comm_bridge.cpp

/***************************************************************************
 *
 * Project:  OpenCPN
 * Purpose:
 * Author:   David Register, Alec Leamas
 *
 ***************************************************************************
 *   Copyright (C) 2022 by David Register, Alec Leamas                     *
 *                                                                         *
 *   This program is free software; you can redistribute it and/or modify  *
 *   it under the terms of the GNU General Public License as published by  *
 *   the Free Software Foundation; either version 2 of the License, or     *
 *   (at your option) any later version.                                   *
 *                                                                         *
 *   This program is distributed in the hope that it will be useful,       *
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *
 *   GNU General Public License for more details.                          *
 *                                                                         *
 *   You should have received a copy of the GNU General Public License     *
 *   along with this program; if not, write to the                         *
 *   Free Software Foundation, Inc.,                                       *
 *   51 Franklin Street, Fifth Floor, Boston, MA 02110-1301,  USA.         *
 **************************************************************************/
 
// For compilers that support precompilation, includes "wx.h".
#include <wx/wxprec.h>
 
#ifndef WX_PRECOMP
#include <wx/wx.h>
#endif  // precompiled headers
 
#include <wx/event.h>
#include <wx/string.h>
#include <wx/tokenzr.h>
#include <wx/fileconf.h>
 
#include "model/comm_ais.h"
#include "model/comm_appmsg_bus.h"
#include "model/comm_bridge.h"
#include "model/comm_drv_registry.h"
#include "model/comm_navmsg_bus.h"
#include "model/comm_vars.h"
#include "model/config_vars.h"
#include "model/cutil.h"
#include "model/gui.h"
#include "model/idents.h"
#include "model/ocpn_types.h"
#include "model/own_ship.h"
#include "model/multiplexer.h"
 
//  comm event definitions
wxDEFINE_EVENT(EVT_N2K_129029, ObservedEvt);
wxDEFINE_EVENT(EVT_N2K_129025, ObservedEvt);
wxDEFINE_EVENT(EVT_N2K_129026, ObservedEvt);
wxDEFINE_EVENT(EVT_N2K_127250, ObservedEvt);
wxDEFINE_EVENT(EVT_N2K_129540, ObservedEvt);
 
wxDEFINE_EVENT(EVT_N0183_RMC, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_HDT, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_HDG, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_HDM, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_VTG, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_GSV, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_GGA, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_GLL, ObservedEvt);
wxDEFINE_EVENT(EVT_N0183_AIVDO, ObservedEvt);
 
wxDEFINE_EVENT(EVT_DRIVER_CHANGE, wxCommandEvent);
 
wxDEFINE_EVENT(EVT_SIGNALK, ObservedEvt);
 
#define N_ACTIVE_LOG_WATCHDOG 300
 
extern Multiplexer* g_pMUX;
 
bool debug_priority = 0;
 
void ClearNavData(NavData& d) {
  d.gLat = NAN;
  d.gLon = NAN;
  d.gSog = NAN;
  d.gCog = NAN;
  d.gHdt = NAN;
  d.gHdm = NAN;
  d.gVar = NAN;
  d.n_satellites = -1;
  d.SID = 0;
}
static NmeaLog* GetDataMonitor() {
  auto w = wxWindow::FindWindowByName(kDataMonitorWindowName);
  return dynamic_cast<NmeaLog*>(w);
}
static BridgeLogCallbacks GetLogCallbacks() {
  BridgeLogCallbacks log_callbacks;
  log_callbacks.log_is_active = [&]() {
    auto log = GetDataMonitor();
    return log && log->IsActive();
  };
  log_callbacks.log_message = [&](Logline ll) {
    NmeaLog* monitor = GetDataMonitor();
    if (monitor && monitor->IsActive()) monitor->Add(ll);
  };
  return log_callbacks;
}
 
class AppNavMsg : public NavMsg {
public:
  AppNavMsg(const std::shared_ptr<const AppMsg>& msg, const std::string& name)
      : NavMsg(NavAddr::Bus::AppMsg,
               std::make_shared<const NavAddrPlugin>("AppMsg")),
        m_to_string(msg->to_string()),
        m_name(name) {}
 
  std::string to_string() const override { return m_to_string; }
 
  std::string key() const override { return "appmsg::" + m_name; }
 
  const std::string m_to_string;
  const std::string m_name;
};
 
static void LogAppMsg(const std::shared_ptr<const AppMsg>& msg,
                      const std::string& name,
                      const BridgeLogCallbacks& log_cb) {
  if (!log_cb.log_is_active()) return;
  auto navmsg = std::make_shared<AppNavMsg>(msg, "basic-navdata");
  NavmsgStatus ns;
  Logline ll(navmsg, ns);
  log_cb.log_message(ll);
}
 
static void SendBasicNavdata(int vflag, BridgeLogCallbacks log_callbacks) {
  auto msg = std::make_shared<BasicNavDataMsg>(
      gLat, gLon, gSog, gCog, gVar, gHdt, vflag, wxDateTime::Now().GetTicks());
  clock_gettime(CLOCK_MONOTONIC, &msg->set_time);
  LogAppMsg(msg, "basic-navdata", log_callbacks);
  AppMsgBus::GetInstance().Notify(std::move(msg));
}
 
static inline double GeodesicRadToDeg(double rads) {
  return rads * 180.0 / M_PI;
}
 
static inline double MS2KNOTS(double ms) { return ms * 1.9438444924406; }
 
// CommBridge implementation
 
BEGIN_EVENT_TABLE(CommBridge, wxEvtHandler)
EVT_TIMER(WATCHDOG_TIMER, CommBridge::OnWatchdogTimer)
END_EVENT_TABLE()
 
CommBridge::CommBridge() {}
 
CommBridge::~CommBridge() {}
 
bool CommBridge::Initialize() {
  m_log_callbacks = GetLogCallbacks();
  InitializePriorityContainers();
  ClearPriorityMaps();
 
