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

#define ECHO_PIN 2
#define TRIG_PIN 3

Servo myservo;  // create servo object to control a servo
#define I2C_ADDR    0x27
#define LCD_COLUMNS 16
#define LCD_LINES   2
LiquidCrystal_I2C lcd(I2C_ADDR, LCD_COLUMNS, LCD_LINES);

int pos = 0;    // variable to store the servo position

float readDistanceCM() {
  digitalWrite(TRIG_PIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIG_PIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG_PIN, LOW);
  int duration = pulseIn(ECHO_PIN, HIGH);
  return duration * 0.034 / 2;
}

void setup() {
  Serial.begin(115200);
  pinMode(LED_BUILTIN, OUTPUT);
  pinMode(TRIG_PIN, OUTPUT);
  pinMode(ECHO_PIN, INPUT);

  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
  // Init LCD
  lcd.init();
  lcd.backlight();

  // Print something
  lcd.setCursor(3, 0);
  lcd.print("Distance: ");
}

void loop() {
  float distance = readDistanceCM();

  bool isNearby = distance < 100;
  digitalWrite(LED_BUILTIN, isNearby);

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

  lcd.clear(); // clear the LCD display

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

  if (distance < 50) {
     // Move servo to 0 degrees if the distance is less than 50 cm
    myservo.write(0);

  } else if (distance >= 50 && distance < 100) {
    // Move servo to 90 degrees if the distance is between 50 and 100 cm
    myservo.write(90);
    
  } else {
     // Move servo to 180 degrees if the distance is greater than or equal to 100 cm
  myservo.write(180);
  }

  delay(100);
}