// Define pins for ultrasonic sensors
const int trigPinNorth = 5;
const int echoPinNorth = 18;
const int trigPinSouth = 19;
const int echoPinSouth = 21;

// Define pins for traffic light LEDs
const int redNorth = 12;
const int yellowNorth = 14;
const int greenNorth = 27;
const int redSouth = 26;
const int yellowSouth = 15;
const int greenSouth = 2;

long durationNorth, distanceNorth;
long durationSouth, distanceSouth;

int countNorth = 0;
int countSouth = 0;

enum State {
  NORTH_GREEN,
  NORTH_YELLOW,
  SOUTH_GREEN,
  SOUTH_YELLOW
};

State currentState = NORTH_GREEN;

void setup() {
  Serial.begin(115200);
  
  pinMode(trigPinNorth, OUTPUT);
  pinMode(echoPinNorth, INPUT);
  pinMode(trigPinSouth, OUTPUT);
  pinMode(echoPinSouth, INPUT);
  
  pinMode(redNorth, OUTPUT);
  pinMode(yellowNorth, OUTPUT);
  pinMode(greenNorth, OUTPUT);
  pinMode(redSouth, OUTPUT);
  pinMode(yellowSouth, OUTPUT);
  pinMode(greenSouth, OUTPUT);
  
  digitalWrite(redNorth, LOW);
  digitalWrite(yellowNorth, LOW);
  digitalWrite(greenNorth, LOW);
  digitalWrite(redSouth, LOW);
  digitalWrite(yellowSouth, LOW);
  digitalWrite(greenSouth, LOW);
}

void loop() {
  unsigned long currentMillis = millis();
  
  // Measure distance and count vehicles for the north side
  distanceNorth = measureDistance(trigPinNorth, echoPinNorth);
  if (distanceNorth < 50) { // Vehicle detected
    countNorth++;
    delay(500); // Debounce delay
  }
  
  // Measure distance and count vehicles for the south side
  distanceSouth = measureDistance(trigPinSouth, echoPinSouth);
  if (distanceSouth < 50) { // Vehicle detected
    countSouth++;
    delay(500); // Debounce delay
  }
  
  // Traffic light control logic
  if (countNorth > countSouth) {
    if (currentState != NORTH_GREEN) {
      // Transition to yellow light
      digitalWrite(greenNorth, LOW);
      digitalWrite(redNorth, LOW);
      digitalWrite(redSouth, LOW);
      digitalWrite(greenSouth, LOW);
      digitalWrite(yellowNorth, HIGH);
      digitalWrite(yellowSouth, HIGH);
      delay(2000);
      digitalWrite(yellowNorth, LOW);
      digitalWrite(yellowSouth, LOW);
      currentState = NORTH_GREEN;
    }
    digitalWrite(greenNorth, HIGH);
    digitalWrite(redNorth, LOW);
    digitalWrite(greenSouth, LOW);
    digitalWrite(redSouth, HIGH);
  } 
  else {
    if (currentState != SOUTH_GREEN) {
      // Transition to yellow light
      digitalWrite(greenNorth, LOW);
      digitalWrite(redNorth, LOW);
      digitalWrite(redSouth, LOW);
      digitalWrite(greenSouth, LOW);
      digitalWrite(yellowNorth, HIGH);
      digitalWrite(yellowSouth, HIGH);
      delay(2000);
      digitalWrite(yellowNorth, LOW);
      digitalWrite(yellowSouth, LOW);
      currentState = SOUTH_GREEN;
    }
    digitalWrite(greenNorth, LOW);
    digitalWrite(redNorth, HIGH);
    digitalWrite(greenSouth, HIGH);
    digitalWrite(redSouth, LOW);
  }

  // Display counts
  Serial.print("North Count: ");
  Serial.println(countNorth);
  Serial.print("South Count: ");
  Serial.println(countSouth);
  delay(100);
}

long measureDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  long duration = pulseIn(echoPin, HIGH);
  long distance = duration * 0.034 / 2;
  return distance;
}