/******************************************************************************
 *
 * Project:  XLSX Translator
 * Purpose:  Implements OGRXLSXDataSource class
 * Author:   Even Rouault, even dot rouault at spatialys.com
 *
 ******************************************************************************
 * Copyright (c) 2012-2014, Even Rouault <even dot rouault at spatialys.com>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 ****************************************************************************/

#include "ogr_xlsx.h"
#include "ogr_p.h"
#include "cpl_conv.h"
#include "cpl_time.h"
#include "cpl_vsi_error.h"

#include <algorithm>

CPL_CVSID("$Id$")

namespace OGRXLSX {

constexpr int NUMBER_OF_DAYS_BETWEEN_1900_AND_1970 = 25569;
constexpr int NUMBER_OF_SECONDS_PER_DAY = 86400;

/************************************************************************/
/*                            OGRXLSXLayer()                            */
/************************************************************************/

OGRXLSXLayer::OGRXLSXLayer( OGRXLSXDataSource* poDSIn,
                            const char * pszFilename,
                            const char * pszName,
                            int bUpdatedIn ) :
    OGRMemLayer(pszName, nullptr, wkbNone),
    bInit(CPL_TO_BOOL(bUpdatedIn)),
    poDS(poDSIn),
    osFilename(pszFilename),
    bUpdated(CPL_TO_BOOL(bUpdatedIn)),
    bHasHeaderLine(false)
{}

/************************************************************************/
/*                              Init()                                  */
/************************************************************************/

void OGRXLSXLayer::Init()
{
    if( !bInit )
    {
        bInit = true;
        CPLDebug("XLSX", "Init(%s)", GetName());
        poDS->BuildLayer(this);
    }
}

/************************************************************************/
/*                             Updated()                                */
/************************************************************************/

void OGRXLSXLayer::SetUpdated( bool bUpdatedIn )
{
    if (bUpdatedIn && !bUpdated && poDS->GetUpdatable())
    {
        bUpdated = true;
        poDS->SetUpdated();
    }
    else if( bUpdated && !bUpdatedIn )
    {
        bUpdated = false;
    }
}

/************************************************************************/
/*                           SyncToDisk()                               */
/************************************************************************/

OGRErr OGRXLSXLayer::SyncToDisk()
{
    poDS->FlushCache(false);
    return OGRERR_NONE;
}

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

OGRFeature* OGRXLSXLayer::GetNextFeature()
{
    Init();
    OGRFeature* poFeature = OGRMemLayer::GetNextFeature();
    if (poFeature)
        poFeature->SetFID(poFeature->GetFID() +
                          1 + static_cast<int>(bHasHeaderLine));
    return poFeature;
}

OGRErr OGRXLSXLayer::CreateField( OGRFieldDefn *poField, int bApproxOK )
{
    Init();
    if( GetLayerDefn()->GetFieldCount() >= 2000 )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Maximum number of fields supported is 2000");
        return OGRERR_FAILURE;
    }
    SetUpdated();
    return OGRMemLayer::CreateField(poField, bApproxOK);
}

/************************************************************************/
/*                           GetFeature()                               */
/************************************************************************/

OGRFeature* OGRXLSXLayer::GetFeature( GIntBig nFeatureId )
{
    Init();
    OGRFeature* poFeature =
        OGRMemLayer::GetFeature(nFeatureId -
                                (1 + static_cast<int>(bHasHeaderLine)));
    if (poFeature)
        poFeature->SetFID(nFeatureId);
    return poFeature;
}

/************************************************************************/
/*                           ISetFeature()                               */
/************************************************************************/

OGRErr OGRXLSXLayer::ISetFeature( OGRFeature *poFeature )
{
    Init();
    if (poFeature == nullptr)
        return OGRMemLayer::ISetFeature(poFeature);

    GIntBig nFID = poFeature->GetFID();
    if (nFID != OGRNullFID)
        poFeature->SetFID(nFID - (1 + static_cast<int>(bHasHeaderLine)));
    SetUpdated();
    OGRErr eErr = OGRMemLayer::ISetFeature(poFeature);
    poFeature->SetFID(nFID);
    return eErr;
}

/************************************************************************/
/*                          ICreateFeature()                            */
/************************************************************************/

OGRErr OGRXLSXLayer::ICreateFeature( OGRFeature *poFeature )
{
    Init();

    GIntBig nFID = poFeature->GetFID();
    if (nFID != OGRNullFID)
    {
        // Compensate what ISetFeature() will do since
        // OGRMemLayer::ICreateFeature() will eventually call it
        poFeature->SetFID(nFID + (1 + static_cast<int>(bHasHeaderLine)));
    }
    SetUpdated();
    OGRErr eErr = OGRMemLayer::ICreateFeature(poFeature);
    poFeature->SetFID(nFID);
    return eErr;
}

/************************************************************************/
/*                          DeleteFeature()                             */
/************************************************************************/

OGRErr OGRXLSXLayer::DeleteFeature( GIntBig nFID )
{
    Init();
    SetUpdated();
    return OGRMemLayer::DeleteFeature(nFID -
                                      (1 + static_cast<int>(bHasHeaderLine)));
}

/************************************************************************/
/*                          OGRXLSXDataSource()                         */
/************************************************************************/

OGRXLSXDataSource::OGRXLSXDataSource() :
    pszName(nullptr),
    bUpdatable(false),
    bUpdated(false),
    nLayers(0),
    papoLayers(nullptr),
    bFirstLineIsHeaders(false),
    bAutodetectTypes(!EQUAL(CPLGetConfigOption("OGR_XLSX_FIELD_TYPES", ""),
                            "STRING")),
    oParser(nullptr),
    bStopParsing(false),
    nWithoutEventCounter(0),
    nDataHandlerCounter(0),
    nCurLine(0),
    nCurCol(0),
    poCurLayer(nullptr),
    nStackDepth(0),
    nDepth(0),
    bInCellXFS(false)
{
    stateStack[0].eVal = STATE_DEFAULT;
    stateStack[0].nBeginDepth = 0;
}

/************************************************************************/
/*                         ~OGRXLSXDataSource()                          */
/************************************************************************/

OGRXLSXDataSource::~OGRXLSXDataSource()

{
    OGRXLSXDataSource::FlushCache(true);

    CPLFree( pszName );

    for( int i = 0; i < nLayers; i++ )
        delete papoLayers[i];
    CPLFree( papoLayers );
}

/************************************************************************/
/*                           TestCapability()                           */
/************************************************************************/

int OGRXLSXDataSource::TestCapability( const char * pszCap )

{
    if( EQUAL(pszCap,ODsCCreateLayer) )
        return bUpdatable;
    else if( EQUAL(pszCap,ODsCDeleteLayer) )
        return bUpdatable;
    else if( EQUAL(pszCap,ODsCRandomLayerWrite) )
        return bUpdatable;
    else
        return FALSE;
}

/************************************************************************/
/*                              GetLayer()                              */
/************************************************************************/

OGRLayer *OGRXLSXDataSource::GetLayer( int iLayer )

{
    if (iLayer < 0 || iLayer >= nLayers)
        return nullptr;

    return papoLayers[iLayer];
}

/************************************************************************/
/*                            GetLayerCount()                           */
/************************************************************************/

int OGRXLSXDataSource::GetLayerCount()
{
    return nLayers;
}

/************************************************************************/
/*                                Open()                                */
/************************************************************************/

int OGRXLSXDataSource::Open( const char * pszFilename,
                             const char * pszPrefixedFilename,
                             VSILFILE* fpWorkbook,
                             VSILFILE* fpWorkbookRels,
                             VSILFILE* fpSharedStrings,
                             VSILFILE* fpStyles,
                             int bUpdateIn )

{
    SetDescription(pszFilename);

    bUpdatable = CPL_TO_BOOL(bUpdateIn);

    pszName = CPLStrdup( pszFilename );
    osPrefixedFilename = pszPrefixedFilename;

    AnalyseWorkbookRels(fpWorkbookRels);
    AnalyseWorkbook(fpWorkbook);
    AnalyseSharedStrings(fpSharedStrings);
    AnalyseStyles(fpStyles);

    /* Remove empty layers at the end, which tend to be there */
    while(nLayers > 1)
    {
        if (papoLayers[nLayers-1]->GetFeatureCount() == 0)
        {
            delete papoLayers[nLayers-1];
            nLayers --;
        }
        else
            break;
    }

    return TRUE;
}

/************************************************************************/
/*                             Create()                                 */
/************************************************************************/

int OGRXLSXDataSource::Create( const char * pszFilename,
                               CPL_UNUSED char **papszOptions )
{
    bUpdated = true;
    bUpdatable = true;

    pszName = CPLStrdup( pszFilename );

    return TRUE;
}

/************************************************************************/
/*                           startElementCbk()                          */
/************************************************************************/

static void XMLCALL startElementCbk(void *pUserData, const char *pszNameIn,
                                    const char **ppszAttr)
{
    ((OGRXLSXDataSource*)pUserData)->startElementCbk(pszNameIn, ppszAttr);
}

void OGRXLSXDataSource::startElementCbk(const char *pszNameIn,
                                       const char **ppszAttr)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT: startElementDefault(pszNameIn, ppszAttr); break;
        case STATE_SHEETDATA:   startElementTable(pszNameIn, ppszAttr); break;
        case STATE_ROW:     startElementRow(pszNameIn, ppszAttr); break;
        case STATE_CELL:    startElementCell(pszNameIn, ppszAttr); break;
        case STATE_TEXTV:   break;
        default:            break;
    }
    nDepth++;
}

