/******************************************************************************
 * Project:  OGR
 * Purpose:  OGRGMLASDriver implementation
 * Author:   Even Rouault, <even dot rouault at spatialys dot com>
 *
 * Initial development funded by the European Earth observation programme
 * Copernicus
 *
 ******************************************************************************
 * Copyright (c) 2016, Even Rouault, <even dot rouault at spatialys dot com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "ogr_gmlas.h"
#include "ogr_pgdump.h"
#include "cpl_minixml.h"

/************************************************************************/
/*                           OGRGMLASLayer()                            */
/************************************************************************/

OGRGMLASLayer::OGRGMLASLayer(OGRGMLASDataSource *poDS,
                             const GMLASFeatureClass &oFC,
                             OGRGMLASLayer *poParentLayer,
                             bool bAlwaysGenerateOGRPKId)
    : m_poDS(poDS), m_oFC(oFC),
      m_poFeatureDefn(new OGRFeatureDefn(oFC.GetName())),
      m_poParentLayer(poParentLayer)
{
    m_poFeatureDefn->SetGeomType(wkbNone);
    m_poFeatureDefn->Reference();

    SetDescription(m_poFeatureDefn->GetName());

    // Are we a regular table ?
    if (m_oFC.GetParentXPath().empty())
    {
        if (bAlwaysGenerateOGRPKId)
        {
            OGRFieldDefn oFieldDefn(szOGR_PKID, OFTString);
            oFieldDefn.SetNullable(false);
            m_nIDFieldIdx = m_poFeatureDefn->GetFieldCount();
            m_bIDFieldIsGenerated = true;
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
        }

        // Determine if we have an xs:ID attribute/elt, and if it is compulsory,
        // If so, place it as first field (not strictly required, but more
        // readable) or second field (if we also add a ogr_pkid) Furthermore
        // restrict that to attributes, because otherwise it is impractical in
        // the reader when joining related features.
        const std::vector<GMLASField> &oFields = m_oFC.GetFields();
        for (int i = 0; i < static_cast<int>(oFields.size()); i++)
        {
            if (oFields[i].GetType() == GMLAS_FT_ID &&
                oFields[i].IsNotNullable() &&
                oFields[i].GetXPath().find('@') != std::string::npos)
            {
                OGRFieldDefn oFieldDefn(oFields[i].GetName(), OFTString);
                oFieldDefn.SetNullable(false);
                const int nOGRIdx = m_poFeatureDefn->GetFieldCount();
                if (m_nIDFieldIdx < 0)
                    m_nIDFieldIdx = nOGRIdx;
                m_oMapFieldXPathToOGRFieldIdx[oFields[i].GetXPath()] = nOGRIdx;
                m_oMapOGRFieldIdxtoFCFieldIdx[nOGRIdx] = i;
                m_oMapFieldXPathToFCFieldIdx[oFields[i].GetXPath()] = i;
                m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
                break;
            }
        }

        // If we don't have an explicit ID, then we need
        // to generate one, so that potentially related classes can reference it
        // (We could perhaps try to be clever to determine if we really need it)
        if (m_nIDFieldIdx < 0)
        {
            OGRFieldDefn oFieldDefn(szOGR_PKID, OFTString);
            oFieldDefn.SetNullable(false);
            m_nIDFieldIdx = m_poFeatureDefn->GetFieldCount();
            m_bIDFieldIsGenerated = true;
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
        }
    }

    OGRLayer *poLayersMetadataLayer = m_poDS->GetLayersMetadataLayer();
    OGRFeature *poLayerDescFeature =
        new OGRFeature(poLayersMetadataLayer->GetLayerDefn());
    poLayerDescFeature->SetField(szLAYER_NAME, OGRGMLASLayer::GetName());
    if (!m_oFC.GetParentXPath().empty())
    {
        poLayerDescFeature->SetField(szLAYER_CATEGORY, szJUNCTION_TABLE);
    }
    else
    {
        poLayerDescFeature->SetField(szLAYER_XPATH, m_oFC.GetXPath());

        poLayerDescFeature->SetField(szLAYER_CATEGORY, m_oFC.IsTopLevelElt()
                                                           ? szTOP_LEVEL_ELEMENT
                                                           : szNESTED_ELEMENT);

        if (m_nIDFieldIdx >= 0)
        {
            poLayerDescFeature->SetField(
                szLAYER_PKID_NAME,
                m_poFeatureDefn->GetFieldDefn(m_nIDFieldIdx)->GetNameRef());
        }

        // If we are a child class, then add a field to reference the parent.
        if (m_poParentLayer != nullptr)
        {
            CPLString osFieldName(szPARENT_PREFIX);
            osFieldName += m_poParentLayer->GetLayerDefn()
                               ->GetFieldDefn(m_poParentLayer->GetIDFieldIdx())
                               ->GetNameRef();
            poLayerDescFeature->SetField(szLAYER_PARENT_PKID_NAME,
                                         osFieldName.c_str());
        }

        if (!m_oFC.GetDocumentation().empty())
        {
            poLayerDescFeature->SetField(szLAYER_DOCUMENTATION,
                                         m_oFC.GetDocumentation());
        }
    }
    CPL_IGNORE_RET_VAL(
        poLayersMetadataLayer->CreateFeature(poLayerDescFeature));
    delete poLayerDescFeature;
}

/************************************************************************/
/*                           OGRGMLASLayer()                            */
/************************************************************************/

OGRGMLASLayer::OGRGMLASLayer(const char *pszLayerName)
    : m_bLayerDefnFinalized(true),
      m_poFeatureDefn(new OGRFeatureDefn(pszLayerName))

{
    m_poFeatureDefn->SetGeomType(wkbNone);
    m_poFeatureDefn->Reference();

    SetDescription(m_poFeatureDefn->GetName());
}

/************************************************************************/
/*                         GetSWEChildAndType()                         */
/************************************************************************/

static CPLXMLNode *GetSWEChildAndType(CPLXMLNode *psNode, OGRFieldType &eType,
                                      OGRFieldSubType &eSubType)
{
    eType = OFTString;
    eSubType = OFSTNone;
    CPLXMLNode *psChildNode = nullptr;
    if ((psChildNode = CPLGetXMLNode(psNode, "Time")) != nullptr)
    {
        eType = OFTDateTime;
    }
    else if ((psChildNode = CPLGetXMLNode(psNode, "Quantity")) != nullptr)
    {
        eType = OFTReal;
    }
    else if ((psChildNode = CPLGetXMLNode(psNode, "Category")) != nullptr)
    {
        eType = OFTString;
    }
    else if ((psChildNode = CPLGetXMLNode(psNode, "Count")) != nullptr)
    {
        eType = OFTInteger;
    }
    else if ((psChildNode = CPLGetXMLNode(psNode, "Text")) != nullptr)
    {
        eType = OFTString;
    }
    else if ((psChildNode = CPLGetXMLNode(psNode, "Boolean")) != nullptr)
    {
        eType = OFTInteger;
        eSubType = OFSTBoolean;
    }
    return psChildNode;
}

