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

 *

 * Project:  GDAL

 * Purpose:  gdal "vector concat" 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_vector_concat.h"

#include "gdalalg_vector_write.h"

#include "cpl_conv.h"

#include "cpl_enumerate.h"

#include "gdal_priv.h"

#include "gdal_utils.h"

#include "ogrsf_frmts.h"

#include "ogrlayerdecorator.h"

#include "ogrlayerpool.h"

#include "ogrunionlayer.h"

#include "ogrwarpedlayer.h"

#include <algorithm>

#include <set>

//! @cond Doxygen_Suppress

#ifndef _

#define _(x) (x)

#endif

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

/*        GDALVectorConcatAlgorithm::GDALVectorConcatAlgorithm()        */

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

GDALVectorConcatAlgorithm::GDALVectorConcatAlgorithm(bool bStandalone)

    : GDALVectorPipelineStepAlgorithm(NAME, DESCRIPTION, HELP_URL,

                                      ConstructorOptions()

                                          .SetStandaloneStep(bStandalone)

                                          .SetAddDefaultArguments(bStandalone)

                                          .SetInputDatasetMetaVar("INPUTS")

                                          .SetInputDatasetMaxCount(INT_MAX)

                                          .SetAddOutputLayerNameArgument(false)

                                          .SetAutoOpenInputDatasets(false))

{

    if (!bStandalone)

    {

        AddVectorInputArgs(/* hiddenForCLI = */ false);

    }

    AddArg(

        "mode", 0,

        _("Determine the strategy to create output layers from source layers "),

        &m_mode)

        .SetChoices("merge-per-layer-name", "stack", "single")

        .SetDefault(m_mode);

    AddArg(GDAL_ARG_NAME_OUTPUT_LAYER, 0,

           _("Name of the output vector layer (single mode), or template to "

             "name the output vector layers (stack mode)"),

           &m_layerNameTemplate);

    AddArg("source-layer-field-name", 0,

           _("Name of the new field to add to contain identification of the "

             "source layer, with value determined from "

             "'source-layer-field-content'"),

           &m_sourceLayerFieldName);

    AddArg("source-layer-field-content", 0,

           _("A string, possibly using {AUTO_NAME}, {DS_NAME}, {DS_BASENAME}, "

             "{DS_INDEX}, {LAYER_NAME}, {LAYER_INDEX}"),

           &m_sourceLayerFieldContent);

    AddArg("field-strategy", 0,

           _("How to determine target fields from source fields"),

           &m_fieldStrategy)

        .SetChoices("union", "intersection")

        .SetDefault(m_fieldStrategy);

    AddArg("input-crs", 's', _("Input CRS"), &m_srsCrs)

        .SetIsCRSArg()

        .AddHiddenAlias("s_srs")

        .AddHiddenAlias("src-crs");

    AddArg("output-crs", 'd', _("Output CRS"), &m_dstCrs)

        .SetIsCRSArg()

        .AddHiddenAlias("t_srs")

        .AddHiddenAlias("dst-crs");

}

GDALVectorConcatAlgorithm::~GDALVectorConcatAlgorithm() = default;

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

/*                    GDALVectorConcatOutputDataset                     */

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

class GDALVectorConcatOutputDataset final : public GDALDataset

{

    // The layers read lazily from the objects declared before them, and

    // members are destroyed in reverse declaration order. Do not reorder.

    std::vector<std::unique_ptr<GDALDataset, GDALDatasetUniquePtrReleaser>>

        m_srcDatasets{};

    std::unique_ptr<OGRLayerPool> m_poLayerPool{};

    std::vector<std::unique_ptr<OGRLayer>> m_tempLayers{};

    std::vector<std::unique_ptr<OGRLayer>> m_layers{};

  public:

    GDALVectorConcatOutputDataset() = default;

    /** Add a dataset the layers read from, taking over a reference on it. */

    void AddSrcDatasetRef(GDALDataset *poSrcDS)

    {

        m_srcDatasets.emplace_back(poSrcDS);

    }

    /** Create the pool used by proxied layers, and return a borrowed pointer. */

    OGRLayerPool *CreateLayerPool(int nMaxSimultaneouslyOpened)

