constexpr int8_t redLed = 2;
constexpr int8_t yellowLed = 3;
constexpr int8_t greenLed = 4;

enum ledStates : int8_t {
  STOP,
  READY_TO_GO,
  GO,
  READY_TO_STOP
};

ledStates status = STOP;

void setup() {
  Serial.begin(9600);
  pinMode(redLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
}

void stop() {
  digitalWrite(redLed, HIGH);
  digitalWrite(yellowLed, HIGH);
  digitalWrite(greenLed, HIGH);
  delay(4000);
}

void readyToGo() {
  digitalWrite(redLed, HIGH);
  digitalWrite(yellowLed, HIGH);
  digitalWrite(greenLed, LOW);
  delay(1000);
}

void go() {
  digitalWrite(redLed, LOW);
  digitalWrite(yellowLed, LOW);
  digitalWrite(greenLed, HIGH);
  delay(5000);
}

void readyToStop() {
  digitalWrite(redLed, LOW);
  digitalWrite(yellowLed, LOW);
  digitalWrite(greenLed, HIGH);
  delay(1000);
}

void loop() {
  switch(status) {
    case STOP:
      stop();
    break;

    case READY_TO_GO:
      readyToGo();
    break;

    case GO:
      go();
    break;

    case READY_TO_STOP:
      readyToStop();
    break;
  }
}