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#ifndef QGEOPROJECTION_H
#define QGEOPROJECTION_H

//
//  W A R N I N G
//  -------------
//
// This file is not part of the Qt API.  It exists purely as an
// implementation detail.  This header file may change from version to
// version without notice, or even be removed.
//
// We mean it.
//

#include <QtLocation/private/qlocationglobal_p.h>
#include <QtLocation/private/qgeocameradata_p.h>
#include <QtPositioning/private/qdoublematrix4x4_p.h>

QT_BEGIN_NAMESPACE

class Q_LOCATION_PRIVATE_EXPORT QGeoProjection
{
public:
    QGeoProjection();
    virtual ~QGeoProjection();

    virtual void setViewportSize(const QSize &size) = 0;
    virtual void setCameraData(const QGeoCameraData &cameraData) = 0;

    // returns the minimum zoom at the current viewport size
    virtual double minimumZoom() const = 0;
    virtual double maximumCenterLatitudeAtZoom(const QGeoCameraData &cameraData) const = 0;

    // returns the size of the underlying map, at the current zoom level.
    virtual double mapWidth() const = 0;
    virtual double mapHeight() const = 0;

    // Conversion methods for QGeoCoordinate <-> screen.
    // This currently assumes that the "MapProjection" space is [0, 1][0, 1] for every type of possibly supported map projection
    virtual QDoubleVector2D geoToMapProjection(const QGeoCoordinate &coordinate) const = 0;
    virtual QGeoCoordinate mapProjectionToGeo(const QDoubleVector2D &projection) const = 0;

    virtual QDoubleVector2D wrapMapProjection(const QDoubleVector2D &projection) const = 0;
    virtual QDoubleVector2D unwrapMapProjection(const QDoubleVector2D &wrappedProjection) const = 0;

    virtual QDoubleVector2D wrappedMapProjectionToItemPosition(const QDoubleVector2D &wrappedProjection) const = 0;
    virtual QDoubleVector2D itemPositionToWrappedMapProjection(const QDoubleVector2D &itemPosition) const = 0;

    // Convenience methods to avoid the chain itemPositionToWrappedProjection(wrapProjection(geoToProjection()))
    // These also come with a default implementation that can, however, be overridden.
    virtual QGeoCoordinate itemPositionToCoordinate(const QDoubleVector2D &pos, bool clipToViewport = true) const = 0;
    virtual QDoubleVector2D coordinateToItemPosition(const QGeoCoordinate &coordinate, bool clipToViewport = true) const = 0;
};

class Q_LOCATION_PRIVATE_EXPORT QGeoProjectionWebMercator : public QGeoProjection
{
public:
    QGeoProjectionWebMercator();
    ~QGeoProjectionWebMercator();

    double minimumZoom() const Q_DECL_OVERRIDE;
    double maximumCenterLatitudeAtZoom(const QGeoCameraData &cameraData) const Q_DECL_OVERRIDE;

    // The size of the underlying map, at the current zoom level.
    double mapWidth() const Q_DECL_OVERRIDE;
    double mapHeight() const Q_DECL_OVERRIDE;

    void setViewportSize(const QSize &size) Q_DECL_OVERRIDE;
    void setCameraData(const QGeoCameraData &cameraData) Q_DECL_OVERRIDE;

    QDoubleVector2D geoToMapProjection(const QGeoCoordinate &coordinate) const Q_DECL_OVERRIDE;
    QGeoCoordinate mapProjectionToGeo(const QDoubleVector2D &projection) const Q_DECL_OVERRIDE;

    QDoubleVector2D wrapMapProjection(const QDoubleVector2D &projection) const Q_DECL_OVERRIDE;
    QDoubleVector2D unwrapMapProjection(const QDoubleVector2D &wrappedProjection) const Q_DECL_OVERRIDE;

    QDoubleVector2D wrappedMapProjectionToItemPosition(const QDoubleVector2D &wrappedProjection) const Q_DECL_OVERRIDE;
    QDoubleVector2D itemPositionToWrappedMapProjection(const QDoubleVector2D &itemPosition) const Q_DECL_OVERRIDE;

    QGeoCoordinate itemPositionToCoordinate(const QDoubleVector2D &pos, bool clipToViewport = true) const Q_DECL_OVERRIDE;
    QDoubleVector2D coordinateToItemPosition(const QGeoCoordinate &coordinate, bool clipToViewport = true) const Q_DECL_OVERRIDE;

    bool isProjectable(const QDoubleVector2D &wrappedProjection) const;
private:
    void setupCamera();

private:
    QGeoCameraData m_cameraData;
    double m_mapEdgeSize;
    double m_minimumZoom;
    // mercator to camera transform for coordinates (not tiles!)
    double m_cameraCenterXMercator;
    double m_cameraCenterYMercator;

    // cameraToScreen transform
    double m_viewportWidth; // in pixels
    double m_viewportHeight; // in pixels
    double m_1_viewportWidth;
    double m_1_viewportHeight;

    QDoubleMatrix4x4 m_transformation;
    QDoubleVector3D  m_eye;
    QDoubleVector3D  m_up;
    QDoubleVector3D  m_center;
    QDoubleVector3D  m_view;
    QDoubleVector3D  m_viewNormalized;
    QDoubleVector3D  m_side;
    QDoubleVector3D  m_centerNearPlane;
    double           m_sideLength; // map edge size at integer zoom level
    double           m_aperture;
    double           m_nearPlane;
    double           m_farPlane;
    double           m_halfWidth;
    double           m_halfHeight;

    struct Plane
    {
        Plane() {}
        Plane(const QDoubleVector3D &planePoint, const QDoubleVector3D &planeNormal)
        :   m_point(planePoint), m_normal(planeNormal) { }

        QDoubleVector3D lineIntersection(const QDoubleVector3D &linePoint, const QDoubleVector3D &lineDirection) const
        {
            QDoubleVector3D w = linePoint - m_point;
            // s = -n.dot(w) / n.dot(u).  p = p0 + su; u is lineDirection
            double s = QDoubleVector3D::dotProduct(-m_normal, w) / QDoubleVector3D::dotProduct(m_normal, lineDirection);
            return linePoint + lineDirection * s;
        }

        QDoubleVector3D m_point;
        QDoubleVector3D m_normal;
    } m_plane;
};

QT_END_NAMESPACE

#endif // QGEOPROJECTION_H