/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Kevin Ruddy.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#ifndef lint
static const char copyright[] =
"@(#) Copyright (c) 1990, 1993\n\
	The Regents of the University of California.  All rights reserved.\n";
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)fold.c	8.1 (Berkeley) 6/6/93";
#endif
static const char rcsid[] =
	"$Id: fold.c,v 1.1.1.1.8.3 1997/09/15 08:07:10 jkh Exp $";
#endif /* not lint */

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

#define	DEFLINEWIDTH	80

void fold __P((int));
static void usage __P((void));

char *__progname;

int
main(argc, argv)
	int argc;
	char **argv;
{
	extern int optind;
	extern char *optarg;
	register int ch;
	int width;
	char *p;

	__progname = basename(argv[0]);

	width = -1;
	while ((ch = getopt(argc, argv, "0123456789w:")) != -1)
		switch (ch) {
		case 'w':
			if ((width = atoi(optarg)) <= 0) {
				errx(1, "illegal width value");
			}
			break;
		case '0': case '1': case '2': case '3': case '4':
		case '5': case '6': case '7': case '8': case '9':
			if (width == -1) {
				p = argv[optind - 1];
				if (p[0] == '-' && p[1] == ch && !p[2])
					width = atoi(++p);
				else
					width = atoi(argv[optind] + 1);
			}
			break;
		default:
			usage();
		}
	argv += optind;
	argc -= optind;

	if (width == -1)
		width = DEFLINEWIDTH;
	if (!*argv)
		fold(width);
	else for (; *argv; ++argv)
		if (!freopen(*argv, "r", stdin)) {
			err(1, "%s", *argv);
		} else
			fold(width);
	exit(0);
}

static void
usage()
{
	(void)fprintf(stderr, "usage: fold [-w width] [file ...]\n");
	exit(1);
}

void
fold(width)
	register int width;
{
	register int ch, col, new;

	for (col = 0;;) {
		switch (ch = getchar()) {
		case EOF:
			return;
		case '\b':
			new = col ? col - 1 : 0;
			break;
		case '\n':
		case '\r':
			new = 0;
			break;
		case '\t':
			new = (col + 8) & ~7;
			break;
		default:
			new = col + 1;
			break;
		}

		if (new > width) {
			putchar('\n');
			col = 0;
		}
		putchar(ch);

		switch (ch) {
		case '\b':
			if (col > 0)
				--col;
			break;
		case '\n':
		case '\r':
			col = 0;
			break;
		case '\t':
			col += 8;
			col &= ~7;
			break;
		default:
			++col;
			break;
		}
	}
}