// Interface for posting spots to PSK Reporter web site
// Implemented by Edson Pereira PY2SDR
// Updated by Bill Somerville, G4WJS
//
// Reports will be sent in batch mode every 5 minutes.

#include "PSK_Reporter.hpp"

#include <cmath>
#include <QObject>
#include <QString>
#include <QDateTime>
#include <QSharedPointer>
#include <QUdpSocket>
#include <QTcpSocket>
#include <QHostInfo>
#include <QUDPSocket>
#include <QQueue>
#include <QByteArray>
#include <QDataStream>
#include <QTimer>
#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
#include <QRandomGenerator>
#endif
#include <QDebug>

#include "Configuration.hpp"
#include "pimpl_impl.hpp"


#include "moc_PSK_Reporter.cpp"

namespace
{
  constexpr QLatin1String HOST {"report.pskreporter.info"};
  // constexpr QLatin1String HOST {"127.0.0.1"};
  // constexpr QLatin1String HOST {"192.168.1.195"};
  constexpr quint16 SERVICE_PORT {4739};
  // constexpr quint16 SERVICE_PORT {14739};
  constexpr int MIN_SEND_INTERVAL {60}; // in seconds
  constexpr int FLUSH_INTERVAL {5};     // in send intervals
  constexpr bool ALIGNMENT_PADDING {true};
  constexpr int MIN_PAYLOAD_LENGTH {508};
  constexpr int MAX_PAYLOAD_LENGTH {1400};
}

class PSK_Reporter::impl final
  : public QObject
{
  Q_OBJECT

public:
  impl (PSK_Reporter * self, Configuration const * config, QString const& program_info)
    : self_ {self}
    , config_ {config}
    , sequence_number_ {0u}
    , send_descriptors_ {0}
    , send_receiver_data_ {0}
    , flush_counter_ {0u}
    , prog_id_ {program_info}
  {
#if QT_VERSION < QT_VERSION_CHECK(5, 15, 0)
    observation_id_ = qrand();
#else
    observation_id_ = QRandomGenerator::global ()->generate ();
#endif

    // This timer sets the interval to check for spots to send.
    connect (&report_timer_, &QTimer::timeout, [this] () {send_report ();});
    report_timer_.start (MIN_SEND_INTERVAL * 1000);

    // This timer repeats the sending of IPFIX templates and receiver
    // information if we are using UDP, in case server has been
    // restarted ans lost cached information.
    connect (&descriptor_timer_, &QTimer::timeout, [this] () {
                                                     if (socket_
                                                         && QAbstractSocket::UdpSocket == socket_->socketType ())
                                                       {
                                                         // send templates again
                                                         send_descriptors_ = 3; // three times
                                                         // send receiver data set again
                                                         send_receiver_data_ = 3; // three times
                                                       }
                                                   });
    descriptor_timer_.start (1 * 60 * 60 * 1000); // hourly
  }

  void check_connection ()
  {
    if (!socket_
        || QAbstractSocket::UnconnectedState == socket_->state ()
        || (socket_->socketType () != config_->psk_reporter_tcpip () ? QAbstractSocket::TcpSocket : QAbstractSocket::UdpSocket))
      {
        // we need to create the appropriate socket
        if (socket_
            && QAbstractSocket::UnconnectedState != socket_->state ()
            && QAbstractSocket::ClosingState != socket_->state ())
          {
            // handle re-opening asynchronously
            auto connection = QSharedPointer<QMetaObject::Connection>::create ();
            *connection = connect (socket_.get (), &QAbstractSocket::disconnected, [this, connection] () {
                                                                                     qDebug () << "PSK_Reporter::impl::check_connection: disconnected, socket state:" << socket_->state ();
                                                                                     disconnect (*connection);
                                                                                     check_connection ();
                                                                                   });
            // close gracefully
            socket_->close ();
          }
        else
          {
            reconnect ();
          }
      }
  }

  void handle_socket_error (QAbstractSocket::SocketError e)
  {
    switch (e)
      {
      case QAbstractSocket::RemoteHostClosedError:
        socket_->disconnectFromHost ();
        break;

      case QAbstractSocket::TemporaryError:
        break;

      default:
        spots_.clear ();
        qDebug () << "PSK_Reporter::impl::handle_socket_error:" << socket_->errorString ();
        Q_EMIT self_->errorOccurred (socket_->errorString ());
        break;
      }
  }

  void reconnect ()
  {
    // Using deleteLater for the deleter as we may eventually
    // be called from the disconnected handler above.
    if (config_->psk_reporter_tcpip ())
      {
        socket_.reset (new QTcpSocket, &QObject::deleteLater);
        send_descriptors_ = 1;
        send_receiver_data_ = 1;
      }
    else
      {
        socket_.reset (new QUdpSocket, &QObject::deleteLater);
        send_descriptors_ = 3;
        send_receiver_data_ = 3;
      }