  LoadConfig();
  PresetPriorityContainers();
 
  // Clear the watchdogs
  PresetWatchdogs();
 
  m_watchdog_timer.SetOwner(this, WATCHDOG_TIMER);
  m_watchdog_timer.Start(1000, wxTIMER_CONTINUOUS);
  n_LogWatchdogPeriod = 3600;  // every 60 minutes,
                               // reduced after first position Rx
 
  // Initialize the comm listeners
  InitCommListeners();
 
  // Initialize a listener for driver state changes
  driver_change_listener.Listen(
      CommDriverRegistry::GetInstance().evt_driverlist_change.key, this,
      EVT_DRIVER_CHANGE);
  Bind(EVT_DRIVER_CHANGE, [&](wxCommandEvent ev) { OnDriverStateChange(); });
 
  return true;
}
 
void CommBridge::PresetWatchdogs() {
  m_watchdogs.position_watchdog =
      20;  // A bit longer watchdog for startup latency.
  m_watchdogs.velocity_watchdog = 20;
  m_watchdogs.variation_watchdog = 20;
  m_watchdogs.heading_watchdog = 20;
  m_watchdogs.satellite_watchdog = 20;
}
 
void CommBridge::SelectNextLowerPriority(
    const std::unordered_map<std::string, int>& map, PriorityContainer& pc) {
  int best_prio = 100;
  for (auto it = map.begin(); it != map.end(); it++) {
    if (it->second > pc.active_priority) {
      best_prio = wxMin(best_prio, it->second);
    }
  }
 
  pc.active_priority = best_prio;
  pc.active_source.clear();
  pc.active_identifier.clear();
}
 
void CommBridge::OnWatchdogTimer(wxTimerEvent& event) {
  //  Update and check watchdog timer for GPS data source
  m_watchdogs.position_watchdog--;
  if (m_watchdogs.position_watchdog <= 0) {
    if (m_watchdogs.position_watchdog % 5 == 0) {
      // Send AppMsg telling of watchdog expiry
      auto msg = std::make_shared<GPSWatchdogMsg>(
          GPSWatchdogMsg::WDSource::position, m_watchdogs.position_watchdog);
      auto& msgbus = AppMsgBus::GetInstance();
      msgbus.Notify(std::move(msg));
      LogAppMsg(msg, "watchdog", m_log_callbacks);
 
      if (m_watchdogs.position_watchdog % n_LogWatchdogPeriod == 0) {
        wxString logmsg;
        logmsg.Printf(_T("   ***GPS Watchdog timeout at Lat:%g   Lon: %g"),
                      gLat, gLon);
        wxLogMessage(logmsg);
      }
    }
 
    gSog = NAN;
    gCog = NAN;
    gRmcDate.Empty();
    gRmcTime.Empty();
    active_priority_position.recent_active_time = -1;
 
    // Are there any other lower priority sources?
    // If so, adopt that one.
    SelectNextLowerPriority(priority_map_position, active_priority_position);
  }
 
  //  Update and check watchdog timer for SOG/COG data source
  m_watchdogs.velocity_watchdog--;
  if (m_watchdogs.velocity_watchdog <= 0) {
    gSog = NAN;
    gCog = NAN;
    active_priority_velocity.recent_active_time = -1;
 
    if (g_nNMEADebug && (m_watchdogs.velocity_watchdog == 0))
      wxLogMessage(_T("   ***Velocity Watchdog timeout..."));
    if (m_watchdogs.velocity_watchdog % 5 == 0) {
      // Send AppMsg telling of watchdog expiry
      auto msg = std::make_shared<GPSWatchdogMsg>(
          GPSWatchdogMsg::WDSource::velocity, m_watchdogs.velocity_watchdog);
      auto& msgbus = AppMsgBus::GetInstance();
      msgbus.Notify(std::move(msg));
    }
    // Are there any other lower priority sources?
    // If so, adopt that one.
    SelectNextLowerPriority(priority_map_velocity, active_priority_velocity);
  }
 
  //  Update and check watchdog timer for True Heading data source
  m_watchdogs.heading_watchdog--;
  if (m_watchdogs.heading_watchdog <= 0) {
    gHdt = NAN;
    active_priority_heading.recent_active_time = -1;
    if (g_nNMEADebug && (m_watchdogs.heading_watchdog == 0))
      wxLogMessage(_T("   ***HDT Watchdog timeout..."));
 
    // Are there any other lower priority sources?
    // If so, adopt that one.
    SelectNextLowerPriority(priority_map_heading, active_priority_heading);
  }
 
  //  Update and check watchdog timer for Magnetic Variation data source
  m_watchdogs.variation_watchdog--;
  if (m_watchdogs.variation_watchdog <= 0) {
    g_bVAR_Rx = false;
    active_priority_variation.recent_active_time = -1;
 
    if (g_nNMEADebug && (m_watchdogs.variation_watchdog == 0))
      wxLogMessage(_T("   ***VAR Watchdog timeout..."));
 
    // Are there any other lower priority sources?
    // If so, adopt that one.
    SelectNextLowerPriority(priority_map_variation, active_priority_variation);
  }
 
  //  Update and check watchdog timer for GSV, GGA and SignalK (Satellite data)
  m_watchdogs.satellite_watchdog--;
  if (m_watchdogs.satellite_watchdog <= 0) {
    g_bSatValid = false;
    g_SatsInView = 0;
    g_priSats = 99;
    active_priority_satellites.recent_active_time = -1;
 
    if (g_nNMEADebug && (m_watchdogs.satellite_watchdog == 0))
      wxLogMessage(_T("   ***SAT Watchdog timeout..."));
 
