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#ifndef GEOTESSPOSITIONLINEAR_OBJECT_H
#define GEOTESSPOSITIONLINEAR_OBJECT_H

// **** _SYSTEM INCLUDES_ ******************************************************

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

// use standard library objects
using namespace std;

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

#include "CPPUtils.h"
#include "GeoTessUtils.h"
#include "GeoTessPosition.h"
#include "GeoTessGrid.h"
#include "GeoTessInterpolatorType.h"

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

namespace geotess
{

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

class GeoTessModel;

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

/**
 * \brief Implements linear interpolation in geographic dimensions of a grid.
 *
 * Implements linear interpolation in geographic dimensions of a grid.
 *
 * @author Sandy Ballard
 *
 */
class GEOTESS_EXP_IMP GeoTessPositionLinear: public GeoTessPosition
{
protected:

    /**
     * Set vertices to the 3-element array that stores the corners of the triangle identified during
     * the triangle walk algorithm. Horizontal coefficients are similarly set to the coefficients
     * identified during triangle walk.
     * @throws GeoTessException
     */
    virtual void update2D(int tid)
    {
        vector<int>& vt = vertices[tid];
        vector<double>& hc = hCoefficients[tid];

        vt.clear();
        hc.clear();

        const int* trngl = grid.getTriangleVertexIndexes(getTriangle(tid));

        // if the interpolation point falls on a grid node set the list of interpolation
        // vertices to include only the identified vertex, and the interpolation coefficient = 1.
        if (GeoTessUtils::dot(unitVector, grid.getVertex(trngl[0])) > cos(1e-7))
        { vt.push_back(trngl[0]); hc.push_back(1.0); return; }

        if (GeoTessUtils::dot(unitVector, grid.getVertex(trngl[1])) > cos(1e-7))
        { vt.push_back(trngl[1]); hc.push_back(1.0); return; }

        if (GeoTessUtils::dot(unitVector, grid.getVertex(trngl[2])) > cos(1e-7))
        { vt.push_back(trngl[2]); hc.push_back(1.0); return; }

        // interpolation point is not coincident with a grid node.
        vector<double>& lc = linearCoefficients[tid];
        vt.push_back(trngl[0]);
        hc.push_back(lc[0]);
        vt.push_back(trngl[1]);
        hc.push_back(lc[1]);
        vt.push_back(trngl[2]);
        hc.push_back(lc[2]);
}

public:

    /**
     * Standard constructor.
     */
    GeoTessPositionLinear(GeoTessModel* model,
            const GeoTessInterpolatorType& radialType);

    /**
     * Destructor.
     */
    virtual ~GeoTessPositionLinear();

    /**
     * Retrieve the type of interpolation that this GeoTessPosition object is configured
     * to perform. Either InterpolatorType.LINEAR or InterpolatorType.NATURAL_NEIGHBOR.
     */
    virtual const GeoTessInterpolatorType& getInterpolatorType() const { return GeoTessInterpolatorType::LINEAR; }

    virtual long getMemory() { return (long) sizeof(GeoTessPositionLinear) + memory(); }

};
// end class GeoTessModelLinear

}// end namespace geotess

#endif  // GEOTESSPOSITIONLINEAR_OBJECT_H
