/******************************************************************************
 *
 * Project:  APP ENVISAT Support
 * Purpose:  Reader for ENVISAT format image data.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2001, Atlantis Scientific, Inc.
 * Copyright (c) 2009-2013, Even Rouault <even dot rouault at spatialys.com>
 *
 * SPDX-License-Identifier: MIT
 ****************************************************************************/

#include "adsrange.hpp"
#include "rawdataset.h"
#include "cpl_string.h"
#include "gdal_frmts.h"
#include "gdal_driver.h"
#include "gdal_drivermanager.h"
#include "gdal_openinfo.h"
#include "gdal_cpp_functions.h"
#include "ogr_srs_api.h"
#include "timedelta.hpp"

CPL_C_START
#include "EnvisatFile.h"
#include "records.h"
CPL_C_END

#include <algorithm>

/************************************************************************/
/* ==================================================================== */
/*                        MerisL2FlagBand                         */
/* ==================================================================== */
/************************************************************************/
class MerisL2FlagBand final : public GDALPamRasterBand
{
  public:
    MerisL2FlagBand(GDALDataset *, int, VSILFILE *, vsi_l_offset, int);
    ~MerisL2FlagBand() override;
    CPLErr IReadBlock(int, int, void *) override;

  private:
    vsi_l_offset nImgOffset;
    int nPrefixBytes;
    size_t nBytePerPixel;
    size_t nRecordSize;
    size_t nDataSize;
    GByte *pReadBuf;
    VSILFILE *fpImage;
};

/************************************************************************/
/*                        MerisL2FlagBand()                       */
/************************************************************************/
MerisL2FlagBand::MerisL2FlagBand(GDALDataset *poDSIn, int nBandIn,
                                 VSILFILE *fpImageIn, vsi_l_offset nImgOffsetIn,
                                 int nPrefixBytesIn)
    : nImgOffset(nImgOffsetIn), nPrefixBytes(nPrefixBytesIn), nBytePerPixel(3),
      nRecordSize(0), nDataSize(0), pReadBuf(nullptr)
{
    poDS = poDSIn;
    nBand = nBandIn;

    fpImage = fpImageIn;

    eDataType = GDT_UInt32;

    nBlockXSize = poDS->GetRasterXSize();
    nBlockYSize = 1;
    nRecordSize = nPrefixBytesIn + nBlockXSize * nBytePerPixel;
    nDataSize = nBlockXSize * nBytePerPixel;
    pReadBuf = static_cast<GByte *>(CPLMalloc(nRecordSize));
}

/************************************************************************/
/*                        ~MerisL2FlagBand()                       */
/************************************************************************/
MerisL2FlagBand::~MerisL2FlagBand()
{
    CPLFree(pReadBuf);
}

/************************************************************************/
/*                             IReadBlock()                             */
/************************************************************************/
CPLErr MerisL2FlagBand::IReadBlock(CPL_UNUSED int nBlockXOff, int nBlockYOff,
                                   void *pImage)
{
    CPLAssert(nBlockXOff == 0);
    CPLAssert(pReadBuf != nullptr);

    vsi_l_offset nOffset =
        nImgOffset + nPrefixBytes +
        static_cast<vsi_l_offset>(nBlockYOff) * nBlockYSize * nRecordSize;

    if (VSIFSeekL(fpImage, nOffset, SEEK_SET) != 0)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Seek to %d for scanline %d failed.\n", (int)nOffset,
                 nBlockYOff);
        return CE_Failure;
    }

    if (VSIFReadL(pReadBuf, 1, nDataSize, fpImage) != nDataSize)
    {
        CPLError(CE_Failure, CPLE_FileIO,
                 "Read of %d bytes for scanline %d failed.\n", (int)nDataSize,
                 nBlockYOff);
        return CE_Failure;
    }

    const unsigned int nUInt32Size = 4;
    for (unsigned iImg = 0, iBuf = 0; iImg < nBlockXSize * nUInt32Size;
         iImg += nUInt32Size, iBuf += (unsigned)nBytePerPixel)
    {
#ifdef CPL_LSB
        ((GByte *)pImage)[iImg] = pReadBuf[iBuf + 2];
        ((GByte *)pImage)[iImg + 1] = pReadBuf[iBuf + 1];
        ((GByte *)pImage)[iImg + 2] = pReadBuf[iBuf];
        ((GByte *)pImage)[iImg + 3] = 0;
#else
        ((GByte *)pImage)[iImg] = 0;
        ((GByte *)pImage)[iImg + 1] = pReadBuf[iBuf];
        ((GByte *)pImage)[iImg + 2] = pReadBuf[iBuf + 1];
        ((GByte *)pImage)[iImg + 3] = pReadBuf[iBuf + 2];
#endif
    }

    return CE_None;
}

/************************************************************************/
/* ==================================================================== */
/*                              EnvisatDataset                          */
/* ==================================================================== */
/************************************************************************/

class EnvisatDataset final : public RawDataset
{
    EnvisatFile *hEnvisatFile;
    VSILFILE *fpImage;

    OGRSpatialReference m_oGCPSRS{};
    int nGCPCount;
    GDAL_GCP *pasGCPList;

    char **papszTempMD;

    void ScanForGCPs_ASAR();
    void ScanForGCPs_MERIS();

    void UnwrapGCPs();

    void CollectMetadata(EnvisatFile_HeaderFlag);
    void CollectDSDMetadata();
    void CollectADSMetadata();

