/*-
 * 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++;
        }
}