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

LiquidCrystal_I2C lcd(0x27, 16, 2); // Set the LCD address to 0x27 for a 16 chars and 2 line display

const int trigPin = 2;
const int echoPin = 3;
const int buzzerPin = 4;

const float tankCapacityLiters = 6.0; // Maximum capacity of the water tank in liters
const float tankCapacityCM = 6000.0; // Maximum capacity of the water tank in cubic centimeters
const float minDistanceCM = 2.0; // Minimum distance from the sensor to the water level in centimeters
const float tankDiameterCM = 10.0; // Diameter of the tank in centimeters

void setup() {
  lcd.begin(16, 2); // Initialize the LCD
  lcd.backlight(); // Turn on the backlight

  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(buzzerPin, OUTPUT);
  
  Serial.begin(9600); // Initialize serial communication for debugging
}

void loop() {
  long duration;
  float distance, waterLevelPercentage;
  
  // Send ultrasonic pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);
  
  // Read ultrasonic echo
  duration = pulseIn(echoPin, HIGH);
  
  // Calculate distance in cm
  distance = duration * 0.034 / 2;
  
  // Convert distance to water level percentage
  waterLevelPercentage = ((tankCapacityCM - distance * tankDiameterCM * tankDiameterCM * 0.25) / tankCapacityCM) * 100.0;
  waterLevelPercentage = constrain(waterLevelPercentage, 0, 100); // Ensure percentage is within 0-100 range
  
  // Print distance and water level percentage on Serial Monitor
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.print(" cm, Water Level Percentage: ");
  Serial.print(waterLevelPercentage);
  Serial.println("%");

  // Print water level percentage on LCD
  lcd.clear(); // Clear previous content
  lcd.setCursor(0, 0); // Set cursor to first column, first row
  lcd.print("Water Level:");
  lcd.setCursor(0, 1); // Set cursor to first column, second row
  lcd.print(waterLevelPercentage);
  lcd.print("%");

  // Check if water level is almost full (e.g., 90%)
  if (waterLevelPercentage >= 90) {
    // Activate buzzer for 2 seconds
    digitalWrite(buzzerPin, HIGH);
    delay(2000);
    digitalWrite(buzzerPin, LOW);
  }

  delay(1000); // Delay for readability, adjust as needed
}