TerrainQuery.h

/****************************************************************************
 *
 *   (c) 2017 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.
 *
 ****************************************************************************/

#pragma once

#include "QGCLoggingCategory.h"

#include <QObject>
#include <QGeoCoordinate>
#include <QNetworkAccessManager>
#include <QNetworkReply>
#include <QTimer>

Q_DECLARE_LOGGING_CATEGORY(TerrainQueryLog)

class TerrainAtCoordinateQuery;

// Base class for all terrain query objects
class TerrainQuery : public QObject {
    Q_OBJECT

public:
    TerrainQuery(QObject* parent = NULL);

protected:
    // Send a query to AirMap terrain servers. Data and errors are returned back from super class virtual implementations.
    //  @param path Additional path to add to url
    //  @param urlQuery Query to send
    void _sendQuery(const QString& path, const QUrlQuery& urlQuery);

    // Called when the request to the server fails or succeeds
    virtual void _terrainData(bool success, const QJsonValue& dataJsonValue) = 0;

private slots:
    void _requestFinished(void);

private:
    QNetworkAccessManager _networkManager;
};

/// Used internally by TerrainAtCoordinateQuery to batch coordinate requests together
class TerrainAtCoordinateBatchManager : public TerrainQuery {
    Q_OBJECT

public:
    TerrainAtCoordinateBatchManager(void);

    void addQuery(TerrainAtCoordinateQuery* terrainAtCoordinateQuery, const QList<QGeoCoordinate>& coordinates);

protected:
    // Overrides from TerrainQuery
    void _terrainData(bool success, const QJsonValue& dataJsonValue) final;

private slots:
    void _sendNextBatch         (void);
    void _queryObjectDestroyed  (QObject* elevationProvider);

private:
    typedef struct {
        TerrainAtCoordinateQuery*   terrainAtCoordinateQuery;
        QList<QGeoCoordinate>       coordinates;
    } QueuedRequestInfo_t;

    typedef struct {
        TerrainAtCoordinateQuery*   terrainAtCoordinateQuery;
        bool                        queryObjectDestroyed;
        int                         cCoord;
    } SentRequestInfo_t;


    enum class State {
        Idle,
        Downloading,
    };

    void _batchFailed(void);
    QString _stateToString(State state);

    QList<QueuedRequestInfo_t>  _requestQueue;
    QList<SentRequestInfo_t>    _sentRequests;
    State                       _state = State::Idle;
    const int                   _batchTimeout = 500;
    QTimer                      _batchTimer;
};

/// NOTE: TerrainAtCoordinateQuery is not thread safe. All instances/calls to ElevationProvider must be on main thread.
class TerrainAtCoordinateQuery : public QObject
{
    Q_OBJECT
public:
    TerrainAtCoordinateQuery(QObject* parent = NULL);

    /// Async terrain query for a list of lon,lat coordinates. When the query is done, the terrainData() signal
    /// is emitted.
    ///     @param coordinates to query
    void requestData(const QList<QGeoCoordinate>& coordinates);

    // Internal method
    void _signalTerrainData(bool success, QList<float>& altitudes);

signals:
    void terrainData(bool success, QList<float> altitudes);
};

class TerrainPathQuery : public TerrainQuery
{
    Q_OBJECT

public:
    TerrainPathQuery(QObject* parent = NULL);

    /// Async terrain query for terrain heights between two lat/lon coordinates. When the query is done, the terrainData() signal
    /// is emitted.
    ///     @param coordinates to query
    void requestData(const QGeoCoordinate& fromCoord, const QGeoCoordinate& toCoord);

    typedef struct {
        double          latStep;    ///< Amount of latitudinal distance between each returned height
        double          lonStep;    ///< Amount of longitudinal distance between each returned height
        QList<double>   rgHeight;   ///< Terrain heights along path
    } PathHeightInfo_t;

signals:
    /// Signalled when terrain data comes back from server
    void terrainData(bool success, const PathHeightInfo_t& pathHeightInfo);

protected:
    // Overrides from TerrainQuery
    void _terrainData(bool success, const QJsonValue& dataJsonValue) final;
};

Q_DECLARE_METATYPE(TerrainPathQuery::PathHeightInfo_t)

class TerrainPolyPathQuery : public QObject
{
    Q_OBJECT

public:
    TerrainPolyPathQuery(QObject* parent = NULL);

    /// Async terrain query for terrain heights for the paths between each specified QGeoCoordinate.
    /// When the query is done, the terrainData() signal is emitted.
    ///     @param polyPath List of QGeoCoordinate
    void requestData(const QVariantList& polyPath);
    void requestData(const QList<QGeoCoordinate>& polyPath);

signals:
    /// Signalled when terrain data comes back from server
    void terrainData(bool success, const QList<TerrainPathQuery::PathHeightInfo_t>& rgPathHeightInfo);

private slots:
    void _terrainDataReceived(bool success, const TerrainPathQuery::PathHeightInfo_t& pathHeightInfo);

private:
    int                                         _curIndex;
    QList<QGeoCoordinate>                       _rgCoords;
    QList<TerrainPathQuery::PathHeightInfo_t>   _rgPathHeightInfo;
    TerrainPathQuery                            _pathQuery;
};


class TerrainCarpetQuery : public TerrainQuery
{
    Q_OBJECT

public:
    TerrainCarpetQuery(QObject* parent = NULL);

    /// Async terrain query for terrain information bounded by the specifed corners.
    /// When the query is done, the terrainData() signal is emitted.
    ///     @param swCoord South-West bound of rectangular area to query
    ///     @param neCoord North-East bound of rectangular area to query
    ///     @param statsOnly true: Return only stats, no carpet data
    void requestData(const QGeoCoordinate& swCoord, const QGeoCoordinate& neCoord, bool statsOnly);

signals:
    /// Signalled when terrain data comes back from server
    void terrainData(bool success, double minHeight, double maxHeight, const QList<QList<double>>& carpet);


protected:
    // Overrides from TerrainQuery
    void _terrainData(bool success, const QJsonValue& dataJsonValue) final;

private:
    bool _statsOnly;
};