    {

        m_poLayerPool =

            std::make_unique<OGRLayerPool>(nMaxSimultaneouslyOpened);

        return m_poLayerPool.get();

    }

    /** Add an intermediate layer, and return a borrowed pointer to it. */

    OGRLayer *AddTempLayer(std::unique_ptr<OGRLayer> layer)

    {

        m_tempLayers.push_back(std::move(layer));

        return m_tempLayers.back().get();

    }

    void AddLayer(std::unique_ptr<OGRLayer> layer)

    {

        m_layers.push_back(std::move(layer));

    }

    int GetLayerCount() const override;

    OGRLayer *GetLayer(int idx) const override

    {

        return idx >= 0 && idx < GetLayerCount() ? m_layers[idx].get()

                                                 : nullptr;

    }

    bool TestCapability(const char *pszCap) const override

    {

        if (EQUAL(pszCap, ODsCCurveGeometries) ||

            EQUAL(pszCap, ODsCMeasuredGeometries) ||

            EQUAL(pszCap, ODsCZGeometries))

        {

            return true;

        }

        return false;

    }

};

int GDALVectorConcatOutputDataset::GetLayerCount() const

{

    return static_cast<int>(m_layers.size());

}

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

/*                     GDALVectorConcatRenamedLayer                     */

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

class GDALVectorConcatRenamedLayer final : public OGRLayerDecorator

{

  public:

    GDALVectorConcatRenamedLayer(OGRLayer *poSrcLayer,

                                 const std::string &newName)

        : OGRLayerDecorator(poSrcLayer, false), m_newName(newName)

    {

    }

    const char *GetName() const override;

  private:

    const std::string m_newName;

};

const char *GDALVectorConcatRenamedLayer::GetName() const

{

    return m_newName.c_str();

}

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

/*                           BuildLayerName()                           */

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

static std::string BuildLayerName(const std::string &layerNameTemplate,

                                  int dsIdx, const std::string &dsName,

                                  int lyrIdx, const std::string &lyrName)

{

    CPLString ret = layerNameTemplate;

    std::string baseName;

    VSIStatBufL sStat;

    if (VSIStatL(dsName.c_str(), &sStat) == 0)

        baseName = CPLGetBasenameSafe(dsName.c_str());

    if (baseName == lyrName)

    {

        ret = ret.replaceAll("{AUTO_NAME}", baseName);

    }

    else

    {

        ret = ret.replaceAll("{AUTO_NAME}",

                             std::string(baseName.empty() ? dsName : baseName)

                                 .append("_")

                                 .append(lyrName));

    }

    ret =

        ret.replaceAll("{DS_BASENAME}", !baseName.empty() ? baseName : dsName);

    ret = ret.replaceAll("{DS_NAME}", dsName);

    ret = ret.replaceAll("{DS_INDEX}", std::to_string(dsIdx).c_str());

    ret = ret.replaceAll("{LAYER_NAME}", lyrName);

    ret = ret.replaceAll("{LAYER_INDEX}", std::to_string(lyrIdx).c_str());

    return std::string(std::move(ret));

}

namespace

{

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

/*                          OpenProxiedLayer()                          */

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

struct PooledInitData

{

    std::unique_ptr<GDALDataset> poDS{};

    std::string osDatasetName{};

    // Copies, and not pointers to the algorithm members, as a layer may be

    // (re)opened after the algorithm has been destroyed.

    CPLStringList aosInputFormats{};

    CPLStringList aosOpenOptions{};

    int iLayer = 0;

};

static OGRLayer *OpenProxiedLayer(void *pUserData)

{

    PooledInitData *pData = static_cast<PooledInitData *>(pUserData);

    pData->poDS.reset(GDALDataset::Open(

        pData->osDatasetName.c_str(), GDAL_OF_VECTOR | GDAL_OF_VERBOSE_ERROR,

        pData->aosInputFormats.List(), pData->aosOpenOptions.List(), nullptr));

    if (!pData->poDS)

        return nullptr;

    return pData->poDS->GetLayer(pData->iLayer);

