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

// Initialize the LCD (address 0x27 for most 16x2 I2C LCDs)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pin definitions
const int trigPin = 13;
const int echoPin = 12;
const int relayPin = 14;

// Water level threshold distances in cm
const int minDistance = 10; // Minimum distance to turn on pump (tank empty)
const int maxDistance = 300; // Maximum distance to turn off pump (tank full)

void setup() {
  // Set pin modes
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);
  pinMode(relayPin, OUTPUT);

  // Initialize relay to be off
  digitalWrite(relayPin, LOW);

  // Initialize LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Tank Level:");
}

long getDistance() {
  // Send a 10us pulse to trigger the sensor
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the echo pulse width
  long duration = pulseIn(echoPin, HIGH);

  // Convert the pulse width to distance in cm
  long distance = duration * 0.034 / 2;
  return distance;
}

void loop() {
  long distance = getDistance();

  // Calculate tank level percentage
  int tankLevel = map(distance, minDistance, maxDistance, 100, 0);
  tankLevel = constrain(tankLevel, 0, 100); // Keep value between 0% and 100%

  // Display tank level on LCD
  lcd.setCursor(0, 1);
  lcd.print("Level: ");
  lcd.print(tankLevel);
  lcd.print(" %  ");

  // Pump control logic
  if (distance <= minDistance+1) {
    // Tank is full; turn off pump
    digitalWrite(relayPin, LOW);
  } else if (distance >= 70) {
    // Tank is empty; turn on pump
    digitalWrite(relayPin, HIGH);
  }

  delay(1000); // Update every second
}