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

 *

 * Project:  GSC Geogrid format driver.

 * Purpose:  Implements support for reading and writing GSC Geogrid format.

 * Author:   Frank Warmerdam <warmerdam@pobox.com>

 *

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

 * Copyright (c) 2002, Frank Warmerdam <warmerdam@pobox.com>

 * Copyright (c) 2009-2011, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

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

#include "cpl_string.h"

#include "gdal_frmts.h"

#include "rawdataset.h"

#include <algorithm>

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

/* ==================================================================== */

/*                              GSCDataset                              */

/* ==================================================================== */

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

class GSCDataset final : public RawDataset

{

    VSILFILE *fpImage = nullptr;  // image data file.

    GDALGeoTransform m_gt{};

    CPL_DISALLOW_COPY_ASSIGN(GSCDataset)

    CPLErr Close() override;

  public:

    GSCDataset() = default;

    ~GSCDataset();

    CPLErr GetGeoTransform(GDALGeoTransform &gt) const override;

    static GDALDataset *Open(GDALOpenInfo *);

};

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

/*                            ~GSCDataset()                             */

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

GSCDataset::~GSCDataset()

{

    GSCDataset::Close();

}

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

/*                              Close()                                 */

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

CPLErr GSCDataset::Close()

{

    CPLErr eErr = CE_None;

    if (nOpenFlags != OPEN_FLAGS_CLOSED)

    {

        if (GSCDataset::FlushCache(true) != CE_None)

            eErr = CE_Failure;

        if (fpImage)

        {

            if (VSIFCloseL(fpImage) != 0)

            {

                CPLError(CE_Failure, CPLE_FileIO, "I/O error");

                eErr = CE_Failure;

            }

        }

        if (GDALPamDataset::Close() != CE_None)

            eErr = CE_Failure;

    }

    return eErr;

}

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

/*                          GetGeoTransform()                           */

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

CPLErr GSCDataset::GetGeoTransform(GDALGeoTransform &gt) const

{

    gt = m_gt;

    return CE_None;

}

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

/*                                Open()                                */

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

GDALDataset *GSCDataset::Open(GDALOpenInfo *poOpenInfo)

{

    /* -------------------------------------------------------------------- */

    /*      Does this plausible look like a GSC Geogrid file?               */

    /* -------------------------------------------------------------------- */

    if (poOpenInfo->nHeaderBytes < 20)

        return nullptr;

    if (poOpenInfo->pabyHeader[12] != 0x02 ||

        poOpenInfo->pabyHeader[13] != 0x00 ||

        poOpenInfo->pabyHeader[14] != 0x00 ||

        poOpenInfo->pabyHeader[15] != 0x00)

        return nullptr;

    int nRecordLen =

        CPL_LSBWORD32(reinterpret_cast<GInt32 *>(poOpenInfo->pabyHeader)[0]);

    const int nPixels =

        CPL_LSBWORD32(reinterpret_cast<GInt32 *>(poOpenInfo->pabyHeader)[1]);

    const int nLines =

        CPL_LSBWORD32(reinterpret_cast<GInt32 *>(poOpenInfo->pabyHeader)[2]);

    if (nPixels < 1 || nLines < 1 || nPixels > 100000 || nLines > 100000)

        return nullptr;

    if (nRecordLen != nPixels * 4)

        return nullptr;

    /* -------------------------------------------------------------------- */

    /*      Confirm the requested access is supported.                      */

    /* -------------------------------------------------------------------- */

    if (poOpenInfo->eAccess == GA_Update)

    {

        ReportUpdateNotSupportedByDriver("GSC");

        return nullptr;

    }

    nRecordLen += 8;  // For record length markers.

    /* -------------------------------------------------------------------- */

    /*      Create a corresponding GDALDataset.                             */

    /* -------------------------------------------------------------------- */

    auto poDS = std::make_unique<GSCDataset>();

    poDS->nRasterXSize = nPixels;

    poDS->nRasterYSize = nLines;

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

    /* -------------------------------------------------------------------- */

    /*      Read the header information in the second record.               */

    /* -------------------------------------------------------------------- */

    float afHeaderInfo[8] = {0.0};

    if (VSIFSeekL(poDS->fpImage, nRecordLen + 12, SEEK_SET) != 0 ||

        VSIFReadL(afHeaderInfo, sizeof(float), 8, poDS->fpImage) != 8)

    {

        CPLError(

            CE_Failure, CPLE_FileIO,

            "Failure reading second record of GSC file with %d record length.",

            nRecordLen);

        return nullptr;

    }

    for (int i = 0; i < 8; i++)

    {

        CPL_LSBPTR32(afHeaderInfo + i);

    }

    poDS->m_gt[0] = afHeaderInfo[2];

    poDS->m_gt[1] = afHeaderInfo[0];

    poDS->m_gt[2] = 0.0;

    poDS->m_gt[3] = afHeaderInfo[5];

    poDS->m_gt[4] = 0.0;

    poDS->m_gt[5] = -afHeaderInfo[1];

    /* -------------------------------------------------------------------- */

    /*      Create band information objects.                                */

    /* -------------------------------------------------------------------- */

    auto poBand = RawRasterBand::Create(

        poDS.get(), 1, poDS->fpImage, nRecordLen * 2 + 4, sizeof(float),

        nRecordLen, GDT_Float32, RawRasterBand::ByteOrder::ORDER_LITTLE_ENDIAN,

        RawRasterBand::OwnFP::NO);

    if (!poBand)

        return nullptr;

    poBand->SetNoDataValue(-1.0000000150474662199e+30);

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

    /* -------------------------------------------------------------------- */

    /*      Initialize any PAM information.                                 */

    /* -------------------------------------------------------------------- */

    poDS->SetDescription(poOpenInfo->pszFilename);

    poDS->TryLoadXML();

    /* -------------------------------------------------------------------- */

    /*      Check for overviews.                                            */

    /* -------------------------------------------------------------------- */

    poDS->oOvManager.Initialize(poDS.get(), poOpenInfo->pszFilename);

    return poDS.release();

}

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

/*                          GDALRegister_GSC()                          */

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

void GDALRegister_GSC()

{

    if (GDALGetDriverByName("GSC") != nullptr)

        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription("GSC");

    poDriver->SetMetadataItem(GDAL_DCAP_RASTER, "YES");

    poDriver->SetMetadataItem(GDAL_DMD_LONGNAME, "GSC Geogrid");

    poDriver->SetMetadataItem(GDAL_DMD_HELPTOPIC, "drivers/raster/gsc.html");

    poDriver->SetMetadataItem(GDAL_DCAP_VIRTUALIO, "YES");

    poDriver->pfnOpen = GSCDataset::Open;

    GetGDALDriverManager()->RegisterDriver(poDriver);

}