#include <LiquidCrystal.h>

// Define LCD pins
const int rs = 12;
const int en = 11;
const int d4 = 5;
const int d5 = 4;
const int d6 = 3;
const int d7 = 2;

// Define ultrasonic sensor pins
const int trigPin = 9;
const int echoPin = 10;

// Define LED pin
const int ledPin = 7;

// Define buzzer pin
const int buzzerPin = 6;

// Define slide switch pin
const int switchPin = A0;

// Maximum distance (in cm) the ultrasonic sensor can measure
const int maxDistance = 400;

// Threshold for triggering the buzzer (water level below which alarm triggers)
const int buzzerThreshold = 30;

// Initialize LCD
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);

void setup() {
  // Initialize serial communication
  Serial.begin(9600);

  // Set up LCD
  lcd.begin(16, 2);
  
  // Set up ultrasonic sensor pins
  pinMode(trigPin, OUTPUT);
  pinMode(echoPin, INPUT);

  // Set up LED and buzzer pins
  pinMode(ledPin, OUTPUT);
  pinMode(buzzerPin, OUTPUT);

  // Set up slide switch pin
  pinMode(switchPin, INPUT);
}

void loop() {
  // Variables to store the distance and water level
  float distance;
  int waterLevel;

  // Trigger ultrasonic sensor to send pulse
  digitalWrite(trigPin, LOW);
  delayMicroseconds(2);
  digitalWrite(trigPin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trigPin, LOW);

  // Measure the pulse travel time to calculate distance (in cm)
  distance = pulseIn(echoPin, HIGH) / 58.0; // Divide by conversion factor

  // Map distance to water level percentage
  waterLevel = map(distance, 0, maxDistance, 0, 100);

  // Ensure water level stays within 0-100 range
  waterLevel = constrain(waterLevel, 0, 100);

  // Print water level to serial monitor
  Serial.print("Water Level: ");
  Serial.print(waterLevel);
  Serial.println("%");

  // Display water level on LCD
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Water Level:");
  lcd.setCursor(0, 1);
  lcd.print(waterLevel);
  lcd.print("%");

  // Check if water level is below the buzzer threshold
  if (waterLevel <= buzzerThreshold) {
    // Activate LED and buzzer for alarm
    digitalWrite(ledPin, HIGH);
    tone(buzzerPin, 1000); // Buzzer sound
    // Open the switch
    digitalWrite(switchPin, HIGH);
    Serial.println("Switch is OPEN");
  } else {
    // Turn off LED and buzzer
    digitalWrite(ledPin, LOW);
    noTone(buzzerPin);
    // Close the switch
    digitalWrite(switchPin, LOW);
    Serial.println("Switch is CLOSED");
  }

  // Delay before next reading
  delay(1000);
}