    // Are there any other lower priority sources?
    // If so, adopt that one.
    SelectNextLowerPriority(priority_map_satellites,
                            active_priority_satellites);
  }
}
 
void CommBridge::MakeHDTFromHDM() {
  //    Here is the one place we try to create gHdt from gHdm and gVar,
 
  if (!std::isnan(gHdm)) {
    // Set gVar if needed from manual entry. gVar will be overwritten if
    // WMM plugin is available
    if (std::isnan(gVar) && (g_UserVar != 0.0)) gVar = g_UserVar;
    gHdt = gHdm + gVar;
    if (!std::isnan(gHdt)) {
      if (gHdt < 0)
        gHdt += 360.0;
      else if (gHdt >= 360)
        gHdt -= 360.0;
 
      m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    }
  }
}
 
void CommBridge::InitCommListeners() {
  // Initialize the comm listeners
  auto& msgbus = NavMsgBus::GetInstance();
 
  // GNSS Position Data PGN  129029
  //----------------------------------
  Nmea2000Msg n2k_msg_129029(static_cast<uint64_t>(129029));
  listener_N2K_129029.Listen(n2k_msg_129029, this, EVT_N2K_129029);
 
  Bind(EVT_N2K_129029, [&](ObservedEvt ev) {
    HandleN2K_129029(UnpackEvtPointer<Nmea2000Msg>(ev));
  });
 
  // Position rapid   PGN 129025
  //-----------------------------
  Nmea2000Msg n2k_msg_129025(static_cast<uint64_t>(129025));
  listener_N2K_129025.Listen(n2k_msg_129025, this, EVT_N2K_129025);
  Bind(EVT_N2K_129025, [&](ObservedEvt ev) {
    HandleN2K_129025(UnpackEvtPointer<Nmea2000Msg>(ev));
  });
 
  // COG SOG rapid   PGN 129026
  //-----------------------------
  Nmea2000Msg n2k_msg_129026(static_cast<uint64_t>(129026));
  listener_N2K_129026.Listen(n2k_msg_129026, this, EVT_N2K_129026);
  Bind(EVT_N2K_129026, [&](ObservedEvt ev) {
    HandleN2K_129026(UnpackEvtPointer<Nmea2000Msg>(ev));
  });
 
  // Heading rapid   PGN 127250
  //-----------------------------
  Nmea2000Msg n2k_msg_127250(static_cast<uint64_t>(127250));
  listener_N2K_127250.Listen(n2k_msg_127250, this, EVT_N2K_127250);
  Bind(EVT_N2K_127250, [&](ObservedEvt ev) {
    HandleN2K_127250(UnpackEvtPointer<Nmea2000Msg>(ev));
  });
 
  // GNSS Satellites in View   PGN 129540
  //-----------------------------
  Nmea2000Msg n2k_msg_129540(static_cast<uint64_t>(129540));
  listener_N2K_129540.Listen(n2k_msg_129540, this, EVT_N2K_129540);
  Bind(EVT_N2K_129540, [&](ObservedEvt ev) {
    HandleN2K_129540(UnpackEvtPointer<Nmea2000Msg>(ev));
  });
 
  // NMEA0183
  // RMC
  Nmea0183Msg n0183_msg_RMC("RMC");
  listener_N0183_RMC.Listen(n0183_msg_RMC, this, EVT_N0183_RMC);
 
  Bind(EVT_N0183_RMC, [&](ObservedEvt ev) {
    HandleN0183_RMC(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // HDT
  Nmea0183Msg n0183_msg_HDT("HDT");
  listener_N0183_HDT.Listen(n0183_msg_HDT, this, EVT_N0183_HDT);
 
  Bind(EVT_N0183_HDT, [&](ObservedEvt ev) {
    HandleN0183_HDT(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // HDG
  Nmea0183Msg n0183_msg_HDG("HDG");
  listener_N0183_HDG.Listen(n0183_msg_HDG, this, EVT_N0183_HDG);
 
  Bind(EVT_N0183_HDG, [&](ObservedEvt ev) {
    HandleN0183_HDG(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // HDM
  Nmea0183Msg n0183_msg_HDM("HDM");
  listener_N0183_HDM.Listen(n0183_msg_HDM, this, EVT_N0183_HDM);
 
  Bind(EVT_N0183_HDM, [&](ObservedEvt ev) {
    HandleN0183_HDM(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // VTG
  Nmea0183Msg n0183_msg_VTG("VTG");
  listener_N0183_VTG.Listen(n0183_msg_VTG, this, EVT_N0183_VTG);
 
  Bind(EVT_N0183_VTG, [&](ObservedEvt ev) {
    HandleN0183_VTG(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // GSV
  Nmea0183Msg n0183_msg_GSV("GSV");
  listener_N0183_GSV.Listen(n0183_msg_GSV, this, EVT_N0183_GSV);
 
  Bind(EVT_N0183_GSV, [&](ObservedEvt ev) {
    HandleN0183_GSV(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // GGA
  Nmea0183Msg n0183_msg_GGA("GGA");
  listener_N0183_GGA.Listen(n0183_msg_GGA, this, EVT_N0183_GGA);
 
  Bind(EVT_N0183_GGA, [&](ObservedEvt ev) {
    HandleN0183_GGA(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // GLL
  Nmea0183Msg n0183_msg_GLL("GLL");
  listener_N0183_GLL.Listen(n0183_msg_GLL, this, EVT_N0183_GLL);
 
  Bind(EVT_N0183_GLL, [&](ObservedEvt ev) {
    HandleN0183_GLL(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // AIVDO
  Nmea0183Msg n0183_msg_AIVDO("AIVDO");
  listener_N0183_AIVDO.Listen(n0183_msg_AIVDO, this, EVT_N0183_AIVDO);
 
  Bind(EVT_N0183_AIVDO, [&](ObservedEvt ev) {
    HandleN0183_AIVDO(UnpackEvtPointer<Nmea0183Msg>(ev));
  });
 
  // SignalK
  SignalkMsg sk_msg;
  listener_SignalK.Listen(sk_msg, this, EVT_SIGNALK);
 
