;;;
;;; Difference between dates addition
;;;  to handle date formats of the form
;;;  2/15 for february 15th
;;;
;;;  this file needs to be loaded after difference between dates
;;;


;; tests

;; returns #t if the date is a full-date (rather than a short date)
(define (full-date? date)
  (if (sentence? date)
      #t
      #f))

;; returns #t if date is a short-date
(define (short-date? date)
  (word? date))



;;; selectors

;month-name


(define (month-name date)
  (if (full-date? date)
      (first date)
      (sd-month-name date)
      ))



(define (sd-month-name sd)      
   (cond ((equal? (sd-month-number sd) 1) 'january)
         ((equal? (sd-month-number sd) 2) 'february)
         ((equal? (sd-month-number sd) 3) 'march)
         ((equal? (sd-month-number sd) 4) 'april)
         ((equal? (sd-month-number sd) 5) 'may)
         ((equal? (sd-month-number sd) 6) 'june)
         ((equal? (sd-month-number sd) 7) 'july)
         ((equal? (sd-month-number sd) 8) 'august)
         ((equal? (sd-month-number sd) 9) 'september)
         ((equal? (sd-month-number sd) 10) 'october)
         ((equal? (sd-month-number sd) 11) 'november)
         ((equal? (sd-month-number sd) 12) 'december)
         ))

;; return the month number of the short date
(define (sd-month-number sd)
  (if (equal? "/" (second sd))
      (first sd)
      (word (first sd) (first (bf sd)))  
      ))

#|
;; tests for month-name

(month-name '(january 3))
(month-name '1/3)
(month-name '1/15)
(month-name '11/2)
(month-name '11/25)

|#
     



(define (second wd) (first (bf wd)))
(define (second-last wd) (last (bl wd)))

   
;;;;;   
   
;date-in-month



(define (date-in-month date)
   (if (full-date? date)
      (last date)
      (part-after-slash date)))

      

(define (part-after-slash sd)
   (word
        (if (equal? (last (butlast sd)) "/")
           ""
           (last (butlast sd)))
        (last sd)
        ))


      
#|
;; date-in-month tests
 
(date-in-month '(january 3))
(date-in-month '1/3)
(date-in-month '12/3)
(date-in-month '1/15)
(date-in-month '12/25)
 
 
|#