/************************************************************************/
/*              ProcessDataRecordOfDataArrayCreateFields()              */
/************************************************************************/

void OGRGMLASLayer::ProcessDataRecordOfDataArrayCreateFields(
    OGRGMLASLayer *poParentLayer, CPLXMLNode *psDataRecord,
    OGRLayer *poFieldsMetadataLayer)
{
    {
        CPLString osFieldName(szPARENT_PREFIX);
        osFieldName += poParentLayer->GetLayerDefn()
                           ->GetFieldDefn(poParentLayer->GetIDFieldIdx())
                           ->GetNameRef();
        OGRFieldDefn oFieldDefn(osFieldName, OFTString);
        oFieldDefn.SetNullable(false);
        m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
    }

    for (CPLXMLNode *psIter = psDataRecord->psChild; psIter != nullptr;
         psIter = psIter->psNext)
    {
        if (psIter->eType == CXT_Element &&
            strcmp(psIter->pszValue, "field") == 0)
        {
            const char *pszName = CPLGetXMLValue(psIter, "name", "");
            OGRFieldDefn oFieldDefn(CPLString(pszName).tolower(), OFTString);
            OGRFieldType eType;
            OGRFieldSubType eSubType;
            CPLXMLNode *psNode = GetSWEChildAndType(psIter, eType, eSubType);
            oFieldDefn.SetType(eType);
            oFieldDefn.SetSubType(eSubType);
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

            // Register field in _ogr_fields_metadata
            OGRFeature *poFieldDescFeature =
                new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
            poFieldDescFeature->SetField(szLAYER_NAME, GetName());
            m_nMaxFieldIndex = m_poFeatureDefn->GetFieldCount() - 1;
            poFieldDescFeature->SetField(szFIELD_INDEX, m_nMaxFieldIndex);
            poFieldDescFeature->SetField(szFIELD_NAME, oFieldDefn.GetNameRef());
            if (psNode)
            {
                poFieldDescFeature->SetField(szFIELD_TYPE, psNode->pszValue);
            }
            poFieldDescFeature->SetField(szFIELD_IS_LIST, 0);
            poFieldDescFeature->SetField(szFIELD_MIN_OCCURS, 0);
            poFieldDescFeature->SetField(szFIELD_MAX_OCCURS, 1);
            poFieldDescFeature->SetField(szFIELD_CATEGORY, szSWE_FIELD);
            if (psNode)
            {
                char *pszXML = CPLSerializeXMLTree(psNode);
                poFieldDescFeature->SetField(szFIELD_DOCUMENTATION, pszXML);
                CPLFree(pszXML);
            }
            CPL_IGNORE_RET_VAL(
                poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
            delete poFieldDescFeature;
        }
    }
}

/************************************************************************/
/*                   ProcessDataRecordCreateFields()                    */
/************************************************************************/

void OGRGMLASLayer::ProcessDataRecordCreateFields(
    CPLXMLNode *psDataRecord, const std::vector<OGRFeature *> &apoFeatures,
    OGRLayer *poFieldsMetadataLayer)
{
    for (CPLXMLNode *psIter = psDataRecord->psChild; psIter != nullptr;
         psIter = psIter->psNext)
    {
        if (psIter->eType == CXT_Element &&
            strcmp(psIter->pszValue, "field") == 0)
        {
            const char *pszName = CPLGetXMLValue(psIter, "name", "");
            CPLString osName = CPLString(pszName).tolower();
            OGRFieldDefn oFieldDefn(osName, OFTString);
            OGRFieldType eType;
            OGRFieldSubType eSubType;
            CPLXMLNode *psChildNode =
                GetSWEChildAndType(psIter, eType, eSubType);
            oFieldDefn.SetType(eType);
            oFieldDefn.SetSubType(eSubType);
            if (psChildNode != nullptr &&
                m_oMapSWEFieldToOGRFieldName.find(osName) ==
                    m_oMapSWEFieldToOGRFieldName.end())
            {
                const int nValidFields = m_poFeatureDefn->GetFieldCount();

                CPLString osSWEField(osName);
                if (m_poFeatureDefn->GetFieldIndex(osName) >= 0)
                    osName = "swe_field_" + osName;
                m_oMapSWEFieldToOGRFieldName[osSWEField] = osName;
                oFieldDefn.SetName((osName + "_value").c_str());
                m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

                // Register field in _ogr_fields_metadata
                OGRFeature *poFieldDescFeature =
                    new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
                poFieldDescFeature->SetField(szLAYER_NAME, GetName());
                m_nMaxFieldIndex++;
                poFieldDescFeature->SetField(szFIELD_INDEX, m_nMaxFieldIndex);
                poFieldDescFeature->SetField(szFIELD_NAME,
                                             oFieldDefn.GetNameRef());
                poFieldDescFeature->SetField(szFIELD_TYPE,
                                             psChildNode->pszValue);
                poFieldDescFeature->SetField(szFIELD_IS_LIST, 0);
                poFieldDescFeature->SetField(szFIELD_MIN_OCCURS, 0);
                poFieldDescFeature->SetField(szFIELD_MAX_OCCURS, 1);
                poFieldDescFeature->SetField(szFIELD_CATEGORY, szSWE_FIELD);
                {
                    CPLXMLNode *psDupTree = CPLCloneXMLTree(psChildNode);
                    CPLXMLNode *psValue = CPLGetXMLNode(psDupTree, "value");
                    if (psValue != nullptr)
                    {
                        CPLRemoveXMLChild(psDupTree, psValue);
                        CPLDestroyXMLNode(psValue);
                    }
                    char *pszXML = CPLSerializeXMLTree(psDupTree);
                    CPLDestroyXMLNode(psDupTree);
                    poFieldDescFeature->SetField(szFIELD_DOCUMENTATION, pszXML);
                    CPLFree(pszXML);
                }
                CPL_IGNORE_RET_VAL(
                    poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
                delete poFieldDescFeature;

                for (CPLXMLNode *psIter2 = psChildNode->psChild;
                     psIter2 != nullptr; psIter2 = psIter2->psNext)
                {
                    if (psIter2->eType == CXT_Element &&
                        strcmp(psIter2->pszValue, "value") != 0)
                    {
                        const CPLString osName2 =
                            CPLString(osName + "_" + psIter2->pszValue)
                                .tolower();
                        for (CPLXMLNode *psIter3 = psIter2->psChild;
                             psIter3 != nullptr; psIter3 = psIter3->psNext)
                        {
                            if (psIter3->eType == CXT_Attribute)
                            {
                                const char *pszValue = psIter3->pszValue;
                                const char *pszColon = strchr(pszValue, ':');
                                if (pszColon)
                                    pszValue = pszColon + 1;
                                OGRFieldDefn oFieldDefn2(
                                    CPLString(osName2 + "_" + pszValue)
                                        .tolower(),
                                    OFTString);
                                m_poFeatureDefn->AddFieldDefn(&oFieldDefn2);
                            }
                            else if (psIter3->eType == CXT_Text)
                            {
                                OGRFieldDefn oFieldDefn2(osName2, OFTString);
                                m_poFeatureDefn->AddFieldDefn(&oFieldDefn2);
                            }
                        }
                    }
                }

                int *panRemap = static_cast<int *>(
                    CPLMalloc(sizeof(int) * m_poFeatureDefn->GetFieldCount()));
                for (int i = 0; i < m_poFeatureDefn->GetFieldCount(); ++i)
                {
                    if (i < nValidFields)
                        panRemap[i] = i;
                    else
                        panRemap[i] = -1;
                }

                for (size_t i = 0; i < apoFeatures.size(); i++)
                {
                    apoFeatures[i]->RemapFields(nullptr, panRemap);
                }

