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

 *

 * Project:  GDAL

 * Purpose:  "slope" step of "raster pipeline"

 * Author:   Even Rouault <even dot rouault at spatialys.com>

 *

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

 * Copyright (c) 2025, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

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

#include "gdalalg_raster_slope.h"

#include "gdal_priv.h"

#include "gdal_utils.h"

#include <cmath>

//! @cond Doxygen_Suppress

#ifndef _

#define _(x) (x)

#endif

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

/*         GDALRasterSlopeAlgorithm::GDALRasterSlopeAlgorithm()         */

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

GDALRasterSlopeAlgorithm::GDALRasterSlopeAlgorithm(bool standaloneStep)

    : GDALRasterPipelineStepAlgorithm(NAME, DESCRIPTION, HELP_URL,

                                      standaloneStep)

{

    SetOutputVRTCompatible(false);

    AddBandArg(&m_band).SetDefault(m_band);

    AddArg("unit", 0, _("Unit in which to express slopes"), &m_unit)

        .SetChoices("degree", "percent")

        .SetDefault(m_unit);

    AddArg("xscale", 0, _("Ratio of vertical units to horizontal X axis units"),

           &m_xscale)

        .SetMinValueExcluded(0);

    AddArg("yscale", 0, _("Ratio of vertical units to horizontal Y axis units"),

           &m_yscale)

        .SetMinValueExcluded(0);

    AddArg("gradient-alg", 0, _("Algorithm used to compute terrain gradient"),

           &m_gradientAlg)

        .SetChoices("Horn", "ZevenbergenThorne")

        .SetDefault(m_gradientAlg);

    AddArg("no-edges", 0,

           _("Do not try to interpolate values at dataset edges or close to "

             "nodata values"),

           &m_noEdges);

}

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

/*                 GDALRasterSlopeAlgorithm::RunStep()                  */

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

bool GDALRasterSlopeAlgorithm::RunStep(GDALPipelineStepRunContext &)

{

    const auto poSrcDS = m_inputDataset[0].GetDatasetRef();

    CPLAssert(poSrcDS);

    CPLAssert(m_outputDataset.GetName().empty());

    CPLAssert(!m_outputDataset.GetDatasetRef());

    CPLStringList aosOptions;

    aosOptions.AddString("-of");

    aosOptions.AddString("stream");

    aosOptions.AddString("-b");

    aosOptions.AddString(CPLSPrintf("%d", m_band));

    if (!std::isnan(m_xscale))

    {

        aosOptions.AddString("-xscale");

        aosOptions.AddString(CPLSPrintf("%.17g", m_xscale));

    }

    if (!std::isnan(m_yscale))

    {

        aosOptions.AddString("-yscale");

        aosOptions.AddString(CPLSPrintf("%.17g", m_yscale));

    }

    if (m_unit == "percent")

        aosOptions.AddString("-p");

    aosOptions.AddString("-alg");

    aosOptions.AddString(m_gradientAlg.c_str());

    if (!m_noEdges)

        aosOptions.AddString("-compute_edges");

    GDALDEMProcessingOptions *psOptions =

        GDALDEMProcessingOptionsNew(aosOptions.List(), nullptr);

    auto poOutDS = std::unique_ptr<GDALDataset>(GDALDataset::FromHandle(

        GDALDEMProcessing("", GDALDataset::ToHandle(poSrcDS), "slope", nullptr,

                          psOptions, nullptr)));

    GDALDEMProcessingOptionsFree(psOptions);

    const bool bRet = poOutDS != nullptr;

    if (poOutDS)

    {

        m_outputDataset.Set(std::move(poOutDS));

    }

    return bRet;

}

GDALRasterSlopeAlgorithmStandalone::~GDALRasterSlopeAlgorithmStandalone() =

    default;

//! @endcond