/******************************************************************************
 * $Id$
 *
 * Project:  MapServer
 * Purpose:  Implementation of support for output using GDAL.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2002, Frank Warmerdam
 *
 * 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 of this Software or works derived from this 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 <assert.h>
#include "mapserver.h"
#include "mapthread.h"

MS_CVSID("$Id$")

#if defined(USE_GDAL) || defined(USE_OGR)
#include "cpl_conv.h"
#include "cpl_string.h"
#include "ogr_srs_api.h"
#endif

#ifdef USE_GDAL

#include "gdal.h"

static int    bGDALInitialized = 0;

/************************************************************************/
/*                          msGDALInitialize()                          */
/************************************************************************/

void msGDALInitialize( void )

{
    if( !bGDALInitialized )
    {
        msAcquireLock( TLOCK_GDAL );

        GDALAllRegister();
        CPLPushErrorHandler( CPLQuietErrorHandler );
        msReleaseLock( TLOCK_GDAL );

        bGDALInitialized = 1;
    }
}

/************************************************************************/
/*                           msGDALCleanup()                            */
/************************************************************************/

void msGDALCleanup( void )

{
    if( bGDALInitialized )
    {
        int iRepeat = 5;
        msAcquireLock( TLOCK_GDAL );

#if GDAL_RELEASE_DATE > 20101207
        {
            /* 
            ** Cleanup any unreferenced but open datasets as will tend
            ** to exist due to deferred close requests.  We are careful
            ** to only close one file at a time before refecting the
            ** list as closing some datasets may cause others to be 
            ** closed (subdatasets in a VRT for instance).
            */
            GDALDatasetH *pahDSList = NULL;
            int nDSCount = 0;
            int bDidSomething;

            do {
                int i;
                GDALGetOpenDatasets( &pahDSList, &nDSCount );
                bDidSomething = FALSE;
                for( i = 0; i < nDSCount && !bDidSomething; i++ )
                {
                    if( GDALReferenceDataset( pahDSList[i] ) == 1 )
                    {
                        GDALClose( pahDSList[i] );
                        bDidSomething = TRUE;
                    }
                    else
                        GDALDereferenceDataset( pahDSList[i] );
                }
            } while( bDidSomething );
        }
#endif

        while( iRepeat-- )
            CPLPopErrorHandler();

#if GDAL_RELEASE_DATE > 20021001
        GDALDestroyDriverManager();
#endif

        msReleaseLock( TLOCK_GDAL );

        bGDALInitialized = 0;
    }
}

/************************************************************************/
/*                            CleanVSIDir()                             */
/*                                                                      */
/*      For the temporary /vsimem/msout directory we need to be sure    */
/*      things are clean before we start, and after we are done.        */
/************************************************************************/

void CleanVSIDir( const char *pszDir )

{
    char **papszFiles = CPLReadDir( pszDir );
    int i, nFileCount = CSLCount( papszFiles );

    for( i = 0; i < nFileCount; i++ )
    {
        if( strcasecmp(papszFiles[i],".") == 0 
            || strcasecmp(papszFiles[i],"..") == 0 )
            continue;

        VSIUnlink( papszFiles[i] );
    }

    CSLDestroy( papszFiles );
}

/************************************************************************/
/*                          msSaveImageGDAL()                           */
/************************************************************************/

int msSaveImageGDAL( mapObj *map, imageObj *image, char *filename )

{
    int  bFileIsTemporary = MS_FALSE;
    GDALDatasetH hMemDS, hOutputDS;
    GDALDriverH  hMemDriver, hOutputDriver;
    int          nBands = 1;
    int          iLine;
    GByte       *pabyAlphaLine = NULL;
    char        **papszOptions = NULL;
    outputFormatObj *format = image->format;
    rasterBufferObj rb;
    GDALDataType eDataType = GDT_Byte;
    int bUseXmp = MS_FALSE;

    msGDALInitialize();
    memset(&rb,0,sizeof(rasterBufferObj));
    
