MockLink.cc

/****************************************************************************
 *
 *   (c) 2009-2016 QGROUNDCONTROL PROJECT <http://www.qgroundcontrol.org>
 *
 * QGroundControl is licensed according to the terms in the file
 * COPYING.md in the root of the source code directory.
 *
 ****************************************************************************/


#include "MockLink.h"
#include "QGCLoggingCategory.h"
#include "QGCApplication.h"

#ifdef UNITTEST_BUILD
#include "UnitTest.h"
#endif

#include <QTimer>
#include <QDebug>
#include <QFile>

#include <string.h>

// FIXME: Hack to work around clean headers
#include "FirmwarePlugin/PX4/px4_custom_mode.h"

QGC_LOGGING_CATEGORY(MockLinkLog, "MockLinkLog")
QGC_LOGGING_CATEGORY(MockLinkVerboseLog, "MockLinkVerboseLog")

/// @file
///     @brief Mock implementation of a Link.
///
///     @author Don Gagne <don@thegagnes.com>

// Vehicle position is set close to default Gazebo vehicle location. This allows for multi-vehicle
// testing of a gazebo vehicle and a mocklink vehicle
#if 1
double      MockLink::_defaultVehicleLatitude =     47.397;
double      MockLink::_defaultVehicleLongitude =    8.5455;
double      MockLink::_defaultVehicleAltitude =     488.056;
#else
double      MockLink::_defaultVehicleLatitude =     47.6333022928789;
double      MockLink::_defaultVehicleLongitude =    -122.08833157994995;
double      MockLink::_defaultVehicleAltitude =     19.0;
#endif
int         MockLink::_nextVehicleSystemId =        128;
const char* MockLink::_failParam =                  "COM_FLTMODE6";

const char* MockConfiguration::_firmwareTypeKey =   "FirmwareType";
const char* MockConfiguration::_vehicleTypeKey =    "VehicleType";
const char* MockConfiguration::_sendStatusTextKey = "SendStatusText";
const char* MockConfiguration::_highLatencyKey =    "HighLatency";
const char* MockConfiguration::_failureModeKey =    "FailureMode";

MockLink::MockLink(SharedLinkConfigurationPointer& config)
    : LinkInterface                         (config)
    , _missionItemHandler                   (this, qgcApp()->toolbox()->mavlinkProtocol())
    , _name                                 ("MockLink")
    , _connected                            (false)
    , _mavlinkChannel                       (0)
    , _vehicleSystemId                      (_nextVehicleSystemId++)
    , _vehicleComponentId                   (MAV_COMP_ID_AUTOPILOT1)
    , _inNSH                                (false)
    , _mavlinkStarted                       (true)
    , _mavBaseMode                          (MAV_MODE_FLAG_MANUAL_INPUT_ENABLED | MAV_MODE_FLAG_CUSTOM_MODE_ENABLED)
    , _mavState                             (MAV_STATE_STANDBY)
    , _firmwareType                         (MAV_AUTOPILOT_PX4)
    , _vehicleType                          (MAV_TYPE_QUADROTOR)
    , _vehicleLatitude                      (_defaultVehicleLatitude + ((_vehicleSystemId - 128) * 0.0001))     // Slight offset for each vehicle
    , _vehicleLongitude                     (_defaultVehicleLongitude + ((_vehicleSystemId - 128) * 0.0001))
    , _vehicleAltitude                      (_defaultVehicleAltitude)
    , _fileServer                           (NULL)
    , _sendStatusText                       (false)
    , _apmSendHomePositionOnEmptyList       (false)
    , _failureMode                          (MockConfiguration::FailNone)
    , _sendHomePositionDelayCount           (10)    // No home position for 4 seconds
    , _sendGPSPositionDelayCount            (100)   // No gps lock for 5 seconds
    , _currentParamRequestListComponentIndex(-1)
    , _currentParamRequestListParamIndex    (-1)
    , _logDownloadCurrentOffset             (0)
    , _logDownloadBytesRemaining            (0)
    , _adsbAngle                            (0)
{
    MockConfiguration* mockConfig = qobject_cast<MockConfiguration*>(_config.data());
    _firmwareType = mockConfig->firmwareType();
    _vehicleType = mockConfig->vehicleType();
    _sendStatusText = mockConfig->sendStatusText();
    _highLatency = mockConfig->highLatency();
    _failureMode = mockConfig->failureMode();

    union px4_custom_mode   px4_cm;

    px4_cm.data = 0;
    px4_cm.main_mode = PX4_CUSTOM_MAIN_MODE_MANUAL;
    _mavCustomMode = px4_cm.data;

    _fileServer = new MockLinkFileServer(_vehicleSystemId, _vehicleComponentId, this);
    Q_CHECK_PTR(_fileServer);

    moveToThread(this);

    _loadParams();

    _adsbVehicleCoordinate = QGeoCoordinate(_vehicleLatitude, _vehicleLongitude).atDistanceAndAzimuth(1000, _adsbAngle);
    _adsbVehicleCoordinate.setAltitude(100);
}

MockLink::~MockLink(void)
{
    _disconnect();
    if (!_logDownloadFilename.isEmpty()) {
        QFile::remove(_logDownloadFilename);
    }
}

bool MockLink::_connect(void)
{
    if (!_connected) {
        _connected = true;
        _mavlinkChannel = qgcApp()->toolbox()->linkManager()->_reserveMavlinkChannel();
        if (_mavlinkChannel == 0) {
            qWarning() << "No mavlink channels available";
            return false;
        }
        // MockLinks use Mavlink 2.0
        mavlink_status_t* mavlinkStatus = mavlink_get_channel_status(_mavlinkChannel);
        mavlinkStatus->flags &= ~MAVLINK_STATUS_FLAG_OUT_MAVLINK1;
        start();
        emit connected();
    }

    return true;
}

void MockLink::_disconnect(void)
{
    if (_connected) {
        if (_mavlinkChannel != 0) {
            qgcApp()->toolbox()->linkManager()->_freeMavlinkChannel(_mavlinkChannel);
        }
        _connected = false;
        quit();
        wait();
        emit disconnected();
    }
}

void MockLink::run(void)
{
    QTimer  timer1HzTasks;
    QTimer  timer10HzTasks;
    QTimer  timer500HzTasks;