                CPLFree(panRemap);
            }
        }
    }
}

/************************************************************************/
/*                            SetSWEValue()                             */
/************************************************************************/

static void SetSWEValue(OGRFeature *poFeature, const CPLString &osFieldName,
                        const char *pszValue)
{
    int iField = poFeature->GetDefnRef()->GetFieldIndex(osFieldName);
    const OGRFieldDefn *poFieldDefn = poFeature->GetFieldDefnRef(iField);
    OGRFieldType eType(poFieldDefn->GetType());
    OGRFieldSubType eSubType(poFieldDefn->GetSubType());
    if (eType == OFTInteger && eSubType == OFSTBoolean)
    {
        poFeature->SetField(
            iField, EQUAL(pszValue, "1") || EQUAL(pszValue, "True") ? 1 : 0);
    }
    else
    {
        poFeature->SetField(iField, pszValue);
    }
}

/************************************************************************/
/*                    ProcessDataRecordFillFeature()                    */
/************************************************************************/

void OGRGMLASLayer::ProcessDataRecordFillFeature(CPLXMLNode *psDataRecord,
                                                 OGRFeature *poFeature)
{
    for (CPLXMLNode *psIter = psDataRecord->psChild; psIter != nullptr;
         psIter = psIter->psNext)
    {
        if (psIter->eType == CXT_Element &&
            strcmp(psIter->pszValue, "field") == 0)
        {
            const char *pszName = CPLGetXMLValue(psIter, "name", "");
            CPLString osName = CPLString(pszName).tolower();
            OGRFieldDefn oFieldDefn(osName, OFTString);
            OGRFieldType eType;
            OGRFieldSubType eSubType;
            CPLXMLNode *psChildNode =
                GetSWEChildAndType(psIter, eType, eSubType);
            oFieldDefn.SetType(eType);
            oFieldDefn.SetSubType(eSubType);
            if (psChildNode == nullptr)
                continue;
            const auto oIter = m_oMapSWEFieldToOGRFieldName.find(osName);
            CPLAssert(oIter != m_oMapSWEFieldToOGRFieldName.end());
            osName = oIter->second;
            for (CPLXMLNode *psIter2 = psChildNode->psChild; psIter2 != nullptr;
                 psIter2 = psIter2->psNext)
            {
                if (psIter2->eType == CXT_Element)
                {
                    const CPLString osName2 =
                        CPLString(osName + "_" + psIter2->pszValue).tolower();
                    for (CPLXMLNode *psIter3 = psIter2->psChild;
                         psIter3 != nullptr; psIter3 = psIter3->psNext)
                    {
                        if (psIter3->eType == CXT_Attribute)
                        {
                            const char *pszValue = psIter3->pszValue;
                            const char *pszColon = strchr(pszValue, ':');
                            if (pszColon)
                                pszValue = pszColon + 1;
                            SetSWEValue(
                                poFeature,
                                CPLString(osName2 + "_" + pszValue).tolower(),
                                psIter3->psChild->pszValue);
                        }
                        else if (psIter3->eType == CXT_Text)
                        {
                            SetSWEValue(poFeature, osName2, psIter3->pszValue);
                        }
                    }
                }
            }
        }
    }
}

/************************************************************************/
/*                              PostInit()                              */
/************************************************************************/

void OGRGMLASLayer::PostInit(bool bIncludeGeometryXML)
{
    const std::vector<GMLASField> &oFields = m_oFC.GetFields();

    OGRLayer *poFieldsMetadataLayer = m_poDS->GetFieldsMetadataLayer();
    OGRLayer *poRelationshipsLayer = m_poDS->GetRelationshipsLayer();

    // Is it a junction table ?
    if (!m_oFC.GetParentXPath().empty())
    {
        {
            OGRFieldDefn oFieldDefn(szOCCURRENCE, OFTInteger);
            oFieldDefn.SetNullable(false);
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

            OGRFeature *poFieldDescFeature =
                new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
            poFieldDescFeature->SetField(szLAYER_NAME, GetName());
            poFieldDescFeature->SetField(szFIELD_NAME, oFieldDefn.GetNameRef());
            CPL_IGNORE_RET_VAL(
                poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
            delete poFieldDescFeature;
        }

        {
            OGRFieldDefn oFieldDefn(szPARENT_PKID, OFTString);
            oFieldDefn.SetNullable(false);
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

            OGRFeature *poFieldDescFeature =
                new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
            poFieldDescFeature->SetField(szLAYER_NAME, GetName());
            poFieldDescFeature->SetField(szFIELD_NAME, oFieldDefn.GetNameRef());
            CPL_IGNORE_RET_VAL(
                poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
            delete poFieldDescFeature;
        }
        {
            OGRFieldDefn oFieldDefn(szCHILD_PKID, OFTString);
            oFieldDefn.SetNullable(false);
            m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

            OGRFeature *poFieldDescFeature =
                new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
            poFieldDescFeature->SetField(szLAYER_NAME, GetName());
            poFieldDescFeature->SetField(szFIELD_NAME, oFieldDefn.GetNameRef());
            CPL_IGNORE_RET_VAL(
                poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
            delete poFieldDescFeature;
        }

        return;
    }

    // If we are a child class, then add a field to reference the parent.
    if (m_poParentLayer != nullptr)
    {
        CPLString osFieldName(szPARENT_PREFIX);
        osFieldName += m_poParentLayer->GetLayerDefn()
                           ->GetFieldDefn(m_poParentLayer->GetIDFieldIdx())
                           ->GetNameRef();
        OGRFieldDefn oFieldDefn(osFieldName, OFTString);
        oFieldDefn.SetNullable(false);
        m_nParentIDFieldIdx = m_poFeatureDefn->GetFieldCount();
        m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
    }

    int nFieldIndex = 0;
    for (int i = 0; i < static_cast<int>(oFields.size()); i++)
    {
        OGRGMLASLayer *poRelatedLayer = nullptr;
        const GMLASField &oField(oFields[i]);

        m_oMapFieldXPathToFCFieldIdx[oField.GetXPath()] = i;
        if (oField.IsIgnored())
            continue;

        const GMLASField::Category eCategory(oField.GetCategory());
        if (!oField.GetRelatedClassXPath().empty())
        {
            poRelatedLayer =
                m_poDS->GetLayerByXPath(oField.GetRelatedClassXPath());
            if (poRelatedLayer != nullptr)
            {
                OGRFeature *poRelationshipsFeature =
                    new OGRFeature(poRelationshipsLayer->GetLayerDefn());
                poRelationshipsFeature->SetField(szPARENT_LAYER, GetName());
                poRelationshipsFeature->SetField(
                    szPARENT_PKID, GetLayerDefn()
                                       ->GetFieldDefn(GetIDFieldIdx())
                                       ->GetNameRef());
                if (!oField.GetName().empty())
                {
                    poRelationshipsFeature->SetField(szPARENT_ELEMENT_NAME,
                                                     oField.GetName());
                }
                poRelationshipsFeature->SetField(szCHILD_LAYER,
                                                 poRelatedLayer->GetName());
                if (eCategory ==
                        GMLASField::PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE ||
                    eCategory == GMLASField::PATH_TO_CHILD_ELEMENT_WITH_LINK)
                {
                    poRelationshipsFeature->SetField(
                        szCHILD_PKID,
                        poRelatedLayer->GetLayerDefn()
                            ->GetFieldDefn(poRelatedLayer->GetIDFieldIdx())
                            ->GetNameRef());
                }
                else
                {
                    CPLAssert(eCategory ==
                                  GMLASField::PATH_TO_CHILD_ELEMENT_NO_LINK ||
                              eCategory == GMLASField::GROUP);

                    poRelationshipsFeature->SetField(
                        szCHILD_PKID, (CPLString(szPARENT_PREFIX) +
                                       GetLayerDefn()
                                           ->GetFieldDefn(GetIDFieldIdx())
                                           ->GetNameRef())
                                          .c_str());
                }
                CPL_IGNORE_RET_VAL(poRelationshipsLayer->CreateFeature(
                    poRelationshipsFeature));
                delete poRelationshipsFeature;
            }
            else
            {
                CPLDebug("GMLAS", "Cannot find class matching %s",
                         oField.GetRelatedClassXPath().c_str());
            }
        }