#ifdef USE_EXEMPI
    bUseXmp = msXmpPresent(map);
#endif        


/* -------------------------------------------------------------------- */
/*      Identify the proposed output driver.                            */
/* -------------------------------------------------------------------- */
    msAcquireLock( TLOCK_GDAL );
    hOutputDriver = GDALGetDriverByName( format->driver+5 );
    if( hOutputDriver == NULL )
    {
        msReleaseLock( TLOCK_GDAL );
        msSetError( MS_MISCERR, "Failed to find %s driver.",
                    "msSaveImageGDAL()", format->driver+5 );
        return MS_FAILURE;
    }

/* -------------------------------------------------------------------- */
/*      We will need to write the output to a temporary file and        */
/*      then stream to stdout if no filename is passed.  If the         */
/*      driver supports virtualio then we hold the temporary file in    */
/*      memory, otherwise we try to put it in a reasonable temporary    */
/*      file location.                                                  */
/* -------------------------------------------------------------------- */
    if( filename == NULL )
    {
        const char *pszExtension = format->extension;
        if( pszExtension == NULL )
            pszExtension = "img.tmp";

#ifdef GDAL_DCAP_VIRTUALIO
        if( bUseXmp == MS_FALSE && GDALGetMetadataItem( hOutputDriver, GDAL_DCAP_VIRTUALIO, NULL ) 
            != NULL )
        {
            CleanVSIDir( "/vsimem/msout" );
            filename = msTmpFile(map, NULL, "/vsimem/msout/", pszExtension );
        }
#endif
        if( filename == NULL && map != NULL)
            filename = msTmpFile(map, map->mappath,NULL,pszExtension);
        else if( filename == NULL )
        {
            filename = msTmpFile(map, NULL, NULL, pszExtension );
        }
            
        bFileIsTemporary = MS_TRUE;
    }
    
/* -------------------------------------------------------------------- */
/*      Establish the characteristics of our memory, and final          */
/*      dataset.                                                        */
/* -------------------------------------------------------------------- */

    if( format->imagemode == MS_IMAGEMODE_RGB )
    {
        nBands = 3;
        assert( MS_RENDERER_PLUGIN(format) && format->vtable->supports_pixel_buffer );
        format->vtable->getRasterBufferHandle(image,&rb);
    }
    else if( format->imagemode == MS_IMAGEMODE_RGBA )
    {
        pabyAlphaLine = (GByte *) calloc(image->width,1);
        if (pabyAlphaLine == NULL)
        {
            msReleaseLock( TLOCK_GDAL );
            msSetError( MS_MEMERR, "Out of memory allocating %u bytes.\n", "msSaveImageGDAL()", image->width);
            return MS_FAILURE;
        }
        nBands = 4;
        assert( MS_RENDERER_PLUGIN(format) && format->vtable->supports_pixel_buffer );
        format->vtable->getRasterBufferHandle(image,&rb);
    }
    else if( format->imagemode == MS_IMAGEMODE_INT16 )
    {
        nBands = format->bands;
        eDataType = GDT_Int16;
    }
    else if( format->imagemode == MS_IMAGEMODE_FLOAT32 )
    {
        nBands = format->bands;
        eDataType = GDT_Float32;
    }
    else if( format->imagemode == MS_IMAGEMODE_BYTE )
    {
        nBands = format->bands;
        eDataType = GDT_Byte;
    }
    else
    {
        assert( format->imagemode == MS_IMAGEMODE_PC256
                && format->renderer == MS_RENDER_WITH_GD );
    }

/* -------------------------------------------------------------------- */
/*      Create a memory dataset which we can use as a source for a      */
/*      CreateCopy().                                                   */
/* -------------------------------------------------------------------- */
    hMemDriver = GDALGetDriverByName( "MEM" );
    if( hMemDriver == NULL )
    {
        msReleaseLock( TLOCK_GDAL );
        msSetError( MS_MISCERR, "Failed to find MEM driver.",
                    "msSaveImageGDAL()" );
        return MS_FAILURE;
    }
   
    hMemDS = GDALCreate( hMemDriver, "msSaveImageGDAL_temp", 
                         image->width, image->height, nBands, 
                         eDataType, NULL );
    if( hMemDS == NULL )
    {
        msReleaseLock( TLOCK_GDAL );
        msSetError( MS_MISCERR, "Failed to create MEM dataset.",
                    "msSaveImageGDAL()" );
        return MS_FAILURE;
    }
    
