#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <Servo.h>

LiquidCrystal_I2C lcd(0x27, 20, 4);
Servo myservo;

#define triggerPin 12
#define echoPin 13
#define ledPin 2
#define buzzerPin 10
#define buttonPin 7
#define SERVO_PIN 5

const int thresholdDistance = 20;
bool alarmOn = true;

void setup() {
  lcd.begin(16, 2);
  lcd.backlight();

  myservo.attach(SERVO_PIN);
  myservo.write(90);

  pinMode(triggerPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(buttonPin, INPUT_PULLUP);

  Serial.begin(9600);
}

void loop() {
  digitalWrite(triggerPin, LOW);
  delayMicroseconds(2);
  digitalWrite(triggerPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(triggerPin, LOW);

  unsigned long duration = pulseIn(echoPin, HIGH);
  int distance = duration * 0.0343 / 2;

  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" cm");

  if (alarmOn) {
    if (distance < thresholdDistance) {
      lcd.setCursor(0, 1);
      lcd.print("Intruder Alert!");
      digitalWrite(ledPin, HIGH);
      tone(buzzerPin, 3000);
      myservo.write(0);
    } else {
      lcd.setCursor(0, 1);
      lcd.print("Safe!           ");
      digitalWrite(ledPin, LOW);
      noTone(buzzerPin);
      myservo.write(100);
    }
  } else {
    lcd.setCursor(0, 1);
    lcd.print("Alarm OFF");
    digitalWrite(ledPin, LOW);
    noTone(buzzerPin);
    myservo.write(90);
  }

  if (digitalRead(buttonPin) == LOW) {
    delay(200);  
    alarmOn = !alarmOn;  
    lcd.clear();
    lcd.print(alarmOn ? "Alarm ON" : "Alarm OFF");
    delay(100);
  }

  delay(100);
}