(load "huffman.scm")

;; 2e)


;; hjelpeprosedyre
(define (member? item list)
  (if (leaf? list)
      (eq? item (cadr list))
      (if (eq? (member item (caddr list)) #f)
      #f
      #t)))


(define  (encode items tree)
  (define (recur items current-branch bits)
    (if (null? items)
        bits
        (if (leaf? current-branch)
               (if (equal? (symbol-leaf current-branch) (car items))
                   (recur (cdr items) tree bits)
                   '())
                (if (member? (car items) (left-branch current-branch))
                    (recur items (left-branch current-branch) (append bits '(0)))
                    (recur items (right-branch current-branch) (append bits '(1)))))))
  (recur items tree '()))



(encode '(ninjas fight ninjas by night) sample-tree)
(decode (encode '(ninjas fight ninjas by night) sample-tree) sample-tree)

;;2f


(define (grow-huffman-tree freqs)
  (define (recur leaf-set)
    (if (null? (cdr leaf-set))
        (car leaf-set)
        (recur (adjoin-set (make-code-tree (car leaf-set) (cadr leaf-set))(cddr leaf-set)))))
  (recur (make-leaf-set freqs)))

(define freqs '((a 2) (b 2) (c 1) (d 3) (e 1) (f 3)))
(define codebook (grow-huffman-tree freqs))
(decode (encode '(a b c) codebook) codebook)