    QObject::connect(&timer1HzTasks,  &QTimer::timeout, this, &MockLink::_run1HzTasks);
    QObject::connect(&timer10HzTasks, &QTimer::timeout, this, &MockLink::_run10HzTasks);
    QObject::connect(&timer500HzTasks, &QTimer::timeout, this, &MockLink::_run500HzTasks);

    timer1HzTasks.start(1000);
    timer10HzTasks.start(100);
    timer500HzTasks.start(2);

    exec();

    QObject::disconnect(&timer1HzTasks,  &QTimer::timeout, this, &MockLink::_run1HzTasks);
    QObject::disconnect(&timer10HzTasks, &QTimer::timeout, this, &MockLink::_run10HzTasks);
    QObject::disconnect(&timer500HzTasks, &QTimer::timeout, this, &MockLink::_run500HzTasks);

    _missionItemHandler.shutdown();
}

void MockLink::_run1HzTasks(void)
{
    if (_mavlinkStarted && _connected) {
        if (_highLatency) {
            _sendHighLatency2();
        } else {
            _sendVibration();
            _sendADSBVehicles();
            if (!qgcApp()->runningUnitTests()) {
                // Sending RC Channels during unit test breaks RC tests which does it's own RC simulation
                _sendRCChannels();
            }
            if (_sendHomePositionDelayCount > 0) {
                // We delay home position for better testing
                _sendHomePositionDelayCount--;
            } else {
                _sendHomePosition();
            }
            if (_sendStatusText) {
                _sendStatusText = false;
                _sendStatusTextMessages();
            }
        }
    }
}

void MockLink::_run10HzTasks(void)
{
    if (_highLatency) {
        return;
    }

    if (_mavlinkStarted && _connected) {
        _sendHeartBeat();
        if (_sendGPSPositionDelayCount > 0) {
            // We delay gps position for better testing
            _sendGPSPositionDelayCount--;
        } else {
            _sendGpsRawInt();
        }
    }
}

void MockLink::_run500HzTasks(void)
{
    if (_highLatency) {
        return;
    }

    if (_mavlinkStarted && _connected) {
        _paramRequestListWorker();
        _logDownloadWorker();
    }
}

void MockLink::_loadParams(void)
{
    QFile paramFile;

    if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
        if (_vehicleType == MAV_TYPE_FIXED_WING) {
            paramFile.setFileName(":/FirmwarePlugin/APM/Plane.OfflineEditing.params");
        } else if (_vehicleType == MAV_TYPE_SUBMARINE ) {
            paramFile.setFileName(":/MockLink/APMArduSubMockLink.params");
        } else if (_vehicleType == MAV_TYPE_GROUND_ROVER ) {
            paramFile.setFileName(":/FirmwarePlugin/APM/Rover.OfflineEditing.params");
        } else {
            paramFile.setFileName(":/FirmwarePlugin/APM/Copter.OfflineEditing.params");
        }
    } else {
        paramFile.setFileName(":/MockLink/PX4MockLink.params");
    }


    bool success = paramFile.open(QFile::ReadOnly);
    Q_UNUSED(success);
    Q_ASSERT(success);

    QTextStream paramStream(&paramFile);

    while (!paramStream.atEnd()) {
        QString line = paramStream.readLine();

        if (line.startsWith("#")) {
            continue;
        }

        QStringList paramData = line.split("\t");
        Q_ASSERT(paramData.count() == 5);

        int compId = paramData.at(1).toInt();
        QString paramName = paramData.at(2);
        QString valStr = paramData.at(3);
        uint paramType = paramData.at(4).toUInt();

        QVariant paramValue;
        switch (paramType) {
        case MAV_PARAM_TYPE_REAL32:
            paramValue = QVariant(valStr.toFloat());
            break;
        case MAV_PARAM_TYPE_UINT32:
            paramValue = QVariant(valStr.toUInt());
            break;
        case MAV_PARAM_TYPE_INT32:
            paramValue = QVariant(valStr.toInt());
            break;
        case MAV_PARAM_TYPE_UINT16:
            paramValue = QVariant((quint16)valStr.toUInt());
            break;
        case MAV_PARAM_TYPE_INT16:
            paramValue = QVariant((qint16)valStr.toInt());
            break;
        case MAV_PARAM_TYPE_UINT8:
            paramValue = QVariant((quint8)valStr.toUInt());
            break;
        case MAV_PARAM_TYPE_INT8:
            paramValue = QVariant((qint8)valStr.toUInt());
            break;
        default:
            qCritical() << "Unknown type" << paramType;
            paramValue = QVariant(valStr.toInt());
            break;
        }

        qCDebug(MockLinkVerboseLog) << "Loading param" << paramName << paramValue;

        _mapParamName2Value[compId][paramName] = paramValue;
        _mapParamName2MavParamType[compId][paramName] = static_cast<MAV_PARAM_TYPE>(paramType);
    }
}

void MockLink::_sendHeartBeat(void)
{
    mavlink_message_t   msg;

    mavlink_msg_heartbeat_pack_chan(_vehicleSystemId,
                                    _vehicleComponentId,
                                    _mavlinkChannel,
                                    &msg,
                                    _vehicleType,        // MAV_TYPE
                                    _firmwareType,      // MAV_AUTOPILOT
                                    _mavBaseMode,        // MAV_MODE
                                    _mavCustomMode,      // custom mode
                                    _mavState);          // MAV_STATE

    respondWithMavlinkMessage(msg);
}

void MockLink::_sendHighLatency2(void)
{
    mavlink_message_t   msg;

    union px4_custom_mode   px4_cm;
    px4_cm.data = _mavCustomMode;

    qDebug() << "Sending" << _mavCustomMode;
    mavlink_msg_high_latency2_pack_chan(_vehicleSystemId,
                                        _vehicleComponentId,
                                        _mavlinkChannel,
                                        &msg,
                                        0,                          // timestamp
                                        _vehicleType,               // MAV_TYPE
                                        _firmwareType,              // MAV_AUTOPILOT
                                        px4_cm.custom_mode_hl,      // custom_mode
                                        (int32_t)(_vehicleLatitude  * 1E7),
                                        (int32_t)(_vehicleLongitude * 1E7),
                                        (int16_t)_vehicleAltitude,
                                        (int16_t)_vehicleAltitude,  // target_altitude,
                                        0,                          // heading
                                        0,                          // target_heading
                                        0,                          // target_distance
                                        0,                          // throttle
                                        0,                          // airspeed
                                        0,                          // airspeed_sp
                                        0,                          // groundspeed
                                        0,                          // windspeed,
                                        0,                          // wind_heading
                                        UINT8_MAX,                  // eph not known
                                        UINT8_MAX,                  // epv not known
                                        0,                          // temperature_air
                                        0,                          // climb_rate
                                        -1,                         // battery, do not use?
                                        0,                          // wp_num
                                        0,                          // failure_flags
                                        0, 0, 0);                   // custom0, custom1, custom2
    respondWithMavlinkMessage(msg);
}