#if QT_VERSION >= QT_VERSION_CHECK(5, 15, 0)
    connect (socket_.get (), &QAbstractSocket::errorOccurred, this, &PSK_Reporter::impl::handle_socket_error);
#else
    connect (socket_.get (), QOverload<QAbstractSocket::SocketError>::of (&QAbstractSocket::error), this, &PSK_Reporter::impl::handle_socket_error);
#endif

    // use this for pseudo connection with UDP, allows us to use
    // QIODevice::write() instead of QUDPSocket::writeDatagram()
    socket_->connectToHost (HOST, SERVICE_PORT, QAbstractSocket::WriteOnly);
  }

  void send_report (bool send_residue = false);
  void build_preamble (QDataStream&);

  bool flushing ()
  {
    return FLUSH_INTERVAL && !(++flush_counter_ % FLUSH_INTERVAL);
  }

  PSK_Reporter * self_;
  Configuration const * config_;
  QSharedPointer<QAbstractSocket> socket_;
  int dns_lookup_id_;
  QByteArray payload_;
  quint32 sequence_number_;
  int send_descriptors_;

  // Currently PSK Reporter requires that  a receiver data set is sent
  // in every  data flow. This  memeber variable  can be used  to only
  // send that information at session start (3 times for UDP), when it
  // changes (3  times for UDP), or  once per hour (3  times) if using
  // UDP. Uncomment the relevant code to enable that fuctionality.
  int send_receiver_data_;

  unsigned flush_counter_;
  quint32 observation_id_;
  QString rx_call_;
  QString rx_grid_;
  QString rx_ant_;
  QString prog_id_;
  QByteArray tx_data_;
  QByteArray tx_residue_;
  struct Spot
  {
    bool operator == (Spot const& rhs)
    {
      return
        call_ == rhs.call_
        && grid_ == rhs.grid_
        && mode_ == rhs.mode_
        && std::abs (Radio::FrequencyDelta (freq_ - rhs.freq_)) < 50;
    }

    QString call_;
    QString grid_;
    int snr_;
    Radio::Frequency freq_;
    QString mode_;
    QDateTime time_;
  };
  QQueue<Spot> spots_;
  QTimer report_timer_;
  QTimer descriptor_timer_;
};
  
#include "PSK_Reporter.moc"

namespace
{
  void writeUtfString (QDataStream& out, QString const& s)
  {
    auto const& utf = s.toUtf8 ().left (254);
    out << quint8 (utf.size ());
    out.writeRawData (utf, utf.size ());
  }

  constexpr
  int num_pad_bytes (int len)
  {
    return ALIGNMENT_PADDING ? (4 - len % 4) % 4 : 0;
  }

  void set_length (QDataStream& out, QByteArray& b)
  {
    // pad with nulls modulo 4
    auto pad_len = num_pad_bytes (b.size ());
    out.writeRawData (QByteArray {pad_len, '\0'}.constData (), pad_len);
    auto pos = out.device ()->pos ();
    out.device ()->seek (sizeof (quint16));
    // insert length
    out << static_cast<quint16> (b.size ());
    out.device ()->seek (pos);
  }
}

void PSK_Reporter::impl::build_preamble (QDataStream& message)
{
  // Message Header
  message
    << quint16 (10u)          // Version Number
    << quint16 (0u)           // Length (place-holder filled in later)
    << quint32 (0u)           // Export Time (place-holder filled in later)
    << ++sequence_number_     // Sequence Number
    << observation_id_;       // Observation Domain ID