        OGRFeature *poFieldDescFeature =
            new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
        poFieldDescFeature->SetField(szLAYER_NAME, GetName());

        ++nFieldIndex;
        m_nMaxFieldIndex = nFieldIndex;
        poFieldDescFeature->SetField(szFIELD_INDEX, nFieldIndex);

        if (oField.GetName().empty())
        {
            CPLAssert(eCategory == GMLASField::PATH_TO_CHILD_ELEMENT_NO_LINK ||
                      eCategory == GMLASField::GROUP);
        }
        else
        {
            poFieldDescFeature->SetField(szFIELD_NAME,
                                         oField.GetName().c_str());
        }
        if (!oField.GetXPath().empty())
        {
            poFieldDescFeature->SetField(szFIELD_XPATH,
                                         oField.GetXPath().c_str());
        }
        else if (!oField.GetAlternateXPaths().empty())
        {
            CPLString osXPath;
            const std::vector<CPLString> &aoXPaths =
                oField.GetAlternateXPaths();
            for (size_t j = 0; j < aoXPaths.size(); j++)
            {
                if (j != 0)
                    osXPath += ",";
                osXPath += aoXPaths[j];
            }
            poFieldDescFeature->SetField(szFIELD_XPATH, osXPath.c_str());
        }
        if (oField.GetTypeName().empty())
        {
            CPLAssert(
                eCategory == GMLASField::PATH_TO_CHILD_ELEMENT_NO_LINK ||
                eCategory ==
                    GMLASField::PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE ||
                eCategory == GMLASField::GROUP);
        }
        else
        {
            poFieldDescFeature->SetField(szFIELD_TYPE,
                                         oField.GetTypeName().c_str());
        }
        poFieldDescFeature->SetField(szFIELD_IS_LIST,
                                     static_cast<int>(oField.IsList()));
        if (oField.GetMinOccurs() != -1)
        {
            poFieldDescFeature->SetField(szFIELD_MIN_OCCURS,
                                         oField.GetMinOccurs());
        }
        if (oField.GetMaxOccurs() == MAXOCCURS_UNLIMITED)
        {
            poFieldDescFeature->SetField(szFIELD_MAX_OCCURS, INT_MAX);
        }
        else if (oField.GetMaxOccurs() != -1)
        {
            poFieldDescFeature->SetField(szFIELD_MAX_OCCURS,
                                         oField.GetMaxOccurs());
        }
        if (oField.GetMaxOccurs() == MAXOCCURS_UNLIMITED ||
            oField.GetMaxOccurs() > 1)
        {
            poFieldDescFeature->SetField(szFIELD_REPETITION_ON_SEQUENCE,
                                         oField.GetRepetitionOnSequence() ? 1
                                                                          : 0);
        }
        if (!oField.GetFixedValue().empty())
        {
            poFieldDescFeature->SetField(szFIELD_FIXED_VALUE,
                                         oField.GetFixedValue());
        }
        if (!oField.GetDefaultValue().empty())
        {
            poFieldDescFeature->SetField(szFIELD_DEFAULT_VALUE,
                                         oField.GetDefaultValue());
        }
        switch (eCategory)
        {
            case GMLASField::REGULAR:
                poFieldDescFeature->SetField(szFIELD_CATEGORY, szREGULAR);
                break;
            case GMLASField::PATH_TO_CHILD_ELEMENT_NO_LINK:
                poFieldDescFeature->SetField(szFIELD_CATEGORY,
                                             szPATH_TO_CHILD_ELEMENT_NO_LINK);
                break;
            case GMLASField::PATH_TO_CHILD_ELEMENT_WITH_LINK:
                poFieldDescFeature->SetField(szFIELD_CATEGORY,
                                             szPATH_TO_CHILD_ELEMENT_WITH_LINK);
                break;
            case GMLASField::PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE:
                poFieldDescFeature->SetField(
                    szFIELD_CATEGORY,
                    szPATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE);
                break;
            case GMLASField::GROUP:
                poFieldDescFeature->SetField(szFIELD_CATEGORY, szGROUP);
                break;
            default:
                CPLAssert(FALSE);
                break;
        }
        if (poRelatedLayer != nullptr)
        {
            poFieldDescFeature->SetField(szFIELD_RELATED_LAYER,
                                         poRelatedLayer->GetName());
        }

        if (eCategory == GMLASField::PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE)
        {
            const CPLString &osAbstractElementXPath(
                oField.GetAbstractElementXPath());
            const CPLString &osNestedXPath(oField.GetRelatedClassXPath());
            CPLAssert(!osAbstractElementXPath.empty());
            CPLAssert(!osNestedXPath.empty());

            OGRGMLASLayer *poJunctionLayer = m_poDS->GetLayerByXPath(
                osAbstractElementXPath + "|" + osNestedXPath);
            if (poJunctionLayer != nullptr)
            {
                poFieldDescFeature->SetField(szFIELD_JUNCTION_LAYER,
                                             poJunctionLayer->GetName());
            }
        }

        if (!oField.GetDocumentation().empty())
        {
            poFieldDescFeature->SetField(szFIELD_DOCUMENTATION,
                                         oField.GetDocumentation());
        }

        CPL_IGNORE_RET_VAL(
            poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
        delete poFieldDescFeature;

        // Check whether the field is OGR instanciable
        if (eCategory == GMLASField::PATH_TO_CHILD_ELEMENT_NO_LINK ||
            eCategory ==
                GMLASField::PATH_TO_CHILD_ELEMENT_WITH_JUNCTION_TABLE ||
            eCategory == GMLASField::GROUP)
        {
            continue;
        }

