/**
 * vim: tabstop=2:shiftwidth=2:softtabstop=2:expandtab
 *
 * str_replace.c implements a str_replace PHP like function
 * Copyright (C) 2010  chantra <chantra__A__debuntu__D__org>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 * gcc -o str_replace_all str_replace_all.c
 */

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

void usage(char *p){
  fprintf(stderr, "USAGE: %s string tok replacement\n", p );
}

char *
str_replace ( const char *string, const char *substr, const char *replacement ){
  char *tok = NULL;
  char *newstr = NULL;
  char *oldstr = NULL;

  /* if either substr or replacement is NULL, duplicate string a let caller handle it */
  if ( substr == NULL || replacement == NULL ) return strdup (string);
  newstr = strdup (string);
  while ( (tok = strstr ( newstr, substr ))){
    oldstr = newstr;
    newstr = malloc ( strlen ( oldstr ) - strlen ( substr ) + strlen ( replacement ) + 1 );
    /*failed to alloc mem, free old string and return NULL */
    if ( newstr == NULL ){
      free (oldstr);
      return NULL;
    }
    memcpy ( newstr, oldstr, tok - oldstr );
    memcpy ( newstr + (tok - oldstr), replacement, strlen ( replacement ) );
    memcpy ( newstr + (tok - oldstr) + strlen( replacement ), tok + strlen ( substr ), strlen ( oldstr ) - strlen ( substr ) - ( tok - oldstr ) );
    memset ( newstr + strlen ( oldstr ) - strlen ( substr ) + strlen ( replacement ) , 0, 1 );
    free (oldstr);
  }
  return newstr;
}

int main( int argc, char **argv ){
  char *ns = NULL;
  if( argc != 4 ) {
    usage(argv[0]);
    return 1;
  }
  ns = str_replace( argv[1], argv[2], argv[3] );
  fprintf( stdout, "Old string: %s\nTok: %s\nReplacement: %s\nNew string: %s\n", argv[1], argv[2], argv[3], ns );
  free(ns);
  return 0;
}