(require-extension posix)

(define h-last-modified-time 0)

(define h-set-timestamp
  (lambda (f)
    (unless (string=? f "mistieput")
      (let ((s (file-modification-time f)))
        (write
          `(if (> ,s h-last-modified-time)
               (set! h-last-modified-time ,s)) h-aux-port)
        (newline h-aux-port)))))

(define h-timestamp-already-printed? #f)

(define h-print-timestamp
  (lambda ()
    (unless h-timestamp-already-printed?
      (set! h-timestamp-already-printed? #t)
      (unless (= h-last-modified-time 0)
        (display "<p><div align=right><small><font color=gray>")
        (display "Last modified: ")
        (display (h-seconds->human-time h-last-modified-time))
        (display "</font></small></div><p>")
        (newline)))))

(define h-seconds->human-time
  (lambda (s)
    (let ((d (seconds->local-time s)))
      (string-append
        (h-month-in-words (vector-ref d 4))
        " "
        (number->string (vector-ref d 3))
        ", "
        (number->string (+ 1900 (vector-ref d 5)))))))

(define h-the-months
  (vector "Jan." "Feb." "March" "April" "May" "June"
          "July" "Aug." "Sept." "Oct." "Nov." "Dec."))

(define h-month-in-words
  (lambda (n)
    (vector-ref h-the-months n)))