const int redPin = 12;
const int yellowPin = 11;
const int greenPin = 10;
const int walkPin = 9;
const int buttonPin = 2;

unsigned long previousMillis = 0;
const long yellowTime = 2000;    // 2 seconds yellow
const long walkTime = 4000;      // 4 seconds walk signal

int state = 0;
bool buttonPressed = false;

void setup() {
  pinMode(redPin, OUTPUT);
  pinMode(yellowPin, OUTPUT);
  pinMode(greenPin, OUTPUT);
  pinMode(walkPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);

  // Initial state: red light
  digitalWrite(redPin, HIGH);
  digitalWrite(yellowPin, LOW);
  digitalWrite(greenPin, LOW);
  digitalWrite(walkPin, LOW);

  Serial.begin(9600);
}

void loop() {
  unsigned long currentMillis = millis();

  // Check button press (active LOW)
  if (digitalRead(buttonPin) == LOW) {
    delay(50); // debounce
    if (digitalRead(buttonPin) == LOW) {
      buttonPressed = true;
    }
  }

  switch (state) {
    case 0: // Green light (idle state)
      digitalWrite(redPin, LOW);
      digitalWrite(yellowPin, LOW);
      digitalWrite(greenPin, HIGH);
      digitalWrite(walkPin, LOW);

      if (buttonPressed) {
        state = 1;
        previousMillis = currentMillis;
        buttonPressed = false;
      }
      break;

    case 1: // Green + Yellow
      digitalWrite(greenPin, HIGH);
      digitalWrite(redPin, LOW);
      digitalWrite(yellowPin, HIGH);
      digitalWrite(walkPin, LOW);

      if (currentMillis - previousMillis >= yellowTime) {
        state = 2;
        previousMillis = currentMillis;
      }
      break;

    case 2: // Red + Walk
      digitalWrite(greenPin, LOW);
      digitalWrite(redPin, HIGH);
      digitalWrite(yellowPin, LOW);
      digitalWrite(walkPin, HIGH);

      if (currentMillis - previousMillis >= walkTime) {
        state = 0;
        previousMillis = currentMillis;
      }
      break;
  }
}