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#ifndef HORIZON_H_
#define HORIZON_H_
// **** _SYSTEM INCLUDES_ ******************************************************

#include <iostream>
#include <string>
#include <fstream>

// use standard library objects
using namespace std;

// **** _LOCAL INCLUDES_ *******************************************************

#include "CPPUtils.h"
#include "CPPGlobals.h"
#include "GeoTessProfile.h"

// **** _BEGIN GEOTESS NAMESPACE_ **********************************************

namespace geotess {

// **** _FORWARD REFERENCES_ ***************************************************

class GeoTessPosition;

// **** _CLASS DEFINITION_ *****************************************************

/**
 * \brief An abstract class that represents a single "surface" within a
 * model.
 *
 * Horizon is an abstract class that represents a single "surface" within a
 * model. This might be a surface of constant radius, constant depth, the top or
 * bottom of a layer, etc. The surface can be constrained to a specified layer,
 * or can cross layer boundaries.  There are derived classes for each of these,
 * HorizonRadius, HorizonDepth, and HorizonLayer.  A Horizon class implements
 * a single basic function, getRadius().  That method can take either a
 * GeoTessPosition object or a vertex position and the 1D array of
 * Profiles associated with that vertex.
 *
 * @author sballar
 *
 */
class GEOTESS_EXP_IMP GeoTessHorizon
{

private:

protected:

    /**
     * If layerIndex is >= 0 and < the number of layers represented in a model,
     * then the returned radius will be constrained to be between the top and
     * bottom of the specified layer.  Otherwise, the radius will not be
     * so constrained.
     */
    int layerIndex;


public:

    /**
     * Default constructor.
     */
    GeoTessHorizon(const int& lyrIndex) { layerIndex =  lyrIndex; } ;

    virtual ~GeoTessHorizon() {};

    virtual string class_name() { return "Horizon"; };

    /**
     * HorizonDepth objects return depth, HorizonRadius
     * object return radius, and HorizonLayer object return fraction.
     */
    virtual double getValue() = ABSTRACT;

    /**
     * Return the radius of the Horizon at the specified geographic position
     * and constrained by the specified array of Profiles, all of which are
     * assumed to reside at the specified position.
     * @param position the unit vector representing the position where the
     * radius is to be determined.  This should correspond to the position
     * of the supplied array of Profiles.
     * @param profiles a 1D array of profiles at the specified position.
     * The number of elements must be equal to the number of layers in the
     * model with the first layer being the deepest (closest to the center
     * of the Earth) and the last layer being the shallowest (farthest from
     * the center of the Earth).
     * @return the radius of the Horizon at the specified position and
     * perhaps constrained to reside in the specified layer.  Units are km.
     */
    virtual double getRadius(const double* position, GeoTessProfile** profiles) = ABSTRACT;

    /**
     * Return the radius of the Horizon at the position of the specified
     * GeoTessPosition object.
     * @param position
     * @return the radius of the Horizon at the specified position and
     * perhaps constrained to reside in the specified layer.  Units are km.
     * @throws GeoTessException
     */
    virtual double getRadius(GeoTessPosition& position) = ABSTRACT;

    /**
     * Retrieve the index of the layer that was specified at construction.
     * If >= 0 and < the number of layers in the model then the
     * radius of this Horizon object will be constrained to be within the radii of
     * the top and bottom of this layer.
     * @return layer index, or -1.
     */
    virtual int getLayerIndex() { return layerIndex; };

    virtual string str() = ABSTRACT;

};
// end class Horizon

}// end namespace geotess

#endif /* HORIZON_H_ */
