/**
 * @file       TinyGsmClientUBLOX.h
 * @author     Volodymyr Shymanskyy
 * @license    LGPL-3.0
 * @copyright  Copyright (c) 2016 Volodymyr Shymanskyy
 * @date       Nov 2016
 */

#ifndef TinyGsmClientUBLOX_h
#define TinyGsmClientUBLOX_h
//#pragma message("TinyGSM:  TinyGsmClientUBLOX")

//#define TINY_GSM_DEBUG Serial

#define TINY_GSM_MUX_COUNT 7

#include <TinyGsmCommon.h>

#define GSM_NL "\r\n"
static const char GSM_OK[] TINY_GSM_PROGMEM = "OK" GSM_NL;
static const char GSM_ERROR[] TINY_GSM_PROGMEM = "ERROR" GSM_NL;
static const char GSM_CME_ERROR[] TINY_GSM_PROGMEM = GSM_NL "+CME ERROR:";

enum SimStatus {
  SIM_ERROR = 0,
  SIM_READY = 1,
  SIM_LOCKED = 2,
};

enum RegStatus {
  REG_UNREGISTERED = 0,
  REG_SEARCHING    = 2,
  REG_DENIED       = 3,
  REG_OK_HOME      = 1,
  REG_OK_ROAMING   = 5,
  REG_UNKNOWN      = 4,
};


class TinyGsmUBLOX : public TinyGsmModem
{

public:

class GsmClient : public Client
{
  friend class TinyGsmUBLOX;
  typedef TinyGsmFifo<uint8_t, TINY_GSM_RX_BUFFER> RxFifo;

public:
  GsmClient() {}

  GsmClient(TinyGsmUBLOX& modem, uint8_t mux = 0) {
    init(&modem, mux);
  }

  bool init(TinyGsmUBLOX* modem, uint8_t mux = 0) {
    this->at = modem;
    this->mux = mux;
    sock_available = 0;
    prev_check = 0;
    sock_connected = false;
    got_data = false;
    return true;
  }

public:
  virtual int connect(const char *host, uint16_t port) {
    if (sock_connected) {
      stop();
      // If we're creating a new connection on the same client, we need to wait
      // until the async close has finished on Cat-M modems.
      // After close has completed, the +UUSOCL should appear.
      if (at->isCatM) {
        DBG("Waiting for +UUSOCL URC on", mux);
        for (unsigned long start = millis(); millis() - start < 120000L; ) {
          at->maintain();
          if (!sock_connected) break;
        }
      }
    }
    TINY_GSM_YIELD();
    rx.clear();
    sock_connected = at->modemConnect(host, port, &mux);
    at->sockets[mux] = this;
    at->maintain();
    return sock_connected;
  }

  virtual int connect(IPAddress ip, uint16_t port) {
    String host; host.reserve(16);
    host += ip[0];
    host += ".";
    host += ip[1];
    host += ".";
    host += ip[2];
    host += ".";
    host += ip[3];
    return connect(host.c_str(), port);
  }

  virtual void stop() {
    TINY_GSM_YIELD();
    // Read and dump anything remaining in the modem's internal buffer.
    // The socket will appear open in response to connected() even after it
    // closes until all data is read from the buffer.
    // Doing it this way allows the external mcu to find and get all of the data
    // that it wants from the socket even if it was closed externally.
    rx.clear();
    at->maintain();
    while (sock_available > 0) {
      sock_available -= at->modemRead(TinyGsmMin((uint16_t)rx.free(), sock_available), mux);
      rx.clear();
      at->maintain();
    }
    at->modemDisconnect(mux);
    // We don't actually know if the CatM modem has finished closing because
    // we're using an "asynchronous" close
    if (!at->isCatM) sock_connected = false;
  }

  virtual size_t write(const uint8_t *buf, size_t size) {
    TINY_GSM_YIELD();
    at->maintain();
    return at->modemSend(buf, size, mux);
  }

  virtual size_t write(uint8_t c) {
    return write(&c, 1);
  }

  virtual size_t write(const char *str) {
    if (str == NULL) return 0;
    return write((const uint8_t *)str, strlen(str));
  }