        OGRFieldType eType = OFTString;
        OGRFieldSubType eSubType = OFSTNone;
        CPLString osOGRFieldName(oField.GetName());
        switch (oField.GetType())
        {
            case GMLAS_FT_STRING:
                eType = OFTString;
                break;
            case GMLAS_FT_ID:
            {
                eType = OFTString;
                if (oField.IsNotNullable())
                {
                    continue;
                }
                break;
            }
            case GMLAS_FT_BOOLEAN:
                eType = OFTInteger;
                eSubType = OFSTBoolean;
                break;
            case GMLAS_FT_SHORT:
                eType = OFTInteger;
                eSubType = OFSTInt16;
                break;
            case GMLAS_FT_INT32:
                eType = OFTInteger;
                break;
            case GMLAS_FT_INT64:
                eType = OFTInteger64;
                break;
            case GMLAS_FT_FLOAT:
                eType = OFTReal;
                eSubType = OFSTFloat32;
                break;
            case GMLAS_FT_DOUBLE:
                eType = OFTReal;
                break;
            case GMLAS_FT_DECIMAL:
                eType = OFTReal;
                break;
            case GMLAS_FT_DATE:
                eType = OFTDate;
                break;
            case GMLAS_FT_GYEAR:
                eType = OFTInteger;
                break;
            case GMLAS_FT_GYEAR_MONTH:
                eType = OFTDate;
                break;
            case GMLAS_FT_TIME:
                eType = OFTTime;
                break;
            case GMLAS_FT_DATETIME:
                eType = OFTDateTime;
                break;
            case GMLAS_FT_BASE64BINARY:
            case GMLAS_FT_HEXBINARY:
                eType = OFTBinary;
                break;
            case GMLAS_FT_ANYURI:
                eType = OFTString;
                break;
            case GMLAS_FT_ANYTYPE:
                eType = OFTString;
                break;
            case GMLAS_FT_ANYSIMPLETYPE:
                eType = OFTString;
                break;
            case GMLAS_FT_GEOMETRY:
            {
                // Create a geometry field
                OGRGeomFieldDefn oGeomFieldDefn(osOGRFieldName,
                                                oField.GetGeomType());
                m_poFeatureDefn->AddGeomFieldDefn(&oGeomFieldDefn);

                const int iOGRGeomIdx =
                    m_poFeatureDefn->GetGeomFieldCount() - 1;
                if (!oField.GetXPath().empty())
                {
                    m_oMapFieldXPathToOGRGeomFieldIdx[oField.GetXPath()] =
                        iOGRGeomIdx;
                }
                else
                {
                    const std::vector<CPLString> &aoXPaths =
                        oField.GetAlternateXPaths();
                    for (size_t j = 0; j < aoXPaths.size(); j++)
                    {
                        m_oMapFieldXPathToOGRGeomFieldIdx[aoXPaths[j]] =
                            iOGRGeomIdx;
                    }
                }

                m_oMapOGRGeomFieldIdxtoFCFieldIdx[iOGRGeomIdx] = i;

                // Suffix the regular non-geometry field
                osOGRFieldName += szXML_SUFFIX;
                eType = OFTString;
                break;
            }
            default:
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Unhandled type in enum: %d", oField.GetType());
                break;
        }

        if (oField.GetType() == GMLAS_FT_GEOMETRY && !bIncludeGeometryXML)
        {
            continue;
        }

        if (oField.IsArray())
        {
            switch (eType)
            {
                case OFTString:
                    eType = OFTStringList;
                    break;
                case OFTInteger:
                    eType = OFTIntegerList;
                    break;
                case OFTInteger64:
                    eType = OFTInteger64List;
                    break;
                case OFTReal:
                    eType = OFTRealList;
                    break;
                default:
                    CPLError(CE_Warning, CPLE_AppDefined,
                             "Unhandled type in enum: %d", eType);
                    break;
            }
        }
        OGRFieldDefn oFieldDefn(osOGRFieldName, eType);
        oFieldDefn.SetSubType(eSubType);
        if (oField.IsNotNullable())
            oFieldDefn.SetNullable(false);
        CPLString osDefaultOrFixed = oField.GetDefaultValue();
        if (osDefaultOrFixed.empty())
            osDefaultOrFixed = oField.GetFixedValue();
        if (!osDefaultOrFixed.empty())
        {
            char *pszEscaped = CPLEscapeString(osDefaultOrFixed, -1, CPLES_SQL);
            oFieldDefn.SetDefault(
                (CPLString("'") + pszEscaped + CPLString("'")).c_str());
            CPLFree(pszEscaped);
        }
        oFieldDefn.SetWidth(oField.GetWidth());
        m_poFeatureDefn->AddFieldDefn(&oFieldDefn);

        const int iOGRIdx = m_poFeatureDefn->GetFieldCount() - 1;
        if (!oField.GetXPath().empty())
        {
            m_oMapFieldXPathToOGRFieldIdx[oField.GetXPath()] = iOGRIdx;
        }
        else
        {
            const std::vector<CPLString> &aoXPaths =
                oField.GetAlternateXPaths();
            for (size_t j = 0; j < aoXPaths.size(); j++)
            {
                m_oMapFieldXPathToOGRFieldIdx[aoXPaths[j]] = iOGRIdx;
            }
        }

        m_oMapOGRFieldIdxtoFCFieldIdx[iOGRIdx] = i;

        // Create field to receive resolved xlink:href content, if needed
        if (oField.GetXPath().find(szAT_XLINK_HREF) != std::string::npos &&
            m_poDS->GetConf().m_oXLinkResolution.m_bDefaultResolutionEnabled &&
            m_poDS->GetConf().m_oXLinkResolution.m_eDefaultResolutionMode ==
                GMLASXLinkResolutionConf::RawContent)
        {
            CPLString osRawContentFieldname(osOGRFieldName);
            size_t nPos = osRawContentFieldname.find(szHREF_SUFFIX);
            if (nPos != std::string::npos)
                osRawContentFieldname.resize(nPos);
            osRawContentFieldname += szRAW_CONTENT_SUFFIX;
            OGRFieldDefn oFieldDefnRaw(osRawContentFieldname, OFTString);
            m_poFeatureDefn->AddFieldDefn(&oFieldDefnRaw);

            m_oMapFieldXPathToOGRFieldIdx
                [GMLASField::MakeXLinkRawContentFieldXPathFromXLinkHrefXPath(
                    oField.GetXPath())] = m_poFeatureDefn->GetFieldCount() - 1;
        }

        CPL_IGNORE_RET_VAL(osOGRFieldName);
    }

    CreateCompoundFoldedMappings();
}

/************************************************************************/
/*                    CreateCompoundFoldedMappings()                    */
/************************************************************************/

// In the case we have nested elements but we managed to fold into top
// level class, then register intermediate paths so they are not reported
// as unexpected in debug traces
void OGRGMLASLayer::CreateCompoundFoldedMappings()
{
    CPLString oFCXPath(m_oFC.GetXPath());
    if (m_oFC.IsRepeatedSequence())
    {
        size_t iPosExtra = oFCXPath.find(szEXTRA_SUFFIX);
        if (iPosExtra != std::string::npos)
        {
            oFCXPath.resize(iPosExtra);
        }
    }

    const std::vector<GMLASField> &oFields = m_oFC.GetFields();
    for (size_t i = 0; i < oFields.size(); i++)
    {
        std::vector<CPLString> aoXPaths = oFields[i].GetAlternateXPaths();
        if (aoXPaths.empty())
            aoXPaths.push_back(oFields[i].GetXPath());
        for (size_t j = 0; j < aoXPaths.size(); j++)
        {
            if (aoXPaths[j].size() > oFCXPath.size())
            {
                // Split on both '/' and '@'
                char **papszTokens = CSLTokenizeString2(
                    aoXPaths[j].c_str() + oFCXPath.size() + 1, "/@", 0);
                CPLString osSubXPath = oFCXPath;
                for (int k = 0;
                     papszTokens[k] != nullptr && papszTokens[k + 1] != nullptr;
                     k++)
                {
                    osSubXPath += "/";
                    osSubXPath += papszTokens[k];
                    if (m_oMapFieldXPathToOGRFieldIdx.find(osSubXPath) ==
                        m_oMapFieldXPathToOGRFieldIdx.end())
                    {
                        m_oMapFieldXPathToOGRFieldIdx[osSubXPath] =
                            IDX_COMPOUND_FOLDED;
                    }
                }
                CSLDestroy(papszTokens);
            }
        }
    }
}

