/* $NetBSD: tabs.c,v 1.6 2021/08/27 18:28:41 rillig Exp $ */

/*-
 * Copyright (c) 2008 The NetBSD Foundation, Inc.
 * All rights reserved.
 *
 * This code is derived from software contributed to The NetBSD Foundation
 * by Roy Marples.
 *
 * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
 */

#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 2008 \
The NetBSD Foundation, inc. All rights reserved.");
__RCSID("$NetBSD: tabs.c,v 1.6 2021/08/27 18:28:41 rillig Exp $");
#endif /* not lint */

#include <sys/ioctl.h>
#include <sys/types.h>

#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <term.h>
#include <unistd.h>

#define NSTOPS 20

struct tabspec {
        const char *opt;
        const char *spec;
};
static const struct tabspec tabspecs[] = {
        {"a",   "1,10,16,36,72"},
        {"a2",  "1,10,16,40,72"},
        {"c",   "1,8,12,16,20,55"},
        {"c2",  "1,6,10,14,49"},
        {"c3",  "1,6,10,14,18,22,26,30,34,38,42,46,50,54,58,62,67"},
        {"f",   "1,7,11,15,19,23"},
        {"p",   "1,5,9,13,17,21,25,29,33,37,41,45,49,53,57,61"},
        {"s",   "1,10,55"},
        {"u",   "1,12,20,44"}
};
static const size_t ntabspecs = sizeof(tabspecs) / sizeof(tabspecs[0]);

__dead static void
usage(void)
{
        fprintf(stderr,
                "usage: tabs [-n|-a|-a2|-c|-c2|-c3|-f|-p|-s|-u] [+m[n]]"
                " [-T type]\n"
                "       tabs [-T type] [+[n]] n1[,n2,...]\n");
        exit(EXIT_FAILURE);
        /* NOTREACHED */
}

int
main(int argc, char **argv)
{
        char *term, *arg, *token, *end, *tabs = NULL, *p;
        const char *cr, *spec = NULL;
        int i, n, inc = 8, stops[NSTOPS], nstops, last, cols, margin = 0;
        long num = 0;
        size_t j;
        struct winsize ws;

        term = getenv("TERM");
        for (i = 1; i < argc; i++) {
                if (argv[i][0] == '+') {
                        arg = argv[i] + 1;
                        if (arg[0] == 'm')
                                arg++;
                        if (arg[0] == '\0')
                                margin = 10;
                        else {
                                errno = 0;
                                num = strtol(arg, &end, 10);
                                if (errno != 0 || *end != '\0' ||
                                    num < 0 || num > INT_MAX)
                                        errx(EXIT_FAILURE,
                                             "%s: invalid margin", arg);
                                margin = (int)num;
                        }
                        continue;
                }
                if (argv[i][0] != '-') {
                        tabs = argv[i];
                        break;
                }
                arg = argv[i] + 1;
                if (arg[0] == '\0') 
                        usage();
                if (arg[0] == '-' && arg[1] == '\0') {
                        if (argv[i + 1] != NULL)
                                tabs = argv[i + 1];
                        break;
                }
                if (arg[0] == 'T' && arg[1] == '\0') {
                        term = argv[++i];
                        if (term == NULL)
                                usage();
                        continue;
                }
                if (isdigit((unsigned char)arg[0])) {
                        if (arg[1] != '\0')
                                errx(EXIT_FAILURE,
                                     "%s: invalid increment", arg);
                        inc = arg[0] - '0';
                        continue;
                }
                for (j = 0; j < ntabspecs; j++) {
                        if (arg[0] == tabspecs[j].opt[0] &&
                            arg[1] == tabspecs[j].opt[1]) {
                                spec = tabspecs[j].spec;
                                break;
                        }
                }
                if (j == ntabspecs)
                        usage();
        }
        if (tabs == NULL && spec != NULL)
                tabs = strdup(spec);

        if (tabs != NULL)
                last = nstops = 0;
        else
                nstops = -1;
        p = tabs;
        while ((token = strsep(&p, ", ")) != NULL) {
                if (*token == '\0')
                        continue;
                if (nstops >= NSTOPS)
                        errx(EXIT_FAILURE,
                             "too many tab stops (max %d)", NSTOPS);
                errno = 0;
                num = strtol(token, &end, 10);
                if (errno != 0 || *end != '\0' || num <= 0 || num > INT_MAX)
                        errx(EXIT_FAILURE, "%s: invalid tab stop", token);
                n = (int)num;
                if (*token == '+') {
                        if (nstops == 0)
                                errx(EXIT_FAILURE,
                                     "first tab stop may not be relative");
                        n += last;
                }
                if (last > n)
                        errx(EXIT_FAILURE, "tab stops may not go backwards");
                last = stops[nstops++] = n;
        }

        if (term == NULL)
                errx(EXIT_FAILURE, "no value for $TERM and -T not given");
        if (setupterm(term, STDOUT_FILENO, NULL) != 0)
                err(EXIT_FAILURE, "setupterm:");
        cr = carriage_return;
        if (cr == NULL)
                cr = "\r";
        if (clear_all_tabs == NULL)
                errx(EXIT_FAILURE, "terminal cannot clear tabs");
        if (set_tab == NULL)
                errx(EXIT_FAILURE, "terminal cannot set tabs");

        /* Clear existing tabs */
        putp(cr);
        putp(clear_all_tabs);
        putp(cr);

        if (set_lr_margin != NULL) {
                printf("%*s", margin, "");
                putp(set_lr_margin);
        } else if (margin != 0)
                warnx("terminal cannot set left margin");

        if (nstops >= 0) {
                printf("%*s", stops[0] - 1, "");
                putp(set_tab);
                for (i = 1; i < nstops; i++) {
                        printf("%*s", stops[i] - stops[i - 1], "");
                        putp(set_tab);
                }
        } else if (inc > 0) {
                cols = 0;
                term = getenv("COLUMNS");
                if (term != NULL) {
                        errno = 0;
                        num = strtol(term, &end, 10);
                        if (errno == 0 && *end == '\0' &&
                            0 <= cols && cols <= INT_MAX)
                                cols = (int)num;
                }
                if (cols == 0) {
                        if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0)
                                cols = ws.ws_col;
                        else {
                                cols = tigetnum("cols");
                                if (cols == 0) {
                                        cols = 80;
                                        warnx("terminal does not specify number"
                                              "columns; defaulting to %d",
                                              cols);
                                }
                        }
                }
                for (i = 0; i < cols / inc; i++) {
                        printf("%*s", inc, "");
                        putp(set_tab);
                }
        }
        putp(cr);

        exit(EXIT_SUCCESS);
        /* NOTREACHED */
}