  virtual int available() {
    TINY_GSM_YIELD();
    if (!rx.size()) {
      // Workaround: sometimes SARA R410 forgets to notify about data arrival.
      // TODO: Currently we ping the module periodically,
      // but maybe there's a better indicator that we need to poll
      if (millis() - prev_check > 250) {
        got_data = true;
        prev_check = millis();
      }
      at->maintain();
    }
    return rx.size() + sock_available;
  }

  virtual int read(uint8_t *buf, size_t size) {
    TINY_GSM_YIELD();
    at->maintain();
    size_t cnt = 0;
    while (cnt < size) {
      size_t chunk = TinyGsmMin(size-cnt, rx.size());
      if (chunk > 0) {
        rx.get(buf, chunk);
        buf += chunk;
        cnt += chunk;
        continue;
      }
      // Workaround: sometimes SARA R410 forgets to notify about data arrival.
      // TODO: Currently we ping the module periodically,
      // but maybe there's a better indicator that we need to poll
      if (millis() - prev_check > 250) {
        got_data = true;
        prev_check = millis();
      }
      at->maintain();
      // TODO: Read directly into user buffer?
      if (sock_available > 0) {
        sock_available -= at->modemRead(TinyGsmMin((uint16_t)rx.free(), sock_available), mux);
      } else {
        break;
      }
    }
    return cnt;
  }

  virtual int read() {
    uint8_t c;
    if (read(&c, 1) == 1) {
      return c;
    }
    return -1;
  }

  virtual int peek() { return -1; } //TODO
  virtual void flush() { at->stream.flush(); }

  virtual uint8_t connected() {
    if (available()) {
      return true;
    }
    return sock_connected;
  }
  virtual operator bool() { return connected(); }

  /*
   * Extended API
   */

  String remoteIP() TINY_GSM_ATTR_NOT_IMPLEMENTED;

private:
  TinyGsmUBLOX* at;
  uint8_t       mux;
  uint16_t      sock_available;
  uint32_t      prev_check;
  bool          sock_connected;
  bool          got_data;
  RxFifo        rx;
};


class GsmClientSecure : public GsmClient
{
public:
  GsmClientSecure() {}

  GsmClientSecure(TinyGsmUBLOX& modem, uint8_t mux = 1)
    : GsmClient(modem, mux)
  {}

public:
  virtual int connect(const char *host, uint16_t port) {
    stop();
    TINY_GSM_YIELD();
    rx.clear();
    sock_connected = at->modemConnect(host, port, &mux, true);
    at->sockets[mux] = this;
    at->maintain();
    return sock_connected;
  }
};


public:

  TinyGsmUBLOX(Stream& stream)
    : TinyGsmModem(stream), stream(stream)
  {
    memset(sockets, 0, sizeof(sockets));
    isCatM = false;  // For SARA R4 and N4 series
  }

  /*
   * Basic functions
   */

  bool init(const char* pin = NULL) {
    DBG(GF("### TinyGSM Version:"), TINYGSM_VERSION);
    if (!testAT()) {
      return false;
    }
    sendAT(GF("E0"));   // Echo Off
    if (waitResponse() != 1) {
      return false;
    }

#ifdef TINY_GSM_DEBUG
    sendAT(GF("+CMEE=2"));  // turn on verbose error codes
#else
    sendAT(GF("+CMEE=0"));  // turn off error codes
#endif
    waitResponse();

    String name = getModemName();
    DBG(GF("### Modem:"), name);
    if (name.startsWith("u-blox SARA-R4") or name.startsWith("u-blox SARA-N4")) {
      isCatM = true;
    }
    else if (name.startsWith("u-blox SARA-N2")) {
      DBG(GF("### SARA N2 NB-IoT modems not supported!"), name);
    }
    int ret = getSimStatus();
    // if the sim isn't ready and a pin has been provided, try to unlock the sim
    if (ret != SIM_READY && pin != NULL && strlen(pin) > 0) {
      simUnlock(pin);
      return (getSimStatus() == SIM_READY);
    }
    // if the sim is ready, or it's locked but no pin has been provided, return true
    else {
      return (ret == SIM_READY || ret == SIM_LOCKED);
    }
  }