}

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

/*                        ReleaseProxiedLayer()                         */

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

static void ReleaseProxiedLayer(OGRLayer *, void *pUserData)

{

    PooledInitData *pData = static_cast<PooledInitData *>(pUserData);

    pData->poDS.reset();

}

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

/*                      FreeProxiedLayerUserData()                      */

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

static void FreeProxiedLayerUserData(void *pUserData)

{

    delete static_cast<PooledInitData *>(pUserData);

}

}  // namespace

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

/*                 GDALVectorConcatAlgorithm::RunStep()                 */

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

bool GDALVectorConcatAlgorithm::RunStep(GDALPipelineStepRunContext &)

{

    std::unique_ptr<OGRSpatialReference> poSrcCRS;

    if (!m_srsCrs.empty())

    {

        poSrcCRS = std::make_unique<OGRSpatialReference>();

        poSrcCRS->SetFromUserInput(m_srsCrs.c_str());

        poSrcCRS->SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);

    }

    OGRSpatialReference oDstCRS;

    if (!m_dstCrs.empty())

    {

        oDstCRS.SetFromUserInput(m_dstCrs.c_str());

        oDstCRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);

    }

    struct LayerDesc

    {

        int iDS = 0;

        int iLayer = 0;

        std::string osDatasetName{};

    };

    if (m_layerNameTemplate.empty())

    {

        if (m_mode == "single")

            m_layerNameTemplate = "merged";

        else if (m_mode == "stack")

            m_layerNameTemplate = "{AUTO_NAME}";

    }

    else if (m_mode == "merge-per-layer-name")

    {

        ReportError(CE_Failure, CPLE_IllegalArg,

                    "'layer-name' name argument cannot be specified in "

                    "mode=merge-per-layer-name");

        return false;

    }

    if (m_sourceLayerFieldContent.empty())

        m_sourceLayerFieldContent = "{AUTO_NAME}";

    else if (m_sourceLayerFieldName.empty())

        m_sourceLayerFieldName = "source_ds_lyr";

    const int nMaxSimultaneouslyOpened =

        std::max(atoi(CPLGetConfigOption(

                     "GDAL_VECTOR_CONCAT_MAX_OPENED_DATASETS", "100")),

                 1);

    // First pass on input layers

    std::map<std::string, std::vector<LayerDesc>> allLayerNames;

    int iDS = 0;

    int nonOpenedDSCount = 0;

    for (auto &srcDS : m_inputDataset)

    {

        GDALDataset *poSrcDS = srcDS.GetDatasetRef();

        std::unique_ptr<GDALDataset> poTmpDS;

        if (!poSrcDS)

        {

            poTmpDS.reset(GDALDataset::Open(

                srcDS.GetName().c_str(), GDAL_OF_VECTOR | GDAL_OF_VERBOSE_ERROR,

                CPLStringList(m_inputFormats).List(),

                CPLStringList(m_openOptions).List(), nullptr));

            poSrcDS = poTmpDS.get();

            if (!poSrcDS)

                return false;

            if (static_cast<int>(m_inputDataset.size()) <=

                nMaxSimultaneouslyOpened)

            {

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

                poSrcDS = srcDS.GetDatasetRef();

            }

            else

            {

                ++nonOpenedDSCount;

            }

        }

        int iLayer = 0;

        for (const auto &poLayer : poSrcDS->GetLayers())

        {

            if (m_inputLayerNames.empty() ||

                std::find(m_inputLayerNames.begin(), m_inputLayerNames.end(),

                          poLayer->GetName()) != m_inputLayerNames.end())

            {

                if (!m_dstCrs.empty() && m_srsCrs.empty() &&

                    poLayer->GetSpatialRef() == nullptr)

                {

                    ReportError(

                        CE_Failure, CPLE_AppDefined,

                        "Layer '%s' of '%s' has no spatial reference system",

                        poLayer->GetName(), poSrcDS->GetDescription());

                    return false;