    CPLErr Close() override;

  public:
    EnvisatDataset();
    ~EnvisatDataset() override;

    int GetGCPCount() override;
    const OGRSpatialReference *GetGCPSpatialRef() const override;
    const GDAL_GCP *GetGCPs() override;
    char **GetMetadataDomainList() override;
    char **GetMetadata(const char *pszDomain) override;

    static GDALDataset *Open(GDALOpenInfo *);
};

/************************************************************************/
/* ==================================================================== */
/*                              EnvisatDataset                          */
/* ==================================================================== */
/************************************************************************/

/************************************************************************/
/*                            EnvisatDataset()                          */
/************************************************************************/

EnvisatDataset::EnvisatDataset()
    : hEnvisatFile(nullptr), fpImage(nullptr), nGCPCount(0),
      pasGCPList(nullptr), papszTempMD(nullptr)
{
    m_oGCPSRS.SetAxisMappingStrategy(OAMS_TRADITIONAL_GIS_ORDER);
    m_oGCPSRS.importFromWkt(SRS_WKT_WGS84_LAT_LONG);
}

/************************************************************************/
/*                            ~EnvisatDataset()                         */
/************************************************************************/

EnvisatDataset::~EnvisatDataset()

{
    EnvisatDataset::Close();
}

/************************************************************************/
/*                              Close()                                 */
/************************************************************************/

CPLErr EnvisatDataset::Close()
{
    CPLErr eErr = CE_None;
    if (nOpenFlags != OPEN_FLAGS_CLOSED)
    {
        if (EnvisatDataset::FlushCache(true) != CE_None)
            eErr = CE_Failure;

        if (hEnvisatFile != nullptr)
            EnvisatFile_Close(hEnvisatFile);

        if (fpImage != nullptr)
            CPL_IGNORE_RET_VAL(VSIFCloseL(fpImage));

        if (nGCPCount > 0)
        {
            GDALDeinitGCPs(nGCPCount, pasGCPList);
            CPLFree(pasGCPList);
        }

        CSLDestroy(papszTempMD);

        if (GDALPamDataset::Close() != CE_None)
            eErr = CE_Failure;
    }
    return eErr;
}

/************************************************************************/
/*                            GetGCPCount()                             */
/************************************************************************/

int EnvisatDataset::GetGCPCount()

{
    return nGCPCount;
}

/************************************************************************/
/*                          GetGCPSpatialRef()                          */
/************************************************************************/

const OGRSpatialReference *EnvisatDataset::GetGCPSpatialRef() const

{
    if (nGCPCount > 0)
        return &m_oGCPSRS;

    return nullptr;
}

/************************************************************************/
/*                               GetGCP()                               */
/************************************************************************/

const GDAL_GCP *EnvisatDataset::GetGCPs()

{
    return pasGCPList;
}

/************************************************************************/
/*                         UnwrapGCPs()                                 */
/************************************************************************/

/* external C++ implementation of the in-place unwrapper */
void EnvisatUnwrapGCPs(int nGCPCount, GDAL_GCP *pasGCPList);

void EnvisatDataset::UnwrapGCPs()
{
    EnvisatUnwrapGCPs(nGCPCount, pasGCPList);
}

/************************************************************************/
/*                          ScanForGCPs_ASAR()                          */
/************************************************************************/

void EnvisatDataset::ScanForGCPs_ASAR()

{
    /* -------------------------------------------------------------------- */
    /*      Do we have a meaningful geolocation grid?                       */
    /* -------------------------------------------------------------------- */
    int nDatasetIndex =
        EnvisatFile_GetDatasetIndex(hEnvisatFile, "GEOLOCATION GRID ADS");
    if (nDatasetIndex == -1)
        return;

    int nNumDSR, nDSRSize;
    if (EnvisatFile_GetDatasetInfo(hEnvisatFile, nDatasetIndex, nullptr,
                                   nullptr, nullptr, nullptr, nullptr, &nNumDSR,
                                   &nDSRSize) != SUCCESS)
        return;

    if (nNumDSR == 0 || nDSRSize != 521)
        return;

    /* -------------------------------------------------------------------- */
    /*      Collect the first GCP set from each record.                     */
    /* -------------------------------------------------------------------- */
    GByte abyRecord[521];
    int nRange = 0;
    int nRangeOffset = 0;
    GUInt32 unValue;

    nGCPCount = 0;
    pasGCPList = (GDAL_GCP *)CPLCalloc(sizeof(GDAL_GCP), (nNumDSR + 1) * 11);

    for (int iRecord = 0; iRecord < nNumDSR; iRecord++)
    {
        if (EnvisatFile_ReadDatasetRecord(hEnvisatFile, nDatasetIndex, iRecord,
                                          abyRecord) != SUCCESS)
            continue;

        memcpy(&unValue, abyRecord + 13, 4);
        nRange = CPL_MSBWORD32(unValue) + nRangeOffset;

        if ((iRecord > 1) &&
            (int(pasGCPList[nGCPCount - 1].dfGCPLine + 0.5) > nRange))
        {
            int delta = (int)(pasGCPList[nGCPCount - 1].dfGCPLine -
                              pasGCPList[nGCPCount - 12].dfGCPLine);
            nRange = int(pasGCPList[nGCPCount - 1].dfGCPLine + 0.5) + delta;
            nRangeOffset = nRange - 1;
        }

        for (int iGCP = 0; iGCP < 11; iGCP++)
        {
            GDALInitGCPs(1, pasGCPList + nGCPCount);

