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

#define MQ4_PIN 34      // Pin analog untuk sensor MQ-4
#define LED_RED 27      // Pin untuk LED Merah
#define LED_GREEN 26    // Pin untuk LED Hijau
#define BUZZER_PIN 25   // Pin untuk Buzzer
#define RELAY_PIN 33    // Pin untuk Relay Kipas

LiquidCrystal_I2C lcd(0x27, 16, 2); // Alamat I2C LCD

void setup() {
  Serial.begin(115200);
  lcd.init();
  lcd.backlight();
  
  pinMode(LED_RED, OUTPUT);
  pinMode(LED_GREEN, OUTPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT); // Atur pin relay sebagai OUTPUT
  
  digitalWrite(LED_RED, LOW);
  digitalWrite(LED_GREEN, LOW);
  digitalWrite(BUZZER_PIN, LOW);
  digitalWrite(RELAY_PIN, LOW); // Pastikan relay mati pada awal
  
  lcd.print("Gas Monitor");
  delay(2000);
  lcd.clear();
}

void loop() {
  int gasLevel = analogRead(MQ4_PIN);
  
  lcd.setCursor(0, 0);
  lcd.print("Gas Level: ");
  lcd.print(gasLevel);
  
  if (gasLevel > 2000) { // Ambang batas untuk gas bocor
    digitalWrite(LED_RED, HIGH);
    digitalWrite(LED_GREEN, LOW);
    digitalWrite(BUZZER_PIN, HIGH);
    tone(BUZZER_PIN, 200);
    digitalWrite(RELAY_PIN, HIGH); // Hidupkan kipas
    lcd.setCursor(0, 1);
    lcd.print("Gas Bocor!");
  } else {
    digitalWrite(LED_RED, LOW);
    digitalWrite(LED_GREEN, HIGH);
    digitalWrite(BUZZER_PIN, LOW);
    noTone(BUZZER_PIN);
    digitalWrite(RELAY_PIN, LOW); // Matikan kipas
    lcd.setCursor(0, 1);
    lcd.print("Gas Aman   ");
  }

  delay(1000); // Pembacaan setiap 1 detik
}