                }

                LayerDesc layerDesc;

                layerDesc.iDS = iDS;

                layerDesc.iLayer = iLayer;

                layerDesc.osDatasetName = poSrcDS->GetDescription();

                const std::string outLayerName =

                    m_mode == "single" ? m_layerNameTemplate

                    : m_mode == "merge-per-layer-name"

                        ? std::string(poLayer->GetName())

                        : BuildLayerName(m_layerNameTemplate, iDS,

                                         poSrcDS->GetDescription(), iLayer,

                                         poLayer->GetName());

                CPLDebugOnly("gdal_vector_concat", "%s,%s->%s",

                             poSrcDS->GetDescription(), poLayer->GetName(),

                             outLayerName.c_str());

                allLayerNames[outLayerName].push_back(std::move(layerDesc));

            }

            ++iLayer;

        }

        ++iDS;

    }

    auto poUnionDS = std::make_unique<GDALVectorConcatOutputDataset>();

    OGRLayerPool *poLayerPool = nullptr;

    if (nonOpenedDSCount > nMaxSimultaneouslyOpened)

        poLayerPool = poUnionDS->CreateLayerPool(nMaxSimultaneouslyOpened);

    bool ret = true;

    for (const auto &[outLayerName, listOfLayers] : allLayerNames)

    {

        const int nLayerCount = static_cast<int>(listOfLayers.size());

        std::unique_ptr<OGRLayer *, VSIFreeReleaser> papoSrcLayers(

            static_cast<OGRLayer **>(

                CPLCalloc(nLayerCount, sizeof(OGRLayer *))));

        for (const auto [i, layer] : cpl::enumerate(listOfLayers))

        {

            auto &srcDS = m_inputDataset[layer.iDS];

            GDALDataset *poSrcDS = srcDS.GetDatasetRef();

            std::unique_ptr<GDALDataset> poTmpDS;

            if (!poSrcDS)

            {

                poTmpDS.reset(GDALDataset::Open(

                    layer.osDatasetName.c_str(),

                    GDAL_OF_VECTOR | GDAL_OF_VERBOSE_ERROR,

                    CPLStringList(m_inputFormats).List(),

                    CPLStringList(m_openOptions).List(), nullptr));

                poSrcDS = poTmpDS.get();

                if (!poSrcDS)

                    return false;

            }

            OGRLayer *poSrcLayer = poSrcDS->GetLayer(layer.iLayer);

            if (poLayerPool)

            {

                auto pData = std::make_unique<PooledInitData>();

                pData->osDatasetName = layer.osDatasetName;

                pData->aosInputFormats = CPLStringList(m_inputFormats);

                pData->aosOpenOptions = CPLStringList(m_openOptions);

                pData->iLayer = layer.iLayer;

                auto proxiedLayer = std::make_unique<OGRProxiedLayer>(

                    poLayerPool, OpenProxiedLayer, ReleaseProxiedLayer,

                    FreeProxiedLayerUserData, pData.release());

                proxiedLayer->SetDescription(poSrcLayer->GetDescription());

                poSrcLayer = poUnionDS->AddTempLayer(std::move(proxiedLayer));

            }

            else if (poTmpDS)

            {

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

            }

            if (m_sourceLayerFieldName.empty())

            {

                papoSrcLayers.get()[i] = poSrcLayer;

            }

            else

            {

                const std::string newSrcLayerName = BuildLayerName(

                    m_sourceLayerFieldContent, listOfLayers[i].iDS,

                    listOfLayers[i].osDatasetName.c_str(),

                    listOfLayers[i].iLayer, poSrcLayer->GetName());

                ret = !newSrcLayerName.empty() && ret;

                papoSrcLayers.get()[i] = poUnionDS->AddTempLayer(

                    std::make_unique<GDALVectorConcatRenamedLayer>(

                        poSrcLayer, newSrcLayerName));

            }

        }

        // Auto-wrap source layers if needed

        if (!m_dstCrs.empty())

        {

            for (int i = 0; ret && i < nLayerCount; ++i)

            {

                const OGRSpatialReference *poSrcLayerCRS;

                if (poSrcCRS)

                    poSrcLayerCRS = poSrcCRS.get();

                else

                    poSrcLayerCRS = papoSrcLayers.get()[i]->GetSpatialRef();

                if (poSrcLayerCRS && !poSrcLayerCRS->IsSame(&oDstCRS))

