/*-
 * SPDX-License-Identifier: BSD-3-Clause
 *
 * Copyright (c) 1980, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * 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. 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.
 */

/*
 * unexpand - put tabs into a file replacing blanks
 */
#include <ctype.h>
#include <err.h>
#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <wchar.h>
#include <wctype.h>

static int	all;
static int	nstops;
static int	tabstops[100];

static void getstops(const char *);
static void usage(void) __dead2;
static int tabify(const char *);

int
main(int argc, char *argv[])
{
	int ch, failed;
	char *filename;

	setlocale(LC_CTYPE, "");

	nstops = 1;
	tabstops[0] = 8;
	while ((ch = getopt(argc, argv, "at:")) != -1) {
		switch (ch) {
		case 'a':	/* Un-expand all spaces, not just leading. */
			all = 1;
			break;
		case 't':	/* Specify tab list, implies -a. */
			getstops(optarg);
			all = 1;
			break;
		default:
			usage();
			/*NOTREACHED*/
		}
	}
	argc -= optind;
	argv += optind;

	failed = 0;
	if (argc == 0)
		failed |= tabify("stdin");
	else {
		while ((filename = *argv++) != NULL) {
			if (freopen(filename, "r", stdin) == NULL) {
				warn("%s", filename);
				failed = 1;
			} else
				failed |= tabify(filename);
		}
	}
	exit(failed != 0);
}

static void
usage(void)
{
	fprintf(stderr, "usage: unexpand [-a | -t tablist] [file ...]\n");
	exit(1);
}

static int
tabify(const char *curfile)
{
	int dcol, doneline, limit, n, ocol, width;
	wint_t ch;

	limit = nstops == 1 ? INT_MAX : tabstops[nstops - 1] - 1;

	doneline = ocol = dcol = 0;
	while ((ch = getwchar()) != WEOF) {
		if (ch == ' ' && !doneline) {
			if (++dcol >= limit)
				doneline = 1;
			continue;
		} else if (ch == '\t') {
			if (nstops == 1) {
				dcol = (1 + dcol / tabstops[0]) *
				    tabstops[0];
				continue;
			} else {
				for (n = 0; n < nstops &&
				    tabstops[n] - 1 < dcol; n++)
					;
				if (n < nstops - 1 && tabstops[n] - 1 < limit) {
					dcol = tabstops[n];
					continue;
				}
				doneline = 1;
			}
		}

		/* Output maximal number of tabs. */
		if (nstops == 1) {
			while (((ocol + tabstops[0]) / tabstops[0])
			    <= (dcol / tabstops[0])) {
				if (dcol - ocol < 2)
					break;
				putwchar('\t');
				ocol = (1 + ocol / tabstops[0]) *
				    tabstops[0];
			}
		} else {
			for (n = 0; n < nstops && tabstops[n] - 1 < ocol; n++)
				;
			while (ocol < dcol && n < nstops && ocol < limit) {
				putwchar('\t');
				ocol = tabstops[n++];
			}
		}

		/* Then spaces. */
		while (ocol < dcol && ocol < limit) {
			putwchar(' ');
			ocol++;
		}

		if (ch == '\b') {
			putwchar('\b');
			if (ocol > 0)
				ocol--, dcol--;
		} else if (ch == '\n') {
			putwchar('\n');
			doneline = ocol = dcol = 0;
			continue;
		} else if (ch != ' ' || dcol > limit) {
			putwchar(ch);
			if ((width = wcwidth(ch)) > 0)
				ocol += width, dcol += width;
		}

		/*
		 * Only processing leading blanks or we've gone past the
		 * last tab stop. Emit remainder of this line unchanged.
		 */
		if (!all || dcol >= limit) {
			while ((ch = getwchar()) != '\n' && ch != WEOF)
				putwchar(ch);
			if (ch == '\n')
				putwchar('\n');
			doneline = ocol = dcol = 0;
		}
	}
	if (ferror(stdin)) {
		warn("%s", curfile);
		return (1);
	}
	return (0);
}

static void
getstops(const char *cp)
{
	int i;

	nstops = 0;
	for (;;) {
		i = 0;
		while (*cp >= '0' && *cp <= '9')
			i = i * 10 + *cp++ - '0';
		if (i <= 0)
			errx(1, "bad tab stop spec");
		if (nstops > 0 && i <= tabstops[nstops-1])
			errx(1, "bad tab stop spec");
		if (nstops == sizeof(tabstops) / sizeof(*tabstops))
			errx(1, "too many tab stops");
		tabstops[nstops++] = i;
		if (*cp == 0)
			break;
		if (*cp != ',' && !isblank((unsigned char)*cp))
			errx(1, "bad tab stop spec");
		cp++;
	}
}