/************************************************************************/
/*                            endElementCbk()                           */
/************************************************************************/

static void XMLCALL endElementCbk(void *pUserData, const char *pszNameIn)
{
    ((OGRXLSXDataSource*)pUserData)->endElementCbk(pszNameIn);
}

void OGRXLSXDataSource::endElementCbk(const char *pszNameIn)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;

    nDepth--;
    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT: break;
        case STATE_SHEETDATA:   endElementTable(pszNameIn); break;
        case STATE_ROW:     endElementRow(pszNameIn); break;
        case STATE_CELL:    endElementCell(pszNameIn); break;
        case STATE_TEXTV:   break;
        default:            break;
    }

    if (stateStack[nStackDepth].nBeginDepth == nDepth)
        nStackDepth --;
}

/************************************************************************/
/*                            dataHandlerCbk()                          */
/************************************************************************/

static void XMLCALL dataHandlerCbk(void *pUserData, const char *data, int nLen)
{
    ((OGRXLSXDataSource*)pUserData)->dataHandlerCbk(data, nLen);
}

void OGRXLSXDataSource::dataHandlerCbk(const char *data, int nLen)
{
    if( bStopParsing ) return;

    nDataHandlerCounter++;
    if( nDataHandlerCounter >= BUFSIZ )
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "File probably corrupted (million laugh pattern)");
        XML_StopParser(oParser, XML_FALSE);
        bStopParsing = true;
        return;
    }

    nWithoutEventCounter = 0;

    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT: break;
        case STATE_SHEETDATA:   break;
        case STATE_ROW:     break;
        case STATE_CELL:    break;
        case STATE_TEXTV:   dataHandlerTextV(data, nLen); break;
        default:            break;
    }
}

/************************************************************************/
/*                                PushState()                           */
/************************************************************************/

void OGRXLSXDataSource::PushState(HandlerStateEnum eVal)
{
    if (nStackDepth + 1 == STACK_SIZE)
    {
        bStopParsing = true;
        return;
    }
    nStackDepth ++;
    stateStack[nStackDepth].eVal = eVal;
    stateStack[nStackDepth].nBeginDepth = nDepth;
}

/************************************************************************/
/*                          GetAttributeValue()                         */
/************************************************************************/

static const char* GetAttributeValue(const char **ppszAttr,
                                     const char* pszKey,
                                     const char* pszDefaultVal)
{
    while(*ppszAttr)
    {
        if (strcmp(ppszAttr[0], pszKey) == 0)
            return ppszAttr[1];
        ppszAttr += 2;
    }
    return pszDefaultVal;
}

/************************************************************************/
/*                            GetOGRFieldType()                         */
/************************************************************************/

OGRFieldType OGRXLSXDataSource::GetOGRFieldType(const char* pszValue,
                                                const char* pszValueType,
                                                OGRFieldSubType& eSubType)
{
    eSubType = OFSTNone;
    if (!bAutodetectTypes || pszValueType == nullptr)
        return OFTString;
    else if (strcmp(pszValueType, "string") == 0)
        return OFTString;
    else if (strcmp(pszValueType, "float") == 0)
    {
        CPLValueType eValueType = CPLGetValueType(pszValue);
        if (eValueType == CPL_VALUE_STRING)
            return OFTString;
        else if (eValueType == CPL_VALUE_INTEGER)
        {
            GIntBig nVal = CPLAtoGIntBig(pszValue);
            if( !CPL_INT64_FITS_ON_INT32(nVal) )
                return OFTInteger64;
            else
                return OFTInteger;
        }
        else
            return OFTReal;
    }
    else if (strcmp(pszValueType, "datetime") == 0 ||
             strcmp(pszValueType, "datetime_ms") == 0)
    {
        return OFTDateTime;
    }
    else if (strcmp(pszValueType, "date") == 0)
    {
        return OFTDate;
    }
    else if (strcmp(pszValueType, "time") == 0)
    {
        return OFTTime;
    }
    else if( strcmp(pszValueType, "bool") == 0 )
    {
        eSubType = OFSTBoolean;
        return OFTInteger;
    }
    else
        return OFTString;
}

/************************************************************************/
/*                              SetField()                              */
/************************************************************************/

static void SetField(OGRFeature* poFeature,
                     int i,
                     const char* pszValue,
                     const char* pszCellType)
{
    if (pszValue[0] == '\0')
        return;

    OGRFieldType eType = poFeature->GetFieldDefnRef(i)->GetType();

    if (strcmp(pszCellType, "time") == 0 ||
        strcmp(pszCellType, "date") == 0 ||
        strcmp(pszCellType, "datetime") == 0 ||
        strcmp(pszCellType, "datetime_ms") == 0)
    {
        struct tm sTm;
        const double dfNumberOfDaysSince1900 = CPLAtof(pszValue);
        if( !(std::fabs(dfNumberOfDaysSince1900) < 365.0 * 10000) )
            return;
        double dfNumberOfSecsSince1900 = dfNumberOfDaysSince1900 * NUMBER_OF_SECONDS_PER_DAY;
        if( std::fabs(dfNumberOfSecsSince1900 - std::round(dfNumberOfSecsSince1900)) < 1e-3 )
            dfNumberOfSecsSince1900 = std::round(dfNumberOfSecsSince1900);
        const GIntBig nUnixTime = static_cast<GIntBig>(dfNumberOfSecsSince1900) -
                static_cast<GIntBig>(NUMBER_OF_DAYS_BETWEEN_1900_AND_1970) * NUMBER_OF_SECONDS_PER_DAY;
        CPLUnixTimeToYMDHMS(nUnixTime, &sTm);

        if (eType == OFTTime || eType == OFTDate || eType == OFTDateTime)
        {
            double fFracSec = fmod(dfNumberOfSecsSince1900, 1);
            poFeature->SetField(i, sTm.tm_year + 1900, sTm.tm_mon + 1, sTm.tm_mday,
                                sTm.tm_hour, sTm.tm_min,
                                static_cast<float>(sTm.tm_sec + fFracSec), 0 );
        }
        else if (strcmp(pszCellType, "time") == 0)
        {
            poFeature->SetField(i, CPLSPrintf("%02d:%02d:%02d",
                                sTm.tm_hour, sTm.tm_min, sTm.tm_sec));
        }
        else if (strcmp(pszCellType, "date") == 0)
        {
            poFeature->SetField(i, CPLSPrintf("%04d/%02d/%02d",
                                sTm.tm_year + 1900, sTm.tm_mon + 1, sTm.tm_mday));
        }
        else /* if (strcmp(pszCellType, "datetime") == 0) */
        {
            double fFracSec = fmod(dfNumberOfSecsSince1900, 1);
            poFeature->SetField(i,
                                sTm.tm_year + 1900, sTm.tm_mon + 1, sTm.tm_mday,
                                sTm.tm_hour, sTm.tm_min,
                                static_cast<float>(sTm.tm_sec + fFracSec), 0);
        }
    }
    else
        poFeature->SetField(i, pszValue);
}

/************************************************************************/
/*                          DetectHeaderLine()                          */
/************************************************************************/

void OGRXLSXDataSource::DetectHeaderLine()

{
    bool bHeaderLineCandidate = true;

    for( size_t i = 0; i < apoFirstLineTypes.size(); i++ )
    {
        if (apoFirstLineTypes[i] != "string")
        {
            /* If the values in the first line are not text, then it is */
            /* not a header line */
            bHeaderLineCandidate = false;
            break;
        }
    }

    size_t nCountTextOnCurLine = 0;
    size_t nCountNonEmptyOnCurLine = 0;
    for( size_t i = 0; bHeaderLineCandidate && i < apoCurLineTypes.size(); i++ )
    {
        if (apoCurLineTypes[i] == "string")
        {
            /* If there are only text values on the second line, then we cannot */
            /* know if it is a header line or just a regular line */
            nCountTextOnCurLine ++;
        }
        else if (apoCurLineTypes[i] != "")
        {
            nCountNonEmptyOnCurLine ++;
        }
    }

    const char* pszXLSXHeaders = CPLGetConfigOption("OGR_XLSX_HEADERS", "");
    bFirstLineIsHeaders = false;
    if (EQUAL(pszXLSXHeaders, "FORCE"))
        bFirstLineIsHeaders = true;
    else if (EQUAL(pszXLSXHeaders, "DISABLE"))
        bFirstLineIsHeaders = false;
    else if( bHeaderLineCandidate &&
             !apoFirstLineTypes.empty() &&
             apoFirstLineTypes.size() >= apoCurLineTypes.size() &&
             nCountTextOnCurLine != apoFirstLineTypes.size() &&
             nCountNonEmptyOnCurLine != 0 )
    {
        bFirstLineIsHeaders = true;
    }
    CPLDebug("XLSX", "%s %s",
             poCurLayer ? poCurLayer->GetName() : "NULL layer",
             bFirstLineIsHeaders ? "has header line" : "has no header line");
}

/************************************************************************/
/*                          startElementDefault()                       */
/************************************************************************/

void OGRXLSXDataSource::startElementDefault(const char *pszNameIn,
                                            CPL_UNUSED const char **ppszAttr)
{
    if (strcmp(pszNameIn, "sheetData") == 0)
    {
        apoFirstLineValues.resize(0);
        apoFirstLineTypes.resize(0);
        nCurLine = 0;
        PushState(STATE_SHEETDATA);
    }
}

/************************************************************************/
/*                          startElementTable()                        */
/************************************************************************/

void OGRXLSXDataSource::startElementTable(const char *pszNameIn,
                                         const char **ppszAttr)
{
    if (strcmp(pszNameIn, "row") == 0)
    {
        PushState(STATE_ROW);

        nCurCol = 0;
        apoCurLineValues.clear();
        apoCurLineTypes.clear();

        int nNewCurLine = atoi(
            GetAttributeValue(ppszAttr, "r", "0"));
        if( nNewCurLine <= 0 )
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Invalid row: %d", nNewCurLine);
            return;
        }
        nNewCurLine --;
        const int nFields = std::max(
            static_cast<int>(apoFirstLineValues.size()),
            poCurLayer != nullptr ?
                poCurLayer->GetLayerDefn()->GetFieldCount() : 0);
        if( nNewCurLine > nCurLine &&
            (nNewCurLine - nCurLine > 10000 ||
             (nFields > 0 && nNewCurLine - nCurLine > 100000 / nFields)) )
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Invalid row: %d. Too big gap with previous valid row",
                     nNewCurLine);
            return;
        }
        for(;nCurLine<nNewCurLine;)
        {
            const int nCurLineBefore = nCurLine;
            endElementRow("row");

            nCurCol = 0;
            apoCurLineValues.clear();
            apoCurLineTypes.clear();
            if( nCurLineBefore == nCurLine )
                break;
        }

