const int redLedPin = 1;
const int yellowLedPin = 2;
const int greenLedPin = 3;
const int buttonPin = 7;

unsigned long previusMillis = 0;
const long redInterval = 3000;
const long yellowInterval = 2000;
const long greenInterval = 3000;

long extraRedInterval = 3000;
long currentInterval = 0;

int ledState = LOW;
int currentLed = 0;
bool extraTime;

void setup() {
  // put your setup code here, to run once:
  pinMode(redLedPin, OUTPUT);
  pinMode(yellowLedPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  pinMode(buttonPin, INPUT);
}

void loop() {
  unsigned long currentMillis = millis();
  int buttonState = digitalRead(buttonPin);

  if(buttonState == HIGH){
    extraTime = true;
  }

  if(currentMillis - previusMillis >= currentInterval){
    previusMillis = currentMillis;

    turnOffLeds();

    if(currentLed == 0){
      digitalWrite(redLedPin, HIGH);
      currentInterval = redInterval;

      if(extraTime){
        currentInterval += extraRedInterval;
        extraTime = false;
      }
      currentLed = 1;
    }
    else if (currentLed == 1){
      digitalWrite(yellowLedPin, HIGH);
      currentInterval = yellowInterval;
      currentLed = 2;
    }
    else if (currentLed == 2){
      digitalWrite(greenLedPin, HIGH);
      currentInterval = greenInterval;
      currentLed = 0;
    }
  }
}

void turnOffLeds(){
  digitalWrite(redLedPin, LOW);
  digitalWrite(yellowLedPin, LOW);
  digitalWrite(greenLedPin, LOW);
}