  String getModemName() {
    sendAT(GF("+CGMI"));
    String res1;
    if (waitResponse(1000L, res1) != 1) {
      return "u-blox Cellular Modem";
    }
    res1.replace(GSM_NL "OK" GSM_NL, "");
    res1.trim();

    sendAT(GF("+GMM"));
    String res2;
    if (waitResponse(1000L, res2) != 1) {
      return "u-blox Cellular Modem";
    }
    res2.replace(GSM_NL "OK" GSM_NL, "");
    res2.trim();

    return res1 + String(' ') + res2;
  }

  void setBaud(unsigned long baud) {
    sendAT(GF("+IPR="), baud);
  }

  bool testAT(unsigned long timeout = 10000L) {
    for (unsigned long start = millis(); millis() - start < timeout; ) {
      sendAT(GF(""));
      if (waitResponse(200) == 1) return true;
      delay(100);
    }
    return false;
  }

  void maintain() {
    for (int mux = 0; mux < TINY_GSM_MUX_COUNT; mux++) {
      GsmClient* sock = sockets[mux];
      if (sock && sock->got_data) {
        sock->got_data = false;
        sock->sock_available = modemGetAvailable(mux);
      }
    }
    while (stream.available()) {
      waitResponse(15, NULL, NULL);
    }
  }

  bool factoryDefault() {
    if (!isCatM) {
      sendAT(GF("+UFACTORY=0,1"));  // No factory restore, erase NVM
      waitResponse();
      sendAT(GF("+CFUN=16"));   // Reset
      return waitResponse() == 1;
    }
    else {
      sendAT(GF("&F"));  // Resets the current profile, other NVM not affected
      return waitResponse() == 1;
    }
  }

  String getModemInfo() {
    sendAT(GF("I"));
    String res;
    if (waitResponse(1000L, res) != 1) {
      return "";
    }
    res.replace(GSM_NL "OK" GSM_NL, "");
    res.replace(GSM_NL, " ");
    res.trim();
    return res;
  }

  bool hasSSL() {
    return true;
  }

  bool hasWifi() {
    return false;
  }

  bool hasGPRS() {
    return true;
  }

  /*
   * Power functions
   */

  bool restart() {
    if (!testAT()) {
      return false;
    }
    if (!isCatM)
    {
      sendAT(GF("+CFUN=16"));
    }
    else
    {
      sendAT(GF("+CFUN=15"));
    }
    if (waitResponse(10000L) != 1) {
      return false;
    }
    delay(3000);  // TODO:  Verify delay timing here
    return init();
  }

  bool poweroff() {
    sendAT(GF("+CPWROFF"));
    return waitResponse(40000L) == 1;
  }

  bool radioOff() {
    sendAT(GF("+CFUN=0"));
    if (waitResponse(10000L) != 1) {
      return false;
    }
    delay(3000);
    return true;
  }

  bool sleepEnable(bool enable = true) TINY_GSM_ATTR_NOT_IMPLEMENTED;

  /*
   * SIM card functions
   */

  bool simUnlock(const char *pin) {
    sendAT(GF("+CPIN=\""), pin, GF("\""));
    return waitResponse() == 1;
  }

  String getSimCCID() {
    sendAT(GF("+CCID"));
    if (waitResponse(GF(GSM_NL "+CCID:")) != 1) {
      return "";
    }
    String res = stream.readStringUntil('\n');
    waitResponse();
    res.trim();
    return res;
  }

  String getIMEI() {
    sendAT(GF("+CGSN"));
    if (waitResponse(GF(GSM_NL)) != 1) {
      return "";
    }
    String res = stream.readStringUntil('\n');
    waitResponse();
    res.trim();
    return res;
  }

  SimStatus getSimStatus(unsigned long timeout = 10000L) {
    for (unsigned long start = millis(); millis() - start < timeout; ) {
      sendAT(GF("+CPIN?"));
      if (waitResponse(GF(GSM_NL "+CPIN:")) != 1) {
        delay(1000);
        continue;
      }
      int status = waitResponse(GF("READY"), GF("SIM PIN"), GF("SIM PUK"), GF("NOT INSERTED"));
      waitResponse();
      switch (status) {
        case 2:
        case 3:  return SIM_LOCKED;
        case 1:  return SIM_READY;
        default: return SIM_ERROR;
      }
    }
    return SIM_ERROR;
  }