/* -------------------------------------------------------------------- */
/*      Copy the gd image into the memory dataset.                      */
/* -------------------------------------------------------------------- */
    for( iLine = 0; iLine < image->height; iLine++ )
    {
        int iBand;

        for( iBand = 0; iBand < nBands; iBand++ )
        {
            GDALRasterBandH hBand = GDALGetRasterBand( hMemDS, iBand+1 );

            if( format->imagemode == MS_IMAGEMODE_INT16 )
            {
                GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                              image->img.raw_16bit + iLine * image->width
                              + iBand * image->width * image->height,
                              image->width, 1, GDT_Int16, 2, 0 );
                
            }
            else if( format->imagemode == MS_IMAGEMODE_FLOAT32 )
            {
                GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                              image->img.raw_float + iLine * image->width
                              + iBand * image->width * image->height,
                              image->width, 1, GDT_Float32, 4, 0 );
            }
            else if( format->imagemode == MS_IMAGEMODE_BYTE )
            {
                GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                              image->img.raw_byte + iLine * image->width
                              + iBand * image->width * image->height,
                              image->width, 1, GDT_Byte, 1, 0 );
            }
            else if(format->renderer == MS_RENDER_WITH_GD) {
               gdImagePtr img = (gdImagePtr)image->img.plugin;
               GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                              img->pixels[iLine], 
                              image->width, 1, GDT_Byte, 0, 0 );
            }
            else {
               GByte *pabyData;
               unsigned char *pixptr = NULL;
               assert( rb.type == MS_BUFFER_BYTE_RGBA );
               switch(iBand) {
               case 0:
                  pixptr = rb.data.rgba.r;
                  break;
               case 1:
                  pixptr = rb.data.rgba.g;
                  break;
               case 2:
                  pixptr = rb.data.rgba.b;
                  break;
               case 3:
                  pixptr = rb.data.rgba.a;
                  break;
               }
               assert(pixptr);
               if( pixptr == NULL )
               {
                   msReleaseLock( TLOCK_GDAL );
                   msSetError( MS_MISCERR, "Missing RGB or A buffer.\n",
                               "msSaveImageGDAL()" );
                   return MS_FAILURE;
               }

               pabyData = (GByte *)(pixptr + iLine*rb.data.rgba.row_step);

               if( rb.data.rgba.a == NULL || iBand == 3 )
               {
                   GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                                 pabyData, image->width, 1, GDT_Byte, 
                                 rb.data.rgba.pixel_step, 0 );
               }
               else /* We need to un-pre-multiple RGB by alpha. */
               {
                   GByte *pabyUPM = (GByte*) malloc(image->width);
                   GByte *pabyAlpha= (GByte *)(rb.data.rgba.a + iLine*rb.data.rgba.row_step);
                   int i;

                   for( i = 0; i < image->width; i++ )
                   {
                       int alpha = pabyAlpha[i*rb.data.rgba.pixel_step];

                       if( alpha == 0 )
                           pabyUPM[i] = 0;
                       else
                       {
                           int result = (pabyData[i*rb.data.rgba.pixel_step] * 255) / alpha;
                           
                           if( result > 255 )
                               result = 255;

                           pabyUPM[i] = result;
                       }
                   }

                   GDALRasterIO( hBand, GF_Write, 0, iLine, image->width, 1, 
                                 pabyUPM, image->width, 1, GDT_Byte, 1, 0 );
                   free( pabyUPM );
               }
            }
        }
    }

    if( pabyAlphaLine != NULL )
        free( pabyAlphaLine );

