/*
 * Copyright (c) 2015 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <err.h>
#include <stdlib.h>
#include <string.h>
#include <wchar.h>

int
mbsavis(char** outp, const char *mbs)
{
        const char *src;  /* Iterate mbs. */
        char     *dst;  /* Iterate *outp. */
        wchar_t   wc;
        int       total_width;  /* Display width of the whole string. */
        int       width;  /* Display width of a single Unicode char. */
        int       len;  /* Length in bytes of UTF-8 encoded string. */

        len = strlen(mbs);
        if ((*outp = malloc(len + 1)) == NULL)
                err(1, NULL);

        if (MB_CUR_MAX == 1) {
                memcpy(*outp, mbs, len + 1);
                return len;
        }

        src = mbs;
        dst = *outp;
        total_width = 0;
        while (*src != '\0') {
                if ((len = mbtowc(&wc, src, MB_CUR_MAX)) == -1) {
                        total_width++;
                        *dst++ = '?';
                        src++;
                } else if ((width = wcwidth(wc)) == -1) {
                        total_width++;
                        *dst++ = '?';
                        src += len;
                } else {
                        total_width += width;
                        while (len-- > 0)
                                *dst++ = *src++;
                }
        }
        *dst = '\0';
        return total_width;
}