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

#define trig_pin 3
#define echo_pin 4
int led = 11;
int buzer = 10;
#define dht_pin 9
#define dht_type DHT22

DHT dht(dht_pin, dht_type);
Servo myServo;
#define PIR_pin 2
#define smoke_pin A0  // If this is analog input

LiquidCrystal_I2C lcd(0x27, 16, 2);
long distance;
int duration;

// Threshold for smoke/gas detection (adjust based on your sensor)
#define SMOKE_THRESHOLD 300

void setup() {
  myServo.attach(5);
  pinMode(led, OUTPUT);
  pinMode(buzer, OUTPUT);
  pinMode(PIR_pin, INPUT);
  // Note: smoke_pin is analog, so no pinMode needed for analog input
  pinMode(trig_pin, OUTPUT);
  pinMode(echo_pin, INPUT);
  
  Serial.begin(9600);
  dht.begin();
  
  // Initialize LCD properly
  lcd.init();
  lcd.backlight();
  
  // Welcome message
  lcd.setCursor(0, 0);
  lcd.print("System Starting");
  delay(1000);
  lcd.clear();
}

void loop() {
  // Clear LCD at beginning of each loop
  lcd.clear();
  
  // Read DHT sensor
  float temp = dht.readTemperature();
  float humidity = dht.readHumidity();
  
  // Check if DHT readings are valid
  if (isnan(temp) || isnan(humidity)) {
    Serial.println("Failed to read from DHT sensor!");
    lcd.setCursor(0, 0);
    lcd.print("DHT Error!");
  } else {
    Serial.print("Temperature: ");
    Serial.print(temp);
    Serial.print("°C  Humidity: ");
    Serial.print(humidity);
    Serial.println("%");
    
    // Display on LCD (first line)
    lcd.setCursor(0, 0);
    lcd.print("T:");
    lcd.print(temp, 1);  // Display with 1 decimal
    lcd.print("C H:");
    lcd.print(humidity, 0);  // Display without decimals
    lcd.print("%");
  }
  
  delay(500);
  
  // Ultrasonic sensor reading
  digitalWrite(trig_pin, LOW);
  delayMicroseconds(2);
  digitalWrite(trig_pin, HIGH);
  delayMicroseconds(10);
  digitalWrite(trig_pin, LOW);
  
  duration = pulseIn(echo_pin, HIGH);
  distance = duration * 0.034 / 2;
  
  Serial.print("Distance: ");
  Serial.print(distance);
  Serial.println(" cm");
  
  // Display distance on LCD (second line)
  lcd.setCursor(0, 1);
  lcd.print("Dist:");
  lcd.print(distance);
  lcd.print("cm  ");
  
  // PIR motion sensor
  int motion = digitalRead(PIR_pin);
  if (motion == HIGH) {
    Serial.println("Motion Detected!");
  }
  
  // Gas/smoke sensor - FIXED THIS PART
  // Since smoke_pin is defined as A0 (analog pin), use analogRead
  int gasValue = analogRead(smoke_pin);
  Serial.print("Gas Level: ");
  Serial.println(gasValue);
  
  // Check if gas level exceeds threshold
  if (gasValue > SMOKE_THRESHOLD) {
    Serial.println("Gas Detected!");
    tone(buzer, 1000);
    
    // Display gas warning on LCD
    lcd.setCursor(10, 1);  // Position on second line
    lcd.print("GAS!");
  } else {
    noTone(buzer);
  }
  
  // Distance-based control
  if (distance < 10) {
    digitalWrite(led, HIGH);
    myServo.write(90);
    Serial.println("Object detected - LED ON, Servo at 90°");
  } else {
    digitalWrite(led, LOW);
    myServo.write(0);
  }
  
  delay(1000);
}