; (define-struct posn (x y))      ; Included from draw.ss.
;
; A <i>posn</i> is:
;   - (make-posn <var>num</var> <var>num</var>)
;
; Examples:
(define origin (make-posn 0 0))
(define p34    (make-posn 3 4))


; A <i>color</i> is one of {'red, 'yellow, 'white, 'black, 'blue, 'green}.
;
;  Examples of color: (explicitly enumerated in data def'n).

;; translate: posn, num, num --&gt; posn
;; Return the point which is a-point offset by (+x, +y).
;;
(define (translate a-point x y)
  (make-posn (+ (posn-x a-point) x)
             (+ (posn-y a-point) y)))

(translate p34 5 12) = (make-posn 8 16)
(translate origin 3 4) = p34
(translate p34 -3 -4) = origin


(define-struct circle (location radius color))
;
; A <i>circle</i> is:
;    (make-circle <var>posn</var> <var>num</var> <var>symbol</var> <var>color</var>)
;
; Examples of circles:
;
(define circle1  (make-circle p34     1 'red))    ; A little red dot.
(define circle23 (make-circle origin 23 'blue))    
(define circ1  circle1)
(define circ23 circle23)

(define-struct rectangle (location width height color))

;A <i>rectangle</i> is:
;    (make-rectangle <var>posn</var> <var>num</var> <var>num</var> <var>color</var>)
;
;Examples:
(define rectangle1 (make-rectangle (make-posn 10 10) 15 30 'yellow))
(define rectangle2 (make-rectangle (make-posn  0  0)  2  2 'red))
(define rect1 rectangle1)
(define rect2 rectangle2)




;; A shape is a structure that contains
;; - a circle, or
;; - a rectangle

#|
;; Examples of shapes:
;;
circle1
circle23
rectangle1
rectangle2
|#

#|
;; Template:
;;
(define (shape-func a-shape)
   (cond [(circle? a-shape) ..(circle-location a-shape)..
                            ..(circle-radius   a-shape)..
                            ..(circle-color a-shape)..]
         [(rectangle? a-shape) ..(rectangle-location a-shape)..
                               ..(rectangle-width a-shape)..
                               ..(rectangle-height a-shape)..
                               ..(rectangle-color a-shape)..]))
|#



;; translate-shape: Shape Num Num --&gt; Shape
;; Return a shape which is like a-shape, but moved by (+x,+y).
;;
(define (translate-shape a-shape x y)
  (cond [(circle?    a-shape) (make-circle (translate (circle-location a-shape) x y)
                                           (circle-radius a-shape)
                                           (circle-color a-shape))]
        [(rectangle? a-shape) (make-rectangle (translate (rectangle-location a-shape) x y)
                                              (rectangle-width a-shape) 
                                              (rectangle-height a-shape)
                                              (rectangle-color a-shape))]))

#|
;; Tests:
(translate-shape (make-circle (make-posn 0 0) 4 'blue) 2 3)
= (make-circle (make-posn 2 3) 4 'blue)

(translate-shape (make-rectangle (make-posn 3 7) 4 4 'red) 0 1)
= (make-rectangle (make-posn 3 8) 4 4 'red)
|#




;(start 500 500) ; Opens a canvas to draw on.

;; draw-shape: Shape --&gt; true
;; Draw a-shape on the current canvas, and return true.
;;
(define (draw-shape a-shape)
  (cond [(circle?    a-shape) 
         (draw-solid-disk (circle-location a-shape)
                          (circle-radius a-shape) 
                          (circle-color a-shape))]
        [(rectangle? a-shape) 
         (draw-solid-rect (rectangle-location a-shape)
                          (rectangle-width a-shape) 
                          (rectangle-height a-shape)
                          (rectangle-color a-shape))]))

#|
;Test-cases
(draw circle1) = true
(draw circle2) = true
(draw rectangle1) = true
(draw rectangle2) = true
|#





; A constant, used for width of various bands, in part (b).
;
(define band-width 20)



;; v.103  : A color is: one of { RED,  YELLOW,  WHITE,  BLACK,  BLUE,  GREEN}.
;; v.103.5: A color is: one of {'red, 'yellow, 'white, 'black, 'blue, 'green}.


(define (rectangle-tool i)
 (make-rectangle (make-posn (* i band-width) 0)
                  band-width
                  (* i i)
                  'yellow))


;(rectangle-tool 0) = (make-rectangle (make-posn   0 0) 20  0 'yellow)
;(rectangle-tool 7) = (make-rectangle (make-posn 140 0) 20 49 'yellow)


;; circle-tool: number -> true
;; Return a circle centered at canvas position (150,150), 
;; with radius (* i band-width), 
;; and color red if i is odd or blue if i is even.
;;
(define (circle-tool i)
  (make-circle (make-posn 150 150)
               (* i band-width)
               (cond
                 [(odd? i) 'red]
                 [else 'blue])))

(circle-tool 6) = (make-circle (make-posn 150 150) 120 'blue)
(circle-tool 3) = (make-circle (make-posn 150 150) 60 'red)


#|
;; make-shapes: NatNum -> list of shapes
;; Returns a list of shapes created by rectangle-tool,
;; called with n, n-1, n-2, ... 1, 0.
;;
;; Based on the template for natural numbers
;;
|#
(define (make-shapes n)
  (cond
    [(zero? n)     (cons (rectangle-tool 0) empty)]
    [(positive? n) (cons (rectangle-tool n)
                         (make-shapes (sub1 n)))]))


#|
(make-shapes 0)=
(cons (make-rectangle (make-posn 0 0) 20 0 'yellow) empty)

(make-shapes 3)=
(cons
 (make-rectangle (make-posn 60 0) 20 9 'yellow)
 (cons
  (make-rectangle (make-posn 40 0) 20 4 'yellow)
  (cons
   (make-rectangle (make-posn 20 0) 20 1 'yellow)
   (cons (make-rectangle (make-posn 0 0) 20 0 'yellow) empty))))
|#

;; draw-shapes: list-of-shapes --> true
;; Draw each element of los.
;;
(define (draw-shapes los)
  (cond
    [(empty? los) true]
    [(cons?  los) (and (draw-shape  (first los))
                       (draw-shapes (rest  los)))]))


;(start 500 500)
;
;(draw-list-of-shapes (make-shapes 11)) = true