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

// Define DHT sensor type and pin
#define DHTTYPE DHT11
#define DHTPIN 2
DHT dht(DHTPIN, DHTTYPE);

// Initialize LCD (16x2)
LiquidCrystal_I2C lcd(0x27, 16, 2);

// Define sensor and output pins
#define MQ135_PIN A0
#define IR_PIN 3
#define BUZZER_PIN 8
#define RED_LED 9
#define GREEN_LED 10

// Thresholds
#define GAS_THRESHOLD 300
#define TEMP_THRESHOLD 50

void setup() {
  // Initialize LCD, DHT, and pins
  lcd.begin(16,2);
  lcd.backlight();
  dht.begin();
  
  pinMode(MQ135_PIN, INPUT);
  pinMode(IR_PIN, INPUT);
  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RED_LED, OUTPUT);
  pinMode(GREEN_LED, OUTPUT);
  
  lcd.setCursor(0, 0);
  lcd.print("Fire & Gas Alarm");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read MQ135 gas sensor
  int gasValue = analogRead(MQ135_PIN);
  
  // Read DHT sensor
  float temp = dht.readTemperature();
  float hum = dht.readHumidity();
  
  // Read IR sensor
  bool flameDetected = digitalRead(IR_PIN);
  
  // Display data on LCD
  lcd.setCursor(0, 0);
  lcd.print("Gas: ");
  lcd.print(gasValue);
  lcd.setCursor(0, 1);
  lcd.print("Temp: ");
  lcd.print(temp);
  lcd.print("C");
  
  // Normal operation (Green LED ON)
  digitalWrite(GREEN_LED, HIGH);
  digitalWrite(RED_LED, LOW);
  digitalWrite(BUZZER_PIN, LOW);
  
  // Check gas levels
  if (gasValue > GAS_THRESHOLD) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("GAS ALERT!");
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER_PIN, HIGH);
    delay(1000);
  }
  
  // Check temperature for fire
  if (temp > TEMP_THRESHOLD || flameDetected) {
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("FIRE ALERT!");
    digitalWrite(RED_LED, HIGH);
    digitalWrite(GREEN_LED, LOW);
    digitalWrite(BUZZER_PIN, HIGH);
    delay(1000);
  }
  
  delay(500);
}