  Bind(EVT_SIGNALK, [&](ObservedEvt ev) {
    HandleSignalK(UnpackEvtPointer<SignalkMsg>(ev));
  });
}
 
void CommBridge::OnDriverStateChange() {
  // Reset all active priority states
  PresetPriorityContainers();
}
 
std::string CommBridge::GetPriorityMap(
    std::unordered_map<std::string, int>& map) {
#define MAX_SOURCES 10
  std::string sa[MAX_SOURCES];
  std::string result;
 
  for (auto& it : map) {
    if ((it.second >= 0) && (it.second < MAX_SOURCES)) sa[it.second] = it.first;
  }
 
  // build the packed string result
  for (int i = 0; i < MAX_SOURCES; i++) {
    if (sa[i].size()) {
      result += sa[i];
      result += "|";
    }
  }
 
  return result;
}
 
std::vector<std::string> CommBridge::GetPriorityMaps() {
  std::vector<std::string> result;
 
  result.push_back(GetPriorityMap(priority_map_position));
  result.push_back(GetPriorityMap(priority_map_velocity));
  result.push_back(GetPriorityMap(priority_map_heading));
  result.push_back(GetPriorityMap(priority_map_variation));
  result.push_back(GetPriorityMap(priority_map_satellites));
 
  return result;
}
 
void CommBridge::ApplyPriorityMap(
    std::unordered_map<std::string, int>& priority_map, wxString& new_prio,
    int category) {
  priority_map.clear();
  wxStringTokenizer tk(new_prio, "|");
  int index = 0;
  while (tk.HasMoreTokens()) {
    wxString entry = tk.GetNextToken();
    std::string s_entry(entry.c_str());
    priority_map[s_entry] = index;
    index++;
  }
}
 
void CommBridge::ApplyPriorityMaps(std::vector<std::string> new_maps) {
  wxString new_prio_string;
 
  new_prio_string = wxString(new_maps[0].c_str());
  ApplyPriorityMap(priority_map_position, new_prio_string, 0);
 
  new_prio_string = wxString(new_maps[1].c_str());
  ApplyPriorityMap(priority_map_velocity, new_prio_string, 1);
 
  new_prio_string = wxString(new_maps[2].c_str());
  ApplyPriorityMap(priority_map_heading, new_prio_string, 2);
 
  new_prio_string = wxString(new_maps[3].c_str());
  ApplyPriorityMap(priority_map_variation, new_prio_string, 3);
 
  new_prio_string = wxString(new_maps[4].c_str());
  ApplyPriorityMap(priority_map_satellites, new_prio_string, 4);
}
 
void CommBridge::PresetPriorityContainer(
    PriorityContainer& pc,
    const std::unordered_map<std::string, int>& priority_map) {
  // Extract some info from the preloaded map
  // Find the key corresponding to priority 0, the highest
  std::string key0;
  for (auto& it : priority_map) {
    if (it.second == 0) key0 = it.first;
  }
 
  wxString this_key(key0.c_str());
  wxStringTokenizer tkz(this_key, _T(";"));
  wxString wxs_this_source = tkz.GetNextToken();
  std::string source = wxs_this_source.ToStdString();
  wxString wxs_this_identifier = tkz.GetNextToken();
  std::string this_identifier = wxs_this_identifier.ToStdString();
 
  wxStringTokenizer tka(wxs_this_source, _T(":"));
  tka.GetNextToken();
  int source_address = atoi(tka.GetNextToken().ToStdString().c_str());
 
  pc.active_priority = 0;
  pc.active_source = source;
  pc.active_identifier = this_identifier;
  pc.active_source_address = source_address;
  pc.recent_active_time = -1;
}
 
void CommBridge::PresetPriorityContainers() {
  PresetPriorityContainer(active_priority_position, priority_map_position);
  PresetPriorityContainer(active_priority_velocity, priority_map_velocity);
  PresetPriorityContainer(active_priority_heading, priority_map_heading);
  PresetPriorityContainer(active_priority_variation, priority_map_variation);
  PresetPriorityContainer(active_priority_satellites, priority_map_satellites);
}
 
bool CommBridge::HandleN2K_129029(std::shared_ptr<const Nmea2000Msg> n2k_msg) {
  std::vector<unsigned char> v = n2k_msg->payload;
 
  // extract and verify PGN
  uint64_t pgn = 0;
  unsigned char* c = (unsigned char*)&pgn;
  *c++ = v.at(3);
  *c++ = v.at(4);
  *c++ = v.at(5);
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodePGN129029(v, temp_data)) return false;
 
  int valid_flag = 0;
  if (!N2kIsNA(temp_data.gLat) && !N2kIsNA(temp_data.gLon)) {
    if (EvalPriority(n2k_msg, active_priority_position,
                     priority_map_position)) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_UPDATE;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
  }
 
  if (temp_data.n_satellites >= 0) {
    if (EvalPriority(n2k_msg, active_priority_satellites,
                     priority_map_satellites)) {
      g_SatsInView = temp_data.n_satellites;
      g_bSatValid = true;
      m_watchdogs.satellite_watchdog = sat_watchdog_timeout_ticks;
    }
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN2K_129025(std::shared_ptr<const Nmea2000Msg> n2k_msg) {
  std::vector<unsigned char> v = n2k_msg->payload;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodePGN129025(v, temp_data)) return false;
 
  int valid_flag = 0;
  if (!N2kIsNA(temp_data.gLat) && !N2kIsNA(temp_data.gLon)) {
    if (EvalPriority(n2k_msg, active_priority_position,
                     priority_map_position)) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_UPDATE;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
  }
  // FIXME (dave) How to notify user of errors?
  else {
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN2K_129026(std::shared_ptr<const Nmea2000Msg> n2k_msg) {
  std::vector<unsigned char> v = n2k_msg->payload;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodePGN129026(v, temp_data)) return false;
 
