;;; -*- lexical-binding: t -*-
;;
;; this file:
;;   https://dataswamp.org/~incal/terror-3/ev3-motor-turn.el

(require 'ev3-motor)

(defun get-turn-speed (way)
  (let*((step  100)
        (motor (if (eq way 'left)
                   'right
                 'left) )
        (speed (abs (get-motor-speed motor))) )
    (if (< speed step)
        step
      (+ speed step) )))

(defun ev3-turn (dir way &optional reduce)
  (or reduce (setq reduce 2))
  (let*((major-speed (get-turn-speed way))
        (minor-speed (/ major-speed reduce))
        (speeds (if (eq way 'left)
                    `(,minor-speed ,major-speed)
                  `(,major-speed ,minor-speed) ))
        (speeds-dir (if (eq dir 'reverse)
                        (cl-map 'list (lambda (e) (- e)) speeds)
                      speeds) ))
    (set-motor-left  (car  speeds-dir))
    (set-motor-right (cadr speeds-dir)) ))

(defun ev3-turn-forward-left ()
  (interactive)
  (ev3-turn 'forward 'left) )

(defun ev3-turn-forward-right ()
  (interactive)
  (ev3-turn 'forward 'right) )

(let ((minor-frac 3))

  (defun ev3-turn-forward-sharp-left ()
    (interactive)
    (ev3-turn 'forward 'left minor-frac) )

  (declare-function ev3-turn-forward-sharp-left nil)

  (defun ev3-turn-forward-sharp-right ()
    (interactive)
    (ev3-turn 'forward 'right minor-frac) )

  (declare-function ev3-turn-forward-sharp-right nil) )

(defun ev3-turn-reverse-left ()
  (interactive)
  (ev3-turn 'reverse 'left) )

(defun ev3-turn-reverse-right ()
  (interactive)
  (ev3-turn 'reverse 'right) )

(provide 'ev3-motor-turn)