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

 *

 * Project:  Ground-based SAR Applitcations Testbed File Format driver

 * Purpose:  Support in GDAL for Sandia National Laboratory's GFF format

 *           blame Tisham for putting me up to this

 * Author:   Philippe Vachon <philippe@cowpig.ca>

 *

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

 * Copyright (c) 2007, Philippe Vachon

 * Copyright (c) 2008-2012, Even Rouault <even dot rouault at spatialys.com>

 *

 * SPDX-License-Identifier: MIT

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

#include "cpl_conv.h"

#include "cpl_port.h"

#include "cpl_string.h"

#include "cpl_vsi.h"

#include "gdal_frmts.h"

#include "gdal_pam.h"

#include "gdal_priv.h"

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

 * Declaration of the GFFDataset class                             *

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

class GFFRasterBand;

class GFFDataset final : public GDALPamDataset

{

    friend class GFFRasterBand;

    VSILFILE *fp;

    GDALDataType eDataType;

    unsigned int nEndianness;

    /* Some relevant headers */

    unsigned short nVersionMajor;

    unsigned short nVersionMinor;

    unsigned int nLength;

    // char *pszCreator;

    //  TODO: Needs a better explanation.

    /* I am taking this at face value (are they insane?) */

    // float fBPP;

    unsigned int nBPP;

    /* Good information to know */

    unsigned int nFrameCnt;

    unsigned int nImageType;

    unsigned int nRowMajor;

    unsigned int nRgCnt;

    unsigned int nAzCnt;

    // long nScaleExponent;

    // long nScaleMantissa;

    // long nOffsetExponent;

    // long nOffsetMantissa;

  public:

    GFFDataset();

    ~GFFDataset() override;

    static GDALDataset *Open(GDALOpenInfo *);

    static int Identify(GDALOpenInfo *poOpenInfo);

};

GFFDataset::GFFDataset()

    : fp(nullptr), eDataType(GDT_Unknown), nEndianness(0), nVersionMajor(0),

      nVersionMinor(0), nLength(0), nBPP(0), nFrameCnt(0), nImageType(0),

      nRowMajor(0), nRgCnt(0), nAzCnt(0)

{

}

GFFDataset::~GFFDataset()

{

    if (fp != nullptr)

        VSIFCloseL(fp);

}

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

 * Declaration and implementation of the GFFRasterBand Class         *

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

class GFFRasterBand final : public GDALPamRasterBand

{

    long nRasterBandMemory;

    int nSampleSize;

  public:

    GFFRasterBand(GFFDataset *, int, GDALDataType);

    CPLErr IReadBlock(int, int, void *) override;

};

static unsigned long GFFSampleSize(GDALDataType eDataType)

{

    // Determine the number of bytes per sample.

    unsigned long nBytes = 1;

    switch (eDataType)

    {

        case GDT_CInt16:

            nBytes = 4;

            break;

        case GDT_CInt32:

        case GDT_CFloat32:

            nBytes = 8;

            break;

        default:

            nBytes = 1;

    }

    return nBytes;

}

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

/*                           GFFRasterBand()                            */

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

GFFRasterBand::GFFRasterBand(GFFDataset *poDSIn, int nBandIn,

                             GDALDataType eDataTypeIn)

    : nRasterBandMemory(GFFSampleSize(eDataTypeIn) * poDSIn->GetRasterXSize()),

      nSampleSize(static_cast<int>(GFFSampleSize(eDataTypeIn)))

{

    poDS = poDSIn;

    nBand = nBandIn;

    eDataType = eDataTypeIn;

    nBlockXSize = poDS->GetRasterXSize();

    nBlockYSize = 1;

}

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

/*                             IReadBlock()                             */

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

CPLErr GFFRasterBand::IReadBlock(int /* nBlockXOff */, int nBlockYOff,

                                 void *pImage)

{

    GFFDataset *poGDS = cpl::down_cast<GFFDataset *>(poDS);

    long nOffset = poGDS->nLength;

    VSIFSeekL(poGDS->fp,

              nOffset + (static_cast<vsi_l_offset>(poGDS->GetRasterXSize()) *

                         nBlockYOff * (nSampleSize)),

              SEEK_SET);

    /* Ingest entire range line */

    if (VSIFReadL(pImage, nRasterBandMemory, 1, poGDS->fp) != 1)

        return CE_Failure;

#if defined(CPL_MSB)

    if (GDALDataTypeIsComplex(eDataType))

    {

        int nWordSize = GDALGetDataTypeSize(eDataType) / 16;

        GDALSwapWords(pImage, nWordSize, nBlockXSize, 2 * nWordSize);

        GDALSwapWords(((GByte *)pImage) + nWordSize, nWordSize, nBlockXSize,

                      2 * nWordSize);

    }

#endif

    return CE_None;

}

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

 * ================================================================ *

 * Implementation of the GFFDataset Class                           *

 * ================================================================ *

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

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

/*                              Identify()                              */

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

int GFFDataset::Identify(GDALOpenInfo *poOpenInfo)

{

    if (poOpenInfo->nHeaderBytes < 7)

        return 0;

    if (STARTS_WITH_CI((char *)poOpenInfo->pabyHeader, "GSATIMG"))

        return 1;

    return 0;