    }
}

/************************************************************************/
/*                           endElementTable()                          */
/************************************************************************/

void OGRXLSXDataSource::endElementTable(CPL_UNUSED const char *pszNameIn)
{
    if (stateStack[nStackDepth].nBeginDepth == nDepth && poCurLayer != nullptr)
    {
        CPLAssert(strcmp(pszNameIn, "sheetData") == 0);

        if (nCurLine == 0 ||
            (nCurLine == 1 && apoFirstLineValues.empty()))
        {
            /* We could remove empty sheet, but too late now */
        }
        else if (nCurLine == 1)
        {
            /* If we have only one single line in the sheet */
            for( size_t i = 0; i < apoFirstLineValues.size(); i++ )
            {
                const char* pszFieldName = CPLSPrintf("Field%d", (int)i + 1);
                OGRFieldSubType eSubType = OFSTNone;
                OGRFieldType eType = GetOGRFieldType(apoFirstLineValues[i].c_str(),
                                                     apoFirstLineTypes[i].c_str(),
                                                     eSubType);
                OGRFieldDefn oFieldDefn(pszFieldName, eType);
                oFieldDefn.SetSubType(eSubType);
                if( poCurLayer->CreateField(&oFieldDefn) != OGRERR_NONE )
                {
                    return;
                }
            }

            OGRFeature* poFeature = new OGRFeature(poCurLayer->GetLayerDefn());
            for( size_t i = 0; i < apoFirstLineValues.size(); i++ )
            {
                SetField(poFeature, static_cast<int>(i), apoFirstLineValues[i].c_str(),
                         apoFirstLineTypes[i].c_str());
            }
            CPL_IGNORE_RET_VAL(poCurLayer->CreateFeature(poFeature));
            delete poFeature;
        }

        if (poCurLayer)
        {
            ((OGRMemLayer*)poCurLayer)->SetUpdatable(CPL_TO_BOOL(bUpdatable));
            ((OGRMemLayer*)poCurLayer)->SetAdvertizeUTF8(true);
            ((OGRXLSXLayer*)poCurLayer)->SetUpdated(false);
        }

        poCurLayer = nullptr;
    }
}

/************************************************************************/
/*                            startElementRow()                         */
/************************************************************************/

void OGRXLSXDataSource::startElementRow(const char *pszNameIn,
                                       const char **ppszAttr)
{
    if (strcmp(pszNameIn, "c") == 0)
    {
        PushState(STATE_CELL);

        const char* pszR = GetAttributeValue(ppszAttr, "r", nullptr);
        if (pszR && pszR[0] >= 'A' && pszR[0] <= 'Z')
        {
            /* Convert col number from base 26 */
            /*
            A Z   AA AZ   BA BZ   ZA   ZZ   AAA    ZZZ      AAAA
            0 25  26 51   52 77   676  701  702    18277    18278
            */
            int nNewCurCol = (pszR[0] - 'A');
            int i = 1;
            while(pszR[i] >= 'A' && pszR[i] <= 'Z' && nNewCurCol <= 2000)
            {
                // We wouldn't need the +1 if this was a proper base 26
                nNewCurCol = (nNewCurCol + 1) * 26 + (pszR[i] - 'A');
                i ++;
            }
            if( nNewCurCol > 2000 )
            {
                CPLError(CE_Warning, CPLE_AppDefined,
                         "Limiting number of columns to 2000");
                nNewCurCol = 2000;
            }
            for(;nCurCol<nNewCurCol;nCurCol++)
            {
                apoCurLineValues.push_back("");
                apoCurLineTypes.push_back("");
            }
        }

        osValueType = "float";

        const char* pszS = GetAttributeValue(ppszAttr, "s", "-1");
        int nS = atoi(pszS);
        if (nS >= 0 && nS < (int)apoStyles.size())
        {
            XLSXFieldTypeExtended eType = apoStyles[nS];
            if (eType.eType == OFTDateTime)
            {
                if( eType.bHasMS )
                    osValueType = "datetime_ms";
                else
                    osValueType = "datetime";
            }
            else if (eType.eType == OFTDate)
                osValueType = "date";
            else if (eType.eType == OFTTime)
                osValueType = "time";
        }
        else if (nS != -1)
            CPLDebug("XLSX", "Cannot find style %d", nS);

        const char* pszT = GetAttributeValue(ppszAttr, "t", "");
        if ( EQUAL(pszT,"s"))
            osValueType = "stringLookup";
        else if( EQUAL(pszT,"inlineStr") )
            osValueType = "string";
        else if ( EQUAL(pszT,"b"))
            osValueType = "bool";

        osValue = "";
    }
}

/************************************************************************/
/*                            endElementRow()                           */
/************************************************************************/

void OGRXLSXDataSource::endElementRow(CPL_UNUSED const char *pszNameIn)
{
    if (stateStack[nStackDepth].nBeginDepth == nDepth && poCurLayer != nullptr)
    {
        CPLAssert(strcmp(pszNameIn, "row") == 0);

        /* Backup first line values and types in special arrays */
        if (nCurLine == 0)
        {
            apoFirstLineTypes = apoCurLineTypes;
            apoFirstLineValues = apoCurLineValues;

    #if skip_leading_empty_rows
            if (apoFirstLineTypes.empty())
            {
                /* Skip leading empty rows */
                apoFirstLineTypes.resize(0);
                apoFirstLineValues.resize(0);
                return;
            }
    #endif
        }

        if (nCurLine == 1)
        {
            DetectHeaderLine();

            poCurLayer->SetHasHeaderLine(bFirstLineIsHeaders);

            if( bFirstLineIsHeaders )
            {
                for( size_t i = 0; i < apoFirstLineValues.size(); i++ )
                {
                    const char* pszFieldName = apoFirstLineValues[i].c_str();
                    if (pszFieldName[0] == '\0')
                        pszFieldName = CPLSPrintf("Field%d", (int)i + 1);
                    bool bUnknownType = true;
                    OGRFieldType eType = OFTString;
                    OGRFieldSubType eSubType = OFSTNone;
                    if (i < apoCurLineValues.size() && !apoCurLineValues[i].empty())
                    {
                        eType = GetOGRFieldType(apoCurLineValues[i].c_str(),
                                                apoCurLineTypes[i].c_str(),
                                                eSubType);
                        bUnknownType = false;
                    }
                    OGRFieldDefn oFieldDefn(pszFieldName, eType);
                    oFieldDefn.SetSubType(eSubType);
                    if( bUnknownType)
                    {
                        poCurLayer->oSetFieldsOfUnknownType.insert(
                            poCurLayer->GetLayerDefn()->GetFieldCount());
                    }
                    if( poCurLayer->CreateField(&oFieldDefn) != OGRERR_NONE )
                    {
                        return;
                    }
                }
            }
            else
            {
                for( size_t i = 0; i < apoFirstLineValues.size(); i++ )
                {
                    const char* pszFieldName =
                        CPLSPrintf("Field%d", (int)i + 1);
                    OGRFieldSubType eSubType = OFSTNone;
                    OGRFieldType eType = GetOGRFieldType(
                                            apoFirstLineValues[i].c_str(),
                                            apoFirstLineTypes[i].c_str(),
                                            eSubType);
                    OGRFieldDefn oFieldDefn(pszFieldName, eType);
                    oFieldDefn.SetSubType(eSubType);
                    if( poCurLayer->CreateField(&oFieldDefn) != OGRERR_NONE )
                    {
                        return;
                    }
                }

                OGRFeature* poFeature = new OGRFeature(poCurLayer->GetLayerDefn());
                for( size_t i = 0; i < apoFirstLineValues.size(); i++ )
                {
                    SetField(poFeature, static_cast<int>(i), apoFirstLineValues[i].c_str(),
                             apoFirstLineTypes[i].c_str());
                }
                CPL_IGNORE_RET_VAL(poCurLayer->CreateFeature(poFeature));
                delete poFeature;
            }
        }

        if (nCurLine >= 1)
        {
            /* Add new fields found on following lines. */
            if (apoCurLineValues.size() >
                (size_t)poCurLayer->GetLayerDefn()->GetFieldCount())
            {
                GIntBig nFeatureCount = poCurLayer->GetFeatureCount(false);
                if( nFeatureCount > 0 &&
                    static_cast<size_t>(apoCurLineValues.size() -
                        poCurLayer->GetLayerDefn()->GetFieldCount()) >
                            static_cast<size_t>(100000 / nFeatureCount) )
                {
                    CPLError(CE_Failure, CPLE_NotSupported,
                             "Adding too many columns to too many "
                             "existing features");
                    return;
                }
                for( size_t i = (size_t)poCurLayer->GetLayerDefn()->GetFieldCount();
                     i < apoCurLineValues.size();
                     i++ )
                {
                    const char* pszFieldName =
                        CPLSPrintf("Field%d", (int)i + 1);
                    OGRFieldSubType eSubType = OFSTNone;
                    OGRFieldType eType = GetOGRFieldType(
                                                apoCurLineValues[i].c_str(),
                                                apoCurLineTypes[i].c_str(),
                                                eSubType);
                    OGRFieldDefn oFieldDefn(pszFieldName, eType);
                    oFieldDefn.SetSubType(eSubType);
                    if( poCurLayer->CreateField(&oFieldDefn) != OGRERR_NONE )
                    {
                        return;
                    }
                }
            }

            /* Update field type if necessary */
            if (bAutodetectTypes)
            {
                for( size_t i = 0; i < apoCurLineValues.size(); i++ )
                {
                    if (!apoCurLineValues[i].empty() )
                    {
                        OGRFieldSubType eValSubType = OFSTNone;
                        OGRFieldType eValType = GetOGRFieldType(
                                                apoCurLineValues[i].c_str(),
                                                apoCurLineTypes[i].c_str(),
                                                eValSubType);
                        OGRFieldDefn* poFieldDefn =
                            poCurLayer->GetLayerDefn()->GetFieldDefn(static_cast<int>(i));
                        const OGRFieldType eFieldType = poFieldDefn->GetType();
                        auto oIter = poCurLayer->oSetFieldsOfUnknownType.find(static_cast<int>(i));
                        if (oIter != poCurLayer->oSetFieldsOfUnknownType.end() )
                        {
                            poCurLayer->oSetFieldsOfUnknownType.erase(oIter);

