;; The first three lines of this file were inserted by DrScheme. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname draw_shapes) (read-case-sensitive #t) (teachpacks ((lib "testing.ss" "teachpack" "htdp") (lib "guess.ss" "teachpack" "htdp") (lib "master.ss" "teachpack" "htdp") (lib "draw.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "testing.ss" "teachpack" "htdp") (lib "guess.ss" "teachpack" "htdp") (lib "master.ss" "teachpack" "htdp") (lib "draw.ss" "teachpack" "htdp")))))
;; The structure represents a circle 
;; center is the position (posn structure) of the center
;; radius is its radius (a non-negative number), and
;; color is a symbol representing a color
(define-struct circle (center radius color))

;; draw-a-circle: circle -> true
;; the function draws a circle structure as a disk
;; and returns true
(define (draw-a-circle a-circle)
  (draw-solid-disk (circle-center a-circle)
                   (circle-radius a-circle)
                   (circle-color a-circle)) 
)

;; clear-a-circle: circle -> true
;; the function clears a disk corresponding to a circle
;; and returns true
(define (clear-a-circle a-circle)
  (clear-solid-disk (circle-center a-circle)
                   (circle-radius a-circle))
)

(define (move-circle a-circle x-shift y-shift)
  (make-circle
   (make-posn (+ (posn-x (circle-center a-circle)) x-shift) 
              (+ (posn-y (circle-center a-circle)) y-shift))
   (circle-radius a-circle)
   (circle-color a-circle)
  )
)

;; The structure represents a rectangle 
;; left-upper is the position (posn structure) of its 
;; left upper corner, height and width are its height and
;; width (non-negative numbers), and
;; color is a symbol representing a color
(define-struct rectangle (left-upper height width color))

;; draw-a-rectangle: rectangle -> true
;; the function draws a rectangle structure as a solid rectangle
;; and returns true
(define (draw-a-rectangle a-rectangle)
  (draw-solid-rect (rectangle-left-upper a-rectangle)
                   (rectangle-width a-rectangle)
                   (rectangle-height a-rectangle)
                   (rectangle-color a-rectangle))
)


(define (clear-a-rectangle a-rectangle)
  (clear-solid-rect (rectangle-left-upper a-rectangle)
                   (rectangle-width a-rectangle)
                   (rectangle-height a-rectangle))
)

(define (move-rectangle a-rect x-shift y-shift)
  (make-rectangle
   (make-posn 
    (+ (posn-x (rectangle-left-upper a-rect)) x-shift) (+ (posn-y (rectangle-left-upper a-rect)) y-shift))  
   (rectangle-height a-rect)
   (rectangle-width a-rect)   
   (rectangle-color a-rect)
  ))


(define shapes
  (cons (make-circle (make-posn 200 200) 100 'red)
   (cons (make-rectangle (make-posn 150 220) 20 100 'yellow) 
     (cons (make-rectangle (make-posn 144 150) 20 20 'black) 
       (cons (make-rectangle (make-posn 225 150) 20 20 'black) empty)))))

(start 400 400)

;; draw-shapes: a list of shapes -> boolean
;; the function takes a list of shapes (circles, rectangles)
;; and draws them on the canvas in order
(define (draw-shapes the-shapes)
  (cond
    [(empty? the-shapes) true]
    [(circle? (first the-shapes)) 
     (and (draw-a-circle (first the-shapes)) 
          (draw-shapes (rest the-shapes)))]
    [(rectangle? (first the-shapes)) 
     (and (draw-a-rectangle (first the-shapes)) 
          (draw-shapes (rest the-shapes)))]
    [else false]
  )
)

(draw-shapes shapes)

(sleep-for-a-while 1)

(define (clear-shapes the-shapes)
  (cond
    [(empty? the-shapes) true]
    [(circle? (first the-shapes)) 
     (and (clear-a-circle (first the-shapes)) 
          (clear-shapes (rest the-shapes)))]
    [(rectangle? (first the-shapes)) 
     (and (clear-a-rectangle (first the-shapes)) 
          (clear-shapes (rest the-shapes)))]
    [else false]
  )
)

(clear-shapes shapes)

(define (move-shapes the-shapes x-shift y-shift)
  (cond
   [(empty? the-shapes) empty]
   [(circle? (first the-shapes)) 
    (cons (move-circle (first the-shapes) x-shift y-shift)
          (move-shapes (rest the-shapes) x-shift y-shift))]
   [(rectangle? (first the-shapes)) 
    (cons (move-rectangle (first the-shapes) x-shift y-shift)
          (move-shapes (rest the-shapes) x-shift y-shift))]
  )
)

;(draw-shapes (move-shapes shapes 100 -100))

(define rand1 (- (random 200) 100))
(define rand2 (- (random 200) 100))
(draw-shapes (move-shapes shapes rand1 rand2))
(sleep-for-a-while 1)
(clear-shapes (move-shapes shapes rand1 rand2))

(draw-shapes (move-shapes shapes (- (random 200) 100)
                          (- (random 200) 100)))