            CPLFree(pasGCPList[nGCPCount].pszId);

            char szId[128];
            snprintf(szId, sizeof(szId), "%d", nGCPCount + 1);
            pasGCPList[nGCPCount].pszId = CPLStrdup(szId);

            memcpy(&unValue, abyRecord + 25 + iGCP * 4, 4);
            int nSample = CPL_MSBWORD32(unValue);

            memcpy(&unValue, abyRecord + 25 + 176 + iGCP * 4, 4);
            pasGCPList[nGCPCount].dfGCPX =
                ((int)CPL_MSBWORD32(unValue)) * 0.000001;

            memcpy(&unValue, abyRecord + 25 + 132 + iGCP * 4, 4);
            pasGCPList[nGCPCount].dfGCPY =
                ((int)CPL_MSBWORD32(unValue)) * 0.000001;

            pasGCPList[nGCPCount].dfGCPZ = 0.0;

            pasGCPList[nGCPCount].dfGCPLine = nRange - 0.5;
            pasGCPList[nGCPCount].dfGCPPixel = nSample - 0.5;

            nGCPCount++;
        }
    }

    /* -------------------------------------------------------------------- */
    /*      We also collect the bottom GCPs from the last granule.          */
    /* -------------------------------------------------------------------- */
    memcpy(&unValue, abyRecord + 17, 4);
    nRange = nRange + CPL_MSBWORD32(unValue) - 1;

    for (int iGCP = 0; iGCP < 11; iGCP++)
    {
        GDALInitGCPs(1, pasGCPList + nGCPCount);

        CPLFree(pasGCPList[nGCPCount].pszId);

        char szId[128];
        snprintf(szId, sizeof(szId), "%d", nGCPCount + 1);
        pasGCPList[nGCPCount].pszId = CPLStrdup(szId);

        memcpy(&unValue, abyRecord + 279 + iGCP * 4, 4);
        int nSample = CPL_MSBWORD32(unValue);

        memcpy(&unValue, abyRecord + 279 + 176 + iGCP * 4, 4);
        pasGCPList[nGCPCount].dfGCPX = ((int)CPL_MSBWORD32(unValue)) * 0.000001;

        memcpy(&unValue, abyRecord + 279 + 132 + iGCP * 4, 4);
        pasGCPList[nGCPCount].dfGCPY = ((int)CPL_MSBWORD32(unValue)) * 0.000001;

        pasGCPList[nGCPCount].dfGCPZ = 0.0;

        pasGCPList[nGCPCount].dfGCPLine = nRange - 0.5;
        pasGCPList[nGCPCount].dfGCPPixel = nSample - 0.5;

        nGCPCount++;
    }
}

/************************************************************************/
/*                         ScanForGCPs_MERIS()                          */
/************************************************************************/

void EnvisatDataset::ScanForGCPs_MERIS()

{
    /* -------------------------------------------------------------------- */
    /*      Do we have a meaningful geolocation grid?  Search for a         */
    /*      DS_TYPE=A and a name containing "geolocation" or "tie           */
    /*      points".                                                        */
    /* -------------------------------------------------------------------- */
    int nDatasetIndex =
        EnvisatFile_GetDatasetIndex(hEnvisatFile, "Tie points ADS");
    if (nDatasetIndex == -1)
        return;

    int nNumDSR, nDSRSize;
    if (EnvisatFile_GetDatasetInfo(hEnvisatFile, nDatasetIndex, nullptr,
                                   nullptr, nullptr, nullptr, nullptr, &nNumDSR,
                                   &nDSRSize) != SUCCESS)
        return;

    if (nNumDSR == 0)
        return;

    /* -------------------------------------------------------------------- */
    /*      Figure out the tiepoint space, and how many we have.            */
    /* -------------------------------------------------------------------- */
    int nLinesPerTiePoint =
        EnvisatFile_GetKeyValueAsInt(hEnvisatFile, SPH, "LINES_PER_TIE_PT", 0);
    int nSamplesPerTiePoint = EnvisatFile_GetKeyValueAsInt(
        hEnvisatFile, SPH, "SAMPLES_PER_TIE_PT", 0);

    if (nLinesPerTiePoint == 0 || nSamplesPerTiePoint == 0)
        return;

    int nTPPerColumn = nNumDSR;
    int nTPPerLine = DIV_ROUND_UP(GetRasterXSize(), nSamplesPerTiePoint);

    /* -------------------------------------------------------------------- */
    /*      Find a measurement type dataset to use as a reference raster    */
    /*      band.                                                           */
    /* -------------------------------------------------------------------- */

    int nMDSIndex = 0;

    for (; true; nMDSIndex++)
    {
        const char *pszDSType = nullptr;
        if (EnvisatFile_GetDatasetInfo(hEnvisatFile, nMDSIndex, nullptr,
                                       &pszDSType, nullptr, nullptr, nullptr,
                                       nullptr, nullptr) == FAILURE)
        {
            CPLDebug("EnvisatDataset", "Unable to find MDS in Envisat file.");
            return;
        }
        if (EQUAL(pszDSType, "M"))
            break;
    }

    /* -------------------------------------------------------------------- */
    /*      Get subset of TP ADS records matching the MDS records           */
    /* -------------------------------------------------------------------- */

    /* get the MDS line sampling time interval */
    TimeDelta tdMDSSamplingInterval(
        0, 0,
        EnvisatFile_GetKeyValueAsInt(hEnvisatFile, SPH, "LINE_TIME_INTERVAL",
                                     0));

