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

// Inisialisasi LCD: Alamat 0x27 dan ukuran 16x2
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Definisi Pin
const int pinGas = 34;    
const int pinApi = 35;    
const int pinBuzzer = 25; 
const int pinLED = 26;

// Ambang Batas (Threshold)
int batasGas = 1200; 
int batasApi = 500; 

void setup() {
  Serial.begin(115200);
  
  // Setup LCD
  lcd.init();
  lcd.backlight();
  lcd.setCursor(0, 0);
  lcd.print("Sistem Proteksi");
  lcd.setCursor(0, 1);
  lcd.print("Memanaskan...");

  pinMode(pinGas, INPUT);
  pinMode(pinApi, INPUT);
  pinMode(pinBuzzer, OUTPUT);
  pinMode(pinLED, OUTPUT);

  delay(2000); 
  lcd.clear();
}

void loop() {
  int nilaiGas = analogRead(pinGas);
  int nilaiApi = analogRead(pinApi);

  // Monitoring Serial
  Serial.print("Gas: "); Serial.print(nilaiGas);
  Serial.print(" | Api: "); Serial.println(nilaiApi);

  // Tampilan Standar LCD
  lcd.setCursor(0, 0);
  lcd.print("G:"); lcd.print(nilaiGas);
  lcd.print("  A:"); lcd.print(nilaiApi);
  lcd.print("   "); // Menghapus sisa angka sebelumnya

  if (nilaiGas > batasGas || nilaiApi < batasApi) {
    // Tampilan Bahaya di LCD
    lcd.setCursor(0, 1);
    lcd.print("!!! BAHAYA !!!  ");
    digitalWrite(pinLED, HIGH);

    // Nada Alarm Sirine (Naik-Turun)
    for (int hz = 600; hz <= 1200; hz += 20) {
      tone(pinBuzzer, hz);
      delay(5);
    }
    for (int hz = 1200; hz >= 600; hz -= 20) {
      tone(pinBuzzer, hz);
      delay(5);
    }
  } else {
    // Tampilan Aman di LCD
    lcd.setCursor(0, 1);
    lcd.print("Status: Aman    ");
    digitalWrite(pinLED, LOW);
    noTone(pinBuzzer);
  }

  delay(200); 
}