/************************************************************************/
/*                           ~OGRGMLASLayer()                           */
/************************************************************************/

OGRGMLASLayer::~OGRGMLASLayer()
{
    m_poFeatureDefn->Release();
}

/************************************************************************/
/*                         DeleteTargetIndex()                          */
/************************************************************************/

static void DeleteTargetIndex(std::map<CPLString, int> &oMap, int nIdx)
{
    bool bIterToRemoveValid = false;
    std::map<CPLString, int>::iterator oIterToRemove;
    std::map<CPLString, int>::iterator oIter = oMap.begin();
    for (; oIter != oMap.end(); ++oIter)
    {
        if (oIter->second > nIdx)
            oIter->second--;
        else if (oIter->second == nIdx)
        {
            bIterToRemoveValid = true;
            oIterToRemove = oIter;
        }
    }
    if (bIterToRemoveValid)
        oMap.erase(oIterToRemove);
}

/************************************************************************/
/*                            RemoveField()                             */
/************************************************************************/

bool OGRGMLASLayer::RemoveField(int nIdx)
{
    if (nIdx == m_nIDFieldIdx || nIdx == m_nParentIDFieldIdx)
        return false;

    m_poFeatureDefn->DeleteFieldDefn(nIdx);

    // Refresh maps
    DeleteTargetIndex(m_oMapFieldXPathToOGRFieldIdx, nIdx);

    {
        std::map<int, int> oMapOGRFieldIdxtoFCFieldIdx;
        for (const auto &oIter : m_oMapOGRFieldIdxtoFCFieldIdx)
        {
            if (oIter.first < nIdx)
                oMapOGRFieldIdxtoFCFieldIdx[oIter.first] = oIter.second;
            else if (oIter.first > nIdx)
                oMapOGRFieldIdxtoFCFieldIdx[oIter.first - 1] = oIter.second;
        }
        m_oMapOGRFieldIdxtoFCFieldIdx = std::move(oMapOGRFieldIdxtoFCFieldIdx);
    }

    OGRLayer *poFieldsMetadataLayer = m_poDS->GetFieldsMetadataLayer();
    OGRFeature *poFeature;
    poFieldsMetadataLayer->ResetReading();
    while ((poFeature = poFieldsMetadataLayer->GetNextFeature()) != nullptr)
    {
        if (strcmp(poFeature->GetFieldAsString(szLAYER_NAME), GetName()) == 0 &&
            poFeature->GetFieldAsInteger(szFIELD_INDEX) == nIdx)
        {
            poFeature->SetField(szFIELD_INDEX, -1);
            CPL_IGNORE_RET_VAL(poFieldsMetadataLayer->SetFeature(poFeature));
            delete poFeature;
            break;
        }
        delete poFeature;
    }
    poFieldsMetadataLayer->ResetReading();

    return true;
}

/************************************************************************/
/*                         InsertTargetIndex()                          */
/************************************************************************/

static void InsertTargetIndex(std::map<CPLString, int> &oMap, int nIdx)
{
    for (auto &oIter : oMap)
    {
        if (oIter.second >= nIdx)
            oIter.second++;
    }
}

/************************************************************************/
/*                           InsertNewField()                           */
/************************************************************************/

void OGRGMLASLayer::InsertNewField(int nInsertPos,
                                   const OGRFieldDefn &oFieldDefn,
                                   const CPLString &osXPath)
{
    CPLAssert(nInsertPos >= 0 &&
              nInsertPos <= m_poFeatureDefn->GetFieldCount());
    m_poFeatureDefn->AddFieldDefn(&oFieldDefn);
    int *panMap = new int[m_poFeatureDefn->GetFieldCount()];
    for (int i = 0; i < nInsertPos; ++i)
    {
        panMap[i] = i;
    }
    panMap[nInsertPos] = m_poFeatureDefn->GetFieldCount() - 1;
    for (int i = nInsertPos + 1; i < m_poFeatureDefn->GetFieldCount(); ++i)
    {
        panMap[i] = i - 1;
    }
    m_poFeatureDefn->ReorderFieldDefns(panMap);
    delete[] panMap;

    // Refresh maps
    InsertTargetIndex(m_oMapFieldXPathToOGRFieldIdx, nInsertPos);
    m_oMapFieldXPathToOGRFieldIdx[osXPath] = nInsertPos;

    {
        std::map<int, int> oMapOGRFieldIdxtoFCFieldIdx;
        for (const auto &oIter : m_oMapOGRFieldIdxtoFCFieldIdx)
        {
            if (oIter.first < nInsertPos)
                oMapOGRFieldIdxtoFCFieldIdx[oIter.first] = oIter.second;
            else
                oMapOGRFieldIdxtoFCFieldIdx[oIter.first + 1] = oIter.second;
        }
        m_oMapOGRFieldIdxtoFCFieldIdx = std::move(oMapOGRFieldIdxtoFCFieldIdx);
    }

    OGRLayer *poFieldsMetadataLayer = m_poDS->GetFieldsMetadataLayer();
    OGRFeature *poFeature;
    poFieldsMetadataLayer->ResetReading();
    while ((poFeature = poFieldsMetadataLayer->GetNextFeature()) != nullptr)
    {
        if (strcmp(poFeature->GetFieldAsString(szLAYER_NAME), GetName()) == 0)
        {
            int nFieldIndex = poFeature->GetFieldAsInteger(szFIELD_INDEX);
            if (nFieldIndex >= nInsertPos && nFieldIndex < INT_MAX)
            {
                poFeature->SetField(szFIELD_INDEX, nFieldIndex + 1);
                CPL_IGNORE_RET_VAL(
                    poFieldsMetadataLayer->SetFeature(poFeature));
            }
        }
        delete poFeature;
    }
    poFieldsMetadataLayer->ResetReading();
}

/************************************************************************/
/*                     GetOGRFieldIndexFromXPath()                      */
/************************************************************************/

int OGRGMLASLayer::GetOGRFieldIndexFromXPath(const CPLString &osXPath) const
{
    const auto oIter = m_oMapFieldXPathToOGRFieldIdx.find(osXPath);
    if (oIter == m_oMapFieldXPathToOGRFieldIdx.end())
        return -1;
    return oIter->second;
}

/************************************************************************/
/*                     GetXPathFromOGRFieldIndex()                      */
/************************************************************************/

CPLString OGRGMLASLayer::GetXPathFromOGRFieldIndex(int nIdx) const
{
    const int nFCIdx = GetFCFieldIndexFromOGRFieldIdx(nIdx);
    if (nFCIdx >= 0)
        return m_oFC.GetFields()[nFCIdx].GetXPath();

    for (const auto &oIter : m_oMapFieldXPathToOGRFieldIdx)
    {
        if (oIter.second == nIdx)
            return oIter.first;
    }
    return CPLString();
}

/************************************************************************/
/*                   GetOGRGeomFieldIndexFromXPath()                    */
/************************************************************************/

int OGRGMLASLayer::GetOGRGeomFieldIndexFromXPath(const CPLString &osXPath) const
{
    const auto oIter = m_oMapFieldXPathToOGRGeomFieldIdx.find(osXPath);
    if (oIter == m_oMapFieldXPathToOGRGeomFieldIdx.end())
        return -1;
    return oIter->second;
}

