#include <Servo.h>

Servo lidServo;

const int trigPin = 9;
const int echoPin = 10;
const int servoPin = 6;

long duration;
int distance;
bool lidOpen = false;   // state variable

void setup() {
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  lidServo.attach(servoPin);
  lidServo.write(0);   // lid closed

  Serial.begin(9600);
}

void loop() {
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);

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

  duration = pulseIn(echoPin, HIGH, 30000);
  if (duration == 0) return;

  distance = duration * 0.034 / 2;

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

  // Open lid if hand is detected and lid is closed
  if (distance <= 15 && !lidOpen) {
    lidServo.write(0);
    lidOpen = true;
  }

  // Close lid when hand is removed
  if (distance > 15 && lidOpen) {
    lidServo.write(90);
    lidOpen = false;
  }

  delay(200);
}