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

// Define pin connections
#define DHTPIN 2           // Pin connected to the DHT22
#define FLAME_SENSOR_PIN A3 // Analog pin connected to the flame sensor
#define MQ2_PIN A0         // Analog pin connected to MQ-2 gas sensor
#define SERVO_PIN 9        // Pin connected to servo motor

// Initialize the LCD and DHT22 sensor
LiquidCrystal_I2C lcd(0x27, 20, 4); // I2C address might vary, adjust if necessary
DHT dht(DHTPIN, DHT22);
Servo servo;

// Define thresholds
float tempThreshold = 35.0; // Temperature threshold in Celsius for both temp and gas check
float tempOnlyThreshold = 33.0; // Temperature threshold for temperature-only check
int gasThreshold = 750;     // Gas threshold level (adjust as needed)

// Timing variables
unsigned long previousMillis = 0;
const long interval = 1000; // Interval for updating the display (1000 ms = 1 second)

void setup() {
  // Start LCD, servo, and sensors
  lcd.begin(20, 4);  // Specify 20 columns and 4 rows
  lcd.backlight();
  dht.begin();
  servo.attach(SERVO_PIN);
  servo.write(0); // Set servo to initial position
  
  // Display initial messages
  lcd.setCursor(0, 0);
  lcd.print("System Initializing");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read data from sensors
  float temp = dht.readTemperature();
  float humidity = dht.readHumidity();
  int flameDetected = analogRead(FLAME_SENSOR_PIN) < 500; // Adjust threshold for flame detection
  int gasLevel = analogRead(MQ2_PIN);
  
  // Servo control based on temperature, gas, and flame thresholds
  if (temp > tempThreshold && gasLevel > gasThreshold && flameDetected) {
    servo.write(65); // Move servo to 65 degrees if all three conditions are met
    lcd.setCursor(11, 3);
    lcd.print("ALERT");
  } 
  else if (temp > tempOnlyThreshold) {
    servo.write(45); // Move servo to 45 degrees if only the temperature exceeds 33°C
  } 
  else {
    servo.write(0); 
    lcd.setCursor(11, 3);
    lcd.print("      "); // Clear alert message
  }

  // Check if 1 second has passed to update the display
  unsigned long currentMillis = millis();
  if (currentMillis - previousMillis >= interval) {
    previousMillis = currentMillis; // Save the last time the display was updated

    // Update display every second
    lcd.setCursor(0, 0);
    lcd.print("Temp: ");
    lcd.print(temp);
    lcd.print(" C");
    
    lcd.setCursor(0, 1);
    lcd.print("Hum: ");
    lcd.print(humidity);
    lcd.print(" %");
    
    lcd.setCursor(0, 2);
    lcd.print("Gas Level: ");
    lcd.print(gasLevel);
    
    lcd.setCursor(0, 3);
    lcd.print("Flame: ");
    lcd.print(flameDetected ? "Yes" : "No ");
  }
}