    /* get range of TiePoint ADS records matching the measurements */
    ADSRangeLastAfter arTP(*hEnvisatFile, nDatasetIndex, nMDSIndex,
                           tdMDSSamplingInterval);

    /* check if there are any TPs to be used */
    if (arTP.getDSRCount() <= 0)
    {
        CPLDebug("EnvisatDataset", "No tiepoint covering "
                                   "the measurement records.");
        return; /* No TPs - no extraction. */
    }

    /* check if TPs cover the whole range of MDSRs */
    if ((arTP.getFirstOffset() < 0) || (arTP.getLastOffset() < 0))
    {
        CPLDebug("EnvisatDataset", "The tiepoints do not cover "
                                   "whole range of measurement records.");
        /* Not good but we can still extract some of the TPS, can we? */
    }

    /* Check TP record spacing */
    if ((1 +
         (arTP.getFirstOffset() + arTP.getLastOffset() + GetRasterYSize() - 1) /
             nLinesPerTiePoint) != arTP.getDSRCount())
    {
        CPLDebug("EnvisatDataset",
                 "Not enough tiepoints per column! "
                 "received=%d expected=%d",
                 nTPPerColumn,
                 1 + (arTP.getFirstOffset() + arTP.getLastOffset() +
                      GetRasterYSize() - 1) /
                         nLinesPerTiePoint);
        return;  // That is far more serious - we risk misplacing TPs.
    }

    bool isBrowseProduct;
    if (50 * nTPPerLine + 13 == nDSRSize) /* regular product */
    {
        isBrowseProduct = false;
    }
    else if (8 * nTPPerLine + 13 == nDSRSize) /* browse product */
    {
        /* although BPs are rare there is no reason not to support them */
        isBrowseProduct = true;
    }
    else
    {
        CPLDebug("EnvisatDataset",
                 "Unexpected size of 'Tie points ADS' !"
                 " received=%d expected=%d or %d",
                 nDSRSize, 50 * nTPPerLine + 13, 8 * nTPPerLine + 13);
        return;
    }

    /* -------------------------------------------------------------------- */
    /*      Collect the first GCP set from each record.                     */
    /* -------------------------------------------------------------------- */

    GByte *pabyRecord = (GByte *)CPLMalloc(nDSRSize - 13);

    GUInt32 *tpLat =
        reinterpret_cast<GUInt32 *>(pabyRecord) + nTPPerLine * 0; /* latitude */
    GUInt32 *tpLon = reinterpret_cast<GUInt32 *>(pabyRecord) +
                     nTPPerLine * 1; /* longitude */
    GUInt32 *tpLtc = reinterpret_cast<GUInt32 *>(pabyRecord) +
                     nTPPerLine * 4; /* lat. DEM correction */
    GUInt32 *tpLnc = reinterpret_cast<GUInt32 *>(pabyRecord) +
                     nTPPerLine * 5; /* lon. DEM correction */

    nGCPCount = 0;
    pasGCPList = (GDAL_GCP *)CPLCalloc(
        sizeof(GDAL_GCP), static_cast<size_t>(arTP.getDSRCount()) * nTPPerLine);

    for (int ir = 0; ir < arTP.getDSRCount(); ir++)
    {
        int iRecord = ir + arTP.getFirstIndex();

        double dfGCPLine =
            0.5 + (iRecord * nLinesPerTiePoint - arTP.getFirstOffset());

        if (EnvisatFile_ReadDatasetRecordChunk(hEnvisatFile, nDatasetIndex,
                                               iRecord, pabyRecord, 13,
                                               -1) != SUCCESS)
            continue;

        for (int iGCP = 0; iGCP < nTPPerLine; iGCP++)
        {
            GDALInitGCPs(1, pasGCPList + nGCPCount);

            CPLFree(pasGCPList[nGCPCount].pszId);

            char szId[128];
            snprintf(szId, sizeof(szId), "%d", nGCPCount + 1);
            pasGCPList[nGCPCount].pszId = CPLStrdup(szId);

#define INT32(x) ((GInt32)CPL_MSBWORD32(x))

            pasGCPList[nGCPCount].dfGCPX = 1e-6 * INT32(tpLon[iGCP]);
            pasGCPList[nGCPCount].dfGCPY = 1e-6 * INT32(tpLat[iGCP]);
            pasGCPList[nGCPCount].dfGCPZ = 0.0;

            if (!isBrowseProduct) /* add DEM corrections */
            {
                pasGCPList[nGCPCount].dfGCPX += 1e-6 * INT32(tpLnc[iGCP]);
                pasGCPList[nGCPCount].dfGCPY += 1e-6 * INT32(tpLtc[iGCP]);
            }

#undef INT32

            pasGCPList[nGCPCount].dfGCPLine = dfGCPLine;
            pasGCPList[nGCPCount].dfGCPPixel = iGCP * nSamplesPerTiePoint + 0.5;

            nGCPCount++;
        }
    }
    CPLFree(pabyRecord);
}

/************************************************************************/
/*                      GetMetadataDomainList()                         */
/************************************************************************/

char **EnvisatDataset::GetMetadataDomainList()
{
    return CSLAddString(GDALDataset::GetMetadataDomainList(), "envisat-ds-*-*");
}

/************************************************************************/
/*                            GetMetadata()                             */
/************************************************************************/

char **EnvisatDataset::GetMetadata(const char *pszDomain)

{
    if (pszDomain == nullptr || !STARTS_WITH_CI(pszDomain, "envisat-ds-"))
        return GDALDataset::GetMetadata(pszDomain);

