// Define the pins for LEDs and IR sensors for each lane
const int redPin[] = {4, 7, 10, 13};
const int yellowPin[] = {3, 6, 9, 12};
const int greenPin[] = {2, 5, 8, 11};
const int irSensorPin[] = {A0, A1, A2, A3};

// Define traffic density threshold
const int trafficThreshold = 50; // Adjust this value based on your setup

void setup() {
  for (int i = 0; i < 4; i++) {
    pinMode(redPin[i], OUTPUT);
    pinMode(yellowPin[i], OUTPUT);
    pinMode(greenPin[i], OUTPUT);
    pinMode(irSensorPin[i], INPUT);
  }
}

void loop() {
  // Check traffic density on each lane
  int trafficDensity[4];
  for (int i = 0; i < 4; i++) {
    trafficDensity[i] = analogRead(irSensorPin[i]);
  }

  // Round-robin algorithm for traffic lights
  for (int i = 0; i < 4; i++) {
    // All lights are red initially
    digitalWrite(redPin[i], HIGH);
    digitalWrite(yellowPin[i], LOW);
    digitalWrite(greenPin[i], LOW);
  }

  delay(2000); // Red light duration

  // Check if traffic density is below threshold to allow vehicles to pass
  if (trafficDensity[0] < trafficThreshold && trafficDensity[1] < trafficThreshold && trafficDensity[2] < trafficThreshold && trafficDensity[3] < trafficThreshold) {
    // Change to yellow for 1 second then green
    for (int i = 0; i < 4; i++) {
      digitalWrite(redPin[i], LOW);
      digitalWrite(yellowPin[i], HIGH);
    }

    delay(1000); // Yellow light duration

    for (int i = 0; i < 4; i++) {
      digitalWrite(yellowPin[i], LOW);
      digitalWrite(greenPin[i], HIGH);
    }

    // Wait until traffic density decreases
    bool highDensity = true;
    while (highDensity) {
      highDensity = false;
      for (int i = 0; i < 4; i++) {
        trafficDensity[i] = analogRead(irSensorPin[i]);
        if (trafficDensity[i] >= trafficThreshold) {
          highDensity = true;
          break;
        }
      }
    }
  }
}