#include <Servo.h>

#define BUTTON_PIN 3
#define RED_LED_PIN 2
#define GREEN_LED_PIN 10
#define SWITCH_PIN 12
#define DIAL_PIN A0
#define RIGHTSERVO_PIN 9
#define LEFTSERVO_PIN 6

Servo leftservo, rightservo;  // create servo object to control a servo

int pos = 90;
int dialval = 0;    

void setup() {
  leftservo.attach(LEFTSERVO_PIN);  // attaches the servo on pin 9 to the servo object
  rightservo.attach(RIGHTSERVO_PIN);  // attaches the servo on pin 9 to the servo object
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  pinMode(SWITCH_PIN, INPUT);
  pinMode(RED_LED_PIN, OUTPUT);
  pinMode(GREEN_LED_PIN, OUTPUT); 
}

void loop() {
  if  ( digitalRead(SWITCH_PIN) == HIGH )  { // switch is on the right
    //the dial controls the servo positions

    //change the LED's
    digitalWrite(RED_LED_PIN,LOW);
    digitalWrite(GREEN_LED_PIN,HIGH);

    dialval = analogRead(DIAL_PIN);            // reads the value of the potentiometer (value between 0 and 1023)
    pos = map(dialval, 0, 1023, 0, 180);     // scale it to use it with the servo (value between 0 and 180)
    leftservo.write(pos);      // tell servos to go to their positions
    rightservo.write(180-pos);  //the servo is rotated 180 deg, so notice: 180 - rightpos 
    delay(10); 
     
  } else {  // the switch is on the left

    //change the LED's
    digitalWrite(RED_LED_PIN,HIGH);
    digitalWrite(GREEN_LED_PIN,LOW);

    if ( digitalRead(BUTTON_PIN)  == LOW ) { 
      //the green button centers the servos 
      leftservo.write(90);      
      rightservo.write(90);
    }

  }
}