/****************************************************************
 *
 * MODULE:       v.external
 * 
 * AUTHOR(S):    Radim Blazek
 *               
 * PURPOSE:      Create a new vector as a link to OGR layer (read-only)
 *               
 * COPYRIGHT:    (C) 2003 by the GRASS Development Team
 *
 *               This program is free software under the 
 *               GNU General Public License (>=v2). 
 *               Read the file COPYING that comes with GRASS
 *               for details.
 *
 **************************************************************/
#include <grass/config.h>
#include <stdlib.h> 
#include <string.h> 
#include <unistd.h>
#include <grass/gis.h>
#include <grass/dbmi.h>
#include <grass/Vect.h>
#include <grass/glocale.h>
#include "ogr_api.h"

int 
main (int argc, char *argv[])
{
    int    i;
    struct GModule *module;
    struct Option *dsn_opt, *layer_opt, *out_opt;
    char   buf[2000];
    FILE   *fd;
    struct Map_info Map;
    OGRDataSourceH Ogr_ds;
    OGRSFDriverH Ogr_driver;  
    OGRLayerH Ogr_layer;	
    OGRFeatureDefnH Ogr_featuredefn;
    int nlayers; 
    int layer;
    char *layer_name;

    G_gisinit(argv[0]);

    OGRRegisterAll();

    /* Module options */
    sprintf ( buf, "Create a new vector as a read-only link to OGR layer. Available drivers:\n" );
    for ( i = 0; i < OGRGetDriverCount(); i++ ) {
	Ogr_driver = OGRGetDriver( i );
	if ( i == 0) 
	  sprintf (buf, "%s%s", buf, OGR_Dr_GetName ( Ogr_driver) ); 
	else
	  sprintf (buf, "%s,%s", buf, OGR_Dr_GetName ( Ogr_driver) ); 
    }
    module = G_define_module();
    module->keywords = _("vector");
    module->description = G_store(buf);

    dsn_opt = G_define_option();
    dsn_opt->key = "dsn";
    dsn_opt->type =  TYPE_STRING;
    dsn_opt->required = YES;
    dsn_opt->gisprompt = "old_file,file,dsn";
    dsn_opt->description = "OGR datasource name. Examples:\n"
			   "\t\tESRI Shapefile: directory containing shapefiles\n"
			   "\t\tMapInfo File: directory containing mapinfo files";

    out_opt = G_define_standard_option(G_OPT_V_OUTPUT);
    out_opt->required = NO;
    out_opt->description = _("Output vector, if not given, available layers are printed only"); 

    layer_opt = G_define_option();
    layer_opt->key = "layer";
    layer_opt->type = TYPE_STRING;
    layer_opt->required = NO;
    layer_opt->multiple = NO;
    layer_opt->description = _("OGR layer name. If not given, available layers are printed only. Examples:\n"
			   "\t\tESRI Shapefile: shapefile name\n"
			   "\t\tMapInfo File: mapinfo file name");

    if (G_parser (argc, argv))
	exit(EXIT_FAILURE); 

    if ( !out_opt->answer && layer_opt->answer )
	G_fatal_error ( "Output vector name was not specified.");

    /* Open OGR DSN */
    Ogr_ds = OGROpen( dsn_opt->answer, FALSE, NULL );
    if( Ogr_ds == NULL ) G_fatal_error ("Cannot open data source");

    /* Make a list of available layers */
    nlayers = OGR_DS_GetLayerCount(Ogr_ds);
    
    if ( !layer_opt->answer )
        fprintf ( stdout, "Data source contains %d layers:\n", nlayers );
    
    layer = -1;
    for ( i = 0; i < nlayers; i++ ) {
	Ogr_layer =  OGR_DS_GetLayer( Ogr_ds, i );
	Ogr_featuredefn = OGR_L_GetLayerDefn( Ogr_layer );
	layer_name = (char *)OGR_FD_GetName( Ogr_featuredefn );
	
	if ( !layer_opt->answer ) {
	    if ( i > 0 ) fprintf ( stdout, ", " );
	    fprintf ( stdout, "%s", layer_name );
	} else {
	    if ( strcmp( layer_name, layer_opt->answer) == 0 ) {
		layer = i;
	    }
	}
    }
    
    if ( !layer_opt->answer ) {
	fprintf ( stdout, "\n" );
        exit(0) ;
    }

    if ( layer == -1 ) {
	G_fatal_error ("Layer '%s' not available", layer_opt->answer);
    }

    G_debug (2, "layer '%s' was found", layer_opt->answer );

    OGR_DS_Destroy( Ogr_ds );

    Vect_open_new (&Map, out_opt->answer, 0 ); 
    Vect_hist_command ( &Map );
    Vect_close ( &Map );

    /* Vect_open_new created 'head', 'coor', 'hist' -> delete 'coor' and create 'frmt' */
    sprintf ( buf, "%s/%s/vector/%s/coor", G_location_path(), G_mapset(), out_opt->answer );
    G_debug (2, "Delete '%s'", buf );
    if ( unlink(buf) == -1 ) {
	G_fatal_error ( "Cannot delete '%s'", buf );
    }

    /* Create frmt */
    sprintf (buf, "%s/%s", GRASS_VECT_DIRECTORY, out_opt->answer );    
    fd = G_fopen_new (buf, GRASS_VECT_FRMT_ELEMENT);
    if ( fd == NULL ) {
	G_fatal_error ( "Cannot open 'frmt' file." );
    }
 
    fprintf ( fd, "FORMAT: ogr\n" );
    fprintf ( fd, "DSN: %s\n", dsn_opt->answer );
    fprintf ( fd, "LAYER: %s\n", layer_opt->answer );
     
    fclose ( fd );

    Vect_open_old (&Map, out_opt->answer, G_mapset() );
    Vect_build ( &Map, stderr );
    Vect_close ( &Map );
    
    exit(EXIT_SUCCESS) ;
}