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#include <BLEDevice.h>
#include <BLEServer.h>
#include <BLEUtils.h>
#include <BLE2902.h>

#define ble_max_conn 4

BLEServer* pServer = NULL;
BLECharacteristic* pCharacteristic = NULL;
bool deviceConnected = false;
bool oldDeviceConnected = false;
uint32_t value = 0;

// Array to store client characteristic configuration descriptors
BLE2902* clientConfigDescriptors[4];
bool buttonPressed = false;
const int buttonPin = 27;
int buttonState = LOW;
int lastButtonState = LOW;
unsigned long lastDebounceTime = 0;
unsigned long debounceDelay = 50;

#define SERVICE_UUID        "4fafc201-1fb5-459e-8fcc-c5c9c331914b"
#define CHARACTERISTIC_UUID "beb5483e-36e1-4688-b7f5-ea07361b26a8"

class MyServerCallbacks : public BLEServerCallbacks {
    void onConnect(BLEServer* pServer) {
        deviceConnected = true;

        delay(100);
        pCharacteristic->notify();

        BLEDevice::startAdvertising();
    }

    void onDisconnect(BLEServer* pServer) {
        deviceConnected = false;
    }
};

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

    // Create the BLE Device
    BLEDevice::init("ESP32");
    BLEDevice::setMTU(500); // Allow multiple connections
    BLEDevice:

    // Create the BLE Server
    pServer = BLEDevice::createServer();
    pServer->setCallbacks(new MyServerCallbacks());

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

    // Create a BLE Characteristic
    pCharacteristic = pService->createCharacteristic(
        CHARACTERISTIC_UUID,
        BLECharacteristic::PROPERTY_READ |
        BLECharacteristic::PROPERTY_WRITE |
        BLECharacteristic::PROPERTY_NOTIFY |
        BLECharacteristic::PROPERTY_INDICATE
    );

    // Create a BLE Descriptor
    pCharacteristic->addDescriptor(new BLE2902());

    // Start the service
    pService->start();

    // Start advertising
    BLEAdvertising *pAdvertising = BLEDevice::getAdvertising();
    pAdvertising->addServiceUUID(SERVICE_UUID);
    pAdvertising->setScanResponse(false);
    pAdvertising->setMinPreferred(0x0);
    BLEDevice::startAdvertising();

    // Set up the button as an input
    pinMode(buttonPin, INPUT_PULLUP);
}

void loop() {
    int reading = digitalRead(buttonPin);

    if (reading != lastButtonState) {
        lastDebounceTime = millis();
    }

    if ((millis() - lastDebounceTime) > debounceDelay) {
        if (reading != buttonState) {
            buttonState = reading;
            if (buttonState == HIGH) {
              Serial.println("Button pressed");
              if (deviceConnected) {
                uint8_t data = 0xFF;
                pCharacteristic->setValue(&data, 1); // Set the value as a byte array
                pCharacteristic->notify();
                Serial.println("Data updated!");
              }
              buttonPressed = true;
            } else {
              Serial.println("Button released");
              if (deviceConnected) {
                uint8_t data = 0x00;
                pCharacteristic->setValue(&data, 1); // Set the value as a byte array
                pCharacteristic->notify();
                Serial.println("Data updated!");
              }
              buttonPressed = false;
            }
        }
    }

    lastButtonState = reading;

    if (!deviceConnected && oldDeviceConnected) {
        pServer->startAdvertising();
        Serial.println("Start advertising");
        oldDeviceConnected = deviceConnected;
    }

    if (deviceConnected && !oldDeviceConnected) {
        // Actions to perform on connecting
        oldDeviceConnected = deviceConnected;
    }
}