void MockLink::_sendVibration(void)
{
    mavlink_message_t   msg;

    mavlink_msg_vibration_pack_chan(_vehicleSystemId,
                                    _vehicleComponentId,
                                    _mavlinkChannel,
                                    &msg,
                                    0,       // time_usec
                                    50.5,    // vibration_x,
                                    10.5,    // vibration_y,
                                    60.0,    // vibration_z,
                                    1,       // clipping_0
                                    2,       // clipping_0
                                    3);      // clipping_0

    respondWithMavlinkMessage(msg);
}

void MockLink::respondWithMavlinkMessage(const mavlink_message_t& msg)
{
    uint8_t buffer[MAVLINK_MAX_PACKET_LEN];

    int cBuffer = mavlink_msg_to_send_buffer(buffer, &msg);
    QByteArray bytes((char *)buffer, cBuffer);
    emit bytesReceived(this, bytes);
}

/// @brief Called when QGC wants to write bytes to the MAV
void MockLink::_writeBytes(const QByteArray bytes)
{
    if (_inNSH) {
        _handleIncomingNSHBytes(bytes.constData(), bytes.count());
    } else {
        if (bytes.startsWith(QByteArray("\r\r\r"))) {
            _inNSH  = true;
            _handleIncomingNSHBytes(&bytes.constData()[3], bytes.count() - 3);
        }

        _handleIncomingMavlinkBytes((uint8_t *)bytes.constData(), bytes.count());
    }
}

/// @brief Handle incoming bytes which are meant to be interpreted by the NuttX shell
void MockLink::_handleIncomingNSHBytes(const char* bytes, int cBytes)
{
    Q_UNUSED(cBytes);

    // Drop back out of NSH
    if (cBytes == 4 && bytes[0] == '\r' && bytes[1] == '\r' && bytes[2] == '\r') {
        _inNSH  = false;
        return;
    }

    if (cBytes > 0) {
        qDebug() << "NSH:" << (const char*)bytes;

#if 0
        // MockLink not quite ready to handle this correctly yet
        if (strncmp(bytes, "sh /etc/init.d/rc.usb\n", cBytes) == 0) {
            // This is the mavlink start command
            _mavlinkStarted = true;
        }
#endif
    }
}

/// @brief Handle incoming bytes which are meant to be handled by the mavlink protocol
void MockLink::_handleIncomingMavlinkBytes(const uint8_t* bytes, int cBytes)
{
    mavlink_message_t msg;
    mavlink_status_t comm;

    for (qint64 i=0; i<cBytes; i++)
    {
        if (!mavlink_parse_char(_mavlinkChannel, bytes[i], &msg, &comm)) {
            continue;
        }

        if (_missionItemHandler.handleMessage(msg)) {
            continue;
        }

        switch (msg.msgid) {
        case MAVLINK_MSG_ID_HEARTBEAT:
            _handleHeartBeat(msg);
            break;

        case MAVLINK_MSG_ID_PARAM_REQUEST_LIST:
            _handleParamRequestList(msg);
            break;

        case MAVLINK_MSG_ID_SET_MODE:
            _handleSetMode(msg);
            break;

        case MAVLINK_MSG_ID_PARAM_SET:
            _handleParamSet(msg);
            break;

        case MAVLINK_MSG_ID_PARAM_REQUEST_READ:
            _handleParamRequestRead(msg);
            break;

        case MAVLINK_MSG_ID_FILE_TRANSFER_PROTOCOL:
            _handleFTP(msg);
            break;

        case MAVLINK_MSG_ID_COMMAND_LONG:
            _handleCommandLong(msg);
            break;

        case MAVLINK_MSG_ID_MANUAL_CONTROL:
            _handleManualControl(msg);
            break;

        case MAVLINK_MSG_ID_LOG_REQUEST_LIST:
            _handleLogRequestList(msg);
            break;

        case MAVLINK_MSG_ID_LOG_REQUEST_DATA:
            _handleLogRequestData(msg);
            break;

        default:
            break;
        }
    }
}

void MockLink::_handleHeartBeat(const mavlink_message_t& msg)
{
    Q_UNUSED(msg);
    qCDebug(MockLinkLog) << "Heartbeat";
}

void MockLink::_handleSetMode(const mavlink_message_t& msg)
{
    mavlink_set_mode_t request;
    mavlink_msg_set_mode_decode(&msg, &request);

    Q_ASSERT(request.target_system == _vehicleSystemId);

    _mavBaseMode = request.base_mode;
    _mavCustomMode = request.custom_mode;
}

void MockLink::_handleManualControl(const mavlink_message_t& msg)
{
    mavlink_manual_control_t manualControl;
    mavlink_msg_manual_control_decode(&msg, &manualControl);

    qCDebug(MockLinkLog) << "MANUAL_CONTROL" << manualControl.x << manualControl.y << manualControl.z << manualControl.r;
}

void MockLink::_setParamFloatUnionIntoMap(int componentId, const QString& paramName, float paramFloat)
{
    mavlink_param_union_t   valueUnion;

    Q_ASSERT(_mapParamName2Value.contains(componentId));
    Q_ASSERT(_mapParamName2Value[componentId].contains(paramName));
    Q_ASSERT(_mapParamName2MavParamType[componentId].contains(paramName));

    valueUnion.param_float = paramFloat;

    MAV_PARAM_TYPE paramType = _mapParamName2MavParamType[componentId][paramName];

    QVariant paramVariant;

    switch (paramType) {
    case MAV_PARAM_TYPE_REAL32:
        paramVariant = QVariant::fromValue(valueUnion.param_float);
        break;

    case MAV_PARAM_TYPE_UINT32:
        paramVariant = QVariant::fromValue(valueUnion.param_uint32);
        break;

    case MAV_PARAM_TYPE_INT32:
        paramVariant = QVariant::fromValue(valueUnion.param_int32);
        break;

    case MAV_PARAM_TYPE_UINT16:
        paramVariant = QVariant::fromValue(valueUnion.param_uint16);
        break;

    case MAV_PARAM_TYPE_INT16:
        paramVariant = QVariant::fromValue(valueUnion.param_int16);
        break;

    case MAV_PARAM_TYPE_UINT8:
        paramVariant = QVariant::fromValue(valueUnion.param_uint8);
        break;

    case MAV_PARAM_TYPE_INT8:
        paramVariant = QVariant::fromValue(valueUnion.param_int8);
        break;

    default:
        qCritical() << "Invalid parameter type" << paramType;
        paramVariant = QVariant::fromValue(valueUnion.param_int32);
        break;
    }

    qCDebug(MockLinkLog) << "_setParamFloatUnionIntoMap" << paramName << paramVariant;
    _mapParamName2Value[componentId][paramName] = paramVariant;
}

