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

LiquidCrystal_I2C lcd(0x27, 16, 2);
Servo servoMotor;

#define MQ2_ANA A1
#define MQ2_DIG 2
#define Threshold 400
#define buttonPin 7  
#define servoPin 9   

int buzzerPin = 13;
int redLedPin = 5;
int greenLedPin = 6;

bool gasOn = true;  

void setup() {
  lcd.init();
  lcd.backlight();
  lcd.setCursor(2,0);
  lcd.print("smoke detecting");
  lcd.setCursor(4,1);
  lcd.print("Project");
  delay(4000);
  lcd.clear();
  
  Serial.begin(9600);
  
  pinMode(MQ2_ANA, INPUT);
  pinMode(MQ2_DIG, INPUT);
  pinMode(buzzerPin, OUTPUT);
  pinMode(redLedPin, OUTPUT);
  pinMode(greenLedPin, OUTPUT);
  
  pinMode(buttonPin, INPUT_PULLUP);  
  servoMotor.attach(servoPin);       
}

void loop() {
  Serial.print("Analog: ");
  Serial.println(analogRead(MQ2_ANA));
  Serial.print("Digital: ");
  Serial.println(digitalRead(MQ2_DIG));
  delay(300);
  
  lcd.setCursor(2,0);
  lcd.print("Smoke = ");
  lcd.setCursor(10,0);
  lcd.print(analogRead(MQ2_ANA));
  
  if (analogRead(MQ2_ANA) > Threshold) {
    tone(buzzerPin, 200);
    digitalWrite(redLedPin, HIGH); 
    digitalWrite(greenLedPin, LOW);
    lcd.setCursor(0, 1);
    lcd.print("Gas Warning!"); 
    if (gasOn) {
      closeGas();  
      gasOn = false;
    }
    
    servoMotor.write(0);
  }
  else {
    noTone(buzzerPin);
    digitalWrite(redLedPin, LOW); 
    digitalWrite(greenLedPin, HIGH);
    lcd.setCursor(0, 1);
    lcd.print("               "); 
    if (!gasOn) {
      openGas();  
      gasOn = true;
    }
    
    servoMotor.write(90); 
  }
  

  if (digitalRead(buttonPin) == LOW) {
    if (servoMotor.read() == 0) {
      servoMotor.write(90); 
    } else {
      servoMotor.write(0);   
    }
    delay(500); 
  }
  
  delay(300);
}


void closeGas() {

  servoMotor.write(0);
}


void openGas() {
  
  servoMotor.write(90);  
}