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

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

const int thresholdDistance = 10;
const int maxDistance = 80; 

LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  
  Serial.begin(9600);

  lcd.init();
  lcd.backlight();
  lcd.clear();
  
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(LED_BUILTIN, OUTPUT);

}

void loop() {

  long duration;
  int distance;
  
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  duration = pulseIn(echoPin, HIGH);
  distance = duration * 0.034 / 2;
  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  lcd.setCursor(0, 0);
  lcd.print("Distance: ");
  lcd.print(distance);
  lcd.print(" cm");

  float percentageFilled = ((float)(maxDistance - distance) / maxDistance) * 100;
  
  Serial.print("Percentage Filled: ");
  Serial.print(percentageFilled);
  Serial.println("%");

  if (distance < thresholdDistance && distance < maxDistance) {
    Serial.println("Alert: Dustbin is almost full!");
    lcd.setCursor(0, 1);
    lcd.print("Dustbin Full!");
    digitalWrite(LED_BUILTIN, HIGH);
  } else if (distance >= maxDistance) {
    Serial.println("Dustbin is empty.");
    lcd.setCursor(0, 1);
    lcd.print("Dustbin Empty");
    digitalWrite(LED_BUILTIN, LOW); 
  } else {
    lcd.setCursor(0, 1);
    lcd.print("                ");
    digitalWrite(LED_BUILTIN, LOW);
  }
  
  delay(4000);
}