(define-struct Container (contents capacity))
(define-struct Simple (name weight))

;Each container has a capacity and contents which is a list
;of items that are either containers or simple objects.
;Each simple object has a weight and the capacity constraint
;is violated if the total sum of the weight of the items is greater
;than the capacity.

;; --- MF added ---
;; A Container is (make-Container (Listof Item) Number).
;;
;; An Item is one of:
;;  -- (make-Simple Symbol Number)
;;  -- Container
;; --- end added ---

;; Test object c1 in Scheme

;; --- MF changed ---
(define c-1
  (make-Container (list (make-Simple "apple" 1))
                  1))

(define c0
  (make-Container (list (make-Simple "pencil" 1)
                        c-1
                        (make-Simple "orange" 1))
                  1))

(define c1
  (make-Container (list (make-Simple "apple" 1)
                        c0
                        (make-Simple "orange" 1)
                        (make-Simple "kiwi" 1))
                  5))
;; --- end changed ---

;; Karl's problem
;; check returns the total number of capacity violations in a container
;; check: Container -> int

(define (check ac)
  (local (;; Container -> Number
          ;; the weight of a container
          ;; effect: the number of capacity violations in a container
          (define (weight-container ac)
            (local ([define witems (weight-loi (Container-contents
ac))])
              (when (> witems (Container-capacity ac))
                (set! violations (+ 1 violations)))
              witems))
          ;; (Listof Item) -> Number
          ;; the weight of a list of items
          (define (weight-loi l)
            (foldr + 0 (map weight-item l)))
          ;; Item -> Number
          ;; the weight of an item
          (define (weight-item l)
            (cond
              [(Simple? l) (Simple-weight l)]
              [(Container? l) (weight-container l)]))
          ;; Number
          ;; the number of violations detected
          (define violations 0))
    (weight-container ac)
    violations))

;; test
(= (check c1) 2)