/// Convert from a parameter variant to the float value from mavlink_param_union_t
float MockLink::_floatUnionForParam(int componentId, const QString& paramName)
{
    mavlink_param_union_t   valueUnion;

    Q_ASSERT(_mapParamName2Value.contains(componentId));
    Q_ASSERT(_mapParamName2Value[componentId].contains(paramName));
    Q_ASSERT(_mapParamName2MavParamType[componentId].contains(paramName));

    MAV_PARAM_TYPE paramType = _mapParamName2MavParamType[componentId][paramName];
    QVariant paramVar = _mapParamName2Value[componentId][paramName];

    switch (paramType) {
    case MAV_PARAM_TYPE_REAL32:
        valueUnion.param_float = paramVar.toFloat();
        break;

    case MAV_PARAM_TYPE_UINT32:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toUInt();
        } else {
            valueUnion.param_uint32 = paramVar.toUInt();
        }
        break;

    case MAV_PARAM_TYPE_INT32:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toInt();
        } else {
            valueUnion.param_int32 = paramVar.toInt();
        }
        break;

    case MAV_PARAM_TYPE_UINT16:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toUInt();
        } else {
            valueUnion.param_uint16 = paramVar.toUInt();
        }
        break;

    case MAV_PARAM_TYPE_INT16:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toInt();
        } else {
            valueUnion.param_int16 = paramVar.toInt();
        }
        break;

    case MAV_PARAM_TYPE_UINT8:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toUInt();
        } else {
            valueUnion.param_uint8 = paramVar.toUInt();
        }
        break;

    case MAV_PARAM_TYPE_INT8:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = (unsigned char)paramVar.toChar().toLatin1();
        } else {
            valueUnion.param_int8 = (unsigned char)paramVar.toChar().toLatin1();
        }
        break;

    default:
        if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
            valueUnion.param_float = paramVar.toInt();
        } else {
            valueUnion.param_int32 = paramVar.toInt();
        }
        qCritical() << "Invalid parameter type" << paramType;
    }

    return valueUnion.param_float;
}

void MockLink::_handleParamRequestList(const mavlink_message_t& msg)
{
    if (_failureMode == MockConfiguration::FailParamNoReponseToRequestList) {
        return;
    }

    mavlink_param_request_list_t request;

    mavlink_msg_param_request_list_decode(&msg, &request);

    Q_ASSERT(request.target_system == _vehicleSystemId);
    Q_ASSERT(request.target_component == MAV_COMP_ID_ALL);

    // Start the worker routine
    _currentParamRequestListComponentIndex = 0;
    _currentParamRequestListParamIndex = 0;
}

/// Sends the next parameter to the vehicle
void MockLink::_paramRequestListWorker(void)
{
    if (_currentParamRequestListComponentIndex == -1) {
        // Initial request complete
        return;
    }

    int componentId = _mapParamName2Value.keys()[_currentParamRequestListComponentIndex];
    int cParameters = _mapParamName2Value[componentId].count();
    QString paramName = _mapParamName2Value[componentId].keys()[_currentParamRequestListParamIndex];

    if ((_failureMode == MockConfiguration::FailMissingParamOnInitialReqest || _failureMode == MockConfiguration::FailMissingParamOnAllRequests) && paramName == _failParam) {
        qCDebug(MockLinkLog) << "Skipping param send:" << paramName;
    } else {

        char paramId[MAVLINK_MSG_ID_PARAM_VALUE_LEN];
        mavlink_message_t responseMsg;

        Q_ASSERT(_mapParamName2Value[componentId].contains(paramName));
        Q_ASSERT(_mapParamName2MavParamType[componentId].contains(paramName));

        MAV_PARAM_TYPE paramType = _mapParamName2MavParamType[componentId][paramName];

        Q_ASSERT(paramName.length() <= MAVLINK_MSG_ID_PARAM_VALUE_LEN);
        strncpy(paramId, paramName.toLocal8Bit().constData(), MAVLINK_MSG_ID_PARAM_VALUE_LEN);

        qCDebug(MockLinkLog) << "Sending msg_param_value" << componentId << paramId << paramType << _mapParamName2Value[componentId][paramId];

        mavlink_msg_param_value_pack_chan(_vehicleSystemId,
                                          componentId,                                   // component id
                                          _mavlinkChannel,
                                          &responseMsg,                                  // Outgoing message
                                          paramId,                                       // Parameter name
                                          _floatUnionForParam(componentId, paramName),   // Parameter value
                                          paramType,                                     // MAV_PARAM_TYPE
                                          cParameters,                                   // Total number of parameters
                                          _currentParamRequestListParamIndex);           // Index of this parameter
        respondWithMavlinkMessage(responseMsg);
    }

    // Move to next param index
    if (++_currentParamRequestListParamIndex >= cParameters) {
        // We've sent the last parameter for this component, move to next component
        if (++_currentParamRequestListComponentIndex >= _mapParamName2Value.keys().count()) {
            // We've finished sending the last parameter for the last component, request is complete
            _currentParamRequestListComponentIndex = -1;
        } else {
            _currentParamRequestListParamIndex = 0;
        }
    }
}

void MockLink::_handleParamSet(const mavlink_message_t& msg)
{
    mavlink_param_set_t request;
    mavlink_msg_param_set_decode(&msg, &request);

    Q_ASSERT(request.target_system == _vehicleSystemId);
    int componentId = request.target_component;

    // Param may not be null terminated if exactly fits
    char paramId[MAVLINK_MSG_PARAM_SET_FIELD_PARAM_ID_LEN + 1];
    paramId[MAVLINK_MSG_PARAM_SET_FIELD_PARAM_ID_LEN] = 0;
    strncpy(paramId, request.param_id, MAVLINK_MSG_PARAM_SET_FIELD_PARAM_ID_LEN);

    qCDebug(MockLinkLog) << "_handleParamSet" << componentId << paramId << request.param_type;

