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

 *

 * Project:  GDAL

 * Purpose:  gdal "raster rgb-to-palette" subcommand

 * 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_rgb_to_palette.h"

#include "cpl_string.h"

#include "gdal_alg.h"

#include "gdal_alg_priv.h"

#include "gdal_priv.h"

#include <algorithm>

#include <limits>

//! @cond Doxygen_Suppress

#ifndef _

#define _(x) (x)

#endif

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

/*                  GDALRasterRGBToPaletteAlgorithm()                   */

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

GDALRasterRGBToPaletteAlgorithm::GDALRasterRGBToPaletteAlgorithm(

    bool standaloneStep)

    : GDALRasterPipelineNonNativelyStreamingAlgorithm(NAME, DESCRIPTION,

                                                      HELP_URL, standaloneStep)

{

    AddArg("color-count", 0,

           _("Select the number of colors in the generated color table"),

           &m_colorCount)

        .SetDefault(m_colorCount)

        .SetMinValueIncluded(2)

        .SetMaxValueIncluded(256);

    AddArg("color-map", 0, _("Color map filename"), &m_colorMap);

    AddArg("dst-nodata", 0, _("Destination nodata value"), &m_dstNoData)

        .SetMinValueIncluded(0)

        .SetMaxValueIncluded(255);

    AddArg("no-dither", 0, _("Disable Floyd-Steinberg dithering"), &m_noDither);

    AddArg("bit-depth", 0,

           _("Bit depth of color palette component (8 bit causes longer "

             "computation time)"),

           &m_bitDepth)

        .SetDefault(m_bitDepth)

        .SetChoices("5", "8");

}

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

/*              GDALRasterRGBToPaletteAlgorithm::RunStep()              */

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

bool GDALRasterRGBToPaletteAlgorithm::RunStep(GDALPipelineStepRunContext &ctxt)

{

    auto pfnProgress = ctxt.m_pfnProgress;

    auto pProgressData = ctxt.m_pProgressData;

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

    CPLAssert(poSrcDS);

    const int nSrcBandCount = poSrcDS->GetRasterCount();

    if (nSrcBandCount < 3)

    {

        ReportError(CE_Failure, CPLE_NotSupported,

                    "Input dataset must have at least 3 bands");

        return false;

    }

    else if (nSrcBandCount == 4 &&

             poSrcDS->GetRasterBand(4)->GetColorInterpretation() ==

                 GCI_AlphaBand)

    {

        // nothing to do

    }

    else if (nSrcBandCount >= 4)

    {

        ReportError(

            CE_Warning, CPLE_AppDefined,

            "Only R,G,B bands of input dataset will be taken into account");

    }

    std::map<GDALColorInterp, GDALRasterBandH> mapBands;

    int nFound = 0;

    for (int i = 1; i <= nSrcBandCount; ++i)

    {

        auto poSrcBand = poSrcDS->GetRasterBand(i);

        if (poSrcBand->GetRasterDataType() != GDT_UInt8)

        {

            ReportError(CE_Failure, CPLE_NotSupported,

                        "Non-byte band found and not supported");

            return false;

        }

        const auto eColorInterp = poSrcBand->GetColorInterpretation();

        for (const auto eInterestColorInterp :

             {GCI_RedBand, GCI_GreenBand, GCI_BlueBand})

        {

            if (eColorInterp == eInterestColorInterp)

            {

                if (mapBands.find(eColorInterp) != mapBands.end())

                {

                    ReportError(CE_Failure, CPLE_NotSupported,

                                "Several %s bands found",

                                GDALGetColorInterpretationName(eColorInterp));

                    return false;

                }

                ++nFound;

                mapBands[eColorInterp] = GDALRasterBand::ToHandle(poSrcBand);

            }

        }

    }

    if (nFound < 3)

    {

        if (nFound > 0)

        {

            ReportError(

                CE_Warning, CPLE_AppDefined,

                "Assuming first band is red, second green and third blue, "

                "despite at least one band with one of those color "

                "interpretation "

                "found");

        }

        mapBands[GCI_RedBand] =

            GDALRasterBand::ToHandle(poSrcDS->GetRasterBand(1));

        mapBands[GCI_GreenBand] =

            GDALRasterBand::ToHandle(poSrcDS->GetRasterBand(2));

        mapBands[GCI_BlueBand] =

            GDALRasterBand::ToHandle(poSrcDS->GetRasterBand(3));

    }

    auto poTmpDS = CreateTemporaryDataset(

        poSrcDS->GetRasterXSize(), poSrcDS->GetRasterYSize(), 1, GDT_UInt8,

        /* bTiledIfPossible = */ true, poSrcDS, /* bCopyMetadata = */ true);

    if (!poTmpDS)

        return false;

    const double oneOverStep = 1.0 / ((m_colorMap.empty() ? 1 : 0) + 1);

    if (m_colorMap.empty() && m_dstNoData < 0)

    {

        int bSrcHasNoDataR = FALSE;

        const double dfSrcNoDataR =

            GDALGetRasterNoDataValue(mapBands[GCI_RedBand], &bSrcHasNoDataR);

        int bSrcHasNoDataG = FALSE;

        const double dfSrcNoDataG =

            GDALGetRasterNoDataValue(mapBands[GCI_GreenBand], &bSrcHasNoDataG);

        int bSrcHasNoDataB = FALSE;

        const double dfSrcNoDataB =

            GDALGetRasterNoDataValue(mapBands[GCI_BlueBand], &bSrcHasNoDataB);

        if (bSrcHasNoDataR && bSrcHasNoDataG && bSrcHasNoDataB &&

            dfSrcNoDataR == dfSrcNoDataG && dfSrcNoDataR == dfSrcNoDataB &&

            dfSrcNoDataR >= 0 && dfSrcNoDataR <= 255 &&

            std::round(dfSrcNoDataR) == dfSrcNoDataR)

