// Define the pins for the lights
const int NSGreen = 2;
const int NSYellow = 3;
const int NSRed = 4;
const int EWGreen = 5;
const int EWYellow = 6;
const int EWRed = 7;

// State representation (2 bits):
// 00 - NS_GREEN
// 01 - NS_YELLOW
// 10 - EW_GREEN
// 11 - EW_YELLOW
uint8_t currentState = 0b00; // Start with NS_GREEN (00)

unsigned long previousMillis = 0; // Timer variable
const unsigned long greenDuration = 7000;  // 7 seconds
const unsigned long yellowDuration = 3000; // 3 seconds

void setup() {
  // Set pins as outputs
  pinMode(NSGreen, OUTPUT);
  pinMode(NSYellow, OUTPUT);
  pinMode(NSRed, OUTPUT);
  pinMode(EWGreen, OUTPUT);
  pinMode(EWYellow, OUTPUT);
  pinMode(EWRed, OUTPUT);

  // Initialize with North-South Green
  digitalWrite(NSGreen, HIGH);
  digitalWrite(EWRed, HIGH);
}

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

  switch (currentState) {
    case 0b00: // NS_GREEN
      if (currentMillis - previousMillis >= greenDuration) {
        // Transition to NS_YELLOW
        digitalWrite(NSGreen, LOW);
        digitalWrite(NSYellow, HIGH);
        currentState = 0b01; // NS_YELLOW
        previousMillis = currentMillis;
      }
      break;

    case 0b01: // NS_YELLOW
      if (currentMillis - previousMillis >= yellowDuration) {
        // Transition to EW_GREEN
        digitalWrite(NSYellow, LOW);
        digitalWrite(NSRed, HIGH);
        digitalWrite(EWRed, LOW);
        digitalWrite(EWGreen, HIGH);
        currentState = 0b10; // EW_GREEN
        previousMillis = currentMillis;
      }
      break;

    case 0b10: // EW_GREEN
      if (currentMillis - previousMillis >= greenDuration) {
        // Transition to EW_YELLOW
        digitalWrite(EWGreen, LOW);
        digitalWrite(EWYellow, HIGH);
        currentState = 0b11; // EW_YELLOW
        previousMillis = currentMillis;
      }
      break;

    case 0b11: // EW_YELLOW
      if (currentMillis - previousMillis >= yellowDuration) {
        // Transition to NS_GREEN
        digitalWrite(EWYellow, LOW);
        digitalWrite(EWRed, HIGH);
        digitalWrite(NSRed, LOW);
        digitalWrite(NSGreen, HIGH);
        currentState = 0b00; // NS_GREEN
        previousMillis = currentMillis;
      }
      break;
  }
}