/* -------------------------------------------------------------------- */
/*      Attach the palette if appropriate.                              */
/* -------------------------------------------------------------------- */
    if( format->renderer == MS_RENDER_WITH_GD )
    {
        GDALColorEntry sEntry;
        int  iColor;
        GDALColorTableH hCT;
        gdImagePtr img = (gdImagePtr)image->img.plugin;
        hCT = GDALCreateColorTable( GPI_RGB );

        for( iColor = 0; iColor < img->colorsTotal; iColor++ )
        {
            sEntry.c1 = img->red[iColor];
            sEntry.c2 = img->green[iColor];
            sEntry.c3 = img->blue[iColor];

            if( iColor == gdImageGetTransparent( img ) )
                sEntry.c4 = 0;
            else if( iColor == 0 
                     && gdImageGetTransparent( img ) == -1 
                     && format->transparent )
                sEntry.c4 = 0;
            else
                sEntry.c4 = 255;

            GDALSetColorEntry( hCT, iColor, &sEntry );
        }
        
        GDALSetRasterColorTable( GDALGetRasterBand( hMemDS, 1 ), hCT );

        GDALDestroyColorTable( hCT );
    }

#if GDAL_VERSION_NUM > 1170
    else if( format->imagemode == MS_IMAGEMODE_RGB )
    {
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 1 ), GCI_RedBand );
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 2 ), GCI_GreenBand );
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 3 ), GCI_BlueBand );
    }
    else if( format->imagemode == MS_IMAGEMODE_RGBA )
    {
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 1 ), GCI_RedBand );
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 2 ), GCI_GreenBand );
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 3 ), GCI_BlueBand );
        GDALSetRasterColorInterpretation( 
            GDALGetRasterBand( hMemDS, 4 ), GCI_AlphaBand );
    }
#endif

/* -------------------------------------------------------------------- */
/*      Assign the projection and coordinate system to the memory       */
/*      dataset.                                                        */
/* -------------------------------------------------------------------- */

    if( map != NULL )
    {
        char *pszWKT;

        GDALSetGeoTransform( hMemDS, map->gt.geotransform );

        pszWKT = msProjectionObj2OGCWKT( &(map->projection) );
        if( pszWKT != NULL )
        {
            GDALSetProjection( hMemDS, pszWKT );
            msFree( pszWKT );
        }
    }

/* -------------------------------------------------------------------- */
/*      Possibly assign a nodata value.                                 */
/* -------------------------------------------------------------------- */
    if( msGetOutputFormatOption(format,"NULLVALUE",NULL) != NULL )
    {
        int iBand;
        const char *nullvalue = msGetOutputFormatOption(format,
                                                        "NULLVALUE",NULL);

        for( iBand = 0; iBand < nBands; iBand++ )
        {
            GDALRasterBandH hBand = GDALGetRasterBand( hMemDS, iBand+1 );
            GDALSetRasterNoDataValue( hBand, atof(nullvalue) );
        }
    }

/* -------------------------------------------------------------------- */
/*  Try to save resolution in the output file.                          */
/* -------------------------------------------------------------------- */
    if( image->resolution > 0 )
    {
      char res[30];

      sprintf( res, "%lf", image->resolution );
      GDALSetMetadataItem( hMemDS, "TIFFTAG_XRESOLUTION", res, NULL );
      GDALSetMetadataItem( hMemDS, "TIFFTAG_YRESOLUTION", res, NULL );
      GDALSetMetadataItem( hMemDS, "TIFFTAG_RESOLUTIONUNIT", "2", NULL );
    }
    
