const int buttonPin = A2;
const int trigPin = A4;
const int echoPin = A3;
const int greenLed = A0;
const int yellowLed = A5;
const int redLed = A1;
const int buzzerPin = A6;
long duration, distance;
int buttonState=0;
void setup() {
  Serial.begin(9600);
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);.
  pinMode(buttonPin, INPUT);
  pinMode(redLed, OUTPUT);
  pinMode(yellowLed, OUTPUT);
  pinMode(greenLed, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
}

void loop() {
  if (digitalRead(buttonPin) == LOW ) {
    digitalWrite(trigPin, HIGH);
    delayMicroseconds(10);
    digitalWrite(trigPin, LOW);
    int duration = pulseIn(echoPin, HIGH);
    float distance = duration / 58.0;
    Serial.print("Distance in CM: ");
    Serial.println(distance);
    if(distance<40){
      digitalWrite(redLed, HIGH);
      digitalWrite(yellowLed, LOW);
      digitalWrite(greenLed, LOW);
      tone(buzzerPin, 1000);}
    else if(distance>=40 && distance<=120){
      digitalWrite(redLed, LOW);
      digitalWrite(yellowLed, HIGH);
      digitalWrite(greenLed, LOW);
      tone(buzzerPin, 300);}
    else if(distance>120){
      digitalWrite(redLed, LOW);
      digitalWrite(yellowLed, LOW);
      digitalWrite(greenLed, HIGH);
      noTone(buzzerPin);
}
}

    delay(1000);
    
  }