/*
 * $Id$
 */

/*
 * Harbour Project source code:
 *   CHARMIX() CT3 function
 *
 * Initial code: Copyright 1999-2001 Viktor Szakats <viktor.szakats@syenar.hu>
 * 
 * CT3 conformity: Copyright 2001 IntTec GmbH, Neunlindenstr 32, 79106 Freiburg, Germany
 *                 Author: Martin Vogel <vogel@inttec.de>
 *
 * www - http://www.harbour-project.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, 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 software; see the file COPYING.  If not, write to
 * the Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307 USA (or visit the web site http://www.gnu.org/).
 *
 * As a special exception, the Harbour Project gives permission for
 * additional uses of the text contained in its release of Harbour.
 *
 * The exception is that, if you link the Harbour libraries with other
 * files to produce an executable, this does not by itself cause the
 * resulting executable to be covered by the GNU General Public License.
 * Your use of that executable is in no way restricted on account of
 * linking the Harbour library code into it.
 *
 * This exception does not however invalidate any other reasons why
 * the executable file might be covered by the GNU General Public License.
 *
 * This exception applies only to the code released by the Harbour
 * Project under the name Harbour.  If you copy code from other
 * Harbour Project or Free Software Foundation releases into a copy of
 * Harbour, as the General Public License permits, the exception does
 * not apply to the code that you add in this way.  To avoid misleading
 * anyone as to the status of such modified files, you must delete
 * this exception notice from them.
 *
 * If you write modifications of your own for Harbour, it is your choice
 * whether to permit this exception to apply to your modifications.
 * If you do not wish that, delete this exception notice.
 *
 */

#include "ct.h"


/*  $DOC$
 *  $FUNCNAME$
 *      CHARMIX()
 *  $CATEGORY$
 *      CT3 string functions
 *  $ONELINER$
 *      Mix two strings
 *  $SYNTAX$
 *      CHARMIX (<cString1>[, <cString2>]) --> cMixedString
 *  $ARGUMENTS$
 *      <cString1>     String that will be mixed with the characters from <cString2>
 *      [<cString2>]   String whose characters will be mixed with the one from
 *                     <cString1>.
 *                     Default: " " (string with one space char)
 *  $RETURNS$
 *      <cMixedString> Mixed string
 *  $DESCRIPTION$
 *      The CHARMIX() function mixes the strings <cString1> and <cString2>. To
 *      do this it takes one character after the other alternatively from
 *      <cString1> and <cString2> and puts them in the output string.
 *      This procedure is stopped when the end of <cString1> is reached. If
 *      <cString2> is shorter than <cString1>, the function will start at
 *      the begin of <cString2> again. If on the other hand <cString2> is
 *      longer than <cString1>, the surplus characters will be omitted.
 *  $EXAMPLES$
 *      ? CHARMIX("ABC", "123")    // "A1B2C3"
 *      ? CHARMIX("ABCDE", "12")   // "A1B2C1D2E1"
 *      ? CHARMIX("AB", "12345")   // "A1B2"
 *      ? CHARMIX("HELLO", " ")    //  "H E L L O "
 *      ? CHARMIX("HELLO", "")     //  "HELLO"
 *  $TESTS$
 *      CHARMIX("ABC", "123")  == "A1B2C3"
 *      CHARMIX("ABCDE", "12") == "A1B2C1D2E1"
 *      CHARMIX("AB", "12345") == "A1B2"
 *      CHARMIX("HELLO", " ")  == "H E L L O "
 *      CHARMIX("HELLO", "")   == "HELLO"
 *  $STATUS$
 *      Ready
 *  $COMPLIANCE$
 *      CHARMIX() is compatible with CT3's CHARMIX().
 *      NOTE: CA-Tools version of CHARMIX() will hang
 *            if the second parameter is an empty string, this version will not.
 *  $PLATFORMS$
 *      All
 *  $FILES$
 *      Source is charmix.c, library is ct3.
 *  $SEEALSO$
 *      CHAREVEN()   CHARODD()
 *  $END$
 */

HB_FUNC( CHARMIX )
{
   if( ISCHAR( 1 ) )
   {
      char *pcString1 = hb_parc( 1 );
      char *pcString2, *pcResult;
      size_t sLen1 = hb_parclen( 1 );
      size_t sLen2, sPos1, sPos2, sResultPos;

      if( sLen1 == 0 )
      {
         int iArgErrorMode = ct_getargerrormode();

         if( iArgErrorMode != CT_ARGERR_IGNORE )
         {
            ct_error( ( USHORT ) iArgErrorMode, EG_ARG, CT_ERROR_CHARMIX, NULL, "CHARMIX", 0,
                      EF_CANDEFAULT, HB_ERR_ARGS_BASEPARAMS );
         }
         hb_retc( NULL );
         return;
      }

      if( ISCHAR( 2 ) )
      {
         pcString2 = hb_parc( 2 );
         sLen2 = hb_parclen( 2 );
         if( sLen2 == 0 )
         {
            int iArgErrorMode = ct_getargerrormode();

            if( iArgErrorMode != CT_ARGERR_IGNORE )
            {
               ct_error( ( USHORT ) iArgErrorMode, EG_ARG, CT_ERROR_CHARMIX,
                         NULL, "CHARMIX", 0,
                         EF_CANDEFAULT, HB_ERR_ARGS_BASEPARAMS );
            }
            hb_retclen( pcString1, sLen1 );
            return;
         }
      }
      else
      {
         pcString2 = " ";     /* NOTE: The original CT3 uses " " as 2nd string
                                 if the 2nd param is not a string ! */
         sLen2 = 1;
      }

      pcResult = ( char * ) hb_xgrab( sLen1 * 2 + 1 );
      sPos2 = sResultPos = 0;
      for( sPos1 = 0; sPos1 < sLen1; )
      {
         pcResult[sResultPos++] = pcString1[sPos1++];
         pcResult[sResultPos++] = pcString2[sPos2++];
         sPos2 %= sLen2;
      }

      hb_retclen_buffer( pcResult, sLen1 * 2 );
   }
   else
   {
      PHB_ITEM pSubst = NULL;
      int iArgErrorMode = ct_getargerrormode();

      if( iArgErrorMode != CT_ARGERR_IGNORE )
      {
         pSubst = ct_error_subst( ( USHORT ) iArgErrorMode, EG_ARG,
                                  CT_ERROR_CHARMIX, NULL, "CHARMIX", 0,
                                  EF_CANSUBSTITUTE, HB_ERR_ARGS_BASEPARAMS );
      }

      if( pSubst != NULL )
         hb_itemReturnRelease( pSubst );
      else
         hb_retc( NULL );
   }
}