    /* -------------------------------------------------------------------- */
    /*      Get the dataset name and record number.                         */
    /* -------------------------------------------------------------------- */
    char szDSName[128];
    strncpy(szDSName, pszDomain + 11, sizeof(szDSName));
    szDSName[sizeof(szDSName) - 1] = 0;

    int nRecord = -1;
    for (int i = 0; i < (int)sizeof(szDSName) - 1; i++)
    {
        if (szDSName[i] == '-')
        {
            szDSName[i] = '\0';
            nRecord = atoi(szDSName + 1);
            break;
        }
    }

    if (nRecord == -1)
        return nullptr;

    /* -------------------------------------------------------------------- */
    /*      Get the dataset index and info.                                 */
    /* -------------------------------------------------------------------- */
    int nDSIndex = EnvisatFile_GetDatasetIndex(hEnvisatFile, szDSName);
    if (nDSIndex == -1)
        return nullptr;

    int nDSRSize, nNumDSR;
    EnvisatFile_GetDatasetInfo(hEnvisatFile, nDSIndex, nullptr, nullptr,
                               nullptr, nullptr, nullptr, &nNumDSR, &nDSRSize);

    if (nDSRSize == -1 || nRecord < 0 || nRecord >= nNumDSR)
        return nullptr;

    /* -------------------------------------------------------------------- */
    /*      Read the requested record.                                      */
    /* -------------------------------------------------------------------- */
    char *pszRecord = (char *)CPLMalloc(nDSRSize + 1);

    if (EnvisatFile_ReadDatasetRecord(hEnvisatFile, nDSIndex, nRecord,
                                      pszRecord) == FAILURE)
    {
        CPLFree(pszRecord);
        return nullptr;
    }

    /* -------------------------------------------------------------------- */
    /*      Massage the data into a safe textual format.  For now we        */
    /*      just turn zero bytes into spaces.                               */
    /* -------------------------------------------------------------------- */
    CSLDestroy(papszTempMD);

    char *pszEscapedRecord =
        CPLEscapeString(pszRecord, nDSRSize, CPLES_BackslashQuotable);
    papszTempMD = CSLSetNameValue(nullptr, "EscapedRecord", pszEscapedRecord);
    CPLFree(pszEscapedRecord);

    for (int i = 0; i < nDSRSize; i++)
        if (pszRecord[i] == '\0')
            pszRecord[i] = ' ';

    papszTempMD = CSLSetNameValue(papszTempMD, "RawRecord", pszRecord);

    CPLFree(pszRecord);

    return papszTempMD;
}

/************************************************************************/
/*                         CollectDSDMetadata()                         */
/*                                                                      */
/*      Collect metadata based on any DSD entries with filenames        */
/*      associated.                                                     */
/************************************************************************/

void EnvisatDataset::CollectDSDMetadata()

{
    const char *pszDSName;
    const char *pszFilename;

    for (int iDSD = 0;
         EnvisatFile_GetDatasetInfo(hEnvisatFile, iDSD, &pszDSName, nullptr,
                                    &pszFilename, nullptr, nullptr, nullptr,
                                    nullptr) == SUCCESS;
         iDSD++)
    {
        if (pszFilename == nullptr || strlen(pszFilename) == 0 ||
            STARTS_WITH_CI(pszFilename, "NOT USED") ||
            STARTS_WITH_CI(pszFilename, "        "))
            continue;

        std::string osKey("DS_");
        osKey += pszDSName;
        // strip trailing spaces.
        {
            const auto nPos = osKey.rfind(' ');
            if (nPos != std::string::npos)
                osKey.resize(nPos);
        }

        // convert spaces into underscores.
        for (char &ch : osKey)
        {
            if (ch == ' ')
                ch = '_';
        }

        osKey += "_NAME";

        std::string osTrimmedName(pszFilename);
        {
            const auto nPos = osTrimmedName.rfind(' ');
            if (nPos != std::string::npos)
                osTrimmedName.resize(nPos);
        }

        SetMetadataItem(osKey.c_str(), osTrimmedName.c_str());
    }
}

/************************************************************************/
/*                         CollectADSMetadata()                         */
/*                                                                      */
/*      Collect metadata from envisat ADS and GADS.                     */
/************************************************************************/

void EnvisatDataset::CollectADSMetadata()
{
    int nNumDsr, nDSRSize;
    const char *pszDSName;
    const char *pszDSType;
    const char *pszDSFilename;

    const char *pszProduct =
        EnvisatFile_GetKeyValueAsString(hEnvisatFile, MPH, "PRODUCT", "");

    for (int nDSIndex = 0;
         EnvisatFile_GetDatasetInfo(hEnvisatFile, nDSIndex, &pszDSName,
                                    &pszDSType, &pszDSFilename, nullptr,
                                    nullptr, &nNumDsr, &nDSRSize) == SUCCESS;
         ++nDSIndex)
    {
        if (STARTS_WITH_CI(pszDSFilename, "NOT USED") || (nNumDsr <= 0))
            continue;
        if (!EQUAL(pszDSType, "A") && !EQUAL(pszDSType, "G"))
            continue;

        for (int nRecord = 0; nRecord < nNumDsr; ++nRecord)
        {
            char szPrefix[128];
            strncpy(szPrefix, pszDSName, sizeof(szPrefix) - 1);
            szPrefix[sizeof(szPrefix) - 1] = '\0';

