/* gopt-usage.c version 8.1: tom.viza@gmail.com PUBLIC DOMAIN 2003-8 */
/*
I, Tom Vajzovic, am the author of this software and its documentation and
permanently abandon all copyright and other intellectual property rights in
them, including the right to be identified as the author.

I am fairly certain that this software does what the documentation says it
does, but I cannot guarantee that it does, or that it does what you think it
should, and I cannot guarantee that it will not have undesirable side effects.

You are free to use, modify and distribute this software as you please, but
you do so at your own risk.  If you remove or hide this warning then you are
responsible for any problems encountered by people that you make the software
available to.

Before modifying or distributing this software I ask that you would please
read http://www.purposeful.co.uk/tfl/
*/

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "gopt.h"

int main( int argc, const char **argv ){

  FILE *out_stream;
  const char *filename;
  int verbosity;
  int i;  
  void *options= gopt_sort( & argc, argv, gopt_start(
      gopt_option( 'h', 0, gopt_shorts( 'h', '?' ), gopt_longs( "help", "HELP" )),
      gopt_option( 'z', 0, gopt_shorts( 0 ), gopt_longs( "version" )),
      gopt_option( 'v', GOPT_REPEAT, gopt_shorts( 'v' ), gopt_longs( "verbose" )),
      gopt_option( 'o', GOPT_ARG, gopt_shorts( 'o' ), gopt_longs( "output" ))));
  /*
   * there are four possible options to this program, some of which have multiple names:
   *
   * -h -? --help --HELP
   * --version
   * -v --verbose  (which may be repeated for more verbosity)
   * -o --output  (which requires an option argument)
   *
   * the program will have been terminated if unrecognised options are specified,
   * or if an option without GOPT_REPEAT was repeated, or if an option without 
   * GOPT_ARG had an option argument, or if one with GOPT_ARG had no argument.
   */

  if( gopt( options, 'h' ) ){
    /*
     * if any of the help options was specified
     */
    fprintf( stdout, "help text\n" );
    exit( EXIT_SUCCESS );
  }

  if( gopt( options, 'z' ) ){
    /*
     * if --version was specified
     * NB: 'z' is just a key within the source code
     * if you specify -z, it will be treated as an unknown option
     */
    fprintf( stdout, "version number\n" );
    exit( EXIT_SUCCESS );
  }

  if( gopt_arg( options, 'o', & filename ) && strcmp( filename, "-" ) ){
    /*
     * if -o or --output was specified, and its argument was not "-"
     */
    out_stream= fopen( filename, "wb" );
    if( ! out_stream ){
      fprintf( stderr, "%s: %s: could not open file for output\n", argv[0], filename );
      exit( EXIT_FAILURE);
    }
  }
  else
    out_stream= stdout;

  verbosity= gopt( options, 'v' );
  /*
   * return value is the number of times that the option was specified
   */

  if( verbosity > 1 )
    fprintf( stderr, "being really verbose\n" );

  else if( verbosity )
    fprintf( stderr, "being verbose\n" );

  gopt_free( options );
  /*
   * release memory used
   * you can no longer call gopt() etc.
   */

  for( i= 0; i < argc; ++i )
    fprintf( out_stream, "%s\n", argv[i] );
    /*
     * all the options have been removed
     * leaving only the program name and operands
     */

  exit( EXIT_SUCCESS );
}
/* To accept an option that can be repeated and takes an argument, use
 * GOPT_REPEAT | GOPT_ARG.  If you do this then you will want to use
 * gopt_arg_i() or gopt_args().  See gopt.h for details.
 */