/******************************************************************************
 *
 * 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 mines-paris dot org>
 *
 * 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 "cpl_string.h"
#include "gdal_frmts.h"
#include "rawdataset.h"

CPL_CVSID("$Id: gscdataset.cpp 36501 2016-11-25 14:09:24Z rouault $");

/************************************************************************/
/* ==================================================================== */
/*                              GSCDataset                              */
/* ==================================================================== */
/************************************************************************/

class GSCDataset : public RawDataset
{
    VSILFILE    *fpImage;  // image data file.

    double      adfGeoTransform[6];

  public:
                GSCDataset();
                ~GSCDataset();

    CPLErr      GetGeoTransform( double * padfTransform ) override;

    static GDALDataset *Open( GDALOpenInfo * );
};

/************************************************************************/
/*                            GSCDataset()                             */
/************************************************************************/

GSCDataset::GSCDataset() :
    fpImage(NULL)
{
    adfGeoTransform[0] = 0.0;
    adfGeoTransform[1] = 1.0;
    adfGeoTransform[2] = 0.0;
    adfGeoTransform[3] = 0.0;
    adfGeoTransform[4] = 0.0;
    adfGeoTransform[5] = 1.0;
}

/************************************************************************/
/*                            ~GSCDataset()                            */
/************************************************************************/

GSCDataset::~GSCDataset()

{
    FlushCache();
    if( fpImage != NULL )
        CPL_IGNORE_RET_VAL(VSIFCloseL( fpImage ));
}

/************************************************************************/
/*                          GetGeoTransform()                           */
/************************************************************************/

CPLErr GSCDataset::GetGeoTransform( double * padfTransform )

{
    memcpy( padfTransform, adfGeoTransform, sizeof(double) * 6 );

    return CE_None;
}

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

GDALDataset *GSCDataset::Open( GDALOpenInfo * poOpenInfo )

{

/* -------------------------------------------------------------------- */
/*      Does this plausible look like a GSC Geogrid file?               */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->nHeaderBytes < 20 )
        return NULL;

    if( poOpenInfo->pabyHeader[12] != 0x02
        || poOpenInfo->pabyHeader[13] != 0x00
        || poOpenInfo->pabyHeader[14] != 0x00
        || poOpenInfo->pabyHeader[15] != 0x00 )
        return NULL;

    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 NULL;

    if( nRecordLen != nPixels * 4 )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Confirm the requested access is supported.                      */
/* -------------------------------------------------------------------- */
    if( poOpenInfo->eAccess == GA_Update )
    {
        CPLError( CE_Failure, CPLE_NotSupported,
                  "The GSC driver does not support update access to existing "
                  "datasets." );
        return NULL;
    }

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

/* -------------------------------------------------------------------- */
/*      Create a corresponding GDALDataset.                             */
/* -------------------------------------------------------------------- */
    GSCDataset *poDS = new GSCDataset();

    poDS->nRasterXSize = nPixels;
    poDS->nRasterYSize = nLines;

/* -------------------------------------------------------------------- */
/*      Assume ownership of the file handled from the GDALOpenInfo.     */
/* -------------------------------------------------------------------- */
    poDS->fpImage = VSIFOpenL(poOpenInfo->pszFilename, "rb");
    if( poDS->fpImage == NULL )
    {
        delete poDS;
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      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 );
        delete poDS;
        return NULL;
    }

    for( int i = 0; i < 8; i++ )
    {
        CPL_LSBPTR32( afHeaderInfo + i );
    }

    poDS->adfGeoTransform[0] = afHeaderInfo[2];
    poDS->adfGeoTransform[1] = afHeaderInfo[0];
    poDS->adfGeoTransform[2] = 0.0;
    poDS->adfGeoTransform[3] = afHeaderInfo[5];
    poDS->adfGeoTransform[4] = 0.0;
    poDS->adfGeoTransform[5] = -afHeaderInfo[1];

/* -------------------------------------------------------------------- */
/*      Create band information objects.                                */
/* -------------------------------------------------------------------- */
#ifdef CPL_LSB
    const bool bNative = true;
#else
    const bool bNative = false;
#endif

    RawRasterBand *poBand = new RawRasterBand( poDS, 1, poDS->fpImage,
                                               nRecordLen * 2 + 4,
                                               sizeof(float), nRecordLen,
                                               GDT_Float32, bNative, TRUE );
    poDS->SetBand( 1, poBand );

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

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

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

    return poDS;
}

/************************************************************************/
/*                          GDALRegister_GSC()                          */
/************************************************************************/

void GDALRegister_GSC()

{
    if( GDALGetDriverByName( "GSC" ) != NULL )
        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,
    //                            "frmt_various.html#GSC" );
    poDriver->SetMetadataItem( GDAL_DCAP_VIRTUALIO, "YES" );

    poDriver->pfnOpen = GSCDataset::Open;

    GetGDALDriverManager()->RegisterDriver( poDriver );
}