            // strip trailing spaces
            for (int i = static_cast<int>(strlen(szPrefix)) - 1;
                 i && szPrefix[i] == ' '; --i)
                szPrefix[i] = '\0';

            // convert spaces into underscores
            for (int i = 0; szPrefix[i] != '\0'; i++)
            {
                if (szPrefix[i] == ' ')
                    szPrefix[i] = '_';
            }

            char *pszRecord = (char *)CPLMalloc(nDSRSize + 1);

            if (EnvisatFile_ReadDatasetRecord(hEnvisatFile, nDSIndex, nRecord,
                                              pszRecord) == FAILURE)
            {
                CPLFree(pszRecord);
                return;
            }

            const EnvisatRecordDescr *pRecordDescr =
                EnvisatFile_GetRecordDescriptor(pszProduct, pszDSName);
            if (pRecordDescr)
            {
                const EnvisatFieldDescr *pField = pRecordDescr->pFields;
                while (pField && pField->szName)
                {
                    char szValue[1024];
                    if (CE_None == EnvisatFile_GetFieldAsString(
                                       pszRecord, nDSRSize, pField, szValue,
                                       sizeof(szValue)))
                    {
                        char szKey[256];
                        if (nNumDsr == 1)
                            snprintf(szKey, sizeof(szKey), "%s_%s", szPrefix,
                                     pField->szName);
                        else
                            // sprintf(szKey, "%s_%02d_%s", szPrefix, nRecord,
                            snprintf(szKey, sizeof(szKey), "%s_%d_%s", szPrefix,
                                     nRecord, pField->szName);
                        SetMetadataItem(szKey, szValue, "RECORDS");
                    }
                    // silently ignore conversion errors

                    ++pField;
                }
            }
            CPLFree(pszRecord);
        }
    }
}

/************************************************************************/
/*                          CollectMetadata()                           */
/*                                                                      */
/*      Collect metadata from the SPH or MPH header fields.             */
/************************************************************************/

void EnvisatDataset::CollectMetadata(EnvisatFile_HeaderFlag eMPHOrSPH)

{
    for (int iKey = 0; true; iKey++)
    {
        const char *pszKey =
            EnvisatFile_GetKeyByIndex(hEnvisatFile, eMPHOrSPH, iKey);
        if (pszKey == nullptr)
            break;

        const char *pszValue = EnvisatFile_GetKeyValueAsString(
            hEnvisatFile, eMPHOrSPH, pszKey, nullptr);

        if (pszValue == nullptr)
            continue;

        // skip some uninteresting structural information.
        if (EQUAL(pszKey, "TOT_SIZE") || EQUAL(pszKey, "SPH_SIZE") ||
            EQUAL(pszKey, "NUM_DSD") || EQUAL(pszKey, "DSD_SIZE") ||
            EQUAL(pszKey, "NUM_DATA_SETS"))
            continue;

        char szHeaderKey[128];
        if (eMPHOrSPH == MPH)
            snprintf(szHeaderKey, sizeof(szHeaderKey), "MPH_%s", pszKey);
        else
            snprintf(szHeaderKey, sizeof(szHeaderKey), "SPH_%s", pszKey);

        SetMetadataItem(szHeaderKey, pszValue);
    }
}

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

GDALDataset *EnvisatDataset::Open(GDALOpenInfo *poOpenInfo)

{
    /* -------------------------------------------------------------------- */
    /*      Check the header.                                               */
    /* -------------------------------------------------------------------- */
    if (poOpenInfo->nHeaderBytes < 8 || poOpenInfo->fpL == nullptr)
        return nullptr;

    if (!STARTS_WITH_CI((const char *)poOpenInfo->pabyHeader, "PRODUCT="))
        return nullptr;

    /* -------------------------------------------------------------------- */
    /*      Try opening the dataset.                                        */
    /* -------------------------------------------------------------------- */
    EnvisatFile *hEnvisatFile = nullptr;
    if (EnvisatFile_Open(&hEnvisatFile, poOpenInfo->pszFilename, "r") ==
        FAILURE)
        return nullptr;

    /* -------------------------------------------------------------------- */
    /*      Find a measurement type dataset to use as our reference          */
    /*      raster band.                                                    */
    /* -------------------------------------------------------------------- */
    int dsr_size, num_dsr, ds_offset;
    const char *pszDSType = nullptr;

    int ds_index = 0;
    for (; true; ds_index++)
    {
        if (EnvisatFile_GetDatasetInfo(hEnvisatFile, ds_index, nullptr,
                                       &pszDSType, nullptr, &ds_offset, nullptr,
                                       &num_dsr, &dsr_size) == FAILURE)
        {
            CPLError(CE_Failure, CPLE_AppDefined,
                     "Unable to find \"MDS1\" measurement dataset in "
                     "Envisat file.");
            EnvisatFile_Close(hEnvisatFile);
            return nullptr;
        }

        /* Have we found what we are looking for?  A Measurement ds. */
        if (EQUAL(pszDSType, "M"))
            break;
    }

    /* -------------------------------------------------------------------- */
    /*      Confirm the requested access is supported.                      */
    /* -------------------------------------------------------------------- */
    if (poOpenInfo->eAccess == GA_Update)
    {
        EnvisatFile_Close(hEnvisatFile);
        ReportUpdateNotSupportedByDriver("ENVISAT");
        return nullptr;
    }
    /* -------------------------------------------------------------------- */
    /*      Create a corresponding GDALDataset.                             */
    /* -------------------------------------------------------------------- */
    auto poDS = std::make_unique<EnvisatDataset>();

    poDS->hEnvisatFile = hEnvisatFile;