  int valid_flag = 0;
  if (!N2kIsNA(temp_data.gSog)) {  // gCog as reported by net may be NaN, but OK
    if (EvalPriority(n2k_msg, active_priority_velocity,
                     priority_map_velocity)) {
      gSog = MS2KNOTS(temp_data.gSog);
      valid_flag += SOG_UPDATE;
 
      if (N2kIsNA(temp_data.gCog))
        gCog = NAN;
      else
        gCog = GeodesicRadToDeg(temp_data.gCog);
      valid_flag += COG_UPDATE;
      m_watchdogs.velocity_watchdog = gps_watchdog_timeout_ticks;
    }
  } else {
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN2K_127250(std::shared_ptr<const Nmea2000Msg> n2k_msg) {
  std::vector<unsigned char> v = n2k_msg->payload;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodePGN127250(v, temp_data)) return false;
 
  int valid_flag = 0;
  if (!N2kIsNA(temp_data.gVar)) {
    if (EvalPriority(n2k_msg, active_priority_variation,
                     priority_map_variation)) {
      gVar = GeodesicRadToDeg(temp_data.gVar);
      valid_flag += VAR_UPDATE;
      m_watchdogs.variation_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!N2kIsNA(temp_data.gHdt)) {
    if (EvalPriority(n2k_msg, active_priority_heading, priority_map_heading)) {
      gHdt = GeodesicRadToDeg(temp_data.gHdt);
      valid_flag += HDT_UPDATE;
      m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!N2kIsNA(temp_data.gHdm)) {
    gHdm = GeodesicRadToDeg(temp_data.gHdm);
    if (EvalPriority(n2k_msg, active_priority_heading, priority_map_heading)) {
      MakeHDTFromHDM();
      valid_flag += HDT_UPDATE;
      if (!std::isnan(gHdt))
        m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN2K_129540(std::shared_ptr<const Nmea2000Msg> n2k_msg) {
  std::vector<unsigned char> v = n2k_msg->payload;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodePGN129540(v, temp_data)) return false;
 
  int valid_flag = 0;
  if (temp_data.n_satellites >= 0) {
    if (EvalPriority(n2k_msg, active_priority_satellites,
                     priority_map_satellites)) {
      g_SatsInView = temp_data.n_satellites;
      g_bSatValid = true;
      m_watchdogs.satellite_watchdog = sat_watchdog_timeout_ticks;
    }
  }
 
  return true;
}
 
bool CommBridge::HandleN0183_RMC(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  bool bvalid = true;
  if (!m_decoder.DecodeRMC(str, temp_data)) bvalid = false;
 
  if (std::isnan(temp_data.gLat) || std::isnan(temp_data.gLon)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_position,
                   priority_map_position)) {
    if (bvalid) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
    valid_flag += POS_UPDATE;
  }
 
  if (EvalPriority(n0183_msg, active_priority_velocity,
                   priority_map_velocity)) {
    if (bvalid) {
      gSog = temp_data.gSog;
      valid_flag += SOG_UPDATE;
      gCog = temp_data.gCog;
      valid_flag += COG_UPDATE;
      m_watchdogs.velocity_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!std::isnan(temp_data.gVar)) {
    if (EvalPriority(n0183_msg, active_priority_variation,
                     priority_map_variation)) {
      if (bvalid) {
        gVar = temp_data.gVar;
        valid_flag += VAR_UPDATE;
        m_watchdogs.variation_watchdog = gps_watchdog_timeout_ticks;
      }
    }
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_HDT(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeHDT(str, temp_data)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_heading, priority_map_heading)) {
    gHdt = temp_data.gHdt;
    valid_flag += HDT_UPDATE;
    m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_HDG(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeHDG(str, temp_data)) return false;
 
  int valid_flag = 0;
 
  bool bHDM = false;
  if (EvalPriority(n0183_msg, active_priority_heading, priority_map_heading)) {
    gHdm = temp_data.gHdm;
    m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    bHDM = true;
  }
 
  if (!std::isnan(temp_data.gVar)) {
    if (EvalPriority(n0183_msg, active_priority_variation,
                     priority_map_variation)) {
      gVar = temp_data.gVar;
      valid_flag += VAR_UPDATE;
      m_watchdogs.variation_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (bHDM) MakeHDTFromHDM();
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_HDM(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeHDM(str, temp_data)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_heading, priority_map_heading)) {
    gHdm = temp_data.gHdm;
    MakeHDTFromHDM();
    valid_flag += HDT_UPDATE;
    m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_VTG(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeVTG(str, temp_data)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_velocity,
                   priority_map_velocity)) {
    gSog = temp_data.gSog;
    valid_flag += SOG_UPDATE;
    gCog = temp_data.gCog;
    valid_flag += COG_UPDATE;
    m_watchdogs.velocity_watchdog = gps_watchdog_timeout_ticks;
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_GSV(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeGSV(str, temp_data)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_satellites,
                   priority_map_satellites)) {
    if (temp_data.n_satellites >= 0) {
      g_SatsInView = temp_data.n_satellites;
      g_bSatValid = true;
 
      m_watchdogs.satellite_watchdog = sat_watchdog_timeout_ticks;
    }
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_GGA(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  bool bvalid = true;
  if (!m_decoder.DecodeGGA(str, temp_data)) bvalid = false;
 
  if (std::isnan(temp_data.gLat) || std::isnan(temp_data.gLon)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_position,
                   priority_map_position)) {
    if (bvalid) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
    valid_flag += POS_UPDATE;
  }
 
  if (EvalPriority(n0183_msg, active_priority_satellites,
                   priority_map_satellites)) {
    if (bvalid) {
      if (temp_data.n_satellites >= 0) {
        g_SatsInView = temp_data.n_satellites;
        g_bSatValid = true;
 
        m_watchdogs.satellite_watchdog = sat_watchdog_timeout_ticks;
      }
    }
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_GLL(std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
  NavData temp_data;
  ClearNavData(temp_data);
 
  bool bvalid = true;
  if (!m_decoder.DecodeGLL(str, temp_data)) bvalid = false;
 
  if (std::isnan(temp_data.gLat) || std::isnan(temp_data.gLon)) return false;
 
  int valid_flag = 0;
  if (EvalPriority(n0183_msg, active_priority_position,
                   priority_map_position)) {
    if (bvalid) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
    valid_flag += POS_UPDATE;
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
bool CommBridge::HandleN0183_AIVDO(
    std::shared_ptr<const Nmea0183Msg> n0183_msg) {
  std::string str = n0183_msg->payload;
 
