;; Teachpack: dir.ss

#| Commented out because these structure definitions are part of dir.ss
(define-struct file (name size content))
(define-struct dir (name dirs files))
|#

;; A File is (make-file Symbol Number empty)
;; A Dir is (make-dir Symbol Dir-List File-List)
;; A File-List is one of
;;  - empty
;;  - (cons File File-List)
;; A Dir-List is one of
;;  - empty
;;  - (cons Dir Dir-List)

;;;; Main Program

;; count-files-in-directory : Dir -> Number
;; counts how many files in this directory
(define (count-files-in-directory d)
  (+ (count-files-in-file-list (dir-files d))
     (count-files-in-directory-list (dir-dirs d))))

;;;; Auxiliaries

;; count-files-in-file-list : File-List -> Number
;; counts how many files in this file list
(define (count-files-in-file-list fl)
  (cond [(empty? fl) 0]
        [else (+ (count-files-in-file (first fl))
                 (count-files-in-file-list (rest fl)))]))

;; count-files-in-directory-list : Dir-List -> Number
;; counts how many files in this directory list
(define (count-files-in-directory-list dl)
  (cond [(empty? dl) 0]
        [else (+ (count-files-in-directory (first dl))
                 (count-files-in-directory-list (rest dl)))]))

;; count-files-in-file : File -> Number
;; counts how many files in this file
(define (count-files-in-file f)
  1)

;;;; Tests

;; Tests of create-dir (part of dir.ss)
(create-dir ".")
;(create-dir "C:\\Program Files") ;; takes a long time to complete!

;; Tests of count-files-in-directory
(count-files-in-directory (create-dir "."))
;(count-files-in-directory (create-dir "C:\\Program Files"))