                            poFieldDefn->SetType(eValType);
                            poFieldDefn->SetSubType(eValSubType);
                        }
                        else if (eFieldType == OFTDateTime &&
                            (eValType == OFTDate || eValType == OFTTime) )
                        {
                            /* ok */
                        }
                        else if (eFieldType == OFTReal && (eValType == OFTInteger || eValType == OFTInteger64))
                        {
                           /* ok */;
                        }
                        else if (eFieldType == OFTInteger64 && eValType == OFTInteger )
                        {
                            /* ok */;
                        }
                        else if (eFieldType != OFTString && eValType != eFieldType)
                        {
                            OGRFieldDefn oNewFieldDefn(poFieldDefn);
                            oNewFieldDefn.SetSubType(OFSTNone);
                            if ((eFieldType == OFTDate || eFieldType == OFTTime) &&
                                   eValType == OFTDateTime)
                                oNewFieldDefn.SetType(OFTDateTime);
                            else if ((eFieldType == OFTInteger || eFieldType == OFTInteger64) &&
                                     eValType == OFTReal)
                                oNewFieldDefn.SetType(OFTReal);
                            else if( eFieldType == OFTInteger && eValType == OFTInteger64 )
                                oNewFieldDefn.SetType(OFTInteger64);
                            else
                                oNewFieldDefn.SetType(OFTString);
                            poCurLayer->AlterFieldDefn(static_cast<int>(i), &oNewFieldDefn,
                                                       ALTER_TYPE_FLAG);
                        }
                        else if( eFieldType == OFTInteger &&
                                 poFieldDefn->GetSubType() == OFSTBoolean &&
                                 eValType == OFTInteger &&
                                 eValSubType != OFSTBoolean )
                        {
                            poFieldDefn->SetSubType(OFSTNone);
                        }
                    }
                }
            }

            /* Add feature for current line */
            OGRFeature* poFeature = new OGRFeature(poCurLayer->GetLayerDefn());
            for( size_t i = 0; i < apoCurLineValues.size(); i++ )
            {
                if (!apoCurLineValues[i].empty())
                {
                  SetField(poFeature, static_cast<int>(i), apoCurLineValues[i].c_str(),
                          apoCurLineTypes[i].c_str());
                }
            }
            CPL_IGNORE_RET_VAL(poCurLayer->CreateFeature(poFeature));
            delete poFeature;
       }

        nCurLine++;
    }
}

/************************************************************************/
/*                           startElementCell()                         */
/************************************************************************/

void OGRXLSXDataSource::startElementCell(const char *pszNameIn,
                                         CPL_UNUSED const char **ppszAttr)
{
    if (osValue.empty() && strcmp(pszNameIn, "v") == 0)
    {
        PushState(STATE_TEXTV);
    }
    else if (osValue.empty() && strcmp(pszNameIn, "t") == 0)
    {
        PushState(STATE_TEXTV);
    }
}

/************************************************************************/
/*                            endElementCell()                          */
/************************************************************************/

void OGRXLSXDataSource::endElementCell(CPL_UNUSED const char *pszNameIn)
{
    if (stateStack[nStackDepth].nBeginDepth == nDepth)
    {
        CPLAssert(strcmp(pszNameIn, "c") == 0);

        if (osValueType == "stringLookup")
        {
            int nIndex = atoi(osValue);
            if (nIndex >= 0 && nIndex < (int)(apoSharedStrings.size()))
                osValue = apoSharedStrings[nIndex];
            else
                CPLDebug("XLSX", "Cannot find string %d", nIndex);
            osValueType = "string";
        }

        apoCurLineValues.push_back(osValue);
        apoCurLineTypes.push_back(osValueType);

        nCurCol += 1;
    }
}

/************************************************************************/
/*                           dataHandlerTextV()                         */
/************************************************************************/

void OGRXLSXDataSource::dataHandlerTextV(const char *data, int nLen)
{
    osValue.append(data, nLen);
}

/************************************************************************/
/*                              BuildLayer()                            */
/************************************************************************/

void OGRXLSXDataSource::BuildLayer( OGRXLSXLayer* poLayer )
{
    poCurLayer = poLayer;

    const char* pszSheetFilename = poLayer->GetFilename().c_str();
    VSILFILE* fp = VSIFOpenL(pszSheetFilename, "rb");
    if (fp == nullptr)
    {
        CPLDebug("XLSX", "Cannot open file %s for sheet %s",
                 pszSheetFilename, poLayer->GetName());
        return;
    }

    const bool bUpdatedBackup = bUpdated;

    oParser = OGRCreateExpatXMLParser();
    XML_SetElementHandler(oParser, OGRXLSX::startElementCbk, OGRXLSX::endElementCbk);
    XML_SetCharacterDataHandler(oParser, OGRXLSX::dataHandlerCbk);
    XML_SetUserData(oParser, this);

    VSIFSeekL( fp, 0, SEEK_SET );

    bStopParsing = false;
    nWithoutEventCounter = 0;
    nDataHandlerCounter = 0;
    nStackDepth = 0;
    nDepth = 0;
    stateStack[0].eVal = STATE_DEFAULT;
    stateStack[0].nBeginDepth = 0;

    char aBuf[BUFSIZ];
    int nDone = 0;
    do
    {
        nDataHandlerCounter = 0;
        unsigned int nLen =
            (unsigned int)VSIFReadL( aBuf, 1, sizeof(aBuf), fp );
        nDone = VSIFEofL(fp);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of %s file failed : %s at line %d, column %d",
                     pszSheetFilename,
                     XML_ErrorString(XML_GetErrorCode(oParser)),
                     (int)XML_GetCurrentLineNumber(oParser),
                     (int)XML_GetCurrentColumnNumber(oParser));
            bStopParsing = true;
        }
        nWithoutEventCounter ++;
    } while( !nDone && !bStopParsing && nWithoutEventCounter < 10 );

    XML_ParserFree(oParser);
    oParser = nullptr;

    if (nWithoutEventCounter == 10)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        bStopParsing = true;
    }

    VSIFCloseL(fp);

    bUpdated = bUpdatedBackup;
}

/************************************************************************/
/*                          startElementSSCbk()                         */
/************************************************************************/

static void XMLCALL startElementSSCbk(void *pUserData, const char *pszNameIn,
                                    const char **ppszAttr)
{
    ((OGRXLSXDataSource*)pUserData)->startElementSSCbk(pszNameIn, ppszAttr);
}

void OGRXLSXDataSource::startElementSSCbk(const char *pszNameIn,
                                          CPL_UNUSED const char **ppszAttr)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT:
        {
            if (strcmp(pszNameIn,"si") == 0)
            {
                PushState(STATE_SI);
                osCurrentString = "";
            }
            break;
        }
        case STATE_SI:
        {
            if (strcmp(pszNameIn,"t") == 0)
            {
                PushState(STATE_T);
            }
            break;
        }
        default:
            break;
    }
    nDepth++;
}

/************************************************************************/
/*                           endElementSSCbk()                          */
/************************************************************************/

static void XMLCALL endElementSSCbk(void *pUserData, const char *pszNameIn)
{
    ((OGRXLSXDataSource*)pUserData)->endElementSSCbk(pszNameIn);
}

void OGRXLSXDataSource::endElementSSCbk(CPL_UNUSED const char *pszNameIn)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;

    nDepth--;
    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT: break;
        case STATE_T: break;
        case STATE_SI:
        {
            if (stateStack[nStackDepth].nBeginDepth == nDepth)
            {
                apoSharedStrings.push_back(osCurrentString);
            }
            break;
        }
        default:            break;
    }

    if (stateStack[nStackDepth].nBeginDepth == nDepth)
        nStackDepth --;
}

/************************************************************************/
/*                           dataHandlerSSCbk()                         */
/************************************************************************/

static void XMLCALL dataHandlerSSCbk(void *pUserData, const char *data, int nLen)
{
    ((OGRXLSXDataSource*)pUserData)->dataHandlerSSCbk(data, nLen);
}

void OGRXLSXDataSource::dataHandlerSSCbk(const char *data, int nLen)
{
    if( bStopParsing ) return;

    nDataHandlerCounter ++;
    if (nDataHandlerCounter >= BUFSIZ)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "File probably corrupted (million laugh pattern)");
        XML_StopParser(oParser, XML_FALSE);
        bStopParsing = true;
        return;
    }

    nWithoutEventCounter = 0;

    switch(stateStack[nStackDepth].eVal)
    {
        case STATE_DEFAULT: break;
        case STATE_SI:      break;
        case STATE_T:       osCurrentString.append(data, nLen); break;
        default:            break;
    }
}

/************************************************************************/
/*                          AnalyseSharedStrings()                      */
/************************************************************************/

void OGRXLSXDataSource::AnalyseSharedStrings(VSILFILE* fpSharedStrings)
{
    if (fpSharedStrings == nullptr)
        return;

    oParser = OGRCreateExpatXMLParser();
    XML_SetElementHandler(oParser, OGRXLSX::startElementSSCbk, OGRXLSX::endElementSSCbk);
    XML_SetCharacterDataHandler(oParser, OGRXLSX::dataHandlerSSCbk);
    XML_SetUserData(oParser, this);

    VSIFSeekL( fpSharedStrings, 0, SEEK_SET );

    bStopParsing = false;
    nWithoutEventCounter = 0;
    nDataHandlerCounter = 0;
    nStackDepth = 0;
    nDepth = 0;
    stateStack[0].eVal = STATE_DEFAULT;
    stateStack[0].nBeginDepth = 0;

    char aBuf[BUFSIZ];
    int nDone = 0;
    do
    {
        nDataHandlerCounter = 0;
        unsigned int nLen =
            (unsigned int)VSIFReadL( aBuf, 1, sizeof(aBuf), fpSharedStrings );
        nDone = VSIFEofL(fpSharedStrings);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of %s file failed : %s at line %d, column %d",
                     "sharedStrings.xml",
                     XML_ErrorString(XML_GetErrorCode(oParser)),
                     (int)XML_GetCurrentLineNumber(oParser),
                     (int)XML_GetCurrentColumnNumber(oParser));
            bStopParsing = true;
        }
        nWithoutEventCounter ++;
    } while( !nDone && !bStopParsing && nWithoutEventCounter < 10 );

