static const unsigned int NoOperation = std::numeric_limits<unsigned int>::max();

virtual unsigned int getFrontRequestOpNr() = 0; //return OpNr of front request or NoOperation if queue is empty

virtual std::unique_ptr<Request> fetchFrontRequest() = 0;

std::unique_ptr<Request> requests [MO_REQUEST_CACHE_MAXSIZE];

size_t front = 0, len = 0;

VolatileRequestQueue();

~VolatileRequestQueue();

void loop();

unsigned int getFrontRequestOpNr() override;

std::unique_ptr<Request> fetchFrontRequest() override;

bool pushRequestBack(std::unique_ptr<Request> request);

Connection& connection;

OperationRegistry& operationRegistry;

RequestEmitter* sendQueues [MO_NUM_REQUEST_QUEUES];

VolatileRequestQueue defaultSendQueue;

VolatileRequestQueue *preBootSendQueue = nullptr;

std::unique_ptr<Request> sendReqFront;

VolatileRequestQueue recvQueue;

std::unique_ptr<Request> recvReqFront;

bool receiveMessage(const char* payload, size_t length); //receive from server: either a request or response

void receiveRequest(JsonArray json);

void receiveRequest(JsonArray json, std::unique_ptr<Request> op);

void receiveResponse(JsonArray json);

unsigned long sockTrackLastConnected = 0;

unsigned int nextOpNr = 10; //Nr 0 - 9 reservered for internal purposes

RequestQueue() = delete;

RequestQueue(const RequestQueue&) = delete;

RequestQueue(const RequestQueue&&) = delete;

RequestQueue(Connection& connection, OperationRegistry& operationRegistry);

void loop(); //polls all reqQueues and decides which request to send (if any)

void sendRequest(std::unique_ptr<Request> request); //send an OCPP operation request to the server; adds request to default queue

void sendRequestPreBoot(std::unique_ptr<Request> request); //send an OCPP operation request to the server; adds request to preBootQueue

void addSendQueue(RequestEmitter* sendQueue);

void setPreBootSendQueue(VolatileRequestQueue *preBootQueue);

unsigned int getNextOpNr();