        {

            m_dstNoData = 0;

        }

        else

        {

            const int nMaskFlags = GDALGetMaskFlags(mapBands[GCI_RedBand]);

            if ((nMaskFlags & GMF_PER_DATASET))

                m_dstNoData = 0;

        }

    }

    GDALColorTable oCT;

    bool bOK = true;

    double dfLastProgress = 0;

    std::unique_ptr<void, decltype(&GDALDestroyScaledProgress)> pScaledData(

        nullptr, GDALDestroyScaledProgress);

    if (m_colorMap.empty())

    {

        pScaledData.reset(GDALCreateScaledProgress(0, oneOverStep, pfnProgress,

                                                   pProgressData));

        dfLastProgress = oneOverStep;

        const int nXSize = poSrcDS->GetRasterXSize();

        const int nYSize = poSrcDS->GetRasterYSize();

        if (m_dstNoData >= 0 && m_colorCount == 256)

            --m_colorCount;

        if (nYSize == 0)

        {

            bOK = false;

        }

        else if (static_cast<GUInt32>(nXSize) <

                 std::numeric_limits<GUInt32>::max() /

                     static_cast<GUInt32>(nYSize))

        {

            bOK =

                GDALComputeMedianCutPCTInternal(

                    mapBands[GCI_RedBand], mapBands[GCI_GreenBand],

                    mapBands[GCI_BlueBand], nullptr, nullptr, nullptr, nullptr,

                    m_colorCount, m_bitDepth, static_cast<GUInt32 *>(nullptr),

                    GDALColorTable::ToHandle(&oCT),

                    pScaledData ? GDALScaledProgress : nullptr,

                    pScaledData.get()) == CE_None;

        }

        else

        {

            bOK =

                GDALComputeMedianCutPCTInternal(

                    mapBands[GCI_RedBand], mapBands[GCI_GreenBand],

                    mapBands[GCI_BlueBand], nullptr, nullptr, nullptr, nullptr,

                    m_colorCount, m_bitDepth, static_cast<GUIntBig *>(nullptr),

                    GDALColorTable::ToHandle(&oCT),

                    pScaledData ? GDALScaledProgress : nullptr,

                    pScaledData.get()) == CE_None;

        }

    }

    else

    {

        GDALDriverH hDriver;

        if ((hDriver = GDALIdentifyDriver(m_colorMap.c_str(), nullptr)) !=

                nullptr &&

            // Palette .txt files may be misidentified by the XYZ driver

            !EQUAL(GDALGetDescription(hDriver), "XYZ"))

        {

            auto poPaletteDS = std::unique_ptr<GDALDataset>(GDALDataset::Open(

                m_colorMap.c_str(), GDAL_OF_RASTER | GDAL_OF_VERBOSE_ERROR,

                nullptr, nullptr, nullptr));

            bOK = poPaletteDS != nullptr && poPaletteDS->GetRasterCount() > 0;

            if (bOK)

            {

                const auto poCT =

                    poPaletteDS->GetRasterBand(1)->GetColorTable();

                if (poCT)

                {

                    oCT = *poCT;

                }

                else

                {

                    bOK = false;

                    ReportError(CE_Failure, CPLE_AppDefined,

                                "Dataset '%s' does not contain a color table",

                                m_colorMap.c_str());

                }

            }

        }

        else

        {

            auto poCT = GDALColorTable::LoadFromFile(m_colorMap.c_str());

            bOK = poCT != nullptr;

            if (bOK)

            {

                oCT = std::move(*(poCT.get()));

            }

        }

        m_colorCount = oCT.GetColorEntryCount();

    }

    if (m_dstNoData >= 0)

    {

        for (int i = std::min(255, m_colorCount); i > m_dstNoData; --i)

        {

            oCT.SetColorEntry(i, oCT.GetColorEntry(i - 1));

        }

        poTmpDS->GetRasterBand(1)->SetNoDataValue(m_dstNoData);

        GDALColorEntry sEntry = {0, 0, 0, 0};

        oCT.SetColorEntry(m_dstNoData, &sEntry);

    }

    if (bOK)

    {

        poTmpDS->GetRasterBand(1)->SetColorTable(&oCT);

        pScaledData.reset(GDALCreateScaledProgress(dfLastProgress, 1.0,

                                                   pfnProgress, pProgressData));

        bOK = GDALDitherRGB2PCTInternal(

                  mapBands[GCI_RedBand], mapBands[GCI_GreenBand],

                  mapBands[GCI_BlueBand],

                  GDALRasterBand::ToHandle(poTmpDS->GetRasterBand(1)),

                  GDALColorTable::ToHandle(&oCT), m_bitDepth,

                  /* pasDynamicColorMap = */ nullptr, !m_noDither,

                  pScaledData ? GDALScaledProgress : nullptr,

                  pScaledData.get()) == CE_None;

    }

    if (bOK)

    {

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

        if (pfnProgress)

            pfnProgress(1.0, "", pProgressData);

    }

    return bOK;

}

GDALRasterRGBToPaletteAlgorithmStandalone::

    ~GDALRasterRGBToPaletteAlgorithmStandalone() = default;

//! @endcond