            replaceAction( Delay( period ) thenOnce this:>drip )
        }
    }

    fun drip() {

        val event = if (Options.instance.moreAcid == 2) "acidDrip" else "drip"
        val dripA = actor.createChild( event )
        val dx = Rand.plusMinus( 0.5 )
        val dy = Math.sqrt( 1 - dx * dx )
        dripA.position.x += dx * actor.appearance.width() /2 * actor.scale.x
        dripA.position.y += dy * actor.appearance.height() * actor.scale.y - 40

        prepareDrip()
    }

    fun isOutside( other : Actor ) : bool {

        val domeY = actor.y
        val otherY = other.y

        if ( otherY > domeY ) {

            // Check if other's actor's center is outside of the ellipse bounded by [rect]
            // [rect] is slightly smaller than the dome, to help compensate for the size of the ship/cargo.
            // If we have BIG ships/cargo, then the ship/cargo will be able to poke through a little bit.
            val otherX = other.x
            val domeX = actor.x

            val dx = (otherX - domeX) / rect.width * 2
            val dy = (otherY - domeY) / rect.height


            return (dx*dx + dy*dy > 1.0)
        }
        
        return false
    }

}