;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/emacs-init/dope.el

(require 'cl-lib)

(defun read-string-1 (ps &optional def hist)
  (setq ps (format-prompt ps def))
  (read-string ps nil hist def))

;; (read-string-1 "name" "Danger")

(defun day (&optional ps)
  (let ((today-str (format-time-string "%F")))
    (if ps
        (read-string-1 ps today-str)
      today-str) ))

;; (day)
;; (day "from")

(defun date-to-time-1 (from)
  (date-to-time (format "%sT00:00+01:00" from)) )

(defun dope (from boxes pills dose)
  (interactive
    (list
      (day "from")
      (read-number "boxes: "     16)
      (read-number "pills/box: " 30)
      (read-number "pills/day: "  5) ))
  (let*((days (/ (* boxes pills) dose))
        (done (time-add (date-to-time-1 from) (days-to-time (1- days))))
        (str  (format-time-string "%F" done))
        (more (format-time-string "%F" (time-add done (days-to-time -8)))) )
    (insert (format "%s  [%s]  %s" from more str) )))

(let ((def-days 21)
      (def-sets  4) )
  (defun add-days (&optional from days sets)
    (interactive
      (list
        (day "from")
        (read-number "days: " def-days)
        (read-number "sets: " def-sets) ))
    (or from (setq from (day)))
    (or days (setq days def-days))
    (or sets (setq sets def-sets))
    (cl-loop
      for s from 1 to (1- sets)
      do (insert
           (format-time-string "%F\n"
             (time-add (date-to-time-1 from) (days-to-time (* s days))) ))))
  (declare-function add-days nil) )

(provide 'dope)