    XML_ParserFree(oParser);
    oParser = nullptr;

    if (nWithoutEventCounter == 10)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        bStopParsing = true;
    }

    VSIFCloseL(fpSharedStrings);
}

/************************************************************************/
/*                        startElementWBRelsCbk()                       */
/************************************************************************/

static void XMLCALL startElementWBRelsCbk(void *pUserData, const char *pszNameIn,
                                    const char **ppszAttr)
{
    ((OGRXLSXDataSource*)pUserData)->startElementWBRelsCbk(pszNameIn, ppszAttr);
}

void OGRXLSXDataSource::startElementWBRelsCbk(const char *pszNameIn,
                                       const char **ppszAttr)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    if (strcmp(pszNameIn,"Relationship") == 0)
    {
        const char* pszId = GetAttributeValue(ppszAttr, "Id", nullptr);
        const char* pszType = GetAttributeValue(ppszAttr, "Type", nullptr);
        const char* pszTarget = GetAttributeValue(ppszAttr, "Target", nullptr);
        if (pszId && pszType && pszTarget &&
            strstr(pszType, "/worksheet") != nullptr)
        {
            oMapRelsIdToTarget[pszId] = pszTarget;
        }
    }
}

/************************************************************************/
/*                          AnalyseWorkbookRels()                       */
/************************************************************************/

void OGRXLSXDataSource::AnalyseWorkbookRels(VSILFILE* fpWorkbookRels)
{
    oParser = OGRCreateExpatXMLParser();
    XML_SetElementHandler(oParser, OGRXLSX::startElementWBRelsCbk, nullptr);
    XML_SetUserData(oParser, this);

    VSIFSeekL( fpWorkbookRels, 0, SEEK_SET );

    bStopParsing = false;
    nWithoutEventCounter = 0;
    nDataHandlerCounter = 0;

    char aBuf[BUFSIZ];
    int nDone = 0;
    do
    {
        nDataHandlerCounter = 0;
        unsigned int nLen =
            (unsigned int)VSIFReadL( aBuf, 1, sizeof(aBuf), fpWorkbookRels );
        nDone = VSIFEofL(fpWorkbookRels);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of %s file failed : %s at line %d, column %d",
                     "xl/_rels/workbook.xml.rels",
                     XML_ErrorString(XML_GetErrorCode(oParser)),
                     (int)XML_GetCurrentLineNumber(oParser),
                     (int)XML_GetCurrentColumnNumber(oParser));
            bStopParsing = true;
        }
        nWithoutEventCounter ++;
    } while( !nDone && !bStopParsing && nWithoutEventCounter < 10 );

    XML_ParserFree(oParser);
    oParser = nullptr;

    if (nWithoutEventCounter == 10)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        bStopParsing = true;
    }

    VSIFCloseL(fpWorkbookRels);
}

/************************************************************************/
/*                           GetUnprefixed()                            */
/************************************************************************/

static const char* GetUnprefixed(const char* pszStr)
{
    const char* pszColumn = strchr(pszStr, ':');
    if( pszColumn )
        return pszColumn + 1;
    return pszStr;
}

/************************************************************************/
/*                          startElementWBCbk()                         */
/************************************************************************/

static void XMLCALL startElementWBCbk(void *pUserData, const char *pszNameIn,
                                    const char **ppszAttr)
{
    ((OGRXLSXDataSource*)pUserData)->startElementWBCbk(pszNameIn, ppszAttr);
}

void OGRXLSXDataSource::startElementWBCbk(const char *pszNameIn,
                                       const char **ppszAttr)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    if (strcmp(GetUnprefixed(pszNameIn),"sheet") == 0)
    {
        const char* pszSheetName = GetAttributeValue(ppszAttr, "name", nullptr);
        const char* pszId = GetAttributeValue(ppszAttr, "r:id", nullptr);
        if (pszSheetName && pszId &&
            oMapRelsIdToTarget.find(pszId) != oMapRelsIdToTarget.end() &&
            m_oSetSheetId.find(pszId) == m_oSetSheetId.end() )
        {
            const auto& osTarget(oMapRelsIdToTarget[pszId]);
            m_oSetSheetId.insert(pszId);
            CPLString osFilename;
            if( osTarget.empty() )
                return;
            if( osTarget[0] == '/' )
            {
                int nIdx = 1;
                while( osTarget[nIdx] == '/' )
                    nIdx ++;
                if( osTarget[nIdx] == '\0' )
                    return;
                // Is it an "absolute" path ?
                osFilename = osPrefixedFilename + osTarget;
            }
            else
            {
                // or relative to the /xl subdirectory
                osFilename = osPrefixedFilename +
                             CPLString("/xl/") + osTarget;
            }
            papoLayers = (OGRLayer**)CPLRealloc(papoLayers, (nLayers + 1) * sizeof(OGRLayer*));
            papoLayers[nLayers++] = new OGRXLSXLayer(this, osFilename,
                pszSheetName);
        }
    }
}

/************************************************************************/
/*                             AnalyseWorkbook()                        */
/************************************************************************/

void OGRXLSXDataSource::AnalyseWorkbook(VSILFILE* fpWorkbook)
{
    oParser = OGRCreateExpatXMLParser();
    XML_SetElementHandler(oParser, OGRXLSX::startElementWBCbk, nullptr);
    XML_SetUserData(oParser, this);

    VSIFSeekL( fpWorkbook, 0, SEEK_SET );

    bStopParsing = false;
    nWithoutEventCounter = 0;
    nDataHandlerCounter = 0;

    char aBuf[BUFSIZ];
    int nDone = 0;
    do
    {
        nDataHandlerCounter = 0;
        unsigned int nLen =
            (unsigned int)VSIFReadL( aBuf, 1, sizeof(aBuf), fpWorkbook );
        nDone = VSIFEofL(fpWorkbook);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of %s file failed : %s at line %d, column %d",
                     "workbook.xml",
                     XML_ErrorString(XML_GetErrorCode(oParser)),
                     (int)XML_GetCurrentLineNumber(oParser),
                     (int)XML_GetCurrentColumnNumber(oParser));
            bStopParsing = true;
        }
        nWithoutEventCounter ++;
    } while( !nDone && !bStopParsing && nWithoutEventCounter < 10 );

    XML_ParserFree(oParser);
    oParser = nullptr;

    if (nWithoutEventCounter == 10)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        bStopParsing = true;
    }

    VSIFCloseL(fpWorkbook);
}

/************************************************************************/
/*                       startElementStylesCbk()                        */
/************************************************************************/

static void XMLCALL startElementStylesCbk(void *pUserData, const char *pszNameIn,
                                    const char **ppszAttr)
{
    ((OGRXLSXDataSource*)pUserData)->startElementStylesCbk(pszNameIn, ppszAttr);
}

void OGRXLSXDataSource::startElementStylesCbk(const char *pszNameIn,
                                       const char **ppszAttr)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    if (strcmp(pszNameIn,"numFmt") == 0)
    {
        const char* pszFormatCode = GetAttributeValue(ppszAttr, "formatCode", nullptr);
        const char* pszNumFmtId = GetAttributeValue(ppszAttr, "numFmtId", "-1");
        int nNumFmtId = atoi(pszNumFmtId);
        if (pszFormatCode && nNumFmtId >= 164)
        {
            int bHasDate = strstr(pszFormatCode, "DD") != nullptr ||
                           strstr(pszFormatCode, "dd") != nullptr ||
                           strstr(pszFormatCode, "YY") != nullptr ||
                           strstr(pszFormatCode, "yy") != nullptr;
            int bHasTime = strstr(pszFormatCode, "HH") != nullptr ||
                           strstr(pszFormatCode, "hh") != nullptr;
            if (bHasDate && bHasTime)
                apoMapStyleFormats[nNumFmtId] = XLSXFieldTypeExtended(OFTDateTime,
                                        strstr(pszFormatCode, "SS.000") != nullptr ||
                                        strstr(pszFormatCode, "ss.000") != nullptr);
            else if (bHasDate)
                apoMapStyleFormats[nNumFmtId] = XLSXFieldTypeExtended(OFTDate);
            else if (bHasTime)
                apoMapStyleFormats[nNumFmtId] = XLSXFieldTypeExtended(OFTTime);
            else
                apoMapStyleFormats[nNumFmtId] = XLSXFieldTypeExtended(OFTReal);
        }
    }
    else if( strcmp(pszNameIn,"cellXfs") == 0 )
    {
        bInCellXFS = true;
    }
    else if( bInCellXFS && strcmp(pszNameIn,"xf") == 0 )
    {
        const char* pszNumFmtId = GetAttributeValue(ppszAttr, "numFmtId", "-1");
        int nNumFmtId = atoi(pszNumFmtId);
        XLSXFieldTypeExtended eType(OFTReal);
        if (nNumFmtId >= 0)
        {
            if (nNumFmtId < 164)
            {
                // From http://social.msdn.microsoft.com/Forums/en-US/oxmlsdk/thread/e27aaf16-b900-4654-8210-83c5774a179c/
                if (nNumFmtId >= 14 && nNumFmtId <= 17)
                    eType = XLSXFieldTypeExtended(OFTDate);
                else if (nNumFmtId >= 18 && nNumFmtId <= 21)
                    eType = XLSXFieldTypeExtended(OFTTime);
                else if (nNumFmtId == 22)
                    eType = XLSXFieldTypeExtended(OFTDateTime);
            }
            else
            {
                std::map<int, XLSXFieldTypeExtended>::iterator oIter = apoMapStyleFormats.find(nNumFmtId);
                if (oIter != apoMapStyleFormats.end())
                    eType = oIter->second;
                else
                    CPLDebug("XLSX", "Cannot find entry in <numFmts> with numFmtId=%d", nNumFmtId);
            }
        }
#if DEBUG_VERBOSE
        printf("style[%lu] = %d\n",/*ok*/
               apoStyles.size(), static_cast<int>(eType.eType));
#endif

        apoStyles.push_back(eType);
    }
}

/************************************************************************/
/*                       endElementStylesCbk()                          */
/************************************************************************/

static void XMLCALL endElementStylesCbk(void *pUserData, const char *pszNameIn)
{
    ((OGRXLSXDataSource*)pUserData)->endElementStylesCbk(pszNameIn);
}

void OGRXLSXDataSource::endElementStylesCbk(const char *pszNameIn)
{
    if( bStopParsing ) return;

    nWithoutEventCounter = 0;
    if (strcmp(pszNameIn,"cellXfs") == 0)
    {
        bInCellXFS = false;
    }
}