  qDebug () << "PSK_Reporter::impl::build_preamble: send_descriptors_:" << send_descriptors_;
  if (send_descriptors_)
    {
      --send_descriptors_;
      {
        // Sender Information descriptor
        QByteArray descriptor;
        QDataStream out {&descriptor, QIODevice::WriteOnly};
        out
          << quint16 (2u)           // Template Set ID
          << quint16 (0u)           // Length (place-holder)
          << quint16 (0x50e3)       // Link ID
          << quint16 (7u)           // Field Count
          << quint16 (0x8000 + 1u)  // Option 1 Information Element ID (senderCallsign)
          << quint16 (0xffff)       // Option 1 Field Length (variable)
          << quint32 (30351u)       // Option 1 Enterprise Number
          << quint16 (0x8000 + 5u)  // Option 2 Information Element ID (frequency)
          << quint16 (4u)           // Option 2 Field Length
          << quint32 (30351u)       // Option 2 Enterprise Number
          << quint16 (0x8000 + 6u)  // Option 3 Information Element ID (sNR)
          << quint16 (1u)           // Option 3 Field Length
          << quint32 (30351u)       // Option 3 Enterprise Number
          << quint16 (0x8000 + 10u) // Option 4 Information Element ID (mode)
          << quint16 (0xffff)       // Option 4 Field Length (variable)
          << quint32 (30351u)       // Option 4 Enterprise Number
          << quint16 (0x8000 + 3u)  // Option 5 Information Element ID (senderLocator)
          << quint16 (0xffff)       // Option 5 Field Length (variable)
          << quint32 (30351u)       // Option 5 Enterprise Number
          << quint16 (0x8000 + 11u) // Option 6 Information Element ID (informationSource)
          << quint16 (1u)           // Option 6 Field Length
          << quint32 (30351u)       // Option 6 Enterprise Number
          << quint16 (150u)         // Option 7 Information Element ID (dateTimeSeconds)
          << quint16 (4u);          // Option 7 Field Length
        // insert Length and move to payload
        set_length (out, descriptor);
        message.writeRawData (descriptor.constData (), descriptor.size ());
      }
      {
        // Receiver Information descriptor
        QByteArray descriptor;
        QDataStream out {&descriptor, QIODevice::WriteOnly};
        out
          << quint16 (3u)          // Options Template Set ID
          << quint16 (0u)          // Length (place-holder)
          << quint16 (0x50e2)      // Link ID
          << quint16 (4u)          // Field Count
          << quint16 (0u)          // Scope Field Count
          << quint16 (0x8000 + 2u) // Option 1 Information Element ID (receiverCallsign)
          << quint16 (0xffff)      // Option 1 Field Length (variable)
          << quint32 (30351u)      // Option 1 Enterprise Number
          << quint16 (0x8000 + 4u) // Option 2 Information Element ID (receiverLocator)
          << quint16 (0xffff)      // Option 2 Field Length (variable)
          << quint32 (30351u)      // Option 2 Enterprise Number
          << quint16 (0x8000 + 8u) // Option 3 Information Element ID (decodingSoftware)
          << quint16 (0xffff)      // Option 3 Field Length (variable)
          << quint32 (30351u)      // Option 3 Enterprise Number
          << quint16 (0x8000 + 9u) // Option 4 Information Element ID (antennaInformation)
          << quint16 (0xffff)      // Option 4 Field Length (variable)
          << quint32 (30351u);     // Option 4 Enterprise Number
        // insert Length
        set_length (out, descriptor);
        message.writeRawData (descriptor.constData (), descriptor.size ());
      }
    }

  qDebug () << "PSK_Reporter::impl::build_preamble: send_receiver_data_:" << send_receiver_data_;
  // if (send_receiver_data_)
  {
    // --send_receiver_data_;

    // Receiver information
    QByteArray data;
    QDataStream out {&data, QIODevice::WriteOnly};

    // Set Header
    out
      << quint16 (0x50e2)     // Template ID
      << quint16 (0u);        // Length (place-holder)

    // Set data
    writeUtfString (out, rx_call_);
    writeUtfString (out, rx_grid_);
    writeUtfString (out, prog_id_);
    writeUtfString (out, rx_ant_);

    // insert Length and move to payload
    set_length (out, data);
    message.writeRawData (data.constData (), data.size ());
  }
}

void PSK_Reporter::impl::send_report (bool send_residue)
{
  check_connection ();
  qDebug () << "PSK_Reporter::impl::send_report: send_residue:" << send_residue;
  if (QAbstractSocket::ConnectedState != socket_->state ()) return;

  QDataStream message {&payload_, QIODevice::WriteOnly | QIODevice::Append};
  QDataStream tx_out {&tx_data_, QIODevice::WriteOnly | QIODevice::Append};

  if (!payload_.size ())
    {
      qDebug () << "PSK_Reporter::impl::send_report: building header";
      // Build header, optional descriptors, and receiver information
      build_preamble (message);
    }

  auto flush = flushing () || send_residue;
  qDebug () << "PSK_Reporter::impl::send_report: flush:" << flush;
  while (spots_.size () || (flush && (tx_data_.size () || tx_residue_.size ())))
    {
      if (!payload_.size ())
        {
          // Build header, optional descriptors, and receiver information
          build_preamble (message);
        }

      if (!tx_data_.size ())
        {
          // Set Header
          tx_out
            << quint16 (0x50e3)     // Template ID
            << quint16 (0u);        // Length (place-holder)
          qDebug () << "PSK_Reporter::impl::send_report: set data set header";
        }