    /* -------------------------------------------------------------------- */
    /*      Setup image definition.                                         */
    /* -------------------------------------------------------------------- */
    EnvisatFile_GetDatasetInfo(hEnvisatFile, ds_index, nullptr, nullptr,
                               nullptr, &ds_offset, nullptr, &num_dsr,
                               &dsr_size);

    poDS->nRasterXSize =
        EnvisatFile_GetKeyValueAsInt(hEnvisatFile, SPH, "LINE_LENGTH", 0);
    poDS->nRasterYSize = num_dsr;
    poDS->eAccess = GA_ReadOnly;

    const char *pszProduct =
        EnvisatFile_GetKeyValueAsString(hEnvisatFile, MPH, "PRODUCT", "");
    const char *pszDataType =
        EnvisatFile_GetKeyValueAsString(hEnvisatFile, SPH, "DATA_TYPE", "");
    const char *pszSampleType =
        EnvisatFile_GetKeyValueAsString(hEnvisatFile, SPH, "SAMPLE_TYPE", "");

    GDALDataType eDataType;
    if (EQUAL(pszDataType, "FLT32") && STARTS_WITH_CI(pszSampleType, "COMPLEX"))
        eDataType = GDT_CFloat32;
    else if (EQUAL(pszDataType, "FLT32"))
        eDataType = GDT_Float32;
    else if (EQUAL(pszDataType, "UWORD"))
        eDataType = GDT_UInt16;
    else if (EQUAL(pszDataType, "SWORD") &&
             STARTS_WITH_CI(pszSampleType, "COMPLEX"))
        eDataType = GDT_CInt16;
    else if (EQUAL(pszDataType, "SWORD"))
        eDataType = GDT_Int16;
    else if (STARTS_WITH_CI(pszProduct, "ATS_TOA_1"))
    {
        /* all 16bit data, no line length provided */
        eDataType = GDT_Int16;
        poDS->nRasterXSize = (dsr_size - 20) / 2;
    }
    else if (poDS->nRasterXSize == 0)
    {
        CPLError(CE_Warning, CPLE_AppDefined,
                 "Envisat product format not recognised.  Assuming 8bit\n"
                 "with no per-record prefix data.  Results may be useless!");
        eDataType = GDT_Byte;
        poDS->nRasterXSize = dsr_size;
    }
    else
    {
        if (dsr_size >= 2 * poDS->nRasterXSize)
            eDataType = GDT_UInt16;
        else
            eDataType = GDT_Byte;
    }

    const int nPrefixBytes =
        dsr_size - (GDALGetDataTypeSizeBytes(eDataType) * poDS->nRasterXSize);

    /* -------------------------------------------------------------------- */
    /*      Fail out if we didn't get non-zero sizes.                       */
    /* -------------------------------------------------------------------- */
    if (poDS->nRasterXSize < 1 || poDS->nRasterYSize < 1)
    {
        CPLError(CE_Failure, CPLE_AppDefined,
                 "Unable to determine organization of dataset.  It would\n"
                 "appear this is an Envisat dataset, but an unsupported\n"
                 "data product.  Unable to utilize.");
        return nullptr;
    }

    std::swap(poDS->fpImage, poOpenInfo->fpL);

    /* -------------------------------------------------------------------- */
    /*      Try to collect GCPs.                                            */
    /* -------------------------------------------------------------------- */

    /* -------------------------------------------------------------------- */
    /*      Scan for all datasets matching the reference dataset.           */
    /* -------------------------------------------------------------------- */
    int num_dsr2, dsr_size2, iBand = 0;
    const char *pszDSName = nullptr;
    char szBandName[128];
    bool bMiltiChannel;

    for (ds_index = 0;
         EnvisatFile_GetDatasetInfo(hEnvisatFile, ds_index, &pszDSName, nullptr,
                                    nullptr, &ds_offset, nullptr, &num_dsr2,
                                    &dsr_size2) == SUCCESS;
         ds_index++)
    {
        if (!EQUAL(pszDSType, "M") || num_dsr2 != num_dsr)
            continue;

        if (STARTS_WITH_CI(pszProduct, "MER") && (pszProduct[8] == '2') &&
            ((strstr(pszDSName, "MDS(16)") != nullptr) ||
             (strstr(pszDSName, "MDS(19)") != nullptr)))
            bMiltiChannel = true;
        else
            bMiltiChannel = false;

        if ((dsr_size2 == dsr_size) && !bMiltiChannel)
        {
            auto poBand = RawRasterBand::Create(
                poDS.get(), iBand + 1, poDS->fpImage, ds_offset + nPrefixBytes,
                GDALGetDataTypeSizeBytes(eDataType), dsr_size, eDataType,
                RawRasterBand::ByteOrder::ORDER_BIG_ENDIAN,
                RawRasterBand::OwnFP::NO);
            if (!poBand)
                return nullptr;
            poBand->SetDescription(pszDSName);
            poDS->SetBand(iBand + 1, std::move(poBand));
            iBand++;
        }
        /* --------------------------------------------------------------------
         */
        /*       Handle MERIS Level 2 datasets with data type different from */
        /*       the one declared in the SPH */
        /* --------------------------------------------------------------------
         */
        else if (STARTS_WITH_CI(pszProduct, "MER") &&
                 (strstr(pszDSName, "Flags") != nullptr))
        {
            if (pszProduct[8] == '1')
            {
                // Flags
                {
                    auto poBand = RawRasterBand::Create(
                        poDS.get(), iBand + 1, poDS->fpImage,
                        ds_offset + nPrefixBytes, 3, dsr_size, GDT_Byte,
                        RawRasterBand::ByteOrder::ORDER_BIG_ENDIAN,
                        RawRasterBand::OwnFP::NO);
                    if (!poBand)
                        return nullptr;
                    poBand->SetDescription(pszDSName);
                    poDS->SetBand(iBand + 1, std::move(poBand));
                    iBand++;
                }