/************************************************************************/
/*                             AnalyseStyles()                          */
/************************************************************************/

void OGRXLSXDataSource::AnalyseStyles(VSILFILE* fpStyles)
{
    if (fpStyles == nullptr)
        return;

    oParser = OGRCreateExpatXMLParser();
    XML_SetElementHandler(oParser, OGRXLSX::startElementStylesCbk, OGRXLSX::endElementStylesCbk);
    XML_SetUserData(oParser, this);

    VSIFSeekL( fpStyles, 0, SEEK_SET );

    bStopParsing = false;
    nWithoutEventCounter = 0;
    nDataHandlerCounter = 0;
    bInCellXFS = false;

    char aBuf[BUFSIZ];
    int nDone = 0;
    do
    {
        nDataHandlerCounter = 0;
        unsigned int nLen =
            (unsigned int)VSIFReadL( aBuf, 1, sizeof(aBuf), fpStyles );
        nDone = VSIFEofL(fpStyles);
        if (XML_Parse(oParser, aBuf, nLen, nDone) == XML_STATUS_ERROR)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "XML parsing of %s file failed : %s at line %d, column %d",
                     "styles.xml",
                     XML_ErrorString(XML_GetErrorCode(oParser)),
                     (int)XML_GetCurrentLineNumber(oParser),
                     (int)XML_GetCurrentColumnNumber(oParser));
            bStopParsing = true;
        }
        nWithoutEventCounter ++;
    } while( !nDone && !bStopParsing && nWithoutEventCounter < 10 );

    XML_ParserFree(oParser);
    oParser = nullptr;

    if (nWithoutEventCounter == 10)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Too much data inside one element. File probably corrupted");
        bStopParsing = true;
    }

    VSIFCloseL(fpStyles);
}

/************************************************************************/
/*                           ICreateLayer()                             */
/************************************************************************/

OGRLayer *
OGRXLSXDataSource::ICreateLayer( const char * pszLayerName,
                                 OGRSpatialReference * /*poSRS*/,
                                 OGRwkbGeometryType /*eType*/,
                                 char ** papszOptions )

{
/* -------------------------------------------------------------------- */
/*      Verify we are in update mode.                                   */
/* -------------------------------------------------------------------- */
    if( !bUpdatable )
    {
        CPLError( CE_Failure, CPLE_NoWriteAccess,
                  "Data source %s opened read-only.\n"
                  "New layer %s cannot be created.\n",
                  pszName, pszLayerName );

        return nullptr;
    }

/* -------------------------------------------------------------------- */
/*      Do we already have this layer?  If so, should we blow it        */
/*      away?                                                           */
/* -------------------------------------------------------------------- */
    for( int iLayer = 0; iLayer < nLayers; iLayer++ )
    {
        if( EQUAL(pszLayerName,papoLayers[iLayer]->GetName()) )
        {
            if( CSLFetchNameValue( papszOptions, "OVERWRITE" ) != nullptr
                && !EQUAL(CSLFetchNameValue(papszOptions,"OVERWRITE"),"NO") )
            {
                DeleteLayer( pszLayerName );
            }
            else
            {
                CPLError( CE_Failure, CPLE_AppDefined,
                          "Layer %s already exists, CreateLayer failed.\n"
                          "Use the layer creation option OVERWRITE=YES to "
                          "replace it.",
                          pszLayerName );
                return nullptr;
            }
        }
    }

/* -------------------------------------------------------------------- */
/*      Create the layer object.                                        */
/* -------------------------------------------------------------------- */
    OGRLayer* poLayer = new OGRXLSXLayer(this,
        CPLSPrintf("/vsizip/%s/xl/worksheets/sheet%d.xml", pszName, nLayers + 1),
        pszLayerName, TRUE);

    papoLayers = (OGRLayer**)CPLRealloc(papoLayers, (nLayers + 1) * sizeof(OGRLayer*));
    papoLayers[nLayers] = poLayer;
    nLayers ++;

    bUpdated = true;

    return poLayer;
}

/************************************************************************/
/*                            DeleteLayer()                             */
/************************************************************************/

void OGRXLSXDataSource::DeleteLayer( const char *pszLayerName )

{
/* -------------------------------------------------------------------- */
/*      Verify we are in update mode.                                   */
/* -------------------------------------------------------------------- */
    if( !bUpdatable )
    {
        CPLError( CE_Failure, CPLE_NoWriteAccess,
                  "Data source %s opened read-only.\n"
                  "Layer %s cannot be deleted.\n",
                  pszName, pszLayerName );

        return;
    }

/* -------------------------------------------------------------------- */
/*      Try to find layer.                                              */
/* -------------------------------------------------------------------- */
    int iLayer = 0;
    for( ; iLayer < nLayers; iLayer++ )
    {
        if( EQUAL(pszLayerName, papoLayers[iLayer]->GetName()) )
            break;
    }

    if( iLayer == nLayers )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Attempt to delete layer '%s', but this layer is not known to OGR.",
                  pszLayerName );
        return;
    }

    DeleteLayer(iLayer);
}

/************************************************************************/
/*                            DeleteLayer()                             */
/************************************************************************/

OGRErr OGRXLSXDataSource::DeleteLayer(int iLayer)
{
    if( iLayer < 0 || iLayer >= nLayers )
    {
        CPLError( CE_Failure, CPLE_AppDefined,
                  "Layer %d not in legal range of 0 to %d.",
                  iLayer, nLayers-1 );
        return OGRERR_FAILURE;
    }

/* -------------------------------------------------------------------- */
/*      Blow away our OGR structures related to the layer.  This is     */
/*      pretty dangerous if anything has a reference to this layer!     */
/* -------------------------------------------------------------------- */

    delete papoLayers[iLayer];
    memmove( papoLayers + iLayer, papoLayers + iLayer + 1,
             sizeof(void *) * (nLayers - iLayer - 1) );
    nLayers--;

    bUpdated = true;

    return OGRERR_NONE;
}

/************************************************************************/
/*                            WriteOverride()                           */
/************************************************************************/

static void WriteOverride( VSILFILE* fp, const char* pszPartName,
                           const char* pszContentType )
{
    VSIFPrintfL(fp, "<Override PartName=\"%s\" ContentType=\"%s\"/>\n",
                pszPartName, pszContentType);
}

static const char XML_HEADER[] = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
static const char MAIN_NS[] =
    "xmlns=\"http://schemas.openxmlformats.org/spreadsheetml/2006/main\"";
static const char SCHEMA_OD[] =
    "http://schemas.openxmlformats.org/officeDocument/2006";
static const char SCHEMA_OD_RS[] =
    "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
static const char SCHEMA_PACKAGE[] =
    "http://schemas.openxmlformats.org/package/2006";
static const char SCHEMA_PACKAGE_RS[] =
    "http://schemas.openxmlformats.org/package/2006/relationships";

/************************************************************************/
/*                           WriteContentTypes()                        */
/************************************************************************/

static bool WriteContentTypes(const char* pszName, int nLayers)
{
    CPLString osTmpFilename(
        CPLSPrintf("/vsizip/%s/[Content_Types].xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    // TODO(schwehr): Convert all strlen(XML_HEADER) to constexpr with
    // switch to C++11 or newer.
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<Types xmlns=\"%s/content-types\">\n", SCHEMA_PACKAGE);
    WriteOverride(fp, "/_rels/.rels", "application/vnd.openxmlformats-package.relationships+xml");
    WriteOverride(fp, "/docProps/core.xml", "application/vnd.openxmlformats-package.core-properties+xml");
    WriteOverride(fp, "/docProps/app.xml", "application/vnd.openxmlformats-officedocument.extended-properties+xml");
    WriteOverride(fp, "/xl/_rels/workbook.xml.rels", "application/vnd.openxmlformats-package.relationships+xml");
    for(int i=0;i<nLayers;i++)
    {
        WriteOverride(fp, CPLSPrintf("/xl/worksheets/sheet%d.xml", i+1),
                      "application/vnd.openxmlformats-officedocument.spreadsheetml.worksheet+xml");
    }
    WriteOverride(fp, "/xl/styles.xml","application/vnd.openxmlformats-officedocument.spreadsheetml.styles+xml");
    WriteOverride(fp, "/xl/workbook.xml","application/vnd.openxmlformats-officedocument.spreadsheetml.sheet.main+xml");
    WriteOverride(fp, "/xl/sharedStrings.xml","application/vnd.openxmlformats-officedocument.spreadsheetml.sharedStrings+xml");
    VSIFPrintfL(fp, "</Types>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                             WriteApp()                               */
/************************************************************************/

static bool WriteApp(const char* pszName)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/docProps/app.xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<Properties xmlns=\"%s/extended-properties\" "
                    "xmlns:vt=\"%s/docPropsVTypes\">\n", SCHEMA_OD, SCHEMA_OD);
    VSIFPrintfL(fp, "<TotalTime>0</TotalTime>\n");
    VSIFPrintfL(fp, "</Properties>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                             WriteCore()                              */
/************************************************************************/

static bool WriteCore(const char* pszName)
{
    CPLString osTmpFilename(
        CPLSPrintf("/vsizip/%s/docProps/core.xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<cp:coreProperties xmlns:cp=\"%s/metadata/core-properties\" "
                    "xmlns:dc=\"http://purl.org/dc/elements/1.1/\" "
                    "xmlns:dcmitype=\"http://purl.org/dc/dcmitype/\" "
                    "xmlns:dcterms=\"http://purl.org/dc/terms/\" "
                    "xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\">\n", SCHEMA_PACKAGE);
    VSIFPrintfL(fp, "<cp:revision>0</cp:revision>\n");
    VSIFPrintfL(fp, "</cp:coreProperties>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                            WriteWorkbook()                           */
/************************************************************************/

