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

 *

 * Project:  GDAL

 * Purpose:  gdal "external" subcommand (always in pipeline)

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

 *

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

 * Copyright (c) 2026, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

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

//! @cond Doxygen_Suppress

#include "gdalalg_external.h"

#include "gdalalg_materialize.h"

#include "gdal_dataset.h"

#include "cpl_atomic_ops.h"

#include "cpl_error.h"

#include "cpl_multiproc.h"

#include <stdio.h>

#if !defined(_WIN32)

#include <sys/wait.h>

#endif

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

/*                     ~GDALExternalAlgorithmBase()                     */

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

GDALExternalAlgorithmBase::~GDALExternalAlgorithmBase()

{

    if (!m_osTempInputFilename.empty())

        VSIUnlink(m_osTempInputFilename.c_str());

    if (!m_osTempOutputFilename.empty() &&

        m_osTempOutputFilename != m_osTempInputFilename)

        VSIUnlink(m_osTempOutputFilename.c_str());

}

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

/*                   GDALExternalAlgorithmBase::Run()                   */

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

bool GDALExternalAlgorithmBase::Run(

    const std::vector<std::string> &inputFormats,

    std::vector<GDALArgDatasetValue> &inputDataset,

    const std::string &outputFormat, GDALArgDatasetValue &outputDataset)

{

    if (!CPLTestBool(CPLGetConfigOption("GDAL_ENABLE_EXTERNAL", "NO")))

    {

        CPLError(CE_Failure, CPLE_AppDefined,

                 "Cannot execute command '%s', because GDAL_ENABLE_EXTERNAL "

                 "configuration option is not set to YES.",

                 m_command.c_str());

        return false;

    }

    const bool bHasInput = m_command.find("<INPUT>") != std::string::npos;

    const bool bHasInputOutput =

        m_command.find("<INPUT-OUTPUT>") != std::string::npos;

    const bool bHasOutput = m_command.find("<OUTPUT>") != std::string::npos;

    const std::string osTempDirname =

        CPLGetDirnameSafe(CPLGenerateTempFilenameSafe(nullptr).c_str());

    if (bHasInput || bHasInputOutput || bHasOutput)

    {

        VSIStatBufL sStat;

        if (VSIStatL(osTempDirname.c_str(), &sStat) != 0 ||

            !VSI_ISDIR(sStat.st_mode))

        {

            CPLError(

                CE_Failure, CPLE_AppDefined,

                "'%s', used for temporary directory, is not a valid directory",

                osTempDirname.c_str());

            return false;

        }

        // Check to avoid any possibility of command injection

        if (osTempDirname.find_first_of("'\"^&|<>%!;") != std::string::npos)

        {

            CPLError(CE_Failure, CPLE_AppDefined,

                     "'%s', used for temporary directory, contains a reserved "

                     "character ('\"^&|<>%%!;)",

                     osTempDirname.c_str());

            return false;

        }

    }

    const auto QuoteFilename = [](const std::string &s)

    {

#ifdef _WIN32

        return "\"" + s + "\"";

#else

        return "'" + s + "'";

#endif

    };

    // Process <INPUT> and <INPUT-OUTPUT> placeholder

    if (bHasInput || bHasInputOutput)

    {

        if (inputDataset.size() != 1 || !inputDataset[0].GetDatasetRef())

        {

            CPLError(CE_Failure, CPLE_AppDefined,

                     "Command '%s' expects an input dataset to be provided, "

                     "but none is available.",

                     m_command.c_str());

            return false;

        }

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

        const std::string osDriverName = !inputFormats.empty() ? inputFormats[0]

                                         : poSrcDS->GetRasterCount() != 0

                                             ? "GTiff"

                                             : "GPKG";

        auto poDriver =

            GetGDALDriverManager()->GetDriverByName(osDriverName.c_str());

        if (!poDriver)

        {

            CPLError(CE_Failure, CPLE_AppDefined, "Driver %s not available",

                     osDriverName.c_str());

            return false;

        }

        const CPLStringList aosExts(CSLTokenizeString2(

            poDriver->GetMetadataItem(GDAL_DMD_EXTENSIONS), " ", 0));

        const char *pszExt = aosExts.size() >= 1 ? aosExts[0] : "bin";

        static int nTempFileCounter = 0;

        m_osTempInputFilename = CPLFormFilenameSafe(

            osTempDirname.c_str(),

            CPLSPrintf("input_%d_%d", CPLGetCurrentProcessID(),

                       CPLAtomicInc(&nTempFileCounter)),

            pszExt);

        if (bHasInputOutput)

        {

            m_command.replaceAll("<INPUT-OUTPUT>",

                                 QuoteFilename(m_osTempInputFilename));

            m_osTempOutputFilename = m_osTempInputFilename;

        }

        else

        {

            m_command.replaceAll("<INPUT>",

                                 QuoteFilename(m_osTempInputFilename));

        }

        std::unique_ptr<GDALPipelineStepAlgorithm> poMaterializeStep;

        if (poSrcDS->GetRasterCount() != 0)

