#include <Wire.h>
#include <LiquidCrystal_I2C.h>  // Include the LCD I2C library
#include <DHT.h>

// Define pins and components
#define DHTPIN 4
#define DHTTYPE DHT22
#define TRIGPIN 18
#define ECHOPIN 19
#define RELAYPIN 25
#define BUZZERPIN 26

// Initialize DHT22
DHT dht(DHTPIN, DHTTYPE);

// Initialize LCD (20x4) with address 0x3F for Wokwi
LiquidCrystal_I2C lcd(0x3F, 20, 4); // Set the LCD address to 0x3F (common in Wokwi) and size to 20x4

// Variables for water level
const float tankHeight = 20.0;  // Tank height in cm for 2L
float waterLevel = 0;            // Water level in liters

// Temperature thresholds
const float tempThresholdOn = 30.0;  // Temperature to turn pump ON
const float tempThresholdOff = 25.0; // Temperature to turn pump OFF

// Buzzer control
bool buzzerState = false;  // To track the buzzer state

// Water level thresholds for pump control
const float waterLevelThresholdLow = 0.3;  // Water level to turn pump off (if below this) 300 mL
const float waterLevelThresholdOn = 1.0;   // Water level to turn pump on (if above this) 1 Liter

void setup() {
  // Initialize serial monitor
  Serial.begin(115200);

  // Initialize DHT sensor
  dht.begin();

  // Initialize LCD
  lcd.begin(20, 4);          // Set up the LCD's number of columns and rows
  lcd.backlight();           // Turn on the LCD backlight

  // Initialize relay and buzzer
  pinMode(RELAYPIN, OUTPUT);
  pinMode(BUZZERPIN, OUTPUT);
  digitalWrite(RELAYPIN, LOW);
  digitalWrite(BUZZERPIN, LOW);

  // Initialize ultrasonic sensor
  pinMode(TRIGPIN, OUTPUT);
  pinMode(ECHOPIN, INPUT);
}

void loop() {
  // Read temperature and humidity
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();

  // Read water level
  waterLevel = readWaterLevel();

  // Control pump based on water level and temperature
  static bool pumpOn = false;

  // If water level is below 300mL or temperature is below 25°C, turn off pump
  if (waterLevel <= waterLevelThresholdLow || temperature <= tempThresholdOff) {
    pumpOn = false;  // Turn off pump
    digitalWrite(RELAYPIN, LOW);  // Turn off pump
  }

  // If water level is above 1L and temperature is above 30°C, turn pump on
  else if (waterLevel >= waterLevelThresholdOn && temperature >= tempThresholdOn && !buzzerState) {
    pumpOn = true;
    digitalWrite(RELAYPIN, HIGH);  // Turn on pump
  }

  // Handle water tank alert
  if (waterLevel <= waterLevelThresholdLow) {
    // Trigger buzzer if water level is low
    buzzerState = true;
    tone(BUZZERPIN, 1500);  // Start buzzer at 1500 Hz
  } else if (waterLevel >= waterLevelThresholdOn) {
    // Stop buzzer if water level is 1L or more
    buzzerState = false;
    noTone(BUZZERPIN);  // Stop buzzer
  }

  // Control buzzer based on buzzerState
  if (buzzerState) {
    digitalWrite(BUZZERPIN, HIGH);  // Turn on buzzer
  } else {
    digitalWrite(BUZZERPIN, LOW);   // Turn off buzzer
  }

  // Update LCD display
  lcd.clear();  // Clear previous screen content

  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(temperature);
  lcd.print(" C");

  lcd.setCursor(0, 1);
  lcd.print("Pump: ");
  lcd.print(pumpOn ? "ON" : "OFF");

  lcd.setCursor(0, 2);
  lcd.print("Level: ");
  lcd.print(waterLevel, 1);
  lcd.print(" L");

  if (waterLevel <= waterLevelThresholdLow) {
    lcd.setCursor(0, 3);
    lcd.print("Alert: Low Tank!");
  }

  // Delay for next update
  delay(1000);
}

// Function to calculate water level
float readWaterLevel() {
  digitalWrite(TRIGPIN, LOW);
  delayMicroseconds(2);
  digitalWrite(TRIGPIN, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIGPIN, LOW);

  float duration = pulseIn(ECHOPIN, HIGH);
  float distance = (duration / 2) * 0.0343;  // Convert to cm

  if (distance > tankHeight) distance = tankHeight;
  return 2.0 * (tankHeight - distance) / tankHeight;  // Convert to liters
}