static bool WriteWorkbook(const char* pszName, GDALDataset* poDS)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/xl/workbook.xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<workbook %s xmlns:r=\"%s\">\n", MAIN_NS, SCHEMA_OD_RS);
    VSIFPrintfL(fp, "<fileVersion appName=\"Calc\"/>\n");
    /*
    VSIFPrintfL(fp, "<workbookPr backupFile=\"false\" showObjects=\"all\" date1904=\"false\"/>\n");
    VSIFPrintfL(fp, "<workbookProtection/>\n");
    VSIFPrintfL(fp, "<bookViews>\n");
    VSIFPrintfL(fp, "<workbookView activeTab=\"0\" firstSheet=\"0\" showHorizontalScroll=\"true\" "
                    "showSheetTabs=\"true\" showVerticalScroll=\"true\" tabRatio=\"600\" windowHeight=\"8192\" "
                    "windowWidth=\"16384\" xWindow=\"0\" yWindow=\"0\"/>\n");
    VSIFPrintfL(fp, "</bookViews>\n");
    */
    VSIFPrintfL(fp, "<sheets>\n");
    for(int i=0;i<poDS->GetLayerCount();i++)
    {
        OGRXLSXLayer* poLayer = (OGRXLSXLayer*) poDS->GetLayer(i);
        const char* pszLayerName = poLayer->GetName();
        char* pszXML = OGRGetXML_UTF8_EscapedString(pszLayerName);
        VSIFPrintfL(fp, "<sheet name=\"%s\" sheetId=\"%d\" state=\"visible\" r:id=\"rId%d\"/>\n", pszXML, i+1, i+2);
        CPLFree(pszXML);
    }
    VSIFPrintfL(fp, "</sheets>\n");
    VSIFPrintfL(fp, "<calcPr iterateCount=\"100\" refMode=\"A1\" iterate=\"false\" iterateDelta=\"0.001\"/>\n");
    VSIFPrintfL(fp, "</workbook>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                            BuildColString()                          */
/************************************************************************/

static CPLString BuildColString(int nCol)
{
    /*
    A Z   AA AZ   BA BZ   ZA   ZZ   AAA    ZZZ      AAAA
    0 25  26 51   52 77   676  701  702    18277    18278
    */
    CPLString osRet;
    osRet += (nCol % 26) + 'A';
    while(nCol >= 26)
    {
        nCol /= 26;
        // We would not need a decrement if this was a proper base 26
        // numeration scheme.
        nCol --;
        osRet += (nCol % 26) + 'A';
    }
    const size_t nSize = osRet.size();
    for(size_t l=0;l<nSize/2;l++)
    {
        char chTmp = osRet[nSize-1-l];
        osRet[nSize-1-l] = osRet[l];
        osRet[l] = chTmp;
    }
    return osRet;
}

/************************************************************************/
/*                             WriteLayer()                             */
/************************************************************************/

static bool WriteLayer(const char* pszName, OGRLayer* poLayer, int iLayer,
                       std::map<std::string,int>& oStringMap,
                       std::vector<std::string>& oStringList)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/xl/worksheets/sheet%d.xml",
                             pszName, iLayer + 1));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<worksheet %s xmlns:r=\"%s\">\n", MAIN_NS, SCHEMA_OD_RS);
    /*
    VSIFPrintfL(fp, "<sheetViews>\n");
    VSIFPrintfL(fp, "<sheetView colorId=\"64\" defaultGridColor=\"true\" rightToLeft=\"false\" showFormulas=\"false\" showGridLines=\"true\" showOutlineSymbols=\"true\" showRowColHeaders=\"true\" showZeros=\"true\" tabSelected=\"%s\" topLeftCell=\"A1\" view=\"normal\" windowProtection=\"false\" workbookViewId=\"0\" zoomScale=\"100\" zoomScaleNormal=\"100\" zoomScalePageLayoutView=\"60\">\n",
                (i == 0) ? "true" : "false");
    VSIFPrintfL(fp, "<selection activeCell=\"A1\" activeCellId=\"0\" pane=\"topLeft\" sqref=\"A1\"/>\n");
    VSIFPrintfL(fp, "</sheetView>\n");
    VSIFPrintfL(fp, "</sheetViews>\n");*/

    poLayer->ResetReading();

    OGRFeature* poFeature = poLayer->GetNextFeature();

    OGRFeatureDefn* poFDefn = poLayer->GetLayerDefn();
    bool bHasHeaders = false;
    int iRow = 1;

    VSIFPrintfL(fp, "<cols>\n");
    for( int j=0;j<poFDefn->GetFieldCount();j++)
    {
        int nWidth = 15;
        if (poFDefn->GetFieldDefn(j)->GetType() == OFTDateTime)
            nWidth = 29;
        VSIFPrintfL(fp, "<col min=\"%d\" max=\"%d\" width=\"%d\"/>\n",
                    j+1, 1024, nWidth);

        if (strcmp(poFDefn->GetFieldDefn(j)->GetNameRef(),
                    CPLSPrintf("Field%d", j+1)) != 0)
            bHasHeaders = true;
    }
    VSIFPrintfL(fp, "</cols>\n");

    VSIFPrintfL(fp, "<sheetData>\n");

    if( bHasHeaders && poFeature != nullptr )
    {
        VSIFPrintfL(fp, "<row r=\"%d\">\n", iRow);
        for( int j=0;j<poFDefn->GetFieldCount();j++)
        {
            const char* pszVal = poFDefn->GetFieldDefn(j)->GetNameRef();
            std::map<std::string,int>::iterator oIter = oStringMap.find(pszVal);
            int nStringIndex = 0;
            if (oIter != oStringMap.end())
                nStringIndex = oIter->second;
            else
            {
                nStringIndex = (int)oStringList.size();
                oStringMap[pszVal] = nStringIndex;
                oStringList.push_back(pszVal);
            }

            CPLString osCol = BuildColString(j);

            VSIFPrintfL(fp, "<c r=\"%s%d\" t=\"s\">\n", osCol.c_str(), iRow);
            VSIFPrintfL(fp, "<v>%d</v>\n", nStringIndex);
            VSIFPrintfL(fp, "</c>\n");
        }
        VSIFPrintfL(fp, "</row>\n");

        iRow ++;
    }

    while(poFeature != nullptr)
    {
        VSIFPrintfL(fp, "<row r=\"%d\">\n", iRow);
        for( int j=0;j<poFeature->GetFieldCount();j++)
        {
            if (poFeature->IsFieldSetAndNotNull(j))
            {
                CPLString osCol = BuildColString(j);

                OGRFieldDefn* poFieldDefn = poFDefn->GetFieldDefn(j);
                OGRFieldType eType = poFieldDefn->GetType();

                if (eType == OFTReal)
                {
                    VSIFPrintfL(fp, "<c r=\"%s%d\">\n", osCol.c_str(), iRow);
                    VSIFPrintfL(fp, "<v>%.16g</v>\n", poFeature->GetFieldAsDouble(j));
                    VSIFPrintfL(fp, "</c>\n");
                }
                else if (eType == OFTInteger)
                {
                    OGRFieldSubType eSubType = poFieldDefn->GetSubType();
                    if( eSubType == OFSTBoolean )
                        VSIFPrintfL(fp, "<c r=\"%s%d\" t=\"b\" s=\"5\">\n", osCol.c_str(), iRow);
                    else
                        VSIFPrintfL(fp, "<c r=\"%s%d\">\n", osCol.c_str(), iRow);
                    VSIFPrintfL(fp, "<v>%d</v>\n", poFeature->GetFieldAsInteger(j));
                    VSIFPrintfL(fp, "</c>\n");
                }
                else if (eType == OFTInteger64)
                {
                    VSIFPrintfL(fp, "<c r=\"%s%d\">\n", osCol.c_str(), iRow);
                    VSIFPrintfL(fp, "<v>" CPL_FRMT_GIB "</v>\n", poFeature->GetFieldAsInteger64(j));
                    VSIFPrintfL(fp, "</c>\n");
                }
                else if (eType == OFTDate || eType == OFTDateTime || eType == OFTTime)
                {
                    int nYear = 0;
                    int nMonth = 0;
                    int nDay = 0;
                    int nHour = 0;
                    int nMinute = 0;
                    int nTZFlag = 0;
                    float fSecond = 0.0f;
                    poFeature->GetFieldAsDateTime(j, &nYear, &nMonth, &nDay,
                                                    &nHour, &nMinute, &fSecond, &nTZFlag );
                    struct tm brokendowntime;
                    memset(&brokendowntime, 0, sizeof(brokendowntime));
                    brokendowntime.tm_year = (eType == OFTTime) ? 70 : nYear - 1900;
                    brokendowntime.tm_mon = (eType == OFTTime) ? 0 : nMonth - 1;
                    brokendowntime.tm_mday = (eType == OFTTime) ? 1 : nDay;
                    brokendowntime.tm_hour = nHour;
                    brokendowntime.tm_min = nMinute;
                    brokendowntime.tm_sec = (int)fSecond;
                    GIntBig nUnixTime = CPLYMDHMSToUnixTime(&brokendowntime);
                    double dfNumberOfDaysSince1900 = (1.0 * nUnixTime / NUMBER_OF_SECONDS_PER_DAY);
                    dfNumberOfDaysSince1900 += fmod(fSecond,1) / NUMBER_OF_SECONDS_PER_DAY;
                    int s = (eType == OFTDate) ? 1 : (eType == OFTDateTime) ? 2 : 3;
                    if( eType == OFTDateTime && OGR_GET_MS(fSecond) )
                        s = 4;
                    VSIFPrintfL(fp, "<c r=\"%s%d\" s=\"%d\">\n", osCol.c_str(), iRow, s);
                    if (eType != OFTTime)
                        dfNumberOfDaysSince1900 += NUMBER_OF_DAYS_BETWEEN_1900_AND_1970;
                    if (eType == OFTDate)
                        VSIFPrintfL(fp, "<v>%d</v>\n", (int)(dfNumberOfDaysSince1900 + 0.1));
                    else
                        VSIFPrintfL(fp, "<v>%.16g</v>\n", dfNumberOfDaysSince1900);
                    VSIFPrintfL(fp, "</c>\n");
                }
                else
                {
                    const char* pszVal = poFeature->GetFieldAsString(j);
                    std::map<std::string,int>::iterator oIter = oStringMap.find(pszVal);
                    int nStringIndex = 0;
                    if (oIter != oStringMap.end())
                        nStringIndex = oIter->second;
                    else
                    {
                        nStringIndex = (int)oStringList.size();
                        oStringMap[pszVal] = nStringIndex;
                        oStringList.push_back(pszVal);
                    }
                    VSIFPrintfL(fp, "<c r=\"%s%d\" t=\"s\">\n", osCol.c_str(), iRow);
                    VSIFPrintfL(fp, "<v>%d</v>\n", nStringIndex);
                    VSIFPrintfL(fp, "</c>\n");
                }
            }
        }
        VSIFPrintfL(fp, "</row>\n");

