// Define pins for LEDs, button, buzzer, and ultrasonic sensor
const int redLightPin = 2;
const int yellowLightPin = 3;
const int greenLightPin = 4;
const int pedestrianGreenPin = 5;
const int buttonPin = 6;
const int buzzerPin = 9;
const int trigPin = 7;
const int echoPin = 8;

// Variables to store the button state
int buttonState = 0;
long duration;
int distance;

void setup() {
  // Set up the LED pins as outputs
  pinMode(redLightPin, OUTPUT);
  pinMode(yellowLightPin, OUTPUT);
  pinMode(greenLightPin, OUTPUT);
  pinMode(pedestrianGreenPin, OUTPUT);

  // Set up the button pin as input with an internal pull-up resistor
  pinMode(buttonPin, INPUT_PULLUP);

  // Set up the buzzer pin as output
  pinMode(buzzerPin, OUTPUT);

  // Set up the ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Initialize the serial communication
  Serial.begin(9600);
}

void loop() {
  // Read the state of the push button
  buttonState = digitalRead(buttonPin);

  if (buttonState == LOW) {
    
    digitalWrite(pedestrianGreenPin, HIGH);
    digitalWrite(redLightPin, HIGH);
    digitalWrite(greenLightPin, LOW);
    digitalWrite(yellowLightPin, LOW);

    // Print status to serial monitor
    Serial.println("Pedestrian crossing activated. Traffic light is red.");

    // Check for vehicle detection
    for (int i = 0; i < 10000; i += 100) {
      detectVehicle();
      delay(100);  // Delay for 100ms between checks
    }

    // Turn off the pedestrian green light
    digitalWrite(pedestrianGreenPin, LOW);

    // Resume normal traffic light sequence
    trafficLightSequence();
  } else {
    // Normal traffic light sequence
    trafficLightSequence();
  }
}

void trafficLightSequence() {
  // Red light on
  digitalWrite(redLightPin, HIGH);
  digitalWrite(greenLightPin, LOW);
  digitalWrite(yellowLightPin, LOW);
  Serial.println("Traffic Light: RED");
  delay(5000);

  // Yellow light on
  digitalWrite(yellowLightPin, HIGH);
  digitalWrite(redLightPin, LOW);
  Serial.println("Traffic Light: YELLOW");
  delay(2000);

  // Green light on
  digitalWrite(greenLightPin, HIGH);
  digitalWrite(yellowLightPin, LOW);
  Serial.println("Traffic Light: GREEN");
  delay(5000);
}

void detectVehicle() {
  // Clear the trigPin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

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

  
  duration = pulseIn(echoPin, HIGH);

  // Calculate the distance
  distance = duration * 0.034 / 2;  

  // Print the distance to the serial monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" m");

  if (distance <= 10 && digitalRead(pedestrianGreenPin) == HIGH) {
    tone(buzzerPin, 150);  // Sound the buzzer
    Serial.println("Vehicle detected! Warning pedestrians.");
  } else {
    noTone(buzzerPin);  // Stop the buzzer
  }
}