const int RED = 8, YELLOW = 9, GREEN = 10;
const int TRIG = 2, ECHO = 3;

void setup() {
  pinMode(RED, OUTPUT);
  pinMode(YELLOW, OUTPUT);
  pinMode(GREEN, OUTPUT);
  pinMode(TRIG, OUTPUT);
  pinMode(ECHO, INPUT);
  Serial.begin(9600);
}

void loop() {
  // Membaca jarak dari sensor ultrasonic
  digitalWrite(TRIG, LOW); delayMicroseconds(2);
  digitalWrite(TRIG, HIGH); delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  
  long duration = pulseIn(ECHO, HIGH);
  int distance = duration * 0.034 / 2;

  // LOGIKA PINTAR:
  // Jika jarak benda < 100cm, anggap ada antrean kendaraan
  if (distance < 100 && distance > 0) {
    Serial.println("Kendaraan terdeteksi! Lampu Hijau Prioritas.");
    digitalWrite(RED, LOW);
    digitalWrite(YELLOW, LOW);
    digitalWrite(GREEN, HIGH);
    delay(5000); // Beri waktu hijau lebih lama
  } else {
    // Siklus Normal
    digitalWrite(GREEN, LOW);
    digitalWrite(RED, HIGH);
    delay(3000);
    digitalWrite(RED, LOW);
    digitalWrite(YELLOW, HIGH);
    delay(1000);
    digitalWrite(YELLOW, LOW);
    digitalWrite(GREEN, HIGH);
    delay(3000);
  }
}