const int buttonPin = 12;
const int redLED = 6;
const int yellowLED = 5;
const int greenLED = 3;
int previousButtonState;
int currentButtonState;
int LEDCounter = 0;

void setup() {
  // put your setup code here, to run once:
    // Initialize serial communication
  Serial.begin(9600);
  
  // Set the button pin as input
  pinMode(buttonPin, INPUT);
  pinMode(redLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);

  digitalWrite(redLED, HIGH);
  previousButtonState = 1;
  currentButtonState = 1;

}

void loop() {
  // put your main code here, to run repeatedly:
  if (buttonWasPressed()) {
    incrementLEDs();
  }
  
  // Print the state of the button
  
  // Delay a little bit to avoid bouncing
  delay(50);

}

bool buttonWasPressed() {
  currentButtonState = digitalRead(buttonPin);
  if ((previousButtonState == 1) && (currentButtonState == 0)) {
    previousButtonState = currentButtonState;
    return true;
  }
  else if ((previousButtonState == 0) && (currentButtonState == 1)) {
    previousButtonState = currentButtonState;
    return false;
  }
  else {
    return false;
  }
}

void incrementLEDs() {
  if (LEDCounter == 2) {
    LEDCounter = 0;
  }
  else {
    LEDCounter += 1;
  }

  if (LEDCounter == 0) {
    digitalWrite(redLED, HIGH);
    digitalWrite(yellowLED, LOW);
    digitalWrite(greenLED, LOW);
  }
  else if (LEDCounter == 1) {
    digitalWrite(redLED, LOW);
    digitalWrite(yellowLED, HIGH);
    digitalWrite(greenLED, LOW);
  }
  else if (LEDCounter == 2) {
    digitalWrite(redLED, LOW);
    digitalWrite(yellowLED, LOW);
    digitalWrite(greenLED, HIGH);
  }

  Serial.println(LEDCounter);
}