// Road A sensor
#define TRIG1 3
#define ECHO1 2
// Road B sensor
#define TRIG2 4
#define ECHO2 5

// Road A LEDs
#define GREEN_A 10
#define YELLOW_A 11
#define RED_A 12

// Road B LEDs
#define GREEN_B 13
#define YELLOW_B 14
#define RED_B 15

long duration;
int distance1, distance2;

void setup() {
  // Sensors
  pinMode(TRIG1, OUTPUT);
  pinMode(ECHO1, INPUT);
  pinMode(TRIG2, OUTPUT);
  pinMode(ECHO2, INPUT);

  // Road A LEDs
  pinMode(GREEN_A, OUTPUT);
  pinMode(YELLOW_A, OUTPUT);
  pinMode(RED_A, OUTPUT);

  // Road B LEDs
  pinMode(GREEN_B, OUTPUT);
  pinMode(YELLOW_B, OUTPUT);
  pinMode(RED_B, OUTPUT);

  Serial.begin(9600);
}

// Generic function to measure distance
int getDistance(int trigPin, int echoPin) {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  duration = pulseIn(echoPin, HIGH);
  return duration * 0.034 / 2; // Convert to cm
}

void loop() {
  // Read both sensors
  distance1 = getDistance(TRIG1, ECHO1);
  distance2 = getDistance(TRIG2, ECHO2);

  Serial.print("Road A distance: ");
  Serial.println(distance1);
  Serial.print("Road B distance: ");
  Serial.println(distance2);

  if (distance1 < 20 && distance2 >= 20) {
    // Road A priority
    Serial.println("Road A has priority");
    digitalWrite(GREEN_A, HIGH);
    digitalWrite(RED_B, HIGH); // Road B stays red
    delay(6000);

    digitalWrite(GREEN_A, LOW);
    digitalWrite(YELLOW_A, HIGH);
    delay(2000);
    digitalWrite(YELLOW_A, LOW);

    digitalWrite(RED_A, HIGH);
    digitalWrite(RED_B, LOW); // Switch to Road B
    delay(4000);
    digitalWrite(RED_A, LOW);

  } else if (distance2 < 20 && distance1 >= 20) {
    // Road B priority
    Serial.println("Road B has priority");
    digitalWrite(GREEN_B, HIGH);
    digitalWrite(RED_A, HIGH); // Road A stays red
    delay(6000);

    digitalWrite(GREEN_B, LOW);
    digitalWrite(YELLOW_B, HIGH);
    delay(2000);
    digitalWrite(YELLOW_B, LOW);

    digitalWrite(RED_B, HIGH);
    digitalWrite(RED_A, LOW); // Switch to Road A
    delay(4000);
    digitalWrite(RED_B, LOW);

  } else {
    // Balanced or no vehicles → default cycle
    Serial.println("Balanced traffic or no vehicles");

    // Road A green, Road B red
    digitalWrite(GREEN_A, HIGH);
    digitalWrite(RED_B, HIGH);
    delay(4000);
    digitalWrite(GREEN_A, LOW);
    digitalWrite(RED_B, LOW);

    digitalWrite(YELLOW_A, HIGH);
    delay(2000);
    digitalWrite(YELLOW_A, LOW);

    digitalWrite(RED_A, HIGH);
    digitalWrite(GREEN_B, HIGH);
    delay(4000);
    digitalWrite(RED_A, LOW);
    digitalWrite(GREEN_B, LOW);

    digitalWrite(YELLOW_B, HIGH);
    delay(2000);
    digitalWrite(YELLOW_B, LOW);

    digitalWrite(RED_B, HIGH);
  }
}