  RegStatus getRegistrationStatus() {
    if (isCatM) {  // Check EPS registration for LTE modules
      sendAT(GF("+CEREG?"));
      if (waitResponse(GF(GSM_NL "+CEREG:")) != 1) {
        return REG_UNKNOWN;
      }
    }
    else {
      sendAT(GF("+CGREG?"));  // Check GPRS registration for others
      if (waitResponse(GF(GSM_NL "+CGREG:")) != 1) {
        return REG_UNKNOWN;
      }
    }
    streamSkipUntil(','); // Skip format (0)
    int status = stream.readStringUntil('\n').toInt();
    waitResponse();
    return (RegStatus)status;
  }

  String getOperator() {
    sendAT(GF("+COPS?"));
    if (waitResponse(GF(GSM_NL "+COPS:")) != 1) {
      return "";
    }
    streamSkipUntil('"'); // Skip mode and format
    String res = stream.readStringUntil('"');
    waitResponse();
    return res;
  }

  /*
   * Generic network functions
   */

  int16_t getSignalQuality() {
    sendAT(GF("+CSQ"));
    if (waitResponse(GF(GSM_NL "+CSQ:")) != 1) {
      return 99;
    }
    int res = stream.readStringUntil(',').toInt();
    waitResponse();
    return res;
  }

  bool isNetworkConnected() {
    RegStatus s = getRegistrationStatus();
    if (s == REG_OK_HOME || s == REG_OK_ROAMING)
      return true;
    else if (s == REG_UNKNOWN)  // for some reason, it can hang at unknown..
      return isGprsConnected();
    else return false;
  }

  bool setURAT( uint8_t urat ) {
    // AT+URAT=<SelectedAcT>[,<PreferredAct>[,<2ndPreferredAct>]]

    sendAT(GF("+COPS=2"));        // Deregister from network
    if (waitResponse() != 1) {
      return false;
    }
    sendAT(GF("+URAT="), urat);  // Radio Access Technology (RAT) selection
    if (waitResponse() != 1) {
      return false;
    }
    sendAT(GF("+COPS=0"));        // Auto-register to the network
    if (waitResponse() != 1) {
      return false;
    }
    return restart();
  }

  /*
   * GPRS functions
   */
  bool gprsConnect(const char* apn, const char* user = NULL, const char* pwd = NULL) {
    gprsDisconnect();

    sendAT(GF("+CGATT=1"));  // attach to GPRS
    if (waitResponse(360000L) != 1) {
      return false;
    }

    // Using CGDCONT sets up an "external" PCP context, i.e. a data connection
    // using the external IP stack (e.g. Windows dial up) and PPP link over the
    // serial interface.  This is the only command set supported by the LTE-M
    // and LTE NB-IoT modules (SARA-R4xx, SARA-N4xx)

    // Setting up the PSD profile/PDP context with the UPSD commands sets up an
    // "internal" PDP context, i.e. a data connection using the internal IP
    // stack and related AT commands for sockets. This is what we're using for
    // all of the other modules.

    if (isCatM) {
      if (user && strlen(user) > 0) {
        sendAT(GF("+CGAUTH=1,0,\""), user, GF("\",\""), pwd, '"');  // Set the authentication
        waitResponse();
      }

      sendAT(GF("+CGDCONT=1,\"IP\",\""), apn, '"');  // Define PDP context 1
      waitResponse();

      sendAT(GF("+CGACT=1,1"));  // activate PDP profile/context 1
      if (waitResponse(150000L) != 1) {
        return false;
      }

      return true;
    }

    else {
      sendAT(GF("+UPSD=0,1,\""), apn, '"');  // Set APN for PSD profile 0
      waitResponse();

      if (user && strlen(user) > 0) {
        sendAT(GF("+UPSD=0,2,\""), user, '"');  // Set user for PSD profile 0
        waitResponse();
      }
      if (pwd && strlen(pwd) > 0) {
        sendAT(GF("+UPSD=0,3,\""), pwd, '"');  // Set password for PSD profile 0
        waitResponse();
      }

      sendAT(GF("+UPSD=0,7,\"0.0.0.0\"")); // Dynamic IP on PSD profile 0
      waitResponse();

