;;;;
;;;; Step 2 - Point Abstraction: Starting a 2-Dimensional Point System
;;;;

;; make-point
(define (make-point x y)
  (cons x y))

;; get-x
(define (get-x p)
  (car p))

;; get-y
(define (get-y p)
  (cdr p))


;; Test Code Instructions:
;;   Define a new point.  Display it.
;;   Display the x and y values separately using your selectors.
;;   You may use this point in future tests as well.

;; Note:
;;   The above is done for you below -- just uncomment those lines.
;;   You may want to define some other points here to use in future steps.

(display+ "--- STEP 2 TEST CASES ---")
;; Example Test Case:
   (define pt1 (make-point 2 4))
   (define pt2 (make-point 4 6))
   (define pt3 (make-point 1 9))
   (define pt4 (make-point 5 7))
   (display+ "Point: "pt1)            ;; Expecting (2 . 4)
   (display+ "X-Coord: " (get-x pt1)) ;; Expecting 2
   (display+ "Y-Coord: " (get-y pt1)) ;; Expecting 4


;;;;
;;;; Step 3 - Maintaining a List of Points
;;;;

;; make-pt-list
(define (make-pt-list p pt-list)
  (cons p pt-list))

;; the-empty-pt-list
(define the-empty-pt-list ())

;; get-first-point
(define (get-first-point pt-list)
  (car pt-list))

;; get-rest-points
(define (get-rest-points pt-list)
  (cdr pt-list))


;; Test Code:
;;   Using make-pt-list and the-empty-pt-list, define a list with 6+ points.
;;   Show the list after each point is added.
;;   Display the entire list, the first point, and all but the first point.
;;   Display the second point.
;;   Display all except the first two points.

(display+ "--- STEP 3 - Building The List ---")
;; How to start building the list:
;;  (define my-point-list (make-pt-list pt1 the-empty-pt-list))
;;  (display+ my-point-list)
;;
;;  (define my-point-list (make-pt-list pt2 my-point-list))
;;  (display+ my-point-list)
;;
;; Continue adding points...


(display+ "--- STEP 3 - First Point ---")
(define my-pt-list (make-pt-list pt1 the-empty-pt-list))
(display+ my-pt-list)
(define my-pt-list (make-pt-list pt2 my-pt-list))
(display+ my-pt-list)
(define my-pt-list (make-pt-list pt3 my-pt-list))
(display+ my-pt-list)
(define my-pt-list (make-pt-list pt4 my-pt-list))
(display+ my-pt-list)
(define my-pt-list (make-pt-list pt3 my-pt-list))
(display+ my-pt-list)
(define my-pt-list (make-pt-list pt2 my-pt-list))
(display+ my-pt-list)

(display+ (get-first-point my-pt-list))
(display+ (get-rest-points my-pt-list))

(display+ "--- STEP 3 - Second Point ---")
(display+ (get-first-point (get-rest-points my-pt-list)))

(display+ "--- STEP 3 - All Except First Two Points ---")
(display+ (get-rest-points (get-rest-points my-pt-list)))