    Q_ASSERT(_mapParamName2Value.contains(componentId));
    Q_ASSERT(_mapParamName2MavParamType.contains(componentId));
    Q_ASSERT(_mapParamName2Value[componentId].contains(paramId));
    Q_ASSERT(request.param_type == _mapParamName2MavParamType[componentId][paramId]);

    // Save the new value
    _setParamFloatUnionIntoMap(componentId, paramId, request.param_value);

    // Respond with a param_value to ack
    mavlink_message_t responseMsg;
    mavlink_msg_param_value_pack_chan(_vehicleSystemId,
                                      componentId,                                               // component id
                                      _mavlinkChannel,
                                      &responseMsg,                                              // Outgoing message
                                      paramId,                                                   // Parameter name
                                      request.param_value,                                       // Send same value back
                                      request.param_type,                                        // Send same type back
                                      _mapParamName2Value[componentId].count(),                  // Total number of parameters
                                      _mapParamName2Value[componentId].keys().indexOf(paramId)); // Index of this parameter
    respondWithMavlinkMessage(responseMsg);
}

void MockLink::_handleParamRequestRead(const mavlink_message_t& msg)
{
    mavlink_message_t   responseMsg;
    mavlink_param_request_read_t request;
    mavlink_msg_param_request_read_decode(&msg, &request);

    const QString paramName(QString::fromLocal8Bit(request.param_id, strnlen(request.param_id, MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN)));
    int componentId = request.target_component;

    // special case for magic _HASH_CHECK value
    if (request.target_component == MAV_COMP_ID_ALL && paramName == "_HASH_CHECK") {
        mavlink_param_union_t   valueUnion;
        valueUnion.type = MAV_PARAM_TYPE_UINT32;
        valueUnion.param_uint32 = 0;
        // Special case of magic hash check value
        mavlink_msg_param_value_pack_chan(_vehicleSystemId,
                                          componentId,
                                          _mavlinkChannel,
                                          &responseMsg,
                                          request.param_id,
                                          valueUnion.param_float,
                                          MAV_PARAM_TYPE_UINT32,
                                          0,
                                          -1);
        respondWithMavlinkMessage(responseMsg);
        return;
    }

    Q_ASSERT(_mapParamName2Value.contains(componentId));

    char paramId[MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN + 1];
    paramId[0] = 0;

    Q_ASSERT(request.target_system == _vehicleSystemId);

    if (request.param_index == -1) {
        // Request is by param name. Param may not be null terminated if exactly fits
        strncpy(paramId, request.param_id, MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN);
    } else {
        // Request is by index

        Q_ASSERT(request.param_index >= 0 && request.param_index < _mapParamName2Value[componentId].count());

        QString key = _mapParamName2Value[componentId].keys().at(request.param_index);
        Q_ASSERT(key.length() <= MAVLINK_MSG_PARAM_REQUEST_READ_FIELD_PARAM_ID_LEN);
        strcpy(paramId, key.toLocal8Bit().constData());
    }

    Q_ASSERT(_mapParamName2Value[componentId].contains(paramId));
    Q_ASSERT(_mapParamName2MavParamType[componentId].contains(paramId));

    if (_failureMode == MockConfiguration::FailMissingParamOnAllRequests && strcmp(paramId, _failParam) == 0) {
        qCDebug(MockLinkLog) << "Ignoring request read for " << _failParam;
        // Fail to send this param no matter what
        return;
    }

    mavlink_msg_param_value_pack_chan(_vehicleSystemId,
                                      componentId,                                               // component id
                                      _mavlinkChannel,
                                      &responseMsg,                                              // Outgoing message
                                      paramId,                                                   // Parameter name
                                      _floatUnionForParam(componentId, paramId),                 // Parameter value
                                      _mapParamName2MavParamType[componentId][paramId],          // Parameter type
                                      _mapParamName2Value[componentId].count(),                  // Total number of parameters
                                      _mapParamName2Value[componentId].keys().indexOf(paramId)); // Index of this parameter
    respondWithMavlinkMessage(responseMsg);
}

void MockLink::emitRemoteControlChannelRawChanged(int channel, uint16_t raw)
{
    uint16_t chanRaw[18];

    for (int i=0; i<18; i++) {
        chanRaw[i] = UINT16_MAX;
    }
    chanRaw[channel] = raw;

    mavlink_message_t responseMsg;
    mavlink_msg_rc_channels_pack_chan(_vehicleSystemId,
                                      _vehicleComponentId,
                                      _mavlinkChannel,
                                      &responseMsg,          // Outgoing message
                                      0,                     // time since boot, ignored
                                      18,                    // channel count
                                      chanRaw[0],            // channel raw value
            chanRaw[1],            // channel raw value
            chanRaw[2],            // channel raw value
            chanRaw[3],            // channel raw value
            chanRaw[4],            // channel raw value
            chanRaw[5],            // channel raw value
            chanRaw[6],            // channel raw value
            chanRaw[7],            // channel raw value
            chanRaw[8],            // channel raw value
            chanRaw[9],            // channel raw value
            chanRaw[10],           // channel raw value
            chanRaw[11],           // channel raw value
            chanRaw[12],           // channel raw value
            chanRaw[13],           // channel raw value
            chanRaw[14],           // channel raw value
            chanRaw[15],           // channel raw value
            chanRaw[16],           // channel raw value
            chanRaw[17],           // channel raw value
            0);                    // rss
    respondWithMavlinkMessage(responseMsg);
}

void MockLink::_handleFTP(const mavlink_message_t& msg)
{
    Q_ASSERT(_fileServer);
    _fileServer->handleFTPMessage(msg);
}

void MockLink::_handleCommandLong(const mavlink_message_t& msg)
{
    static bool firstCmdUser3 = true;
    static bool firstCmdUser4 = true;

    mavlink_command_long_t request;
    uint8_t commandResult = MAV_RESULT_UNSUPPORTED;

    mavlink_msg_command_long_decode(&msg, &request);

