#include "BluetoothSerial.h"

#define BUILTIN_LED 2 // Define the GPIO pin for the built-in LED (often GPIO 2)

// Bluetooth Serial Object (Handle)
BluetoothSerial SerialBT;

// ESP32 Bluetooth (Slave) Device Information
const char *pin = "1234"; // Change this to a more secure PIN.
String device_name = "ESP32-BT-Slave";

// Bluetooth Received Byte & Message Buffer Array
String RxBuffer = "";
char RxByte;

void setup() {
  pinMode(BUILTIN_LED, OUTPUT); // Use defined GPIO pin for the built-in LED
  Serial.begin(115200);
  SerialBT.begin(device_name); // Bluetooth device name
  Serial.printf("The device with name \"%s\" is started.\nNow you can pair it with Bluetooth!\n", device_name.c_str());
  SerialBT.setPin(pin);
  Serial.println("Using PIN");
}

void loop() {
  // Read The Received Bytes & Add Them To Message (RxBuffer) Array
  if (SerialBT.available()){
    RxByte = SerialBT.read();
    if (RxByte != '\n'){
      RxBuffer += String(RxByte);
    }
    else{
      RxBuffer = "";
    }
    Serial.write(RxByte);
  }

  // Check The Received Message & Update Output LED State
  if (RxBuffer == "led_on"){
    digitalWrite(BUILTIN_LED, HIGH); // Turn on the built-in LED
  }
  else if (RxBuffer == "led_off"){
    digitalWrite(BUILTIN_LED, LOW); // Turn off the built-in LED
  }
  
  delay(25);
}