                {

                    auto poCT = std::unique_ptr<OGRCoordinateTransformation>(

                        OGRCreateCoordinateTransformation(poSrcLayerCRS,

                                                          &oDstCRS));

                    auto poReversedCT =

                        std::unique_ptr<OGRCoordinateTransformation>(

                            OGRCreateCoordinateTransformation(&oDstCRS,

                                                              poSrcLayerCRS));

                    ret = (poCT != nullptr) && (poReversedCT != nullptr);

                    if (ret)

                    {

                        papoSrcLayers.get()[i] = poUnionDS->AddTempLayer(

                            std::make_unique<OGRWarpedLayer>(

                                papoSrcLayers.get()[i], /* iGeomField = */ 0,

                                /*bTakeOwnership = */ false, std::move(poCT),

                                std::move(poReversedCT)));

                    }

                }

            }

        }

        auto poUnionLayer = std::make_unique<OGRUnionLayer>(

            outLayerName.c_str(), nLayerCount, papoSrcLayers.release(),

            /* bTakeLayerOwnership = */ false);

        if (!m_sourceLayerFieldName.empty())

        {

            poUnionLayer->SetSourceLayerFieldName(

                m_sourceLayerFieldName.c_str());

        }

        const FieldUnionStrategy eStrategy =

            m_fieldStrategy == "union" ? FIELD_UNION_ALL_LAYERS

                                       : FIELD_INTERSECTION_ALL_LAYERS;

        poUnionLayer->SetFields(eStrategy, 0, nullptr, 0, nullptr);

        poUnionDS->AddLayer(std::move(poUnionLayer));

    }

    if (ret)

    {

        for (auto &srcDS : m_inputDataset)

        {

            if (GDALDataset *poSrcDS = srcDS.GetDatasetIncreaseRefCount())

                poUnionDS->AddSrcDatasetRef(poSrcDS);

        }

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

    }

    return ret;

}

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

/*                 GDALVectorConcatAlgorithm::RunImpl()                 */

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

bool GDALVectorConcatAlgorithm::RunImpl(GDALProgressFunc pfnProgress,

                                        void *pProgressData)

{

    if (m_standaloneStep)

    {

        GDALVectorWriteAlgorithm writeAlg;

        for (auto &arg : writeAlg.GetArgs())

        {

            if (!arg->IsHidden() &&

                arg->GetName() != GDAL_ARG_NAME_OUTPUT_LAYER)

            {

                auto stepArg = GetArg(arg->GetName());

                if (stepArg && stepArg->IsExplicitlySet())

                {

                    arg->SetSkipIfAlreadySet(true);

                    arg->SetFrom(*stepArg);

                }

            }

        }

        // Already checked by GDALAlgorithm::Run()

        CPLAssert(!m_executionForStreamOutput ||

                  EQUAL(m_format.c_str(), "stream"));

        m_standaloneStep = false;

        m_alreadyRun = false;

        bool ret = Run(pfnProgress, pProgressData);

        m_standaloneStep = true;

        if (ret)

        {

            if (m_format == "stream")

            {

                ret = true;

            }

            else

            {

                writeAlg.m_inputDataset.clear();

                writeAlg.m_inputDataset.resize(1);

                writeAlg.m_inputDataset[0].Set(m_outputDataset.GetDatasetRef());

                if (writeAlg.Run(pfnProgress, pProgressData))

                {

                    m_outputDataset.Set(

                        writeAlg.m_outputDataset.GetDatasetRef());

                    ret = true;

                }

            }

        }

        return ret;

    }

    else

    {

        GDALPipelineStepRunContext stepCtxt;

        stepCtxt.m_pfnProgress = pfnProgress;

        stepCtxt.m_pProgressData = pProgressData;

        return RunStep(stepCtxt);

    }

}

GDALVectorConcatAlgorithmStandalone::~GDALVectorConcatAlgorithmStandalone() =

    default;

//! @endcond