#lang racket
(require 2htdp/image)

(define (block c1 c2 c3 s)
  (overlay
   (let* [[d (overlay (circle (* 1/12 s) 'solid c2)
                      (circle (* 1/6 s) 'solid c1))]
          [e (square (* 1/3 s) 0 'black)]
          [dsd (beside d e d)]
          [scs (beside e (circle (* 1/6 s) 'solid c3) e)]]
     (above dsd scs dsd))
   (square (* 2/3 s) 'solid c2)
   (square s 'solid c1)))

(define (step c0 c1 c2 c3 s)
 (let* [[sb (* 4/5 s)]
        [ss (* 1/5 s)]
        [bb (block c1 c0 c2 ss)]
        [by (block c2 c0 c3 ss)]]
   (above
    (beside (if (> sb 50)
                (overlay
                 (square sb 32 c0)
                 (rotate 180 (step c0 c3 c1 c2 sb)))
                (square sb 'solid c0))
            (above by bb by bb))
    (beside by bb by bb by))))

(provide main)
(define (main . args)
  (save-image
   (step 'black 'red 'yellow 'orange 600)
   (car args)))