/* -------------------------------------------------------------------- */
/*      Create a disk image in the selected output format from the      */
/*      memory image.                                                   */
/* -------------------------------------------------------------------- */
    papszOptions = (char**)calloc(sizeof(char *),(format->numformatoptions+1));
    if (papszOptions == NULL)
    {
        msReleaseLock( TLOCK_GDAL );
        msSetError( MS_MEMERR, "Out of memory allocating %u bytes.\n", "msSaveImageGDAL()", 
                    sizeof(char *)*(format->numformatoptions+1));
        return MS_FAILURE;
    }

    memcpy( papszOptions, format->formatoptions, 
            sizeof(char *) * format->numformatoptions );
   
    hOutputDS = GDALCreateCopy( hOutputDriver, filename, hMemDS, FALSE, 
                                papszOptions, NULL, NULL );

    free( papszOptions );

    if( hOutputDS == NULL )
    {
        GDALClose( hMemDS );
        msReleaseLock( TLOCK_GDAL );
        msSetError( MS_MISCERR, "Failed to create output %s file.\n%s",
                    "msSaveImageGDAL()", format->driver+5, 
                    CPLGetLastErrorMsg() );
        return MS_FAILURE;
    }

    /* closing the memory DS also frees all associated resources. */
    GDALClose( hMemDS );

    GDALClose( hOutputDS );
    msReleaseLock( TLOCK_GDAL );


/* -------------------------------------------------------------------- */
/*      Are we writing license info into the image?                     */
/*      If so, add it to the temp file on disk now.                     */
/* -------------------------------------------------------------------- */
#ifdef USE_EXEMPI
    if ( bUseXmp == MS_TRUE )
    {
        if( msXmpWrite(map, filename) == MS_FAILURE )
        {
            /* Something bad happened. */
            msSetError( MS_MISCERR, "XMP write to %s failed.\n%s",
                        "msSaveImageGDAL()", filename);
            return MS_FAILURE;
        }
    }
#endif

/* -------------------------------------------------------------------- */
/*      Is this supposed to be a temporary file?  If so, stream to      */
/*      stdout and delete the file.                                     */
/* -------------------------------------------------------------------- */
    if( bFileIsTemporary )
    {
        FILE *fp; 
        unsigned char block[4000];
        int bytes_read;

        if( msIO_needBinaryStdout() == MS_FAILURE )
            return MS_FAILURE;

        /* We aren't sure how far back GDAL exports the VSI*L API, so 
           we only use it if we suspect we need it.  But we do need it if
           holding temporary file in memory. */
#ifdef GDAL_DCAP_VIRTUALIO
        fp = VSIFOpenL( filename, "rb" );
        if( fp == NULL )
        {
            msSetError( MS_MISCERR, 
                        "Failed to open %s for streaming to stdout.",
                        "msSaveImageGDAL()", filename );
            return MS_FAILURE;
        }

        while( (bytes_read = VSIFReadL(block, 1, sizeof(block), fp)) > 0 )
            msIO_fwrite( block, 1, bytes_read, stdout );

        VSIFCloseL( fp );

        VSIUnlink( filename );
        CleanVSIDir( "/vsimem/msout" );
#else
        fp = fopen( filename, "rb" );
        if( fp == NULL )
        {
            msSetError( MS_MISCERR, 
                        "Failed to open %s for streaming to stdout.",
                        "msSaveImageGDAL()", filename );
            return MS_FAILURE;
        }

        while( (bytes_read = fread(block, 1, sizeof(block), fp)) > 0 )
            msIO_fwrite( block, 1, bytes_read, stdout );

        fclose( fp );

        unlink( filename );
#endif
        free( filename );
    }
    
    return MS_SUCCESS;
}

/************************************************************************/
/*                       msInitGDALOutputFormat()                       */
/************************************************************************/

int msInitDefaultGDALOutputFormat( outputFormatObj *format )

{
    GDALDriverH hDriver; 

    msGDALInitialize();

/* -------------------------------------------------------------------- */
/*      check that this driver exists.  Note visiting drivers should    */
/*      be pretty threadsafe so don't bother acquiring the GDAL         */
/*      lock.                                                           */
/* -------------------------------------------------------------------- */
    hDriver = GDALGetDriverByName( format->driver+5 );
    if( hDriver == NULL )
    {
        msSetError( MS_MISCERR, "No GDAL driver named `%s' available.", 
                    "msInitGDALOutputFormat()", format->driver+5 );
        return MS_FAILURE;
    }

