#include <Wire.h>
#include <DHT.h>
#include <LiquidCrystal.h>

#define DHTPIN 15
#define DHTTYPE DHT22
DHT dht(DHTPIN, DHTTYPE);

#define PPM_ANALOG_PIN 0 // Analog output pin (A0) of MQ135 connected to pin 0 of ESP32

LiquidCrystal lcd(40, 14, 35, 36, 39, 38);

void setup() {
  Serial.begin(115200);
  dht.begin();
  pinMode(20, OUTPUT);
  pinMode(19, OUTPUT);
  lcd.begin(16, 2);
}

void loop() {
  delay(2000);

  float temp = dht.readTemperature();
  float hum = dht.readHumidity();

  // Read analog output from MQ135
  int16_t ppmValue = analogRead(PPM_ANALOG_PIN);
  
  // Convert analog reading to voltage
  float volts = ppmValue * (5.0 / 1023.0);

  // Check if sensor readings are valid
  if (!isnan(temp) && !isnan(hum)) {
    Serial.print("Temperature : ");
    Serial.print(temp);
    Serial.println(" °C");
    Serial.print("Humidity : ");
    Serial.print(hum);
    Serial.println(" %");
    Serial.print("PPM: ");
    Serial.println(volts);

    // Display sensor readings on LCD with scrolling
    displayScrolling("Temp: " + String(temp, 1) + "C  Humidity: " + String(hum, 1) + "%  Air Quality: " + String(volts, 1) + "V");

    // Control LEDs based on temperature
    if (temp > 27) {
      digitalWrite(1, HIGH);
      delay(900);
      digitalWrite(1, LOW);
    } else {
      digitalWrite(0, HIGH);
      delay(900);
      digitalWrite(0, LOW);
    }
  } else {
    Serial.println("Failed to read from DHT sensor!");
  }

  delay(100);
}

// Function to display scrolling text on the LCD
void displayScrolling(String text) {
  for (int i = 0; i < text.length() + 16; i++) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print(text.substring(i, i + 16));
    delay(500); // Adjust the scrolling speed here
  }
}