// --- Include Necessary Libraries ---
#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <DHT.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include "BluetoothSerial.h" // Bluetooth library for local communication

// --- Bluetooth Configuration ---
BluetoothSerial SerialBT; // Create a Bluetooth Serial object

// --- Hardware Pin Definitions ---
#define BUZZER_PIN 15
#define DHT_PIN 27
#define RELAY_PIN 26
#define DHT_TYPE DHT22

// --- Alarm Configuration ---
const float ALARM_TEMPERATURE = 30.0;

// --- Hardware Object Initialization ---
LiquidCrystal_I2C lcd(0x27, 20, 4);
DHT dht(DHT_PIN, DHT_TYPE);
Adafruit_MPU6050 mpu;

// --- State Management Variables ---
bool blinkState = false;
unsigned long lastBlinkTime = 0;
bool alarmState = false; // To track if the alarm is currently active

// =================================================================
//  SETUP FUNCTION
// =================================================================
void setup() {
  Serial.begin(115200);

  // --- Initialize Bluetooth ---
  SerialBT.begin("ESP32_System_Monitor"); // Set the Bluetooth device name
  Serial.println("Bluetooth device is ready to pair.");
  SerialBT.println("Welcome to the ESP32 System Monitor!");
  SerialBT.println("------------------------------------");

  lcd.init();
  lcd.backlight();
  
  lcd.clear();
  lcd.setCursor(0, 0);
  lcd.print("Full System Monitor");
  lcd.setCursor(0, 1);
  lcd.print("Bluetooth Mode");
  delay(2000);

  dht.begin();

  if (!mpu.begin()) {
    Serial.println("Failed to find MPU6050 chip");
    lcd.clear();
    lcd.setCursor(0, 2);
    lcd.print("MPU6050 Error!");
    while (1) {
      delay(10);
    }
  }
  Serial.println("MPU6050 Found!");
  
  mpu.setAccelerometerRange(MPU6050_RANGE_8_G);
  mpu.setGyroRange(MPU6050_RANGE_500_DEG);
  mpu.setFilterBandwidth(MPU6050_BAND_21_HZ);

  pinMode(BUZZER_PIN, OUTPUT);
  pinMode(RELAY_PIN, OUTPUT);
  digitalWrite(RELAY_PIN, LOW);
  
  lcd.clear();
}

// =================================================================
//  LOOP FUNCTION
// =================================================================
void loop() {
  float humidity = dht.readHumidity();
  float currentTemp = dht.readTemperature();

  if (isnan(humidity) || isnan(currentTemp)) {
    Serial.println("Failed to read from DHT sensor!");
    lcd.setCursor(0, 3);
    lcd.print("STATUS: DHT ERROR   ");
    return;
  }

  sensors_event_t a, g, temp;
  mpu.getEvent(&a, &g, &temp);

  // --- Send Data to Bluetooth Serial ---
  String btData = "Temp: " + String(currentTemp, 1) + "C, ";
  btData += "Humi: " + String(humidity, 1) + "%, ";
  btData += "Accel X: " + String(a.acceleration.x, 1) + ", ";
  btData += "Y: " + String(a.acceleration.y, 1) + ", ";
  btData += "Z: " + String(a.acceleration.z, 1);
  SerialBT.println(btData);

  // --- Update LCD Display ---
  lcd.setCursor(0, 0);
  lcd.print("Temp: ");
  lcd.print(currentTemp, 1);
  lcd.print((char)223);
  lcd.print("C        ");

  lcd.setCursor(0, 1);
  lcd.print("Humi: ");
  lcd.print(humidity, 1);
  lcd.print("%       ");

  lcd.setCursor(0, 2);
  lcd.print("X:");
  lcd.print(a.acceleration.x, 1);
  lcd.print(" Y:");
  lcd.print(a.acceleration.y, 1);
  lcd.print(" m/s2 ");


  // --- Main Alarm Logic ---
  if (currentTemp > ALARM_TEMPERATURE) {
    digitalWrite(RELAY_PIN, HIGH);
    tone(BUZZER_PIN, 1500, 500);
    
    if (!alarmState) { // Send alarm message only once when the state changes
        SerialBT.println("!!! ALARM: HIGH TEMPERATURE !!!");
        alarmState = true;
    }

    if (millis() - lastBlinkTime > 500) {
      lastBlinkTime = millis();
      blinkState = !blinkState;
      lcd.setCursor(0, 3);
      if (blinkState) {
        lcd.print("ALARM! HIGH TEMP!   ");
      } else {
        lcd.print("                    ");
      }
    }

  } else {
    digitalWrite(RELAY_PIN, LOW);
    noTone(BUZZER_PIN);

    if (alarmState) { // Send "back to normal" message only once
        SerialBT.println("STATUS: Temperature is back to normal.");
        alarmState = false;
    }

    lcd.setCursor(0, 3);
    lcd.print("Z:");
    lcd.print(a.acceleration.z, 1);
    lcd.print(" Status:NORMAL ");
  }

  delay(1000);
}