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

// LCD setup (0x27 or 0x3F)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Pins
int gasSensorPin = A0;
int buzzerPin = 8;

// Threshold values
int threshold = 500;
int threshold1 = 750;

void setup() {
  lcd.init();
  lcd.backlight();

  pinMode(buzzerPin, OUTPUT);
  pinMode(gasSensorPin, INPUT);

  lcd.setCursor(0, 0);
  lcd.print("Gas Monitoring");
  delay(2000);
  lcd.clear();
}

void loop() {
  int gasValue = analogRead(gasSensorPin);

  lcd.setCursor(0, 0);
  lcd.print("Gas: ");
  lcd.print(gasValue);
  lcd.print("   "); // clear extra chars

  // Check highest danger first
  if (gasValue > threshold1) {
    lcd.setCursor(0, 1);
    lcd.print("VERY DANGEROUS!");
    digitalWrite(buzzerPin, HIGH);
  }
  else if (gasValue > threshold) {
    lcd.setCursor(0, 1);
    lcd.print("GAS DETECTED!  ");
    digitalWrite(buzzerPin, HIGH);
  }
  else {
    lcd.setCursor(0, 1);
    lcd.print("Safe           ");
    digitalWrite(buzzerPin, LOW);
  }

  delay(500);
}