(defpackage backlight
  (:use :cl)
  (:export :main))
(in-package :backlight)

(defun main()
    (if (= (length uiop:*command-line-arguments*) 1)
	(let ((percent (parse-integer (car uiop:*command-line-arguments*) :junk-allowed t))) 
	  (if (and percent (> percent 0) (<= percent 100)) 
	      (let ((max (parse-integer (alexandria:read-file-into-string "/sys/class/backlight/intel_backlight/max_brightness"))))
		(alexandria:write-string-into-file (format nil "~d" (round (/ (* percent max) 100))) "/sys/class/backlight/intel_backlight/brightness" :if-exists :supersede))
	      (syntax-error)))
	(syntax-error)
      ))

(defun syntax-error()
    (format t "Syntax error~%Usage: backlight <percent>~%")
  ;;(quit)
  )