(define title "LOCAL")
(define description "")

;; reminder: two weeks to go to the exam 

(place-image (text "14 days to go" 44 'red) 
             30 50
             (empty-scene 500 500))

;; wouldn't it be nice if we centered this 
;; we need to compute the height and width
;; of the text to get this right ---------

(define txt (text "14 days to go" 44 'red))
(define sce (empty-scene 500 500))
(define lft (quotient (- 500 (image-width txt)) 2))
(define top (quotient (- 500 (image-height txt)) 2))

(place-image txt lft top sce)

;; now let's make all of this independent of
;; the specific str and scene --------------

;; specifics
(define str "14 days to go")
(define scn (empty-scene 500 500))
;; general
(define width  (image-width scn))
(define height (image-height scn))
(define tex (text str 44 'red))
(define lef (quotient (- width (image-width tex)) 2))
(define tpp (quotient (- height (image-height tex)) 2))

(place-image tex lef tpp scn)

;; now let's turn this into a function -------

;; Scene String -> Scene 
;; add the given string to the center of the scene 
(define (add-greeting scn str)
  (place-image (text str 44 'red)
               (quotient (- (image-width scn) 
                            (image-width (text str 44 'red))) 2)
               (quotient (- (image-height scn) 
                            (image-height (text str 44 'red))) 2)
               scn))

;; TESTS
;(equal? (add-greeting scn str) (place-image tex lef tpp scn))

;; oh how painful. Why can't we just make these calculations 
;; inside of the function? ---------------------------------

;; YES: graduated! Use Intermediate now. 

#;
(local ((define ... ...)
        (define ... ...)
        (define ... ...))
  ...)

;; works. Watch! 

(define (+greeting scn str)
  (local ((define width  (image-width scn))
          (define height (image-height scn))
          (define tex (text str 44 'red))
          (define lef (quotient (- width (image-width tex)) 2))
          (define tpp (quotient (- height (image-height tex)) 2)))
    (place-image tex lef tpp scn)))


;(equal? (+greeting scn str) (place-image tex lef tpp scn))

;; don't use check syntax! it's broken on intermediate. bug rpt filed.
;; STEP and demonstrate 

;;; Quiz
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;; AExp is one of
;;; - 'x
;;; - Number
;;; - (make-unary AExp)
;;; - (make-add AExp AExp)

;;; (define-struct unary (exp))
;;; (define-struct add (left right))

;;; subst: AExp Number -> AExp
;;; replace all occurrences of 'x in a with n
;;; (define (subst a n) ...)

;;; 10 minutes to solve

;; ---------------------------------------------------------------

;; NEL (non-empty list of numbers) is one of: 
;; -- (cons Number empty)
;; -- (cons Number NEL)

;; largest : NEL -> Number 
;; determine the largest number in the list 
(define (largest lon)
  (cond [(empty? (rest lon)) (first lon)]
        [else (cond [(> (largest (rest lon)) (first lon))
	             (largest (rest lon))]
                    [else (first lon)])]))

(equal? (largest (list 6 1 2 9 0)) 9)


;; (largest (list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30))
(time (largest (list 1 2 3 4 5 6 7 8 9 10)))
(time (largest (list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20)))


(define (maximum lon)
  (cond [(empty? (rest lon)) (first lon)]
        [else (local ((define fst (first lon))
                      (define max (maximum (rest lon))))
                (cond [(> max (first lon)) max]
                      [else (first lon)]))]))

(equal? (maximum (list 6 1 2 9 0)) 9)

;(maximum (list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30))
(time (maximum (list 1 2 3 4 5 6 7 8 9 10)))
(time (maximum (list 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20)))

;; WHY? STEP 

(largest (list 1 2 3))
(maximum (list 1 2 3))