                // Detector indices
                auto poBand = RawRasterBand::Create(
                    poDS.get(), iBand + 1, poDS->fpImage,
                    ds_offset + nPrefixBytes + 1, 3, dsr_size, GDT_Int16,
                    RawRasterBand::ByteOrder::ORDER_BIG_ENDIAN,
                    RawRasterBand::OwnFP::NO);
                if (!poBand)
                    return nullptr;

                const char *pszSuffix = strstr(pszDSName, "MDS");
                if (pszSuffix != nullptr)
                    snprintf(szBandName, sizeof(szBandName),
                             "Detector index %s", pszSuffix);
                else
                    snprintf(szBandName, sizeof(szBandName), "%s",
                             "Detector index");
                poBand->SetDescription(szBandName);

                poDS->SetBand(iBand + 1, std::move(poBand));
                iBand++;
            }
            else if ((pszProduct[8] == '2') &&
                     (dsr_size2 >= 3 * poDS->nRasterXSize))
            {
                int nFlagPrefixBytes = dsr_size2 - 3 * poDS->nRasterXSize;

                auto poBand =
                    new MerisL2FlagBand(poDS.get(), iBand + 1, poDS->fpImage,
                                        ds_offset, nFlagPrefixBytes);
                poBand->SetDescription(pszDSName);
                poDS->SetBand(iBand + 1, poBand);
                iBand++;
            }
        }
        else if (STARTS_WITH_CI(pszProduct, "MER") && (pszProduct[8] == '2'))
        {
            int nPrefixBytes2, nSubBands, nSubBandIdx, nSubBandOffset;

            int nPixelSize = 1;
            GDALDataType eDataType2 = GDT_Byte;

            nSubBands = dsr_size2 / poDS->nRasterXSize;
            if ((nSubBands < 1) || (nSubBands > 3))
                nSubBands = 0;

            nPrefixBytes2 =
                dsr_size2 - (nSubBands * nPixelSize * poDS->nRasterXSize);

            for (nSubBandIdx = 0; nSubBandIdx < nSubBands; ++nSubBandIdx)
            {
                nSubBandOffset =
                    ds_offset + nPrefixBytes2 + nSubBandIdx * nPixelSize;

                auto poBand = RawRasterBand::Create(
                    poDS.get(), iBand + 1, poDS->fpImage, nSubBandOffset,
                    nPixelSize * nSubBands, dsr_size2, eDataType2,
                    RawRasterBand::ByteOrder::ORDER_BIG_ENDIAN,
                    RawRasterBand::OwnFP::NO);
                if (!poBand)
                    return nullptr;

                if (nSubBands > 1)
                {
                    snprintf(szBandName, sizeof(szBandName), "%s (%d)",
                             pszDSName, nSubBandIdx);
                    poBand->SetDescription(szBandName);
                }
                else
                    poBand->SetDescription(pszDSName);

                poDS->SetBand(iBand + 1, std::move(poBand));
                iBand++;
            }
        }
    }

    /* -------------------------------------------------------------------- */
    /*      Collect metadata.                                               */
    /* -------------------------------------------------------------------- */
    poDS->CollectMetadata(MPH);
    poDS->CollectMetadata(SPH);
    poDS->CollectDSDMetadata();
    poDS->CollectADSMetadata();

    if (STARTS_WITH_CI(pszProduct, "MER"))
        poDS->ScanForGCPs_MERIS();
    else
        poDS->ScanForGCPs_ASAR();

    /* unwrap GCPs for products crossing date border */
    poDS->UnwrapGCPs();

    /* -------------------------------------------------------------------- */
    /*      Initialize any PAM information.                                 */
    /* -------------------------------------------------------------------- */
    poDS->SetDescription(poOpenInfo->pszFilename);
    poDS->TryLoadXML();

    /* -------------------------------------------------------------------- */
    /*      Check for overviews.                                            */
    /* -------------------------------------------------------------------- */
    poDS->oOvManager.Initialize(poDS.get(), poOpenInfo->pszFilename);

    return poDS.release();
}

/************************************************************************/
/*                         GDALRegister_Envisat()                       */
/************************************************************************/

void GDALRegister_Envisat()

{
    if (GDALGetDriverByName("ESAT") != nullptr)
        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription("ESAT");
    poDriver->SetMetadataItem(GDAL_DCAP_RASTER, "YES");
    poDriver->SetMetadataItem(GDAL_DMD_LONGNAME, "Envisat Image Format");
    poDriver->SetMetadataItem(GDAL_DMD_HELPTOPIC, "drivers/raster/esat.html");
    poDriver->SetMetadataItem(GDAL_DMD_EXTENSION, "n1");
    poDriver->SetMetadataItem(GDAL_DCAP_VIRTUALIO, "YES");

    poDriver->pfnOpen = EnvisatDataset::Open;

    GetGDALDriverManager()->RegisterDriver(poDriver);
}