}

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

/*                                Open()                                */

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

GDALDataset *GFFDataset::Open(GDALOpenInfo *poOpenInfo)

{

    /* Check that the dataset is indeed a GSAT File Format (GFF) file */

    if (!GFFDataset::Identify(poOpenInfo) || poOpenInfo->fpL == nullptr)

        return nullptr;

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

    /*      Confirm the requested access is supported.                      */

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

    if (poOpenInfo->eAccess == GA_Update)

    {

        ReportUpdateNotSupportedByDriver("GFF");

        return nullptr;

    }

    GFFDataset *poDS = new GFFDataset();

    poDS->fp = poOpenInfo->fpL;

    poOpenInfo->fpL = nullptr;

    /* Check the endianness of the file */

    VSIFSeekL(poDS->fp, 54, SEEK_SET);

    VSIFReadL(&(poDS->nEndianness), 2, 1, poDS->fp);

    VSIFSeekL(poDS->fp, 8, SEEK_SET);

    VSIFReadL(&poDS->nVersionMinor, 2, 1, poDS->fp);

    CPL_LSBPTR16(&poDS->nVersionMinor);

    VSIFReadL(&poDS->nVersionMajor, 2, 1, poDS->fp);

    CPL_LSBPTR16(&poDS->nVersionMajor);

    VSIFReadL(&poDS->nLength, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nLength);

    unsigned short nCreatorLength = 0;

    VSIFReadL(&nCreatorLength, 2, 1, poDS->fp);

    CPL_LSBPTR16(&nCreatorLength);

    /* Hack for now... I should properly load the date metadata, for

     * example

     */

    VSIFSeekL(poDS->fp, 56, SEEK_SET);

    /* By looking at the Matlab code, one should write something like the

     * following test */

    /* but the results don't seem to be the ones really expected */

    /*if ((poDS->nVersionMajor == 1 && poDS->nVersionMinor > 7) ||

    (poDS->nVersionMajor > 1))

    {

        float fBPP;

        VSIFRead(&fBPP,4,1,poDS->fp);

        poDS->nBPP = fBPP;

    }

    else*/

    {

        VSIFReadL(&poDS->nBPP, 4, 1, poDS->fp);

        CPL_LSBPTR32(&poDS->nBPP);

    }

    VSIFReadL(&poDS->nFrameCnt, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nFrameCnt);

    VSIFReadL(&poDS->nImageType, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nImageType);

    VSIFReadL(&poDS->nRowMajor, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nRowMajor);

    VSIFReadL(&poDS->nRgCnt, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nRgCnt);

    VSIFReadL(&poDS->nAzCnt, 4, 1, poDS->fp);

    CPL_LSBPTR32(&poDS->nAzCnt);

    /* We now have enough information to determine the number format */

    switch (poDS->nImageType)

    {

        case 0:

            poDS->eDataType = GDT_UInt8;

            break;

        case 1:

            if (poDS->nBPP == 4)

                poDS->eDataType = GDT_CInt16;

            else

                poDS->eDataType = GDT_CInt32;

            break;

        case 2:

            poDS->eDataType = GDT_CFloat32;

            break;

        default:

            CPLError(CE_Failure, CPLE_AppDefined, "Unknown image type found!");

            delete poDS;

            return nullptr;

    }

    /* Set raster width/height

     * Note that the images that are complex are listed as having twice the

     * number of X-direction values than there are actual pixels. This is

     * because whoever came up with the format was crazy (actually, my

     * hunch is that they designed it very much for Matlab)

     * */

    if (poDS->nRowMajor)

    {

        poDS->nRasterXSize = poDS->nRgCnt / (poDS->nImageType == 0 ? 1 : 2);

        poDS->nRasterYSize = poDS->nAzCnt;

    }

    else

    {

        poDS->nRasterXSize = poDS->nAzCnt / (poDS->nImageType == 0 ? 1 : 2);

        poDS->nRasterYSize = poDS->nRgCnt;

    }

    if (poDS->nRasterXSize <= 0 || poDS->nRasterYSize <= 0)

    {

        CPLError(CE_Failure, CPLE_AppDefined,

                 "Invalid raster dimensions : %d x %d", poDS->nRasterXSize,

                 poDS->nRasterYSize);

        delete poDS;

        return nullptr;

    }

    poDS->SetBand(1, new GFFRasterBand(poDS, 1, poDS->eDataType));

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

    /*      Initialize any PAM information.                                 */

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

    poDS->SetDescription(poOpenInfo->pszFilename);

    poDS->TryLoadXML();

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

    /*      Support overviews.                                              */

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

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

    return poDS;

}

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

/*                          GDALRegister_GFF()                          */

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

void GDALRegister_GFF()

{

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

        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription("GFF");

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

    poDriver->SetMetadataItem(

        GDAL_DMD_LONGNAME,

        "Ground-based SAR Applications Testbed File Format (.gff)");

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

    poDriver->SetMetadataItem(GDAL_DMD_EXTENSION, "gff");

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

    poDriver->pfnOpen = GFFDataset::Open;

    GetGDALDriverManager()->RegisterDriver(poDriver);

}