#include <BLEDevice.h>
#include <BLEUtils.h>
#include <BLEServer.h>

#define LED1 D3
#define LED2 D5

BLECharacteristic *pCharacteristic;
bool deviceConnected = false;

// UUIDs (must match the ones used in the app)
#define SERVICE_UUID        "12345678-1234-1234-1234-123456789abc"
#define CHARACTERISTIC_UUID "abcdefab-1234-1234-1234-abcdefabcdef"

// Connection callbacks
class MyServerCallbacks: public BLEServerCallbacks {
  void onConnect(BLEServer* pServer) {
    deviceConnected = true;
    Serial.println(">>> Device CONNECTED");
  };

  void onDisconnect(BLEServer* pServer) {
    deviceConnected = false;
    Serial.println(">>> Device DISCONNECTED");

    // Restart advertising after disconnection
    BLEDevice::startAdvertising();
    Serial.println("Restarting advertising...");
  }
};

// Data reception callback
class MyCallbacks: public BLECharacteristicCallbacks {
  void onWrite(BLECharacteristic *pCharacteristic) {
    String value = pCharacteristic->getValue();

    if (value.length() > 0) {
      char cmd = value[0];

      Serial.print("Received: ");
      Serial.println(cmd);

      switch(cmd) {
        case 'A': digitalWrite(LED1, HIGH); break;
        case 'B': digitalWrite(LED1, LOW); break;
        case 'C': digitalWrite(LED2, HIGH); break;
        case 'D': digitalWrite(LED2, LOW); break;
      }
    }
  }
};

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

  pinMode(LED1, OUTPUT);
  pinMode(LED2, OUTPUT);

  digitalWrite(LED1, LOW);
  digitalWrite(LED2, LOW);

  // Initialize BLE
  BLEDevice::init("XIAO_LED");

  Serial.println("=== BLE READY ===");
  Serial.println("Device name: XIAO_LED");

  Serial.print("MAC: ");
  Serial.println(BLEDevice::getAddress().toString().c_str());

  Serial.println("Waiting for connection...");

  // Create BLE server
  BLEServer *pServer = BLEDevice::createServer();
  pServer->setCallbacks(new MyServerCallbacks());

  // Create BLE service
  BLEService *pService = pServer->createService(SERVICE_UUID);

  // Create BLE characteristic
  pCharacteristic = pService->createCharacteristic(
                      CHARACTERISTIC_UUID,
                      BLECharacteristic::PROPERTY_WRITE
                    );

  pCharacteristic->setCallbacks(new MyCallbacks());

  // Start service
  pService->start();

  // Start advertising
  BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
  pAdvertising->start();
}

void loop() {
  // Nothing required here
}