/************************************************************************/
/*                   GetFCFieldIndexFromOGRFieldIdx()                   */
/************************************************************************/

int OGRGMLASLayer::GetFCFieldIndexFromOGRFieldIdx(int iOGRFieldIdx) const
{
    const auto oIter = m_oMapOGRFieldIdxtoFCFieldIdx.find(iOGRFieldIdx);
    if (oIter == m_oMapOGRFieldIdxtoFCFieldIdx.end())
        return -1;
    return oIter->second;
}

/************************************************************************/
/*                      GetFCFieldIndexFromXPath()                      */
/************************************************************************/

int OGRGMLASLayer::GetFCFieldIndexFromXPath(const CPLString &osXPath) const
{
    const auto oIter = m_oMapFieldXPathToFCFieldIdx.find(osXPath);
    if (oIter == m_oMapFieldXPathToFCFieldIdx.end())
        return -1;
    return oIter->second;
}

/************************************************************************/
/*                 GetFCFieldIndexFromOGRGeomFieldIdx()                 */
/************************************************************************/

int OGRGMLASLayer::GetFCFieldIndexFromOGRGeomFieldIdx(
    int iOGRGeomFieldIdx) const
{
    const auto oIter = m_oMapOGRGeomFieldIdxtoFCFieldIdx.find(iOGRGeomFieldIdx);
    if (oIter == m_oMapOGRGeomFieldIdxtoFCFieldIdx.end())
        return -1;
    return oIter->second;
}

/************************************************************************/
/*               GetXPathOfFieldLinkForAttrToOtherLayer()               */
/************************************************************************/

CPLString OGRGMLASLayer::GetXPathOfFieldLinkForAttrToOtherLayer(
    const CPLString &osFieldName, const CPLString &osTargetLayerXPath)
{
    const int nOGRFieldIdx = GetLayerDefn()->GetFieldIndex(osFieldName);
    CPLAssert(nOGRFieldIdx >= 0);
    const int nFCFieldIdx = GetFCFieldIndexFromOGRFieldIdx(nOGRFieldIdx);
    CPLAssert(nFCFieldIdx >= 0);
    CPLString osXPath(m_oFC.GetFields()[nFCFieldIdx].GetXPath());
    size_t nPos = osXPath.find(szAT_XLINK_HREF);
    CPLAssert(nPos != std::string::npos);
    CPLAssert(nPos + strlen(szAT_XLINK_HREF) == osXPath.size());
    CPLString osTargetFieldXPath(osXPath.substr(0, nPos) + osTargetLayerXPath);
    return osTargetFieldXPath;
}

/************************************************************************/
/*                          LaunderFieldName()                          */
/************************************************************************/

CPLString OGRGMLASLayer::LaunderFieldName(const CPLString &osFieldName)
{
    int nCounter = 1;
    CPLString osLaunderedName(osFieldName);
    while (m_poFeatureDefn->GetFieldIndex(osLaunderedName) >= 0)
    {
        nCounter++;
        osLaunderedName = osFieldName + CPLSPrintf("%d", nCounter);
    }

    const int nIdentifierMaxLength = m_poDS->GetConf().m_nIdentifierMaxLength;
    if (nIdentifierMaxLength >= MIN_VALUE_OF_MAX_IDENTIFIER_LENGTH &&
        osLaunderedName.size() > static_cast<size_t>(nIdentifierMaxLength))
    {
        osLaunderedName =
            OGRGMLASTruncateIdentifier(osLaunderedName, nIdentifierMaxLength);
    }

    if (m_poDS->GetConf().m_bPGIdentifierLaundering)
    {
        char *pszLaundered =
            OGRPGCommonLaunderName(osLaunderedName, "GMLAS", false);
        osLaunderedName = pszLaundered;
        CPLFree(pszLaundered);
    }

    if (m_poFeatureDefn->GetFieldIndex(osLaunderedName) >= 0)
    {
        nCounter = 1;
        std::string osCandidate;
        do
        {
            nCounter++;
            osCandidate = OGRGMLASAddSerialNumber(
                osLaunderedName, nCounter, nCounter + 1, nIdentifierMaxLength);
        } while (nCounter < 100 &&
                 m_poFeatureDefn->GetFieldIndex(osCandidate.c_str()) >= 0);
        osLaunderedName = std::move(osCandidate);
    }

    return osLaunderedName;
}

/************************************************************************/
/*                   CreateLinkForAttrToOtherLayer()                    */
/************************************************************************/

/* Create a new field to contain the PKID of the feature pointed by this */
/* osFieldName (a xlink:href attribute), when it is an internal link to */
/* another layer whose xpath is given by osTargetLayerXPath */

CPLString OGRGMLASLayer::CreateLinkForAttrToOtherLayer(
    const CPLString &osFieldName, const CPLString &osTargetLayerXPath)
{
    CPLString osTargetFieldXPath =
        GetXPathOfFieldLinkForAttrToOtherLayer(osFieldName, osTargetLayerXPath);
    const int nExistingTgtOGRFieldIdx =
        GetOGRFieldIndexFromXPath(osTargetFieldXPath);
    if (nExistingTgtOGRFieldIdx >= 0)
    {
        return GetLayerDefn()
            ->GetFieldDefn(nExistingTgtOGRFieldIdx)
            ->GetNameRef();
    }

    const int nOGRFieldIdx = GetLayerDefn()->GetFieldIndex(osFieldName);
    CPLAssert(nOGRFieldIdx >= 0);
    const int nFCFieldIdx = GetFCFieldIndexFromOGRFieldIdx(nOGRFieldIdx);
    CPLAssert(nFCFieldIdx >= 0);
    CPLString osXPath(m_oFC.GetFields()[nFCFieldIdx].GetXPath());
    size_t nPos = osXPath.find(szAT_XLINK_HREF);
    CPLString osXPathStart(osXPath.substr(0, nPos));

    // Find at which position to insert the new field in the layer definition
    // (we could happen at the end, but it will be nicer to insert close to
    // the href field)
    int nInsertPos = -1;
    for (int i = 0; i < m_poFeatureDefn->GetFieldCount(); i++)
    {
        if (GetXPathFromOGRFieldIndex(i).find(osXPathStart) == 0)
        {
            nInsertPos = i + 1;
        }
        else if (nInsertPos >= 0)
            break;
    }

    CPLString osNewFieldName(osFieldName);
    nPos = osFieldName.find(szHREF_SUFFIX);
    if (nPos != std::string::npos)
    {
        osNewFieldName.resize(nPos);
    }
    osNewFieldName += "_";
    OGRGMLASLayer *poTargetLayer = m_poDS->GetLayerByXPath(osTargetLayerXPath);
    CPLAssert(poTargetLayer);
    osNewFieldName += poTargetLayer->GetName();
    osNewFieldName += "_pkid";
    osNewFieldName = LaunderFieldName(osNewFieldName);
    OGRFieldDefn oFieldDefn(osNewFieldName, OFTString);
    InsertNewField(nInsertPos, oFieldDefn, osTargetFieldXPath);

    OGRLayer *poFieldsMetadataLayer = m_poDS->GetFieldsMetadataLayer();
    OGRLayer *poRelationshipsLayer = m_poDS->GetRelationshipsLayer();

