#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <ESP32Servo.h>
#include <OneWire.h>
#include <DallasTemperature.h>

// Pin Definitions
#define LED 13
#define IR 15
#define BZ 17
#define HT 16   
#define MQ 34   
#define SER 33   
#define FAN1 18   // Servo acting as fan 1
#define FAN2 19   // Servo acting as fan 2

int heatThreshold = 65;  
int gasThreshold = 2000;  
int irValue = 0;
int mqValue = 0;
float temperatureC = 0;
bool alarmActive = false;

Servo myServo;
Servo fanServo1;  // Servo for fan 1
Servo fanServo2;  // Servo for fan 2
LiquidCrystal_I2C lcd(0x27, 16, 2);
OneWire oneWire(HT);
DallasTemperature DS18B20(&oneWire);

// Servo positions for fan rotation
const int FAN_STOP = 90;      // Stop position for continuous rotation servos
const int FAN_FORWARD = 0;    // Full speed forward
const int FAN_BACKWARD = 180; // Full speed backward

void setup() {
  Serial.begin(115200);

  // Initialize LCD
  lcd.init();        
  lcd.backlight();   
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("System Starting");

  // Initialize pins
  pinMode(LED, OUTPUT);
  pinMode(BZ, OUTPUT);
  pinMode(IR, INPUT);
  pinMode(MQ, INPUT);
  
  // Allow allocation of all timers for ESP32
  ESP32PWM::allocateTimer(0);
  ESP32PWM::allocateTimer(1);
  ESP32PWM::allocateTimer(2);
  ESP32PWM::allocateTimer(3);
  
  // Initialize door servo - START WITH DOOR OPEN (180°)
  myServo.setPeriodHertz(50);    // Standard 50hz servo
  myServo.attach(SER, 500, 2400); // Attach servo to pin with min/max pulse width
  myServo.write(180); // Door open initially
  
  // Initialize fan servos (continuous rotation servos)
  fanServo1.setPeriodHertz(50);
  fanServo1.attach(FAN1, 500, 2400);
  fanServo1.write(FAN_STOP); // Stop fans initially
  
  fanServo2.setPeriodHertz(50);
  fanServo2.attach(FAN2, 500, 2400);
  fanServo2.write(FAN_STOP); // Stop fans initially
  
  // Initialize temperature sensor
  DS18B20.begin();
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Security System");
  lcd.setCursor(0, 1);
  lcd.print("Door: OPEN");
  delay(2000);
  lcd.clear();
}

void loop() {
  // Read sensors
  irValue = digitalRead(IR);
  mqValue = analogRead(MQ);
  DS18B20.requestTemperatures();
  temperatureC = DS18B20.getTempCByIndex(0);
  
  // Handle invalid temperature readings
  if (temperatureC == DEVICE_DISCONNECTED_C) {
    temperatureC = 0;
  }
  
  // Serial monitor output
  Serial.print("IR Motion: ");
  Serial.print(irValue ? "YES" : "NO");
  Serial.print(" | Temp: ");
  Serial.print(temperatureC);
  Serial.print("C | Gas: ");
  Serial.print(mqValue);
  Serial.print(" | Alarm: ");
  Serial.println(alarmActive ? "ACTIVE" : "INACTIVE");
  
  // Check alarm conditions (HIGH priority - overrides everything)
  if (temperatureC > heatThreshold || mqValue > gasThreshold) {
    alarmActive = true;
    digitalWrite(BZ, HIGH);
    digitalWrite(LED, HIGH);
    myServo.write(180); // CLOSE door during alarm
    
    // Start fan servos (rotate continuously)
    fanServo1.write(FAN_FORWARD);
    fanServo2.write(FAN_FORWARD);
    
    lcd.clear();
    lcd.setCursor(0, 0);
    lcd.print("ALARM ACTIVATED!");
    lcd.setCursor(0, 1);
    if (temperatureC > heatThreshold) {
      lcd.print("High Temp: ");
      lcd.print(temperatureC, 1);
      lcd.print("C");
    } else {
      lcd.print("Gas Leak: ");
      lcd.print(mqValue);
    }
  }
  else {
    alarmActive = false;
    digitalWrite(BZ, LOW);
    
    // Stop fan servos
    fanServo1.write(FAN_STOP);
    fanServo2.write(FAN_STOP);
    
    // NORMAL OPERATION: Motion detection controls door
    if (irValue == 1) { // Motion detected
      digitalWrite(LED, HIGH);
      myServo.write(180); // CLOSE door when motion detected
      
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Motion Detected!");
      lcd.setCursor(0, 1);
      lcd.print("Door: OPENED");
    } else {
      digitalWrite(LED, LOW);
      myServo.write(0); // OPEN door when no motion
      
      lcd.clear();
      lcd.setCursor(0, 0);
      lcd.print("Status: Normal");
      lcd.setCursor(0, 1);
      lcd.print("Door: CLOSED");
    }
    
    // Show sensor readings on second line when no alarm
    lcd.setCursor(10, 1);
    lcd.print("T:");
    lcd.print(temperatureC, 1);
    lcd.print(" ");
  }

  delay(1000); // Wait 1 second between readings
}