/***
*mbtowc.c - Convert multibyte char to wide char.
*
*       Copyright (c) Microsoft Corporation. All rights reserved.
*
*Purpose:
*       Convert a multibyte character into the equivalent wide character.
*
*******************************************************************************/


#include <cruntime.h>
#include <stdlib.h>
#include <errno.h>
#include <dbgint.h>
#include <ctype.h>
#include <internal.h>
#include <locale.h>
#include <mtdll.h>
#include <setlocal.h>

/***
*int mbtowc() - Convert multibyte char to wide character.
*
*Purpose:
*       Convert a multi-byte character into the equivalent wide character,
*       according to the LC_CTYPE category of the current locale.
*       [ANSI].
*
*       NOTE:  Currently, the C libraries support the "C" locale only.
*              Non-C locale support now available under _INTL switch.
*Entry:
*       wchar_t  *pwc = pointer to destination wide character
*       const char *s = pointer to multibyte character
*       size_t      n = maximum length of multibyte character to consider
*
*Exit:
*       If s = NULL, returns 0, indicating we only use state-independent
*       character encodings.
*       If s != NULL, returns:  0 (if *s = null char)
*                               -1 (if the next n or fewer bytes not valid mbc)
*                               number of bytes comprising converted mbc
*
*Exceptions:
*       If errors are encountered, -1 is returned and errno is set to EILSEQ.
*
*******************************************************************************/

extern "C" int __cdecl _mbtowc_l (
        wchar_t  *pwc,
        const char *s,
        size_t n,
        _locale_t plocinfo
        )
{
    if ( !s || n == 0 )
        /* indicate do not have state-dependent encodings,
           handle zero length string */
        return 0;

    if ( !*s )
    {
        /* handle NULL char */
        if (pwc)
            *pwc = 0;
        return 0;
    }


    _LocaleUpdate _loc_update(plocinfo);
    _ASSERTE (_loc_update.GetLocaleT()->locinfo->mb_cur_max == 1 || _loc_update.GetLocaleT()->locinfo->mb_cur_max == 2);

    if ( _loc_update.GetLocaleT()->locinfo->lc_handle[LC_CTYPE] == _CLOCALEHANDLE )
    {
        if (pwc)
            *pwc = (wchar_t)(unsigned char)*s;
        return sizeof(char);
    }

    if ( _isleadbyte_l((unsigned char)*s, _loc_update.GetLocaleT()) )
    {
        /* multi-byte char */

        if ( (_loc_update.GetLocaleT()->locinfo->mb_cur_max <= 1) || ((int)n < _loc_update.GetLocaleT()->locinfo->mb_cur_max) ||
             (MultiByteToWideChar( _loc_update.GetLocaleT()->locinfo->lc_codepage,
                                  MB_PRECOMPOSED | MB_ERR_INVALID_CHARS,
                                  s,
                                  _loc_update.GetLocaleT()->locinfo->mb_cur_max,
                                  pwc,
                                  (pwc) ? 1 : 0 ) == 0) )
        {
            /* validate high byte of mbcs char */
            if ( (n < (size_t)_loc_update.GetLocaleT()->locinfo->mb_cur_max) || (!*(s + 1)) )
            {
                errno = EILSEQ;
                return -1;
            }
        }
        return _loc_update.GetLocaleT()->locinfo->mb_cur_max;
    }
    else {
        /* single byte char */
         if ( MultiByteToWideChar( _loc_update.GetLocaleT()->locinfo->lc_codepage,
                                  MB_PRECOMPOSED | MB_ERR_INVALID_CHARS,
                                  s,
                                  1,
                                  pwc,
                                  (pwc) ? 1 : 0 ) == 0 )
        {
            errno = EILSEQ;
            return -1;
        }
        return sizeof(char);
    }

}

extern "C" int __cdecl mbtowc(
        wchar_t  *pwc,
        const char *s,
        size_t n
        )
{
    return _mbtowc_l(pwc, s, n, NULL);
}