  GenericPosDatEx gpd;
  wxString sentence(str.c_str());
 
  int valid_flag = 0;
 
  AisError nerr = AIS_GENERIC_ERROR;
  nerr = DecodeSingleVDO(sentence, &gpd);
 
  if (nerr == AIS_NoError) {
    if (!std::isnan(gpd.kLat) && !std::isnan(gpd.kLon)) {
      if (EvalPriority(n0183_msg, active_priority_position,
                       priority_map_position)) {
        gLat = gpd.kLat;
        gLon = gpd.kLon;
        valid_flag += POS_UPDATE;
        valid_flag += POS_VALID;
        m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
        n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
      }
    }
 
    if (!std::isnan(gpd.kCog) && !std::isnan(gpd.kSog)) {
      if (EvalPriority(n0183_msg, active_priority_velocity,
                       priority_map_velocity)) {
        gSog = gpd.kSog;
        valid_flag += SOG_UPDATE;
        gCog = gpd.kCog;
        valid_flag += COG_UPDATE;
        m_watchdogs.velocity_watchdog = gps_watchdog_timeout_ticks;
      }
    }
 
    if (!std::isnan(gpd.kHdt)) {
      if (EvalPriority(n0183_msg, active_priority_heading,
                       priority_map_heading)) {
        gHdt = gpd.kHdt;
        valid_flag += HDT_UPDATE;
        m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
      }
    }
 
    SendBasicNavdata(valid_flag, m_log_callbacks);
  }
  return true;
}
 
bool CommBridge::HandleSignalK(std::shared_ptr<const SignalkMsg> sK_msg) {
  std::string str = sK_msg->raw_message;
 
  //  Here we ignore messages involving contexts other than ownship
  if (sK_msg->context_self != sK_msg->context) return false;
 
  g_ownshipMMSI_SK = sK_msg->context_self;
 
  NavData temp_data;
  ClearNavData(temp_data);
 
  if (!m_decoder.DecodeSignalK(str, temp_data)) return false;
 
  int valid_flag = 0;
 
  if (!std::isnan(temp_data.gLat) && !std::isnan(temp_data.gLon)) {
    if (EvalPriority(sK_msg, active_priority_position, priority_map_position)) {
      gLat = temp_data.gLat;
      gLon = temp_data.gLon;
      valid_flag += POS_UPDATE;
      valid_flag += POS_VALID;
      m_watchdogs.position_watchdog = gps_watchdog_timeout_ticks;
      n_LogWatchdogPeriod = N_ACTIVE_LOG_WATCHDOG;  // allow faster dog log
    }
  }
 
  if (!std::isnan(temp_data.gSog)) {
    if (EvalPriority(sK_msg, active_priority_velocity, priority_map_velocity)) {
      gSog = temp_data.gSog;
      valid_flag += SOG_UPDATE;
      if ((gSog > 0.05) && !std::isnan(temp_data.gCog)) {
        gCog = temp_data.gCog;
        valid_flag += COG_UPDATE;
      }
      m_watchdogs.velocity_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!std::isnan(temp_data.gHdt)) {
    if (EvalPriority(sK_msg, active_priority_heading, priority_map_heading)) {
      gHdt = temp_data.gHdt;
      valid_flag += HDT_UPDATE;
      m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!std::isnan(temp_data.gHdm)) {
    if (EvalPriority(sK_msg, active_priority_heading, priority_map_heading)) {
      gHdm = temp_data.gHdm;
      MakeHDTFromHDM();
      valid_flag += HDT_UPDATE;
      m_watchdogs.heading_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  if (!std::isnan(temp_data.gVar)) {
    if (EvalPriority(sK_msg, active_priority_variation,
                     priority_map_variation)) {
      gVar = temp_data.gVar;
      valid_flag += VAR_UPDATE;
      m_watchdogs.variation_watchdog = gps_watchdog_timeout_ticks;
    }
  }
 
  bool sat_update = false;
  if (temp_data.n_satellites > 0) {
    if (EvalPriority(sK_msg, active_priority_satellites,
                     priority_map_satellites)) {
      g_SatsInView = temp_data.n_satellites;
      g_bSatValid = true;
      sat_update = true;
      m_watchdogs.satellite_watchdog = sat_watchdog_timeout_ticks;
    }
  }
 
  if (g_pMUX && g_pMUX->IsLogActive()) {
    std::string logmsg = "Self: ";
    std::string content;
    if (valid_flag & POS_UPDATE) content += "POS;";
    if (valid_flag & POS_VALID) content += "POS_Valid;";
    if (valid_flag & SOG_UPDATE) content += "SOG;";
    if (valid_flag & COG_UPDATE) content += "COG;";
    if (valid_flag & HDT_UPDATE) content += "HDT;";
    if (valid_flag & VAR_UPDATE) content += "VAR;";
    if (sat_update) content += "SAT;";
 
    if (content.empty()) content = "Not used by OCPN, maybe passed to plugins";
 
    logmsg += content;
    g_pMUX->LogInputMessage(sK_msg, false, false);
  }
 
  SendBasicNavdata(valid_flag, m_log_callbacks);
  return true;
}
 
void CommBridge::InitializePriorityContainers() {
  active_priority_position.active_priority = 0;
  active_priority_velocity.active_priority = 0;
  active_priority_heading.active_priority = 0;
  active_priority_variation.active_priority = 0;
  active_priority_satellites.active_priority = 0;
 