#ifdef GDAL_DCAP_CREATE
    if( GDALGetMetadataItem( hDriver, GDAL_DCAP_CREATE, NULL ) == NULL 
        && GDALGetMetadataItem( hDriver, GDAL_DCAP_CREATECOPY, NULL ) == NULL )
    {
        msSetError( MS_MISCERR, "GDAL `%s' driver does not support output.", 
                    "msInitGDALOutputFormat()", format->driver+5 );
        return MS_FAILURE;
    }
#endif

/* -------------------------------------------------------------------- */
/*      Initialize the object.                                          */
/* -------------------------------------------------------------------- */
    format->imagemode = MS_IMAGEMODE_RGB;
    format->renderer = MS_RENDER_WITH_AGG;

#ifdef GDAL_DMD_MIMETYPE 
    if( GDALGetMetadataItem( hDriver, GDAL_DMD_MIMETYPE, NULL ) != NULL )
        format->mimetype = 
            msStrdup(GDALGetMetadataItem(hDriver,GDAL_DMD_MIMETYPE,NULL));
    if( GDALGetMetadataItem( hDriver, GDAL_DMD_EXTENSION, NULL ) != NULL )
        format->extension = 
            msStrdup(GDALGetMetadataItem(hDriver,GDAL_DMD_EXTENSION,NULL));

#else
    if( strcasecmp(format->driver,"GDAL/GTiff") )
    {
        format->mimetype = msStrdup("image/tiff");
        format->extension = msStrdup("tif");
    }
#endif
    
    return MS_SUCCESS;
}

#else

void msGDALInitialize( void ) {}
void msGDALCleanup(void) {}


#endif /* def USE_GDAL */


/************************************************************************/
/*                      msProjectionObj2OGCWKT()                        */
/*                                                                      */
/*      We stick to the C API for OGRSpatialReference object access     */
/*      to allow MapServer+GDAL to be built without C++                 */
/*      complications.                                                  */
/*                                                                      */
/*      Note that this function will return NULL on failure, and the    */
/*      returned string should be freed with msFree().                  */
/************************************************************************/

char *msProjectionObj2OGCWKT( projectionObj *projection )

{

#if !defined(USE_GDAL) && !defined(USE_OGR)
    msSetError(MS_OGRERR, 
               "Not implemented since neither OGR nor GDAL is enabled.",
               "msProjectionObj2OGCWKT()");
    return NULL;

#else /* defined USE_GDAL or USE_OGR */

    OGRSpatialReferenceH hSRS;
    char *pszWKT=NULL, *pszProj4;
    int  nLength = 0, i;
    OGRErr eErr;

    if( projection->proj == NULL )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Form arguments into a full Proj.4 definition string.            */
/* -------------------------------------------------------------------- */
    for( i = 0; i < projection->numargs; i++ )
        nLength += strlen(projection->args[i]) + 2;

    pszProj4 = (char *) CPLMalloc(nLength+2);
    pszProj4[0] = '\0';

    for( i = 0; i < projection->numargs; i++ )
    {
        strcat( pszProj4, "+" );
        strcat( pszProj4, projection->args[i] );
        strcat( pszProj4, " " );
    }

/* -------------------------------------------------------------------- */
/*      Ingest the string into OGRSpatialReference.                     */
/* -------------------------------------------------------------------- */
    hSRS = OSRNewSpatialReference( NULL );
    eErr =  OSRImportFromProj4( hSRS, pszProj4 );
    CPLFree( pszProj4 );

/* -------------------------------------------------------------------- */
/*      Export as a WKT string.                                         */
/* -------------------------------------------------------------------- */
    if( eErr == OGRERR_NONE )
        eErr = OSRExportToWkt( hSRS, &pszWKT );

    OSRDestroySpatialReference( hSRS );

    if( pszWKT )
    {
        char *pszWKT2 = msStrdup(pszWKT);
        CPLFree( pszWKT );

        return pszWKT2;
    }
    else
        return NULL;
#endif /* defined USE_GDAL or USE_OGR */
}