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

(require 'cl-lib)
(require 'ev3-motor-init)
(require 'file-write-to)

;; speed file

(defun get-motor-speed-file (motor)
  "Get the speed file for MOTOR.

Note: Speed file data does not tell the actual speed of the hardware droid."
  (cl-case motor
    ((left quote)  left-motor-speed-file)
    ((right quote) right-motor-speed-file)
    ((m quote)     m-motor-speed-file) ))

(defun get-motor-speed (motor)
  (file-to-integer (get-motor-speed-file motor) ))

(defun set-motor-speed (motor speed)
  (write-to-file (get-motor-speed-file motor) speed) )

;; motor commands, interacts with droid hardware

(defun get-motor-cmd-file (motor)
  (cl-case motor
    ((left quote)  left-motor-cmd-file)
    ((right quote) right-motor-cmd-file)
    ((m quote)     m-motor-cmd-file) ))

(defun motor-cmd (motor cmd)
  (write-to-file (get-motor-cmd-file motor) cmd) )

(defun stop (motor)
  (motor-cmd motor "stop") )

(defun run-forever (motor)
  (motor-cmd motor "run-forever") )

;; software motor control, use these from Elisp

(defun set-motor (motor speed)
  (let*((max-speed 1050) ; TODO: get from file
        (min-speed (- max-speed)) )
    (when (and (<= min-speed speed)
               (<= speed max-speed) )
      (set-motor-speed motor speed)
      (if (zerop speed)
          (stop motor)
        (run-forever motor) ))))

;; set motors

(defun set-motor-m (speed)
  (set-motor 'm speed) )

(defun set-motor-left (speed)
  (set-motor 'left speed) )

(defun set-motor-right (speed)
  (set-motor 'right speed) )

(defun set-motor-both (speed &optional right)
  (or right (setq right speed))
  (set-motor-left  speed)
  (set-motor-right speed) )

;; stop motors

(defun stop-motor-m ()
  (set-motor 'm 0) )

(defun stop-motor-left ()
  (set-motor 'left  0) )

(defun stop-motor-right ()
  (set-motor 'right 0) )

(defun stop-motor-both ()
  (stop-motor-left)
  (stop-motor-right) )

(provide 'ev3-motor)