  active_priority_position.active_source.clear();
  active_priority_velocity.active_source.clear();
  active_priority_heading.active_source.clear();
  active_priority_variation.active_source.clear();
  active_priority_satellites.active_source.clear();
 
  active_priority_position.active_identifier.clear();
  active_priority_velocity.active_identifier.clear();
  active_priority_heading.active_identifier.clear();
  active_priority_variation.active_identifier.clear();
  active_priority_satellites.active_identifier.clear();
 
  active_priority_position.pcclass = "position";
  active_priority_velocity.pcclass = "velocity";
  active_priority_heading.pcclass = "heading";
  active_priority_variation.pcclass = "variation";
  active_priority_satellites.pcclass = "satellites";
 
  active_priority_position.active_source_address = -1;
  active_priority_velocity.active_source_address = -1;
  active_priority_heading.active_source_address = -1;
  active_priority_variation.active_source_address = -1;
  active_priority_satellites.active_source_address = -1;
 
  active_priority_void.active_priority = -1;
}
 
void CommBridge::ClearPriorityMaps() {
  priority_map_position.clear();
  priority_map_velocity.clear();
  priority_map_heading.clear();
  priority_map_variation.clear();
  priority_map_satellites.clear();
}
 
PriorityContainer& CommBridge::GetPriorityContainer(
    const std::string category) {
  if (!category.compare("position"))
    return active_priority_position;
  else if (!category.compare("velocity"))
    return active_priority_velocity;
  else if (!category.compare("heading"))
    return active_priority_heading;
  else if (!category.compare("variation"))
    return active_priority_variation;
  else if (!category.compare("satellites"))
    return active_priority_satellites;
  else
    return active_priority_void;
}
 
void CommBridge::UpdateAndApplyMaps(std::vector<std::string> new_maps) {
  ApplyPriorityMaps(new_maps);
  SaveConfig();
  PresetPriorityContainers();
}
 
bool CommBridge::LoadConfig(void) {
  if (TheBaseConfig()) {
    TheBaseConfig()->SetPath("/Settings/CommPriority");
 
    std::vector<std::string> new_maps;
    std::string s_prio;
    wxString pri_string;
 
    TheBaseConfig()->Read("PriorityPosition", &pri_string);
    s_prio = std::string(pri_string.c_str());
    new_maps.push_back(s_prio);
 
    TheBaseConfig()->Read("PriorityVelocity", &pri_string);
    s_prio = std::string(pri_string.c_str());
    new_maps.push_back(s_prio);
 
    TheBaseConfig()->Read("PriorityHeading", &pri_string);
    s_prio = std::string(pri_string.c_str());
    new_maps.push_back(s_prio);
 
    TheBaseConfig()->Read("PriorityVariation", &pri_string);
    s_prio = std::string(pri_string.c_str());
    new_maps.push_back(s_prio);
 
    TheBaseConfig()->Read("PrioritySatellites", &pri_string);
    s_prio = std::string(pri_string.c_str());
    new_maps.push_back(s_prio);
 
    ApplyPriorityMaps(new_maps);
  }
  return true;
}
 
bool CommBridge::SaveConfig(void) {
  if (TheBaseConfig()) {
    TheBaseConfig()->SetPath("/Settings/CommPriority");
 
    wxString pri_string;
    pri_string = wxString(GetPriorityMap(priority_map_position).c_str());
    TheBaseConfig()->Write("PriorityPosition", pri_string);
 
    pri_string = wxString(GetPriorityMap(priority_map_velocity).c_str());
    TheBaseConfig()->Write("PriorityVelocity", pri_string);
 
    pri_string = wxString(GetPriorityMap(priority_map_heading).c_str());
    TheBaseConfig()->Write("PriorityHeading", pri_string);
 
    pri_string = wxString(GetPriorityMap(priority_map_variation).c_str());
    TheBaseConfig()->Write("PriorityVariation", pri_string);
 
    pri_string = wxString(GetPriorityMap(priority_map_satellites).c_str());
    TheBaseConfig()->Write("PrioritySatellites", pri_string);
  }
 
  return true;
}
 
std::string CommBridge::GetPriorityKey(std::shared_ptr<const NavMsg> msg) {
  std::string source = msg->source->to_string();
  std::string listener_key = msg->key();
 
  std::string this_identifier;
  std::string this_address("0");
  if (msg->bus == NavAddr::Bus::N0183) {
    auto msg_0183 = std::dynamic_pointer_cast<const Nmea0183Msg>(msg);
    if (msg_0183) {
      this_identifier = msg_0183->talker;
      this_identifier += msg_0183->type;
    }
  } else if (msg->bus == NavAddr::Bus::N2000) {
    auto msg_n2k = std::dynamic_pointer_cast<const Nmea2000Msg>(msg);
    if (msg_n2k) {
      this_identifier = msg_n2k->PGN.to_string();
      unsigned char n_source = msg_n2k->payload.at(7);
      char ss[4];
      sprintf(ss, "%d", n_source);
      this_address = std::string(ss);
    }
  } else if (msg->bus == NavAddr::Bus::Signalk) {
    auto msg_sk = std::dynamic_pointer_cast<const SignalkMsg>(msg);
    if (msg_sk) {
      auto addr_sk =
          std::static_pointer_cast<const NavAddrSignalK>(msg->source);
      source = addr_sk->to_string();
      this_identifier = "signalK";
      this_address = msg->source->iface;
    }
  }
 
  return source + ":" + this_address + ";" + this_identifier;
}
 
bool CommBridge::EvalPriority(
    std::shared_ptr<const NavMsg> msg, PriorityContainer& active_priority,
    std::unordered_map<std::string, int>& priority_map) {
  std::string this_key = GetPriorityKey(msg);
  if (debug_priority) printf("This Key: %s\n", this_key.c_str());
 