      // insert any residue
      if (tx_residue_.size ())
        {
          tx_out.writeRawData (tx_residue_.constData (), tx_residue_.size ());
          tx_residue_.clear ();
          qDebug () << "PSK_Reporter::impl::send_report: inserted data residue";
        }

      while (spots_.size () || (flush && tx_data_.size ()))
        {
          auto tx_data_size = tx_data_.size ();
          if (spots_.size ())
            {
              auto const& spot = spots_.dequeue ();
              qDebug () << "PSK_Reporter::impl::send_report: processing spotted call:" << spot.call_;

              // Sender information
              writeUtfString (tx_out, spot.call_);
              tx_out
                << static_cast<quint32> (spot.freq_)
                << static_cast<qint8> (spot.snr_);
              writeUtfString (tx_out, spot.mode_);
              writeUtfString (tx_out, spot.grid_);
              tx_out
                << quint8 (1u)          // REPORTER_SOURCE_AUTOMATIC
                << static_cast<quint32> (spot.time_.toSecsSinceEpoch ());
            }

          auto len = payload_.size () + tx_data_.size ();
          len += num_pad_bytes (tx_data_.size ());
          len += num_pad_bytes (len);
          if (len > MAX_PAYLOAD_LENGTH // our upper datagram size limit
              || (!spots_.size () && len > MIN_PAYLOAD_LENGTH) // spots drained and above lower datagram size limit
              || (flush && !spots_.size () && tx_data_.size ())) // send what we have
            {
              if (len <= MAX_PAYLOAD_LENGTH)
                {
                  tx_data_size = tx_data_.size ();
                  qDebug () << "PSK_Reporter::impl::send_report: sending short payload:" << tx_data_size;
                }
              QByteArray tx {tx_data_.left (tx_data_size)};
              QDataStream out {&tx, QIODevice::WriteOnly | QIODevice::Append};
              // insert Length
              set_length (out, tx);
              message.writeRawData (tx.constData (), tx.size ());

              // insert Length and Export Time
              set_length (message, payload_);
              message.device ()->seek (2 * sizeof (quint16));
              message << static_cast<quint32> (QDateTime::currentDateTime ().toSecsSinceEpoch ());

              // Send data to PSK Reporter site
              socket_->write (payload_); // TODO: handle errors
              qDebug () << "PSK_Reporter::impl::send_report: sent payload:" << payload_.size () << "observation id:" << observation_id_;
              message.device ()->seek (0u);
              payload_.clear ();  // Fresh message
              // Save unsent spots
              tx_residue_ = tx_data_.right (tx_data_.size () - tx_data_size);
              tx_out.device ()->seek (0u);
              tx_data_.clear ();
              qDebug () << "PSK_Reporter::impl::send_report: payload sent residue length:" << tx_residue_.size ();
              break;
            }
        }
    }
}

PSK_Reporter::PSK_Reporter (Configuration const * config, QString const& program_info)
  : m_ {this, config, program_info}
{
}

PSK_Reporter::~PSK_Reporter ()
{
  // m_->send_report (true);       // send any pending spots
}

void PSK_Reporter::reconnect ()
{
  m_->reconnect ();
}

void PSK_Reporter::setLocalStation (QString const& call, QString const& gridSquare, QString const& antenna)
{
  if (call != m_->rx_call_ || gridSquare != m_->rx_grid_ || antenna != m_->rx_ant_)
    {
      m_->send_receiver_data_ = m_->socket_
        && QAbstractSocket::UdpSocket == m_->socket_->socketType () ? 3 : 1;
      m_->rx_call_ = call;
      m_->rx_grid_ = gridSquare;
      m_->rx_ant_ = antenna;
    }
}

bool PSK_Reporter::addRemoteStation (QString const& call, QString const& grid, Radio::Frequency freq
                                     , QString const& mode, int snr)
{
  if (m_->socket_ && m_->socket_->isValid ())
    {
      if (QAbstractSocket::UnconnectedState == m_->socket_->state ())
        {
           reconnect ();
        }
      m_->spots_.enqueue ({call, grid, snr, freq, mode, QDateTime::currentDateTimeUtc ()});
      return true;
    }
  return false;
}

void PSK_Reporter::sendReport ()
{
  m_->send_report (true);
}