/******************************************************************************

 *

 * Project:  Viewshed Generation

 * Purpose:  Core algorithm implementation for viewshed generation.

 * Author:   Tamas Szekeres, szekerest@gmail.com

 *

 * (c) 2024 info@hobu.co

 *

 ******************************************************************************

 *

 * SPDX-License-Identifier: MIT

 ****************************************************************************/

#ifndef VIEWSHED_H_INCLUDED

#define VIEWSHED_H_INCLUDED

#include <algorithm>

#include <array>

#include <cstdint>

#include <functional>

#include <limits>

#include <memory>

#include <mutex>

#include <queue>

#include <string>

#include "cpl_progress.h"

#include "gdal_priv.h"

#include "viewshed_types.h"

namespace gdal

{

namespace viewshed

{

/**

 * Class to support viewshed raster generation.

 */

class Viewshed

{

  public:

    /**

     * Constructor.

     *

     * @param opts Options to use when calculating viewshed.

    */

    CPL_DLL explicit Viewshed(const Options &opts);

    /** Destructor */

    CPL_DLL ~Viewshed();

    CPL_DLL bool run(GDALRasterBandH hBand,

                     GDALProgressFunc pfnProgress = GDALDummyProgress,

                     void *pProgressArg = nullptr);

    CPL_DLL bool run(GDALRasterBandH hBand, GDALRasterBandH hSdBand,

                     GDALProgressFunc pfnProgress = GDALDummyProgress,

                     void *pProgressArg = nullptr);

    /**

     * Fetch a pointer to the created raster band.

     *

     * @return  Unique pointer to the viewshed dataset.

    */

    CPL_DLL DatasetPtr output()

    {

        return std::move(poDstDS);

    }

  private:

    Options oOpts;

    Window oOutExtent{};

    Window oCurExtent{};

    DatasetPtr poDstDS{};

    GDALRasterBand *pSrcBand = nullptr;

    GDALRasterBand *pSdBand = nullptr;

    DatasetPtr execute(int nX, int nY, const std::string &outFilename);

    void setOutput(double &dfResult, double &dfCellVal, double dfZ);

    double calcHeight(double dfZ, double dfZ2);

    bool readLine(int nLine, double *data);

    std::pair<int, int> adjustHeight(int iLine, int nX,

                                     std::vector<double> &thisLineVal);

    bool calcExtents(int nX, int nY, const GDALGeoTransform &invGT);

    Viewshed(const Viewshed &) = delete;

    Viewshed &operator=(const Viewshed &) = delete;

};

double CPL_DLL adjustCurveCoeff(double curveCoeff, GDALDatasetH hSrcDS);

}  // namespace viewshed

}  // namespace gdal

#endif