    switch (request.command) {
    case MAV_CMD_COMPONENT_ARM_DISARM:
        if (request.param1 == 0.0f) {
            _mavBaseMode &= ~MAV_MODE_FLAG_SAFETY_ARMED;
        } else {
            _mavBaseMode |= MAV_MODE_FLAG_SAFETY_ARMED;
        }
        commandResult = MAV_RESULT_ACCEPTED;
        break;
    case MAV_CMD_PREFLIGHT_CALIBRATION:
        _handlePreFlightCalibration(request);
        commandResult = MAV_RESULT_ACCEPTED;
        break;
    case MAV_CMD_PREFLIGHT_STORAGE:
        commandResult = MAV_RESULT_ACCEPTED;
        break;
    case MAV_CMD_REQUEST_AUTOPILOT_CAPABILITIES:
        commandResult = MAV_RESULT_ACCEPTED;
        _respondWithAutopilotVersion();
        break;
    case MAV_CMD_USER_1:
        // Test command which always returns MAV_RESULT_ACCEPTED
        commandResult = MAV_RESULT_ACCEPTED;
        break;
    case MAV_CMD_USER_2:
        // Test command which always returns MAV_RESULT_FAILED
        commandResult = MAV_RESULT_FAILED;
        break;
    case MAV_CMD_USER_3:
        // Test command which returns MAV_RESULT_ACCEPTED on second attempt
        if (firstCmdUser3) {
            firstCmdUser3 = false;
            return;
        } else {
            firstCmdUser3 = true;
            commandResult = MAV_RESULT_ACCEPTED;
        }
        break;
    case MAV_CMD_USER_4:
        // Test command which returns MAV_RESULT_FAILED on second attempt
        if (firstCmdUser4) {
            firstCmdUser4 = false;
            return;
        } else {
            firstCmdUser4 = true;
            commandResult = MAV_RESULT_FAILED;
        }
        break;
    case MAV_CMD_USER_5:
        // No response
        return;
        break;
    }

    mavlink_message_t commandAck;
    mavlink_msg_command_ack_pack_chan(_vehicleSystemId,
                                      _vehicleComponentId,
                                      _mavlinkChannel,
                                      &commandAck,
                                      request.command,
                                      commandResult,
                                      0,    // progress
                                      0,    // result_param2
                                      0,    // target_system
                                      0);   // target_component
    respondWithMavlinkMessage(commandAck);
}

void MockLink::_respondWithAutopilotVersion(void)
{
    mavlink_message_t msg;

    uint8_t customVersion[8] = { };
    uint32_t flightVersion = 0;
#if !defined(NO_ARDUPILOT_DIALECT)
    if (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA) {
        if (_vehicleType == MAV_TYPE_FIXED_WING) {
            flightVersion |= 9 << (8*2);
        } else if (_vehicleType == MAV_TYPE_SUBMARINE ) {
            flightVersion |= 5 << (8*2);
        } else if (_vehicleType == MAV_TYPE_GROUND_ROVER ) {
            flightVersion |= 5 << (8*2);
        } else {
            flightVersion |= 6 << (8*2);
        }
        flightVersion |= 3 << (8*3);    // Major
        flightVersion |= 0 << (8*1);    // Patch
        flightVersion |= FIRMWARE_VERSION_TYPE_DEV << (8*0);
    } else if (_firmwareType == MAV_AUTOPILOT_PX4) {
#endif
        flightVersion |= 1 << (8*3);
        flightVersion |= 4 << (8*2);
        flightVersion |= 1 << (8*1);
        flightVersion |= FIRMWARE_VERSION_TYPE_DEV << (8*0);
#if !defined(NO_ARDUPILOT_DIALECT)
    }
#endif
    mavlink_msg_autopilot_version_pack_chan(_vehicleSystemId,
                                            _vehicleComponentId,
                                            _mavlinkChannel,
                                            &msg,
                                            MAV_PROTOCOL_CAPABILITY_MAVLINK2 | (_firmwareType == MAV_AUTOPILOT_ARDUPILOTMEGA ? 0 : MAV_PROTOCOL_CAPABILITY_MISSION_FENCE | MAV_PROTOCOL_CAPABILITY_MISSION_RALLY),
                                            flightVersion,                   // flight_sw_version,
                                            0,                               // middleware_sw_version,
                                            0,                               // os_sw_version,
                                            0,                               // board_version,
                                            (uint8_t *)&customVersion,       // flight_custom_version,
                                            (uint8_t *)&customVersion,       // middleware_custom_version,
                                            (uint8_t *)&customVersion,       // os_custom_version,
                                            0,                               // vendor_id,
                                            0,                               // product_id,
                                            0,                               // uid
                                            0);                              // uid2
    respondWithMavlinkMessage(msg);
}

void MockLink::setMissionItemFailureMode(MockLinkMissionItemHandler::FailureMode_t failureMode)
{
    _missionItemHandler.setMissionItemFailureMode(failureMode);
}

void MockLink::_sendHomePosition(void)
{
    mavlink_message_t msg;

    float bogus[4];
    bogus[0] = 0.0f;
    bogus[1] = 0.0f;
    bogus[2] = 0.0f;
    bogus[3] = 0.0f;

    mavlink_msg_home_position_pack_chan(_vehicleSystemId,
                                        _vehicleComponentId,
                                        _mavlinkChannel,
                                        &msg,
                                        (int32_t)(_vehicleLatitude * 1E7),
                                        (int32_t)(_vehicleLongitude * 1E7),
                                        (int32_t)(_vehicleAltitude * 1000),
                                        0.0f, 0.0f, 0.0f,
                                        &bogus[0],
            0.0f, 0.0f, 0.0f,
            0);
    respondWithMavlinkMessage(msg);
}

void MockLink::_sendGpsRawInt(void)
{
    static uint64_t timeTick = 0;
    mavlink_message_t msg;

    mavlink_msg_gps_raw_int_pack_chan(_vehicleSystemId,
                                      _vehicleComponentId,
                                      _mavlinkChannel,
                                      &msg,
                                      timeTick++,                            // time since boot
                                      3,                                     // 3D fix
                                      (int32_t)(_vehicleLatitude  * 1E7),
                                      (int32_t)(_vehicleLongitude * 1E7),
                                      (int32_t)(_vehicleAltitude  * 1000),
                                      UINT16_MAX, UINT16_MAX,                // HDOP/VDOP not known
                                      UINT16_MAX,                            // velocity not known
                                      UINT16_MAX,                            // course over ground not known
                                      8,                                     // satellite count
                                      //-- Extension
                                      0,                                    // Altitude (above WGS84, EGM96 ellipsoid), in meters * 1000 (positive for up).
                                      0,                                    // Position uncertainty in meters * 1000 (positive for up).
                                      0,                                    // Altitude uncertainty in meters * 1000 (positive for up).
                                      0,                                    // Speed uncertainty in meters * 1000 (positive for up).
                                      0);                                   // Heading / track uncertainty in degrees * 1e5.
    respondWithMavlinkMessage(msg);
}

