;; -*- mode: Lisp; -*-

;; This cannot be let-bound within `job'.
(define currency-file (string-append (getenv "HOME") "/.cache/currency.units"))

(job
 (lambda (current-time)
   (let* ((seconds-in-a-day (* 60 60 24))
          (currency-time (stat:mtime (stat currency-file))))
     (if (< currency-time (- current-time seconds-in-a-day))
         (next-second)
       ;; TODO: The following does not work while it should.  Report upstream.
       ;; (next-hour-from (next-day) (list (tm:hour (localtime (current-time)))))
       (+ (next-second) (- 86400 (- current-time currency-time))))))
 ;; A string is nicer than Scheme code for `mcron --schedule' output.
 ;; Other we could return '(system* "units_cur" currency-file)
 (string-append "units_cur " currency-file))