class Rock : Movable {

    static val sideSpeed = 20

    var falling = false

    override fun myTurn() {

        var south = lookSouth()

        if (south.squashable( SOUTH )) {
            moveSouth()
            falling = true

        } else {
            if (falling) {
                falling = false    
                south = lookSouth( IMMEDIATELY ).item()
                if (south.isPlayer()) {
                    south.item().actor.die()
                }
            }
            // If we CAN roll around the balloon do NOTHING, and let the balloon roll around the rock.
            val isBalloon = south.item() is Balloon
            if ( south.rounded( NORTH_WEST ) && canRoll(-1) ) {
                if (! isBalloon ) {
                    moveDelta(-1, 0, sideSpeed )
                }
            } else if ( south.rounded( NORTH_EAST ) && canRoll(1) ) {
                if (! isBalloon ) {
                    moveDelta(1, 0, sideSpeed )
                }
            }
        }
    }

    fun canRoll( dx : int ) : boolean {
        val side = lookDelta( dx, 0, sideSpeed )
        if (! ( side.squashable( if (dx == 1) EAST else WEST ) ) ) {
            return false
        }
        val below = square.neighbour( dx, -1 ).look( speed, SOUTH )
        return below.squashable( SOUTH )
    }

    override fun canPush( direction : int, speed : int, strength : int ) : boolean {
        if (strength < 2) return false
        if (isMoving()) return false
        if ( direction == SOUTH ) return false
        val next = look( direction )
        if ( next.squashable( direction ) ) {
            return true
        }
        return next.canPush( direction, speed, strength - 4 )
    }


    override fun moved( movement : Movement ) {
        val south = lookSouth().item()
        if (movement.dy == -1 && south.isPlayer()) {
            south.item().kill()
        } else if (south is Explodes && !south.isMoving()) {
            (south as Explodes).explode()
            actor.die()
        }
        super.moved( movement )
    }

    override fun rounded( direction : int ) = true

    override fun copyable() = true

}