void MockLink::_sendStatusTextMessages(void)
{
    struct StatusMessage {
        MAV_SEVERITY        severity;
        const char*         msg;
    };

    static const struct StatusMessage rgMessages[] = {
    { MAV_SEVERITY_INFO,        "#Testing audio output" },
    { MAV_SEVERITY_EMERGENCY,   "Status text emergency" },
    { MAV_SEVERITY_ALERT,       "Status text alert" },
    { MAV_SEVERITY_CRITICAL,    "Status text critical" },
    { MAV_SEVERITY_ERROR,       "Status text error" },
    { MAV_SEVERITY_WARNING,     "Status text warning" },
    { MAV_SEVERITY_NOTICE,      "Status text notice" },
    { MAV_SEVERITY_INFO,        "Status text info" },
    { MAV_SEVERITY_DEBUG,       "Status text debug" },
};

    for (size_t i=0; i<sizeof(rgMessages)/sizeof(rgMessages[0]); i++) {
        mavlink_message_t msg;
        const struct StatusMessage* status = &rgMessages[i];

        mavlink_msg_statustext_pack_chan(_vehicleSystemId,
                                         _vehicleComponentId,
                                         _mavlinkChannel,
                                         &msg,
                                         status->severity,
                                         status->msg);
        respondWithMavlinkMessage(msg);

        mavlink_msg_statustext_long_pack_chan(_vehicleSystemId,
                                              _vehicleComponentId,
                                              _mavlinkChannel,
                                              &msg,
                                              status->severity,
                                              status->msg);
        respondWithMavlinkMessage(msg);
    }
}

MockConfiguration::MockConfiguration(const QString& name)
    : LinkConfiguration(name)
    , _firmwareType     (MAV_AUTOPILOT_PX4)
    , _vehicleType      (MAV_TYPE_QUADROTOR)
    , _sendStatusText   (false)
    , _highLatency      (false)
    , _failureMode      (FailNone)
{

}

MockConfiguration::MockConfiguration(MockConfiguration* source)
    : LinkConfiguration(source)
{
    _firmwareType =     source->_firmwareType;
    _vehicleType =      source->_vehicleType;
    _sendStatusText =   source->_sendStatusText;
    _highLatency =      source->_highLatency;
    _failureMode =      source->_failureMode;
}

void MockConfiguration::copyFrom(LinkConfiguration *source)
{
    LinkConfiguration::copyFrom(source);
    MockConfiguration* usource = dynamic_cast<MockConfiguration*>(source);

    if (!usource) {
        qWarning() << "dynamic_cast failed" << source << usource;
        return;
    }

    _firmwareType =     usource->_firmwareType;
    _vehicleType =      usource->_vehicleType;
    _sendStatusText =   usource->_sendStatusText;
    _highLatency =      usource->_highLatency;
    _failureMode =      usource->_failureMode;
}

void MockConfiguration::saveSettings(QSettings& settings, const QString& root)
{
    settings.beginGroup(root);
    settings.setValue(_firmwareTypeKey, (int)_firmwareType);
    settings.setValue(_vehicleTypeKey, (int)_vehicleType);
    settings.setValue(_sendStatusTextKey, _sendStatusText);
    settings.setValue(_highLatencyKey, _highLatency);
    settings.setValue(_failureModeKey, (int)_failureMode);
    settings.sync();
    settings.endGroup();
}

void MockConfiguration::loadSettings(QSettings& settings, const QString& root)
{
    settings.beginGroup(root);
    _firmwareType = (MAV_AUTOPILOT)settings.value(_firmwareTypeKey, (int)MAV_AUTOPILOT_PX4).toInt();
    _vehicleType = (MAV_TYPE)settings.value(_vehicleTypeKey, (int)MAV_TYPE_QUADROTOR).toInt();
    _sendStatusText = settings.value(_sendStatusTextKey, false).toBool();
    _highLatency = settings.value(_highLatencyKey, false).toBool();
    _failureMode = (FailureMode_t)settings.value(_failureModeKey, (int)FailNone).toInt();
    settings.endGroup();
}

void MockConfiguration::updateSettings()
{
    if (_link) {
        MockLink* ulink = dynamic_cast<MockLink*>(_link);
        if (ulink) {
            // Restart connect not supported
            qWarning() << "updateSettings not supported";
            //ulink->_restartConnection();
        }
    }
}

MockLink*  MockLink::_startMockLink(MockConfiguration* mockConfig)
{
    LinkManager* linkMgr = qgcApp()->toolbox()->linkManager();

    mockConfig->setDynamic(true);
    SharedLinkConfigurationPointer config = linkMgr->addConfiguration(mockConfig);

    return qobject_cast<MockLink*>(linkMgr->createConnectedLink(config));
}

MockLink* MockLink::_startMockLinkWorker(QString configName, MAV_AUTOPILOT firmwareType, MAV_TYPE vehicleType, bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    MockConfiguration* mockConfig = new MockConfiguration(configName);

    mockConfig->setFirmwareType(firmwareType);
    mockConfig->setVehicleType(vehicleType);
    mockConfig->setSendStatusText(sendStatusText);
    mockConfig->setFailureMode(failureMode);

    return _startMockLink(mockConfig);
}

MockLink*  MockLink::startPX4MockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("PX4 MultiRotor MockLink", MAV_AUTOPILOT_PX4, MAV_TYPE_QUADROTOR, sendStatusText, failureMode);
}

MockLink*  MockLink::startGenericMockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("Generic MockLink", MAV_AUTOPILOT_GENERIC, MAV_TYPE_QUADROTOR, sendStatusText, failureMode);
}

MockLink*  MockLink::startAPMArduCopterMockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("ArduCopter MockLink",MAV_AUTOPILOT_ARDUPILOTMEGA, MAV_TYPE_QUADROTOR, sendStatusText, failureMode);
}

MockLink*  MockLink::startAPMArduPlaneMockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("ArduPlane MockLink", MAV_AUTOPILOT_ARDUPILOTMEGA, MAV_TYPE_FIXED_WING, sendStatusText, failureMode);
}

MockLink*  MockLink::startAPMArduSubMockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("ArduSub MockLink", MAV_AUTOPILOT_ARDUPILOTMEGA, MAV_TYPE_SUBMARINE, sendStatusText, failureMode);
}

