// Pin Definitions
const int redLED = 2;
const int yellowLED = 3;
const int greenLED = 4;
const int pedestrianLED = 5;
const int buttonPin = 6;
const int trigPin = 7;
const int echoPin = 8;
const int buzzerPin = 9;

// Timing variables
const int redDelay = 5000; // 5 seconds for red light
const int yellowDelay = 2000; // 2 seconds for yellow light
const int greenDelay = 5000; // 5 seconds for green light
const int pedestrianDelay = 5000; // 5 seconds for pedestrian light

void setup() {
  // Initialize pins
  pinMode(redLED, OUTPUT);
  pinMode(yellowLED, OUTPUT);
  pinMode(greenLED, OUTPUT);
  pinMode(pedestrianLED, OUTPUT);
  pinMode(buttonPin, INPUT);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);

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

void loop() {
  if (digitalRead(buttonPin) == HIGH) {
    // Activate pedestrian crossing
    digitalWrite(pedestrianLED, HIGH);
    digitalWrite(redLED, HIGH);   // Turn traffic light red
    digitalWrite(yellowLED, LOW);
    digitalWrite(greenLED, LOW);
    Serial.println("Pedestrian Light: GREEN, Traffic Light: RED");
    delay(pedestrianDelay);
    digitalWrite(pedestrianLED, LOW); // Turn off pedestrian light
  } else {
    // Normal traffic light sequence
    trafficLightSequence();
  }

  // Vehicle detection
  checkVehicleDistance();
}

void trafficLightSequence() {
  // Red light
  digitalWrite(redLED, HIGH);
  digitalWrite(yellowLED, LOW);
  digitalWrite(greenLED, LOW);
  Serial.println("Traffic Light: RED");
  delay(redDelay);

  // Green light
  digitalWrite(redLED, LOW);
  digitalWrite(yellowLED, LOW);
  digitalWrite(greenLED, HIGH);
  Serial.println("Traffic Light: GREEN");
  delay(greenDelay);

  // Yellow light
  digitalWrite(redLED, LOW);
  digitalWrite(yellowLED, HIGH);
  digitalWrite(greenLED, LOW);
  Serial.println("Traffic Light: YELLOW");
  delay(yellowDelay);
}

void checkVehicleDistance() {
  // Send a pulse to trigger pin
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Read echo pin
  long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.034 / 2;

  Serial.print("Vehicle Distance: ");
  Serial.print(distance);
  Serial.println(" cm");

  // Sound alarm if vehicle is detected within 10 cm and pedestrian light is green
  if (digitalRead(pedestrianLED) == HIGH && distance <= 10) {
    tone(buzzerPin, 150); // Sound buzzer
    Serial.println("Warning: Vehicle detected! Alarm ON");
  } else {
    noTone(buzzerPin); // Stop buzzer
    Serial.println("No vehicle detected or pedestrian light is off. Alarm OFF");
  }
}