      sendAT(GF("+UPSDA=0,3")); // Activate the PDP context associated with profile 0
      if (waitResponse(360000L) != 1) {
        return false;
      }

      sendAT(GF("+UPSND=0,8")); // Activate PSD profile 0
      if (waitResponse(GF(",8,1")) != 1) {
        return false;
      }
      waitResponse();

      return true;
    }
  }

  bool gprsDisconnect() {

    // LTE-M and NB-IoT modules do not support UPSx commands
    if (isCatM) {
      sendAT(GF("+CGACT=1,0"));  // Deactivate PDP context 1
      if (waitResponse(40000L) != 1) {
        return false;
      }
    }

    else {
      sendAT(GF("+UPSDA=0,4"));  // Deactivate the PDP context associated with profile 0
      if (waitResponse(360000L) != 1)
        return false;
    }

    sendAT(GF("+CGATT=0"));  // detach from GPRS
    if (waitResponse(360000L) != 1)
      return false;

    return true;
  }

  bool isGprsConnected() {
    sendAT(GF("+CGATT?"));
    if (waitResponse(GF(GSM_NL "+CGATT:")) != 1) {
      return false;
    }
    int res = stream.readStringUntil('\n').toInt();
    waitResponse();
    if (res != 1)
      return false;

    return localIP() != IPAddress(0,0,0,0);
  }

  /*
   * IP Address functions
   */

  String getLocalIP() {
    // LTE-M and NB-IoT modules do not support UPSx commands
    if (isCatM) {
      sendAT(GF("+CGPADDR"));
      if (waitResponse(GF(GSM_NL "+CGPADDR:")) != 1) {
        return "";
      }
      streamSkipUntil(',');  // Skip context id
      String res = stream.readStringUntil('\r');
      if (waitResponse() != 1) {
        return "";
      }
      return res;
    }
    else {
      sendAT(GF("+UPSND=0,0"));
      if (waitResponse(GF(GSM_NL "+UPSND:")) != 1) {
        return "";
      }
      streamSkipUntil(',');  // Skip PSD profile
      streamSkipUntil('\"'); // Skip request type
      String res = stream.readStringUntil('\"');
      if (waitResponse() != 1) {
        return "";
      }
      return res;
    }
  }

  /*
   * Phone Call functions
   */

  bool setGsmBusy(bool busy = true) TINY_GSM_ATTR_NOT_AVAILABLE;

  bool callAnswer() TINY_GSM_ATTR_NOT_IMPLEMENTED;

  bool callNumber(const String& number) TINY_GSM_ATTR_NOT_IMPLEMENTED;

  bool callHangup() TINY_GSM_ATTR_NOT_IMPLEMENTED;

  /*
   * Messaging functions
   */

  String sendUSSD(const String& code) TINY_GSM_ATTR_NOT_IMPLEMENTED;

  bool sendSMS(const String& number, const String& text) {
    sendAT(GF("+CSCS=\"GSM\""));  // Set GSM default alphabet
    waitResponse();
    sendAT(GF("+CMGF=1"));  // Set preferred message format to text mode
    waitResponse();
    sendAT(GF("+CMGS=\""), number, GF("\""));  // set the phone number
    if (waitResponse(GF(">")) != 1) {
      return false;
    }
    stream.print(text);  // Actually send the message
    stream.write((char)0x1A);
    stream.flush();
    return waitResponse(60000L) == 1;
  }

  bool sendSMS_UTF16(const String& number, const void* text, size_t len) TINY_GSM_ATTR_NOT_IMPLEMENTED;


  /*
   * Location functions
   */

  String getGsmLocation() {
    sendAT(GF("+ULOC=2,3,0,120,1"));
    if (waitResponse(30000L, GF(GSM_NL "+UULOC:")) != 1) {
      return "";
    }
    String res = stream.readStringUntil('\n');
    waitResponse();
    res.trim();
    return res;
  }

  /*
   * Battery functions
   */
  uint16_t getBattVoltage() TINY_GSM_ATTR_NOT_AVAILABLE;

  int8_t getBattPercent() {
    sendAT(GF("+CIND?"));
    if (waitResponse(GF(GSM_NL "+CIND:")) != 1) {
      return 0;
    }

    int res = stream.readStringUntil(',').toInt();
    waitResponse();
    return res;
  }