        iRow ++;
        delete poFeature;
        poFeature = poLayer->GetNextFeature();
    }
    VSIFPrintfL(fp, "</sheetData>\n");
    VSIFPrintfL(fp, "</worksheet>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                        WriteSharedStrings()                          */
/************************************************************************/

static bool WriteSharedStrings(const char* pszName,
                               CPL_UNUSED std::map<std::string,int>& oStringMap,
                               std::vector<std::string>& oStringList)
{
    CPLString osTmpFilename(
        CPLSPrintf("/vsizip/%s/xl/sharedStrings.xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<sst %s uniqueCount=\"%d\">\n",
                MAIN_NS,
                (int)oStringList.size());
    for(int i = 0; i < (int)oStringList.size(); i++)
    {
        VSIFPrintfL(fp, "<si>\n");
        char* pszXML = OGRGetXML_UTF8_EscapedString(oStringList[i].c_str());
        VSIFPrintfL(fp, "<t>%s</t>\n", pszXML);
        CPLFree(pszXML);
        VSIFPrintfL(fp, "</si>\n");
    }
    VSIFPrintfL(fp, "</sst>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                           WriteStyles()                              */
/************************************************************************/

static bool WriteStyles(const char* pszName)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/xl/styles.xml", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<styleSheet %s>\n", MAIN_NS);
    VSIFPrintfL(fp, "<numFmts count=\"4\">\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"GENERAL\" numFmtId=\"164\"/>\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"DD/MM/YY\" numFmtId=\"165\"/>\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"DD/MM/YYYY\\ HH:MM:SS\" numFmtId=\"166\"/>\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"HH:MM:SS\" numFmtId=\"167\"/>\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"DD/MM/YYYY\\ HH:MM:SS.000\" numFmtId=\"168\"/>\n");
    VSIFPrintfL(fp, "<numFmt formatCode=\"&quot;TRUE&quot;;&quot;TRUE&quot;;&quot;FALSE&quot;\" numFmtId=\"169\"/>\n");
    VSIFPrintfL(fp, "</numFmts>\n");
    VSIFPrintfL(fp, "<fonts count=\"1\">\n");
    VSIFPrintfL(fp, "<font>\n");
    VSIFPrintfL(fp, "<name val=\"Arial\"/>\n");
    VSIFPrintfL(fp, "<family val=\"2\"/>\n");
    VSIFPrintfL(fp, "<sz val=\"10\"/>\n");
    VSIFPrintfL(fp, "</font>\n");
    VSIFPrintfL(fp, "</fonts>\n");
    VSIFPrintfL(fp, "<fills count=\"1\">\n");
    VSIFPrintfL(fp, "<fill>\n");
    VSIFPrintfL(fp, "<patternFill patternType=\"none\"/>\n");
    VSIFPrintfL(fp, "</fill>\n");
    VSIFPrintfL(fp, "</fills>\n");
    VSIFPrintfL(fp, "<borders count=\"1\">\n");
    VSIFPrintfL(fp, "<border diagonalDown=\"false\" diagonalUp=\"false\">\n");
    VSIFPrintfL(fp, "<left/>\n");
    VSIFPrintfL(fp, "<right/>\n");
    VSIFPrintfL(fp, "<top/>\n");
    VSIFPrintfL(fp, "<bottom/>\n");
    VSIFPrintfL(fp, "<diagonal/>\n");
    VSIFPrintfL(fp, "</border>\n");
    VSIFPrintfL(fp, "</borders>\n");
    VSIFPrintfL(fp, "<cellStyleXfs count=\"1\">\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"164\">\n");
    VSIFPrintfL(fp, "</xf>\n");
    VSIFPrintfL(fp, "</cellStyleXfs>\n");
    VSIFPrintfL(fp, "<cellXfs count=\"6\">\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"164\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"165\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"166\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"167\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"168\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "<xf numFmtId=\"169\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "</cellXfs>\n");
    VSIFPrintfL(fp, "<cellStyles count=\"1\">\n");
    VSIFPrintfL(fp, "<cellStyle builtinId=\"0\" customBuiltin=\"false\" name=\"Normal\" xfId=\"0\"/>\n");
    VSIFPrintfL(fp, "</cellStyles>\n");
    VSIFPrintfL(fp, "</styleSheet>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                           WriteWorkbookRels()                        */
/************************************************************************/

static bool WriteWorkbookRels(const char* pszName, int nLayers)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/xl/_rels/workbook.xml.rels",
                             pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<Relationships xmlns=\"%s\">\n", SCHEMA_PACKAGE_RS);
    VSIFPrintfL(fp, "<Relationship Id=\"rId1\" Type=\"%s/styles\" Target=\"styles.xml\"/>\n", SCHEMA_OD_RS);
    for(int i=0;i<nLayers;i++)
    {
        VSIFPrintfL(fp, "<Relationship Id=\"rId%d\" Type=\"%s/worksheet\" Target=\"worksheets/sheet%d.xml\"/>\n",
                    2 + i, SCHEMA_OD_RS, 1 + i);
    }
    VSIFPrintfL(fp, "<Relationship Id=\"rId%d\" Type=\"%s/sharedStrings\" Target=\"sharedStrings.xml\"/>\n",
                2 + nLayers, SCHEMA_OD_RS);
    VSIFPrintfL(fp, "</Relationships>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                             WriteDotRels()                           */
/************************************************************************/

static bool WriteDotRels(const char* pszName)
{
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s/_rels/.rels", pszName));
    VSILFILE* fp = VSIFOpenL(osTmpFilename, "wb");
    if( !fp )
        return false;
    VSIFWriteL(XML_HEADER, strlen(XML_HEADER), 1, fp);
    VSIFPrintfL(fp, "<Relationships xmlns=\"%s\">\n", SCHEMA_PACKAGE_RS);
    VSIFPrintfL(fp, "<Relationship Id=\"rId1\" Type=\"%s/officeDocument\" Target=\"xl/workbook.xml\"/>\n", SCHEMA_OD_RS);
    VSIFPrintfL(fp, "<Relationship Id=\"rId2\" Type=\"%s/metadata/core-properties\" Target=\"docProps/core.xml\"/>\n", SCHEMA_PACKAGE_RS);
    VSIFPrintfL(fp, "<Relationship Id=\"rId3\" Type=\"%s/extended-properties\" Target=\"docProps/app.xml\"/>\n", SCHEMA_OD_RS);
    VSIFPrintfL(fp, "</Relationships>\n");
    VSIFCloseL(fp);
    return true;
}

/************************************************************************/
/*                            FlushCache()                              */
/************************************************************************/

void OGRXLSXDataSource::FlushCache(bool /* bAtClosing */)
{
    if( !bUpdated )
        return;

    /* Cause all layers to be loaded */
    for(int i = 0; i<nLayers; i++)
    {
        ((OGRXLSXLayer*)papoLayers[i])->GetLayerDefn();
    }

    VSIStatBufL sStat;
    if (VSIStatL(pszName, &sStat) == 0)
    {
        if (VSIUnlink( pszName ) != 0)
        {
            CPLError(CE_Failure, CPLE_FileIO,
                    "Cannot delete %s", pszName);
            return;
        }
    }

    CPLConfigOptionSetter oZip64Disable("CPL_CREATE_ZIP64", "NO", false);

    /* Maintain new ZIP files opened */
    CPLString osTmpFilename(CPLSPrintf("/vsizip/%s", pszName));
    VSILFILE* fpZIP = VSIFOpenExL(osTmpFilename, "wb", true);
    if (fpZIP == nullptr)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Cannot create %s: %s", pszName, VSIGetLastErrorMsg());
        return;
    }

    bool bOK = WriteContentTypes(pszName, nLayers);

    //VSIMkdir(CPLSPrintf("/vsizip/%s/docProps", pszName),0755);
    bOK &= WriteApp(pszName);
    bOK &= WriteCore(pszName);

    //VSIMkdir(CPLSPrintf("/vsizip/%s/xl", pszName),0755);
    bOK &= WriteWorkbook(pszName, this);

    std::map<std::string,int> oStringMap;
    std::vector<std::string> oStringList;

    //VSIMkdir(CPLSPrintf("/vsizip/%s/xl/worksheets", pszName),0755);
    for(int i=0;i<nLayers;i++)
    {
        bOK &= WriteLayer(pszName, GetLayer(i), i, oStringMap, oStringList);
    }

    bOK &= WriteSharedStrings(pszName, oStringMap, oStringList);
    bOK &= WriteStyles(pszName);

    //VSIMkdir(CPLSPrintf("/vsizip/%s/xl/_rels", pszName),0755);
    bOK &= WriteWorkbookRels(pszName, nLayers);

    //VSIMkdir(CPLSPrintf("/vsizip/%s/_rels", pszName),0755);
    bOK &= WriteDotRels(pszName);

    /* Now close ZIP file */
    VSIFCloseL(fpZIP);

    /* Reset updated flag at datasource and layer level */
    bUpdated = false;
    for( int i = 0; i<nLayers; i++ )
    {
        ((OGRXLSXLayer*)papoLayers[i])->SetUpdated(false);
    }

    if( !bOK )
    {
        CPLError(CE_Failure, CPLE_FileIO, "Failure when saving %s", pszName);
    }

    return;
}

} /* end of OGRXLSX namespace */
