#include <LiquidCrystal.h>
#include <Servo.h>

// Initialize LCD and Servo
LiquidCrystal lcd(12, 11, 10, 9, 8, 7);
Servo exhaustFan;

// Pin Definitions
const int buzzerPin = 15;  
const int servoPin = 18;   
int gasLevel;  

// Gas thresholds for different gas types (in ppm)
int coThreshold = 50;       
int methaneThreshold = 5000; 
int lpgThreshold = 10000;  

void setup() {
  pinMode(buzzerPin, OUTPUT);  
  exhaustFan.attach(servoPin); 
  // Initialize LCD
  lcd.begin(16, 2);  
  lcd.setCursor(0, 0);
  lcd.print("Gas Detection Init");
  delay(500);  // Reduced init delay

  // Manually set gas type and gas level (simulating user input)
  String gasType = "Methane";  
  gasLevel = 800;        

  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Gas Type: ");
  lcd.print(gasType);
  
  lcd.setCursor(0, 1);
  lcd.print("Gas Level: ");
  lcd.print(gasLevel);

  // Check if the gas level exceeds the threshold for the selected gas type
  if (gasType == "CO" && gasLevel > coThreshold) {
    handleGasAlarm("CO");
  } else if (gasType == "Methane" && gasLevel > methaneThreshold) {
    handleGasAlarm("Methane");
  } else if (gasType == "LPG" && gasLevel > lpgThreshold) {
    handleGasAlarm("LPG");
  } else {
    lcd.setCursor(0, 1);
    lcd.print("No Harmful Gas");
  }
}

void loop() {
  // Nothing to do in loop, one-time check in setup
}

// Function to handle gas alarm based on gas type
void handleGasAlarm(String gasType) {
  lcd.setCursor(0, 1);
  lcd.print("Harmful " + gasType + "!");
  
  // Activate buzzer
  tone(buzzerPin, 1000);  

  // Rotate the exhaust fan (servo) quickly
  for (int angle = 0; angle <= 180; angle += 10) {  
    exhaustFan.write(angle);
    delay(50);  
  }

  for (int angle = 180; angle >= 0; angle -= 10) {  
    exhaustFan.write(angle);
    delay(50);  
  }

  
}