    // Find a relevant location of the field metadata layer into which to
    // insert the new feature (same as above, we could potentially insert just
    // at the end)
    GIntBig nFieldsMetadataIdxPos = -1;
    poFieldsMetadataLayer->ResetReading();
    OGRFeature *poFeature;
    while ((poFeature = poFieldsMetadataLayer->GetNextFeature()) != nullptr)
    {
        if (strcmp(poFeature->GetFieldAsString(szLAYER_NAME), GetName()) == 0)
        {
            if (poFeature->GetFieldAsInteger(szFIELD_INDEX) > nInsertPos)
            {
                delete poFeature;
                break;
            }
            nFieldsMetadataIdxPos = poFeature->GetFID() + 1;
        }
        else if (nFieldsMetadataIdxPos >= 0)
        {
            delete poFeature;
            break;
        }
        delete poFeature;
    }
    poFieldsMetadataLayer->ResetReading();

    // Move down all features beyond that insertion point
    for (GIntBig nFID = poFieldsMetadataLayer->GetFeatureCount() - 1;
         nFID >= nFieldsMetadataIdxPos; nFID--)
    {
        poFeature = poFieldsMetadataLayer->GetFeature(nFID);
        if (poFeature)
        {
            poFeature->SetFID(nFID + 1);
            CPL_IGNORE_RET_VAL(poFieldsMetadataLayer->SetFeature(poFeature));
            delete poFeature;
        }
    }
    if (nFieldsMetadataIdxPos >= 0)
    {
        CPL_IGNORE_RET_VAL(
            poFieldsMetadataLayer->DeleteFeature(nFieldsMetadataIdxPos));
    }

    // Register field in _ogr_fields_metadata
    OGRFeature *poFieldDescFeature =
        new OGRFeature(poFieldsMetadataLayer->GetLayerDefn());
    poFieldDescFeature->SetField(szLAYER_NAME, GetName());
    poFieldDescFeature->SetField(szFIELD_INDEX, nInsertPos);
    poFieldDescFeature->SetField(szFIELD_XPATH, osTargetFieldXPath);
    poFieldDescFeature->SetField(szFIELD_NAME, oFieldDefn.GetNameRef());
    poFieldDescFeature->SetField(szFIELD_TYPE, szXS_STRING);
    poFieldDescFeature->SetField(szFIELD_IS_LIST, 0);
    poFieldDescFeature->SetField(szFIELD_MIN_OCCURS, 0);
    poFieldDescFeature->SetField(szFIELD_MAX_OCCURS, 1);
    poFieldDescFeature->SetField(szFIELD_CATEGORY,
                                 szPATH_TO_CHILD_ELEMENT_WITH_LINK);
    poFieldDescFeature->SetField(szFIELD_RELATED_LAYER,
                                 poTargetLayer->GetName());
    if (nFieldsMetadataIdxPos >= 0)
        poFieldDescFeature->SetFID(nFieldsMetadataIdxPos);
    CPL_IGNORE_RET_VAL(
        poFieldsMetadataLayer->CreateFeature(poFieldDescFeature));
    delete poFieldDescFeature;

    // Register relationship in _ogr_layer_relationships
    OGRFeature *poRelationshipsFeature =
        new OGRFeature(poRelationshipsLayer->GetLayerDefn());
    poRelationshipsFeature->SetField(szPARENT_LAYER, GetName());
    poRelationshipsFeature->SetField(
        szPARENT_PKID,
        GetLayerDefn()->GetFieldDefn(GetIDFieldIdx())->GetNameRef());
    poRelationshipsFeature->SetField(szPARENT_ELEMENT_NAME, osNewFieldName);
    poRelationshipsFeature->SetField(szCHILD_LAYER, poTargetLayer->GetName());
    poRelationshipsFeature->SetField(
        szCHILD_PKID, poTargetLayer->GetLayerDefn()
                          ->GetFieldDefn(poTargetLayer->GetIDFieldIdx())
                          ->GetNameRef());
    CPL_IGNORE_RET_VAL(
        poRelationshipsLayer->CreateFeature(poRelationshipsFeature));
    delete poRelationshipsFeature;

    return osNewFieldName;
}

/************************************************************************/
/*                            GetLayerDefn()                            */
/************************************************************************/

const OGRFeatureDefn *OGRGMLASLayer::GetLayerDefn() const
{
    if (!m_bLayerDefnFinalized && m_poDS->IsLayerInitFinished())
    {
        // If we haven't yet determined the SRS of geometry columns, do it now
        m_bLayerDefnFinalized = true;
        if (m_poFeatureDefn->GetGeomFieldCount() > 0 ||
            m_poDS->GetConf().m_oXLinkResolution.m_bResolveInternalXLinks ||
            !m_poDS->GetConf().m_oXLinkResolution.m_aoURLSpecificRules.empty())
        {
            if (m_poReader == nullptr)
            {
                const_cast<OGRGMLASLayer *>(this)->InitReader();
                // Avoid keeping too many file descriptor opened
                if (m_fpGML != nullptr)
                    m_poDS->PushUnusedGMLFilePointer(
                        const_cast<std::shared_ptr<VSIVirtualHandle> &>(
                            m_fpGML));
                const_cast<OGRGMLASLayer *>(this)->m_poReader.reset();
            }
        }
    }
    return m_poFeatureDefn;
}

/************************************************************************/
/*                            ResetReading()                            */
/************************************************************************/

void OGRGMLASLayer::ResetReading()
{
    m_poReader.reset();
    m_bEOF = false;
}

/************************************************************************/
/*                             InitReader()                             */
/************************************************************************/

bool OGRGMLASLayer::InitReader()
{
    CPLAssert(m_poReader == nullptr);

    m_bLayerDefnFinalized = true;
    m_poReader.reset(m_poDS->CreateReader(m_fpGML));
    if (m_poReader != nullptr)
    {
        m_poReader->SetLayerOfInterest(this);
        return true;
    }
    return false;
}

/************************************************************************/
/*                         GetNextRawFeature()                          */
/************************************************************************/

OGRFeature *OGRGMLASLayer::GetNextRawFeature()
{
    if (m_poReader == nullptr && !InitReader())
        return nullptr;

    return m_poReader->GetNextFeature();
}

/************************************************************************/
/*                           EvaluateFilter()                           */
/************************************************************************/

bool OGRGMLASLayer::EvaluateFilter(OGRFeature *poFeature)
{
    return (m_poFilterGeom == nullptr ||
            FilterGeometry(poFeature->GetGeomFieldRef(m_iGeomFieldFilter))) &&
           (m_poAttrQuery == nullptr || m_poAttrQuery->Evaluate(poFeature));
}

/************************************************************************/
/*                           GetNextFeature()                           */
/************************************************************************/

OGRFeature *OGRGMLASLayer::GetNextFeature()
{
    if (m_bEOF)
        return nullptr;

    while (true)
    {
        OGRFeature *poFeature = GetNextRawFeature();
        if (poFeature == nullptr)
        {
            // Avoid keeping too many file descriptor opened
            if (m_fpGML != nullptr)
                m_poDS->PushUnusedGMLFilePointer(m_fpGML);
            m_poReader.reset();
            m_bEOF = true;
            return nullptr;
        }

        if (EvaluateFilter(poFeature))
        {
            return poFeature;
        }

        delete poFeature;
    }
}