MockLink*  MockLink::startAPMArduRoverMockLink(bool sendStatusText, MockConfiguration::FailureMode_t failureMode)
{
    return _startMockLinkWorker("ArduRover MockLink", MAV_AUTOPILOT_ARDUPILOTMEGA, MAV_TYPE_GROUND_ROVER, sendStatusText, failureMode);
}

void MockLink::_sendRCChannels(void)
{
    mavlink_message_t   msg;

    mavlink_msg_rc_channels_pack_chan(_vehicleSystemId,
                                      _vehicleComponentId,
                                      _mavlinkChannel,
                                      &msg,
                                      0,                     // time_boot_ms
                                      16,                    // chancount
                                      1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500,   // channel 1-8
                                      1500, 1500, 1500, 1500, 1500, 1500, 1500, 1500,   // channel 9-16
                                      UINT16_MAX, UINT16_MAX,
                                      0);                    // rssi

    respondWithMavlinkMessage(msg);

}

void MockLink::_handlePreFlightCalibration(const mavlink_command_long_t& request)
{
    const char* pCalMessage;
    static const char* gyroCalResponse = "[cal] calibration started: 2 gyro";
    static const char* magCalResponse = "[cal] calibration started: 2 mag";
    static const char* accelCalResponse = "[cal] calibration started: 2 accel";

    if (request.param1 == 1) {
        // Gyro cal
        pCalMessage = gyroCalResponse;
    } else if (request.param2 == 1) {
        // Mag cal
        pCalMessage = magCalResponse;
    } else if (request.param5 == 1) {
        // Accel cal
        pCalMessage = accelCalResponse;
    } else {
        return;
    }

    mavlink_message_t msg;
    mavlink_msg_statustext_pack_chan(_vehicleSystemId,
                                     _vehicleComponentId,
                                     _mavlinkChannel,
                                     &msg,
                                     MAV_SEVERITY_INFO,
                                     pCalMessage);
    respondWithMavlinkMessage(msg);
}

void MockLink::_handleLogRequestList(const mavlink_message_t& msg)
{
    mavlink_log_request_list_t request;

    mavlink_msg_log_request_list_decode(&msg, &request);

    if (request.start != 0 && request.end != 0xffff) {
        qWarning() << "MockLink::_handleLogRequestList cannot handle partial requests";
        return;
    }

    mavlink_message_t responseMsg;
    mavlink_msg_log_entry_pack_chan(_vehicleSystemId,
                                    _vehicleComponentId,
                                    _mavlinkChannel,
                                    &responseMsg,
                                    _logDownloadLogId,       // log id
                                    1,                       // num_logs
                                    1,                       // last_log_num
                                    0,                       // time_utc
                                    _logDownloadFileSize);   // size
    respondWithMavlinkMessage(responseMsg);
}

void MockLink::_handleLogRequestData(const mavlink_message_t& msg)
{
    mavlink_log_request_data_t request;

    mavlink_msg_log_request_data_decode(&msg, &request);

    if (_logDownloadFilename.isEmpty()) {
#ifdef UNITTEST_BUILD
        _logDownloadFilename = UnitTest::createRandomFile(_logDownloadFileSize);
#endif
    }

    if (request.id != 0) {
        qWarning() << "MockLink::_handleLogRequestData id must be 0";
        return;
    }

    if (request.ofs > _logDownloadFileSize - 1) {
        qWarning() << "MockLink::_handleLogRequestData offset past end of file request.ofs:size" << request.ofs << _logDownloadFileSize;
        return;
    }

    // This will trigger _logDownloadWorker to send data
    _logDownloadCurrentOffset = request.ofs;
    if (request.ofs + request.count > _logDownloadFileSize) {
        request.count = _logDownloadFileSize - request.ofs;
    }
    _logDownloadBytesRemaining = request.count;
}

void MockLink::_logDownloadWorker(void)
{
    if (_logDownloadBytesRemaining != 0) {
        QFile file(_logDownloadFilename);
        if (file.open(QIODevice::ReadOnly)) {
            uint8_t buffer[MAVLINK_MSG_LOG_DATA_FIELD_DATA_LEN];

            qint64 bytesToRead = qMin(_logDownloadBytesRemaining, (uint32_t)MAVLINK_MSG_LOG_DATA_FIELD_DATA_LEN);
            Q_ASSERT(file.seek(_logDownloadCurrentOffset));
            Q_ASSERT(file.read((char *)buffer, bytesToRead) == bytesToRead);

            qDebug() << "MockLink::_logDownloadWorker" << _logDownloadCurrentOffset << _logDownloadBytesRemaining;

            mavlink_message_t responseMsg;
            mavlink_msg_log_data_pack_chan(_vehicleSystemId,
                                           _vehicleComponentId,
                                           _mavlinkChannel,
                                           &responseMsg,
                                           _logDownloadLogId,
                                           _logDownloadCurrentOffset,
                                           bytesToRead,
                                           &buffer[0]);
            respondWithMavlinkMessage(responseMsg);

            _logDownloadCurrentOffset += bytesToRead;
            _logDownloadBytesRemaining -= bytesToRead;

            file.close();
        } else {
            qWarning() << "MockLink::_logDownloadWorker open failed" << file.errorString();
        }
    }
}

void MockLink::_sendADSBVehicles(void)
{
    _adsbAngle += 2;
    _adsbVehicleCoordinate = QGeoCoordinate(_vehicleLatitude, _vehicleLongitude).atDistanceAndAzimuth(500, _adsbAngle);
    _adsbVehicleCoordinate.setAltitude(100);

    mavlink_message_t responseMsg;
    mavlink_msg_adsb_vehicle_pack_chan(_vehicleSystemId,
                                       _vehicleComponentId,
                                       _mavlinkChannel,
                                       &responseMsg,
                                       12345,                                       // ICAO address
                                       _adsbVehicleCoordinate.latitude() * 1e7,
                                       _adsbVehicleCoordinate.longitude() * 1e7,
                                       ADSB_ALTITUDE_TYPE_GEOMETRIC,
                                       _adsbVehicleCoordinate.altitude() * 1000,    // Altitude in millimeters
                                       10 * 100,                                    // Heading in centidegress
                                       0, 0,                                        // Horizontal/Vertical velocity
                                       "N1234500",                                  // Callsign
                                       ADSB_EMITTER_TYPE_ROTOCRAFT,
                                       1,                                           // Seconds since last communication
                                       ADSB_FLAGS_VALID_COORDS | ADSB_FLAGS_VALID_ALTITUDE | ADSB_FLAGS_VALID_HEADING | ADSB_FLAGS_VALID_CALLSIGN | ADSB_FLAGS_SIMULATED,
                                       0);                                          // Squawk code

    respondWithMavlinkMessage(responseMsg);
}