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

//  CONFIGURATION 
#define SERVICE_UUID "6E400001-B5A3-F393-E0A9-E50E24DCCA9E"
#define RX_UUID      "6E400002-B5A3-F393-E0A9-E50E24DCCA9E"
#define TX_UUID      "6E400003-B5A3-F393-E0A9-E50E24DCCA9E"
#define NEOPIXEL_PIN D10
#define NUM_PIXELS 5

//  GLOBAL OBJECTS 
Adafruit_NeoPixel pixel(NUM_PIXELS, NEOPIXEL_PIN, NEO_GRB + NEO_KHZ800);
BLECharacteristic *txCharacteristic;
bool deviceConnected = false;
int currentLEDCount = 0;

//  FUNCTION DECLARED FIRST 
void updateLEDs(int count) {
  for(int i = 0; i < NUM_PIXELS; i++) {
    pixel.setPixelColor(i, pixel.Color(0, 0, 0));
  }
  for(int i = 0; i < count; i++) {
    pixel.setPixelColor(i, pixel.Color(255, 0, 0));
  }
  pixel.show();
  Serial.print("LEDs lit: ");
  Serial.println(count);
}

//  BLE CALLBACKS 
class ServerCallbacks: public BLEServerCallbacks {
  void onConnect(BLEServer* pServer) {
    deviceConnected = true;
    Serial.println("Phone connected!");
  }
  void onDisconnect(BLEServer* pServer) {
    deviceConnected = false;
    Serial.println("Phone disconnected");
  }
};

class RXCallbacks: public BLECharacteristicCallbacks {
  void onWrite(BLECharacteristic *characteristic) {
    String value = characteristic->getValue();
    Serial.print("Received: ");
    Serial.println(value);
    
    int ledCount = value.toInt();
    if (ledCount < 0) ledCount = 0;
    if (ledCount > NUM_PIXELS) ledCount = NUM_PIXELS;
    
    currentLEDCount = ledCount;
    updateLEDs(currentLEDCount);

    char confirmMsg[20];
    sprintf(confirmMsg, "LEDs: %d", currentLEDCount);
    txCharacteristic->setValue(confirmMsg);
    txCharacteristic->notify();
  }
};

//  SETUP 
void setup() {
  Serial.begin(115200);
  
  pixel.begin();
  pixel.setBrightness(50);
  pixel.show();
  
  BLEDevice::init("XIAO_C3_BLE");
  BLEServer *server = BLEDevice::createServer();
  server->setCallbacks(new ServerCallbacks());
  
  BLEService *service = server->createService(SERVICE_UUID);
  
  txCharacteristic = service->createCharacteristic(
    TX_UUID, BLECharacteristic::PROPERTY_NOTIFY
  );
  txCharacteristic->addDescriptor(new BLE2902());
  
  BLECharacteristic *rxCharacteristic = service->createCharacteristic(
    RX_UUID, BLECharacteristic::PROPERTY_WRITE
  );
  rxCharacteristic->setCallbacks(new RXCallbacks());
  
  service->start();
  server->getAdvertising()->start();
  
  Serial.println("BLE Ready! Connect to 'XIAO_C3_BLE'");
}

//  LOOP 
void loop() {
  delay(10);
}