  // Pull some identifiers from the unique key
  wxStringTokenizer tkz(this_key, _T(";"));
  wxString wxs_this_source = tkz.GetNextToken();
  std::string source = wxs_this_source.ToStdString();
  wxString wxs_this_identifier = tkz.GetNextToken();
  std::string this_identifier = wxs_this_identifier.ToStdString();
 
  wxStringTokenizer tka(wxs_this_source, _T(":"));
  tka.GetNextToken();
  int source_address = atoi(tka.GetNextToken().ToStdString().c_str());
 
  // Special case priority value linkage:
  // If this is a "velocity" record, ensure that a "position"
  // report has been accepted from the same source before accepting the
  // velocity record.
  // This ensures that the data source is fully initialized, and is reporting
  // valid, sensible velocity data.
  if (!strncmp(active_priority.pcclass.c_str(), "velocity", 8)) {
    bool pos_ok = false;
    if (!strcmp(active_priority_position.active_source.c_str(),
                source.c_str())) {
      if (active_priority_position.recent_active_time != -1) {
        pos_ok = true;
      }
    }
    if (!pos_ok) return false;
  }
 
  // Fetch the established priority for the message
  int this_priority;
 
  auto it = priority_map.find(this_key);
  if (it == priority_map.end()) {
    // Not found, so make it default the lowest priority
    size_t n = priority_map.size();
    priority_map[this_key] = n;
  }
 
  this_priority = priority_map[this_key];
 
  if (debug_priority) {
    for (auto it = priority_map.begin(); it != priority_map.end(); it++)
      printf("               priority_map:  %s  %d\n", it->first.c_str(),
             it->second);
  }
 
  // Incoming message priority lower than currently active priority?
  //   If so, drop the message
  if (this_priority > active_priority.active_priority) {
    if (debug_priority)
      printf("      Drop low priority: %s %d %d \n", source.c_str(),
             this_priority, active_priority.active_priority);
    return false;
  }
 
  // A channel returning, after being watchdogged out.
  if (this_priority < active_priority.active_priority) {
    active_priority.active_priority = this_priority;
    active_priority.active_source = source;
    active_priority.active_identifier = this_identifier;
    active_priority.active_source_address = source_address;
    wxDateTime now = wxDateTime::Now();
    active_priority.recent_active_time = now.GetTicks();
 
    if (debug_priority)
      printf("  Restoring high priority: %s %d\n", source.c_str(),
             this_priority);
    return true;
  }
 
  // Do we see two sources with the same priority?
  // If so, we take the first one, and deprioritize this one.
 
  if (active_priority.active_source.size()) {
    if (debug_priority) printf("source: %s\n", source.c_str());
    if (debug_priority)
      printf("active_source: %s\n", active_priority.active_source.c_str());
 
    if (source.compare(active_priority.active_source) != 0) {
      // Auto adjust the priority of these this message down
      // First, find the lowest priority in use in this map
      int lowest_priority = -10;  // safe enough
      for (auto it = priority_map.begin(); it != priority_map.end(); it++) {
        if (it->second > lowest_priority) lowest_priority = it->second;
      }
 
      priority_map[this_key] = lowest_priority + 1;
      if (debug_priority)
        printf("          Lowering priority A: %s :%d\n", source.c_str(),
               priority_map[this_key]);
      return false;
    }
  }
 
  //  For N0183 message, has the Mnemonic (id) changed?
  //  Example:  RMC and AIVDO from same source.
 
  if (msg->bus == NavAddr::Bus::N0183) {
    auto msg_0183 = std::dynamic_pointer_cast<const Nmea0183Msg>(msg);
    if (msg_0183) {
      if (active_priority.active_identifier.size()) {
        if (debug_priority)
          printf("this_identifier: %s\n", this_identifier.c_str());
        if (debug_priority)
          printf("active_priority.active_identifier: %s\n",
                 active_priority.active_identifier.c_str());
 
        if (this_identifier.compare(active_priority.active_identifier) != 0) {
          // if necessary, auto adjust the priority of this message down
          // and drop it
          if (priority_map[this_key] == active_priority.active_priority) {
            int lowest_priority = -10;  // safe enough
            for (auto it = priority_map.begin(); it != priority_map.end();
                 it++) {
              if (it->second > lowest_priority) lowest_priority = it->second;
            }
 
            priority_map[this_key] = lowest_priority + 1;
            if (debug_priority)
              printf("          Lowering priority B: %s :%d\n", source.c_str(),
                     priority_map[this_key]);
          }
 
          return false;
        }
      }
    }
  }
 
  //  Similar for n2k PGN...
 
  else if (msg->bus == NavAddr::Bus::N2000) {
    auto msg_n2k = std::dynamic_pointer_cast<const Nmea2000Msg>(msg);
    if (msg_n2k) {
      if (active_priority.active_identifier.size()) {
        if (this_identifier.compare(active_priority.active_identifier) != 0) {
          // if necessary, auto adjust the priority of this message down
          // and drop it
          if (priority_map[this_key] == active_priority.active_priority) {
            int lowest_priority = -10;  // safe enough
            for (auto it = priority_map.begin(); it != priority_map.end();
                 it++) {
              if (it->second > lowest_priority) lowest_priority = it->second;
            }
 
            priority_map[this_key] = lowest_priority + 1;
            if (debug_priority)
              printf("          Lowering priority: %s :%d\n", source.c_str(),
                     priority_map[this_key]);
          }
 
          return false;
        }
      }
    }
  }
 
  // Update the records
  active_priority.active_source = source;
  active_priority.active_identifier = this_identifier;
  active_priority.active_source_address = source_address;
  wxDateTime now = wxDateTime::Now();
  active_priority.recent_active_time = now.GetTicks();
  if (debug_priority)
    printf("  Accepting high priority: %s %d\n", source.c_str(), this_priority);
 
  return true;
}