/*
 * 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;
}