/******************************************************************************
 * $Id: ogrvrtdriver.cpp 32982 2016-01-14 16:53:57Z goatbar $
 *
 * Project:  OpenGIS Simple Features Reference Implementation
 * Purpose:  Implements OGRVRTDriver class.
 * Author:   Frank Warmerdam, warmerdam@pobox.com
 *
 ******************************************************************************
 * Copyright (c) 2003, Frank Warmerdam <warmerdam@pobox.com>
 * Copyright (c) 2009-2014, 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 "ogr_vrt.h"
#include "cpl_conv.h"

CPL_CVSID("$Id: ogrvrtdriver.cpp 32982 2016-01-14 16:53:57Z goatbar $");

/************************************************************************/
/*                           OGRVRTErrorHandler()                       */
/************************************************************************/

static void CPL_STDCALL OGRVRTErrorHandler(CPL_UNUSED CPLErr eErr,
                                           CPL_UNUSED CPLErrorNum nType,
                                           const char* pszMsg)
{
    std::vector<CPLString>* paosErrors = (std::vector<CPLString>* )CPLGetErrorHandlerUserData();
    paosErrors->push_back(pszMsg);
}

/************************************************************************/
/*                         OGRVRTDriverIdentify()                       */
/************************************************************************/

static int OGRVRTDriverIdentify( GDALOpenInfo* poOpenInfo )
{
    if( !poOpenInfo->bStatOK )
    {
/* -------------------------------------------------------------------- */
/*      Are we being passed the XML definition directly?                */
/*      Skip any leading spaces/blanks.                                 */
/* -------------------------------------------------------------------- */
        const char *pszTestXML = poOpenInfo->pszFilename;
        while( *pszTestXML != '\0' && isspace( (unsigned char)*pszTestXML ) )
            pszTestXML++;
        if( STARTS_WITH_CI(pszTestXML, "<OGRVRTDataSource>") )
        {
            return TRUE;
        }
        return FALSE;
    }

    return ( poOpenInfo->fpL != NULL &&
             strstr((const char*)poOpenInfo->pabyHeader,"<OGRVRTDataSource") != NULL );
}

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

static GDALDataset *OGRVRTDriverOpen( GDALOpenInfo* poOpenInfo )

{
    if( !OGRVRTDriverIdentify(poOpenInfo) )
        return NULL;

/* -------------------------------------------------------------------- */
/*      Are we being passed the XML definition directly?                */
/*      Skip any leading spaces/blanks.                                 */
/* -------------------------------------------------------------------- */
    const char *pszTestXML = poOpenInfo->pszFilename;
    while( *pszTestXML != '\0' && isspace( (unsigned char)*pszTestXML ) )
        pszTestXML++;

    char *pszXML = NULL;
    if( STARTS_WITH_CI(pszTestXML, "<OGRVRTDataSource>") )
    {
        pszXML = CPLStrdup(pszTestXML);
    }

/* -------------------------------------------------------------------- */
/*      Open file and check if it contains appropriate XML.             */
/* -------------------------------------------------------------------- */
    else
    {
        VSIStatBufL sStatBuf;
        if ( VSIStatL( poOpenInfo->pszFilename, &sStatBuf ) != 0 ||
             sStatBuf.st_size > 1024 * 1024 )
        {
            CPLDebug( "VRT", "Unreasonable long file, not likely really VRT" );
            return NULL;
        }

/* -------------------------------------------------------------------- */
/*      It is the right file, now load the full XML definition.         */
/* -------------------------------------------------------------------- */
        int nLen = (int) sStatBuf.st_size;

        pszXML = (char *) VSI_MALLOC_VERBOSE(nLen+1);
        if (pszXML == NULL)
            return NULL;

        pszXML[nLen] = '\0';
        VSIFSeekL( poOpenInfo->fpL, 0, SEEK_SET );
        if( ((int) VSIFReadL( pszXML, 1, nLen, poOpenInfo->fpL )) != nLen )
        {
            CPLFree( pszXML );
            return NULL;
        }
        VSIFCloseL( poOpenInfo->fpL );
        poOpenInfo->fpL = NULL;
    }

/* -------------------------------------------------------------------- */
/*      Parse the XML.                                                  */
/* -------------------------------------------------------------------- */
    CPLXMLNode *psTree = CPLParseXMLString( pszXML );

    if( psTree == NULL )
    {
        CPLFree( pszXML );
        return NULL;
    }

/* -------------------------------------------------------------------- */
/*      XML Validation.                                                 */
/* -------------------------------------------------------------------- */
    if( CPLTestBool(CPLGetConfigOption("GDAL_XML_VALIDATION", "YES")) )
    {
        const char* pszXSD = CPLFindFile( "gdal", "ogrvrt.xsd" );
        if( pszXSD != NULL )
        {
            std::vector<CPLString> aosErrors;
            CPLPushErrorHandlerEx(OGRVRTErrorHandler, &aosErrors);
            int bRet = CPLValidateXML(pszXML, pszXSD, NULL);
            CPLPopErrorHandler();
            if( !bRet )
            {
                if( aosErrors.size() > 0 &&
                    strstr(aosErrors[0].c_str(), "missing libxml2 support") == NULL )
                {
                    for(size_t i = 0; i < aosErrors.size(); i++)
                    {
                        CPLError(CE_Warning, CPLE_AppDefined, "%s", aosErrors[i].c_str());
                    }
                }
            }
            CPLErrorReset();
        }
    }
    CPLFree( pszXML );

/* -------------------------------------------------------------------- */
/*      Create a virtual datasource configured based on this XML input. */
/* -------------------------------------------------------------------- */
    OGRVRTDataSource *poDS
        = new OGRVRTDataSource((GDALDriver*)GDALGetDriverByName( "OGR_VRT" ));

    /* psTree is owned by poDS */
    if( !poDS->Initialize( psTree, poOpenInfo->pszFilename,
                           poOpenInfo->eAccess == GA_Update ) )
    {
        delete poDS;
        return NULL;
    }

    return poDS;
}

/************************************************************************/
/*                           RegisterOGRVRT()                           */
/************************************************************************/

void RegisterOGRVRT()

{
    if( GDALGetDriverByName( "OGR_VRT" ) != NULL )
        return;

    GDALDriver *poDriver = new GDALDriver();

    poDriver->SetDescription( "OGR_VRT" );
    poDriver->SetMetadataItem( GDAL_DCAP_VECTOR, "YES" );
    poDriver->SetMetadataItem( GDAL_DMD_LONGNAME, "VRT - Virtual Datasource" );
    poDriver->SetMetadataItem( GDAL_DMD_EXTENSION, "vrt" );
    poDriver->SetMetadataItem( GDAL_DMD_HELPTOPIC, "drv_vrt.html" );
    poDriver->SetMetadataItem( GDAL_DCAP_VIRTUALIO, "YES" );

    poDriver->pfnOpen = OGRVRTDriverOpen;
    poDriver->pfnIdentify = OGRVRTDriverIdentify;

    GetGDALDriverManager()->RegisterDriver( poDriver );
}