#include <Servo.h>

#define TRIG_PIN   10  // Purple
#define ECHO_PIN   11  // Cyan
#define SERVO_PIN  9   // Blue
#define BUZZER_PIN 8   // Yellow
#define LED_PIN    7   // Green

Servo doorServo;
bool doorOpen = false;
int threshold = 20;

void setup() {
  Serial.begin(9600);
  doorServo.attach(SERVO_PIN);

  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(LED_PIN, OUTPUT);
}

void loop() {
  long duration;
  int distance;

  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);

  duration = pulseIn(ECHO_PIN, HIGH);
  distance = duration * 0.034 / 2;

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

  if (distance < threshold && !doorOpen) {
    openDoor();
    alert();
  } else if (distance >= threshold && doorOpen) {
    closeDoor();
  }

  delay(200);
}

void openDoor() {
  doorServo.write(90);
  doorOpen = true;
  Serial.println("Door Opened");
}

void closeDoor() {
  doorServo.write(0);
  doorOpen = false;
  Serial.println("Door Closed");
}

void alert() {
  digitalWrite(LED_PIN, HIGH);
  tone(BUZZER_PIN, 1000);
  delay(1000);
  noTone(BUZZER_PIN);
  digitalWrite(LED_PIN, LOW);
}