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

const int mq7Pin = 35;  // GPIO35 for MQ-7
const int mq6Pin = 26;  // GPIO26 for MQ-6
const int pirPin = 27;  // GPIO27 for PIR sensor
const int buzzer = 25;
const int led = 13;
const int TRIG = 2;
const int ECHO = 4;

const float SOUND_SPEED = 0.034;  // Kecepatan suara dalam cm/us
const float CM_TO_INCH = 0.393701;  // Konversi cm ke inch

long duration;
float distanceCm, distanceInch;

// Set the LCD address to 0x27 for a 16 chars and 2 line display
LiquidCrystal_I2C lcd(0x27, 16, 2);

void setup() {
  pinMode(buzzer, OUTPUT);
  pinMode(led, OUTPUT);
  pinMode(TRIG, OUTPUT);  // Harus diatur sebagai OUTPUT
  pinMode(ECHO, INPUT);   // Harus diatur sebagai INPUT

  // Start the serial communication
  Serial.begin(115200);

  // Initialize the LCD
  lcd.init();
  lcd.backlight();

  // Initialize the PIR sensor pin
  pinMode(pirPin, INPUT);

  // Print a message to the LCD
  lcd.setCursor(0, 0);
  lcd.print("Aplikasi");
  lcd.setCursor(0, 1);
  lcd.print("Pendeteksi");
  delay(1500);
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Kebocoran");
  lcd.setCursor(0, 1);
  lcd.print("Gas");
  delay(1500);
}

void loop() {
  // Read the analog values from the sensors
  int mq7Value = analogRead(mq7Pin);
  int mq6Value = analogRead(mq6Pin);

  // Clears the TRIG pin
  digitalWrite(TRIG, LOW);
  delayMicroseconds(2);
  
  // Sets the TRIG on HIGH state for 10 microseconds
  digitalWrite(TRIG, HIGH);
  delayMicroseconds(10);
  digitalWrite(TRIG, LOW);
  
  // Reads the ECHO pin, returns the sound wave travel time in microseconds
  duration = pulseIn(ECHO, HIGH);
  
  // Calculate the distance
  distanceCm = duration * SOUND_SPEED / 2;
  distanceInch = distanceCm * CM_TO_INCH;

  // Print the sensor values to the Serial Monitor
  Serial.print("MQ-7 Value: ");
  Serial.print(mq7Value);
  Serial.print(" MQ-6 Value: ");
  Serial.println(mq6Value);

  // Prints the distance in the Serial Monitor
  Serial.print("Distance (cm): ");
  Serial.println(distanceCm);

  // Check for dangerous gas levels (you can adjust these thresholds)
  bool gasDanger = (mq7Value > 300 || mq6Value > 200);  // Example thresholds

  // Read PIR sensor value
  int gerakanPir = digitalRead(pirPin);

  // Clear the LCD for new display
  lcd.clear();

 // Tampilkan nilai gas dan status pada Serial Monitor
Serial.print("MQ-7: ");
Serial.print(mq7Value);
Serial.print(", MQ-6: ");
Serial.println(mq6Value);
Serial.print("Jarak orang: ");
Serial.println(distanceCm);

// Cek bahaya gas dan tampilkan pesan yang sesuai
if (gasDanger) {  // Jika bahaya gas terdeteksi
    if (gerakanPir == HIGH || distanceCm <= 200) {  // Ada gerakan atau jarak <= 200 cm
        Serial.println("Bahaya! Gas Bocor, ada orang!!");
        digitalWrite(led, HIGH);
        tone(buzzer, 700);  // Bunyi buzzer ketika bahaya gas dan ada gerakan
        lcd.setCursor(0, 0);
        lcd.print("Bahaya!");
        lcd.setCursor(0, 1);
        lcd.print("Gas Bocor!!!");
        delay(4000);  // Tunda 4 detik
        lcd.clear(); 
        lcd.setCursor(0, 0);
        lcd.print("Selamatkan");
        lcd.setCursor(0, 1);
        lcd.print("Diri Anda");
        delay(4000);
    } else {  // Bahaya gas, tapi tidak ada gerakan atau jarak lebih dari 200 cm
        Serial.println("Bahaya Gas, tapi tidak ada gerakan");
        digitalWrite(led, HIGH);
        tone(buzzer, 700);  // Bunyi buzzer karena bahaya gas
        lcd.setCursor(0, 0);
        lcd.print("Bahaya!");
        lcd.setCursor(0, 1);
        lcd.print("Gas Bocor!!!");
        delay(4000);
        lcd.clear();
    }
} else {  // Jika tidak ada bahaya gas
    Serial.println("Gas Aman");
    digitalWrite(led, LOW);
    noTone(buzzer);  // Matikan bunyi alarm
    lcd.clear(); 
    lcd.setCursor(0, 0);
    lcd.print("Status: Aman");
    lcd.setCursor(0, 1);
    lcd.print("Gas Aman");
    delay(4000);
}
}