        {

            poMaterializeStep =

                std::make_unique<GDALMaterializeRasterAlgorithm>();

        }

        else

        {

            poMaterializeStep =

                std::make_unique<GDALMaterializeVectorAlgorithm>();

        }

        poMaterializeStep->SetInputDataset(poSrcDS);

        poMaterializeStep->GetArg(GDAL_ARG_NAME_OUTPUT_FORMAT)

            ->Set(osDriverName.c_str());

        poMaterializeStep->GetArg(GDAL_ARG_NAME_OUTPUT)

            ->Set(m_osTempInputFilename);

        if (EQUAL(osDriverName.c_str(), "GTIFF"))

            poMaterializeStep->GetArg(GDAL_ARG_NAME_CREATION_OPTION)

                ->Set("COPY_SRC_OVERVIEWS=NO");

        if (!poMaterializeStep->Run() || !poMaterializeStep->Finalize())

        {

            return false;

        }

    }

    // Process <OUTPUT> placeholder

    if (bHasOutput)

    {

        auto poSrcDS = inputDataset.size() == 1

                           ? inputDataset[0].GetDatasetRef()

                           : nullptr;

        const std::string osDriverName =

            !outputFormat.empty()                       ? outputFormat

            : !inputFormats.empty()                     ? inputFormats[0]

            : poSrcDS && poSrcDS->GetRasterCount() != 0 ? "GTiff"

                                                        : "GPKG";

        auto poDriver =

            GetGDALDriverManager()->GetDriverByName(osDriverName.c_str());

        if (!poDriver)

        {

            CPLError(CE_Failure, CPLE_AppDefined, "Driver %s not available",

                     osDriverName.c_str());

            return false;

        }

        const CPLStringList aosExts(CSLTokenizeString2(

            poDriver->GetMetadataItem(GDAL_DMD_EXTENSIONS), " ", 0));

        const char *pszExt = aosExts.size() >= 1 ? aosExts[0] : "bin";

        m_osTempOutputFilename = CPLResetExtensionSafe(

            CPLGenerateTempFilenameSafe("output").c_str(), pszExt);

        m_command.replaceAll("<OUTPUT>", QuoteFilename(m_osTempOutputFilename));

    }

    CPLDebug("GDAL", "Execute '%s'", m_command.c_str());

#ifdef _WIN32

    wchar_t *pwszCmmand =

        CPLRecodeToWChar(m_command.c_str(), CPL_ENC_UTF8, CPL_ENC_UCS2);

    FILE *fout = _wpopen(pwszCmmand, L"r");

    CPLFree(pwszCmmand);

#else

    FILE *fout = popen(m_command.c_str(), "r");

#endif

    if (!fout)

    {

        CPLError(CE_Failure, CPLE_AppDefined,

                 "Cannot start external command '%s'", m_command.c_str());

        return false;

    }

    // Read child standard output

    std::string s;

    constexpr int BUFFER_SIZE = 1024;

    s.resize(BUFFER_SIZE);

    while (!feof(fout) && !ferror(fout))

    {

        if (fgets(s.data(), BUFFER_SIZE - 1, fout))

        {

            size_t nLineLen = strlen(s.c_str());

            // Remove end-of-line characters

            for (char chEOL : {'\n', '\r'})

            {

                if (nLineLen > 0 && s[nLineLen - 1] == chEOL)

                {

                    --nLineLen;

                    s[nLineLen] = 0;

                }

            }

            if (nLineLen)

            {

                bool bOnlyPrintableChars = true;

                for (size_t i = 0; bOnlyPrintableChars && i < nLineLen; ++i)

                {

                    const char ch = s[i];

                    bOnlyPrintableChars = ch >= 32 || ch == '\t';

                }

                if (bOnlyPrintableChars)

                    CPLDebug("GDAL", "External process: %s", s.c_str());

            }

        }

    }

#ifdef _WIN32

    const int ret = _pclose(fout);

#else

    int ret = pclose(fout);

    if (WIFEXITED(ret))

        ret = WEXITSTATUS(ret);

#endif

    if (ret)

    {

        CPLError(CE_Failure, CPLE_AppDefined,

                 "External command '%s' failed with error code %d",

                 m_command.c_str(), ret);

        return false;

    }

    if (!m_osTempOutputFilename.empty())

    {

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

            m_osTempOutputFilename.c_str(), GDAL_OF_VERBOSE_ERROR));

        if (!poOutDS)

            return false;

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

    }

    else if (inputDataset.size() == 1)

    {

        // If no output dataset was expected from the external command,

        // reuse the input dataset as the output of this step.

        outputDataset.Set(inputDataset[0].GetDatasetRef());

    }

    return true;

}

GDALExternalRasterOrVectorAlgorithm::~GDALExternalRasterOrVectorAlgorithm() =

    default;

GDALExternalRasterAlgorithm::~GDALExternalRasterAlgorithm() = default;

GDALExternalVectorAlgorithm::~GDALExternalVectorAlgorithm() = default;

//! @endcond