/****************************************************************************
 *
 * (c) 2009-2020 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 "TerrainProtocolHandler.h"
#include "TerrainQuery.h"
#include "QGCApplication.h"

QGC_LOGGING_CATEGORY(TerrainProtocolHandlerLog, "TerrainProtocolHandlerLog")

TerrainProtocolHandler::TerrainProtocolHandler(Vehicle* vehicle, TerrainFactGroup* terrainFactGroup, QObject *parent)
    : QObject           (parent)
    , _vehicle          (vehicle)
    , _terrainFactGroup (terrainFactGroup)
{
    _terrainDataSendTimer.setSingleShot(false);
    _terrainDataSendTimer.setInterval(1000.0/12.0);
    connect(&_terrainDataSendTimer, &QTimer::timeout, this, &TerrainProtocolHandler::_sendNextTerrainData);
}

bool TerrainProtocolHandler::mavlinkMessageReceived(const mavlink_message_t message)
{
    switch (message.msgid) {
    case MAVLINK_MSG_ID_TERRAIN_REQUEST:
        _handleTerrainRequest(message);
        return false;
    case MAVLINK_MSG_ID_TERRAIN_REPORT:
        _handleTerrainReport(message);
        return false;
    default:
        return true;
    }
}

void TerrainProtocolHandler::_handleTerrainRequest(const mavlink_message_t& message)
{
    _terrainRequestActive = true;
    mavlink_msg_terrain_request_decode(&message, &_currentTerrainRequest);
    _sendNextTerrainData();
}

void TerrainProtocolHandler::_handleTerrainReport(const mavlink_message_t& message)
{
    mavlink_terrain_report_t terrainReport;
    mavlink_msg_terrain_report_decode(&message, &terrainReport);

    _terrainFactGroup->blocksPending()->setRawValue(terrainReport.pending);
    _terrainFactGroup->blocksLoaded()->setRawValue(terrainReport.loaded);

    if (TerrainProtocolHandlerLog().isDebugEnabled()) {

        bool error;
        QGeoCoordinate coord(static_cast<double>(terrainReport.lat) / 1e7, static_cast<double>(terrainReport.lon) / 1e7);
        QList<double>   altitudes;
        QList<QGeoCoordinate> coordinates;
        coordinates.append(coord);
        bool altAvailable = (TerrainAtCoordinateQuery::getAltitudesForCoordinates(coordinates, altitudes, error));
        QString vehicleAlt = terrainReport.spacing ? QStringLiteral("%1").arg(terrainReport.terrain_height) : QStringLiteral("n/a");
        QString qgcAlt = error ? QStringLiteral("error") :
                                 (altAvailable ? QStringLiteral("%1").arg(altitudes[0]) : QStringLiteral("n/a"));
        qDebug() << "TERRAIN_REPORT" << coord << QStringLiteral("Vehicle(%1) QGC(%2)").arg(vehicleAlt).arg(qgcAlt);
    }
}

void TerrainProtocolHandler::_sendNextTerrainData(void)
{
    if (!_terrainRequestActive) {
        return;
    }

    QGeoCoordinate terrainRequestCoordSWCorner(static_cast<double>(_currentTerrainRequest.lat) / 1e7, static_cast<double>(_currentTerrainRequest.lon) / 1e7);
    int spacingBetweenGrids = _currentTerrainRequest.grid_spacing * 4;

    // Each TERRAIN_DATA sent to vehicle contains a 4x4 grid of heights
    // TERRAIN_REQUEST.mask has a bit for each entry in an 8x7 grid
    // gridBit = 0 refers to the the sw corner of the 8x7 grid

    bool bitFound = false;
    for (int rowIndex=0; rowIndex<7; rowIndex++) {
        for (int colIndex=0; colIndex<8; colIndex++) {
            uint8_t gridBit = (rowIndex * 8) + colIndex;
            uint64_t checkBit = 1ull << gridBit;
            if (_currentTerrainRequest.mask & checkBit) {
                // Move east and then north to generate the coordinate for sw corner of the specific gridBit
                QGeoCoordinate swCorner = terrainRequestCoordSWCorner.atDistanceAndAzimuth(spacingBetweenGrids * colIndex, 90);
                swCorner = swCorner.atDistanceAndAzimuth(spacingBetweenGrids * rowIndex, 0);
                _sendTerrainData(swCorner, gridBit);
                bitFound = true;
                break;
            }
        }
        if (bitFound) {
            break;
        }
    }

    if (bitFound) {
        // Kick timer to send next possible TERRAIN_DATA to vehicle
        _terrainDataSendTimer.start();
    } else {
        _terrainRequestActive = false;
    }
}

void TerrainProtocolHandler::_sendTerrainData(const QGeoCoordinate& swCorner, uint8_t gridBit)
{
    QList<QGeoCoordinate> coordinates;
    for (int rowIndex=0; rowIndex<4; rowIndex++) {
        for (int colIndex=0; colIndex<4; colIndex++) {
            // Move east and then north to generate the coordinate for grid point
            QGeoCoordinate coord = swCorner.atDistanceAndAzimuth(_currentTerrainRequest.grid_spacing * colIndex, 90);
            coord = coord.atDistanceAndAzimuth(_currentTerrainRequest.grid_spacing * rowIndex, 0);
            coordinates.append(coord);
        }
    }

    // Query terrain system for altitudes. If it has them available it will return them. If not they will be queued for download.
    bool            error = false;
    QList<double>   altitudes;
    if (TerrainAtCoordinateQuery::getAltitudesForCoordinates(coordinates, altitudes, error)) {
        if (error) {
            qCWarning(TerrainProtocolHandlerLog) << "_sendTerrainData TerrainAtCoordinateQuery::getAltitudesForCoordinates failed";
        } else {
            // Only clear the bit if the query succeeds. Otherwise just let it try again on the next timer tick
            uint64_t removeBit = ~(1ull << gridBit);
            _currentTerrainRequest.mask &= removeBit;
            int altIndex = 0;
            int16_t terrainData[16];
            for (const double& altitude : altitudes) {
                terrainData[altIndex++] = static_cast<int16_t>(altitude);
            }

            mavlink_message_t msg;
            mavlink_msg_terrain_data_pack_chan(
                        qgcApp()->toolbox()->mavlinkProtocol()->getSystemId(),
                        qgcApp()->toolbox()->mavlinkProtocol()->getComponentId(),
                        _vehicle->priorityLink()->mavlinkChannel(),
                        &msg,
                        _currentTerrainRequest.lat,
                        _currentTerrainRequest.lon,
                        _currentTerrainRequest.grid_spacing,
                        gridBit,
                        terrainData);
            _vehicle->sendMessageOnLinkThreadSafe(_vehicle->priorityLink(), msg);
        }
    }
}