  /*
   * Client related functions
   */

protected:

  bool modemConnect(const char* host, uint16_t port, uint8_t* mux, bool ssl = false) {
    sendAT(GF("+USOCR=6"));  // create a socket
    if (waitResponse(GF(GSM_NL "+USOCR:")) != 1) {  // reply is +USOCR: ## of socket created
      return false;
    }
    *mux = stream.readStringUntil('\n').toInt();
    waitResponse();

    if (ssl) {
      sendAT(GF("+USOSEC="), *mux, ",1");
      waitResponse();
    }

    // Enable NODELAY
    sendAT(GF("+USOSO="), *mux, GF(",6,1,1"));
    waitResponse();

    // Enable KEEPALIVE, 30 sec
    //sendAT(GF("+USOSO="), *mux, GF(",6,2,30000"));
    //waitResponse();

    // connect on the allocated socket
    // TODO:  Use faster "asynchronous" connection?
    // We would have to wait for the +UUSOCO URC to verify connection
    sendAT(GF("+USOCO="), *mux, ",\"", host, "\",", port);
    int rsp = waitResponse(120000L);
    return (1 == rsp);
  }

  bool modemDisconnect(uint8_t mux) {
    TINY_GSM_YIELD();
    if (isCatM) {  //  These modems allow a faster "asynchronous" close
      sendAT(GF("+USOCL="), mux, GF(",1"));
      int rsp = waitResponse(120000L);
      return (1 == rsp);  // but it still can take up to 120s to get a response
    }
    else {  // no async close
      sendAT(GF("+USOCL="), mux);
      return (1 == waitResponse());
    }
  }

  int16_t modemSend(const void* buff, size_t len, uint8_t mux) {
    sendAT(GF("+USOWR="), mux, ',', len);
    if (waitResponse(GF("@")) != 1) {
      return 0;
    }
    // 50ms delay, see AT manual section 25.10.4
    delay(50);
    stream.write((uint8_t*)buff, len);
    stream.flush();
    if (waitResponse(GF(GSM_NL "+USOWR:")) != 1) {
      return 0;
    }
    streamSkipUntil(','); // Skip mux
    int sent = stream.readStringUntil('\n').toInt();
    waitResponse();
    maintain();  // look for a very quick response
    return sent;
  }

  size_t modemRead(size_t size, uint8_t mux) {
    sendAT(GF("+USORD="), mux, ',', size);
    if (waitResponse(GF(GSM_NL "+USORD:")) != 1) {
      return 0;
    }
    streamSkipUntil(','); // Skip mux
    size_t len = stream.readStringUntil(',').toInt();
    streamSkipUntil('\"');

    for (size_t i=0; i<len; i++) {
      while (!stream.available()) { TINY_GSM_YIELD(); }
      char c = stream.read();
      sockets[mux]->rx.put(c);
    }
    streamSkipUntil('\"');
    waitResponse();
    return len;
  }

  size_t modemGetAvailable(uint8_t mux) {
    sendAT(GF("+USORD="), mux, ",0");
    size_t result = 0;
    uint8_t res = waitResponse(GF(GSM_NL "+USORD:"));
    // Will give error "operation not allowed" when attempting to read a socket
    // that you have already told to close
    if (res == 1) {
      streamSkipUntil(','); // Skip mux
      result = stream.readStringUntil('\n').toInt();
      waitResponse();
    }
    if (!result && res != 2 && res != 3) {  // Don't check modemGetConnected after an error
      sockets[mux]->sock_connected = modemGetConnected(mux);
    }
    return result;
  }

  bool modemGetConnected(uint8_t mux) {
    sendAT(GF("+USOCTL="), mux, ",10");
    uint8_t res = waitResponse(GF(GSM_NL "+USOCTL:"));
    if (res != 1)
      return false;

    streamSkipUntil(','); // Skip mux
    streamSkipUntil(','); // Skip type
    int result = stream.readStringUntil('\n').toInt();
    // 0: the socket is in INACTIVE status (it corresponds to CLOSED status
    // defined in RFC793 "TCP Protocol Specification" [112])
    // 1: the socket is in LISTEN status
    // 2: the socket is in SYN_SENT status
    // 3: the socket is in SYN_RCVD status
    // 4: the socket is in ESTABILISHED status
    // 5: the socket is in FIN_WAIT_1 status
    // 6: the socket is in FIN_WAIT_2 status
    // 7: the sokcet is in CLOSE_WAIT status
    // 8: the socket is in CLOSING status
    // 9: the socket is in LAST_ACK status
    // 10: the socket is in TIME_WAIT status
    waitResponse();
    return (result != 0);
  }

public:

  /*
   Utilities
   */

  template<typename... Args>
  void sendAT(Args... cmd) {
    streamWrite("AT", cmd..., GSM_NL);
    stream.flush();
    TINY_GSM_YIELD();
    //DBG("### AT:", cmd...);
  }

  // TODO: Optimize this!
  uint8_t waitResponse(uint32_t timeout, String& data,
                       GsmConstStr r1=GFP(GSM_OK), GsmConstStr r2=GFP(GSM_ERROR),
                       GsmConstStr r3=GFP(GSM_CME_ERROR), GsmConstStr r4=NULL, GsmConstStr r5=NULL)
  {
    /*String r1s(r1); r1s.trim();
    String r2s(r2); r2s.trim();
    String r3s(r3); r3s.trim();
    String r4s(r4); r4s.trim();
    String r5s(r5); r5s.trim();
    DBG("### ..:", r1s, ",", r2s, ",", r3s, ",", r4s, ",", r5s);*/
    data.reserve(64);
    int index = 0;
    unsigned long startMillis = millis();
    do {
      TINY_GSM_YIELD();
      while (stream.available() > 0) {
        int a = stream.read();
        if (a < 0) continue;
        data += (char)a;
        if (r1 && data.endsWith(r1)) {
          index = 1;
          goto finish;
        } else if (r2 && data.endsWith(r2)) {
          index = 2;
          goto finish;
        } else if (r3 && data.endsWith(r3)) {
          index = 3;
          goto finish;
        } else if (r4 && data.endsWith(r4)) {
          index = 4;
          goto finish;
        } else if (r5 && data.endsWith(r5)) {
          index = 5;
          goto finish;
        } else if (data.endsWith(GF(GSM_NL "+UUSORD:"))) {
          int mux = stream.readStringUntil(',').toInt();
          streamSkipUntil('\n');
          if (mux >= 0 && mux < TINY_GSM_MUX_COUNT && sockets[mux]) {
            sockets[mux]->got_data = true;
          }
          data = "";
          DBG("### Got Data:", mux);
        } else if (data.endsWith(GF(GSM_NL "+UUSOCL:"))) {
          int mux = stream.readStringUntil('\n').toInt();
          if (mux >= 0 && mux < TINY_GSM_MUX_COUNT && sockets[mux]) {
            sockets[mux]->sock_connected = false;
          }
          data = "";
          DBG("### Closed:", mux);
        }
      }
    } while (millis() - startMillis < timeout);
finish:
    if (!index) {
      data.trim();
      if (data.length()) {
        DBG("### Unhandled:", data);
      }
      data = "";
    }
    //DBG('<', index, '>');
    return index;
  }

  uint8_t waitResponse(uint32_t timeout,
                       GsmConstStr r1=GFP(GSM_OK), GsmConstStr r2=GFP(GSM_ERROR),
                       GsmConstStr r3=GFP(GSM_CME_ERROR), GsmConstStr r4=NULL, GsmConstStr r5=NULL)
  {
    String data;
    return waitResponse(timeout, data, r1, r2, r3, r4, r5);
  }

  uint8_t waitResponse(GsmConstStr r1=GFP(GSM_OK), GsmConstStr r2=GFP(GSM_ERROR),
                       GsmConstStr r3=GFP(GSM_CME_ERROR), GsmConstStr r4=NULL, GsmConstStr r5=NULL)
  {
    return waitResponse(1000, r1, r2, r3, r4, r5);
  }

public:
  Stream&       stream;

protected:
  GsmClient*    sockets[TINY_GSM_MUX_COUNT];
  bool          isCatM;
};

#endif