/*      $OpenBSD: col.c,v 1.20 2022/12/04 23:50:47 cheloha Exp $        */
/*      $NetBSD: col.c,v 1.7 1995/09/02 05:48:50 jtc Exp $      */

/*-
 * Copyright (c) 1990, 1993, 1994
 *      The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Michael Rendell of the Memorial University of Newfoundland.
 *
 * 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.
 */

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

#define BS      '\b'            /* backspace */
#define TAB     '\t'            /* tab */
#define SPACE   ' '             /* space */
#define NL      '\n'            /* newline */
#define CR      '\r'            /* carriage return */
#define ESC     '\033'          /* escape */
#define SI      '\017'          /* shift in to normal character set */
#define SO      '\016'          /* shift out to alternate character set */
#define VT      '\013'          /* vertical tab (aka reverse line feed) */

/* build up at least this many lines before flushing them out */
#define BUFFER_MARGIN           32

typedef char CSET;

typedef struct char_str {
#define CS_NORMAL       1
#define CS_ALTERNATE    2
        size_t          c_column;       /* column character is in */
        CSET            c_set;          /* character set (currently only 2) */
        char            c_char;         /* character in question */
} CHAR;

typedef struct line_str LINE;
struct line_str {
        CHAR    *l_line;                /* characters on the line */
        LINE    *l_prev;                /* previous line */
        LINE    *l_next;                /* next line */
        size_t  l_lsize;                /* allocated sizeof l_line */
        size_t  l_line_len;             /* strlen(l_line) */
        size_t  l_max_col;              /* max column in the line */
        int     l_needs_sort;           /* set if chars went in out of order */
};

void    addto_lineno(int *, int);
LINE   *alloc_line(void);
void    dowarn(int);
void    flush_line(LINE *);
void    flush_lines(int);
void    flush_blanks(void);
void    free_line(LINE *);
void    usage(void);
void   *xreallocarray(void *, size_t, size_t);

CSET    last_set;               /* char_set of last char printed */
LINE   *lines;
int     compress_spaces;        /* if doing space -> tab conversion */
int     fine;                   /* if `fine' resolution (half lines) */
int     max_bufd_lines;         /* max # of half lines to keep in memory */
int     nblank_lines;           /* # blanks after last flushed line */
int     no_backspaces;          /* if not to output any backspaces */

#define PUTC(ch) \
        if (putchar(ch) == EOF) \
                err(1, "stdout");

int
main(int argc, char *argv[])
{
        int ch;
        CHAR *c;
        CSET cur_set;                   /* current character set */
        LINE *l;                        /* current line */
        int extra_lines;                /* # of lines above first line */
        size_t cur_col;                 /* current column */
        int cur_line;                   /* line number of current position */
        int max_line;                   /* max value of cur_line */
        int this_line;                  /* line l points to */
        int nflushd_lines;              /* number of lines that were flushed */
        int adjust, opt, warned;
        const char *errstr;

        if (pledge("stdio", NULL) == -1)
                err(1, "pledge");

        max_bufd_lines = 256;
        compress_spaces = 1;            /* compress spaces into tabs */
        while ((opt = getopt(argc, argv, "bfhl:x")) != -1)
                switch (opt) {
                case 'b':               /* do not output backspaces */
                        no_backspaces = 1;
                        break;
                case 'f':               /* allow half forward line feeds */
                        fine = 1;
                        break;
                case 'h':               /* compress spaces into tabs */
                        compress_spaces = 1;
                        break;
                case 'l':               /* buffered line count */
                        max_bufd_lines = strtonum(optarg, 1,
                            (INT_MAX - BUFFER_MARGIN) / 2, &errstr) * 2;
                        if (errstr != NULL)
                                errx(1, "bad -l argument, %s: %s", errstr, 
                                        optarg);
                        break;
                case 'x':               /* do not compress spaces into tabs */
                        compress_spaces = 0;
                        break;
                default:
                        usage();
                }

        if (optind != argc)
                usage();

        adjust = extra_lines = warned = 0;
        cur_col = 0;
        cur_line = max_line = nflushd_lines = this_line = 0;
        cur_set = last_set = CS_NORMAL;
        lines = l = alloc_line();

        while ((ch = getchar()) != EOF) {
                if (!isgraph(ch)) {
                        switch (ch) {
                        case BS:                /* can't go back further */
                                if (cur_col == 0)
                                        continue;
                                --cur_col;
                                continue;
                        case CR:
                                cur_col = 0;
                                continue;
                        case ESC:               /* just ignore EOF */
                                /*
                                 * In the input stream, accept both the
                                 * XPG5 sequences ESC-digit and the
                                 * traditional BSD sequences ESC-ctrl.
                                 */
                                switch(getchar()) {
                                case '7':  /* reverse line feed */
                                        /* FALLTHROUGH */
                                case '\007':
                                        addto_lineno(&cur_line, -2);
                                        break;
                                case '8':  /* reverse half-line feed */
                                        /* FALLTHROUGH */
                                case '\010':
                                        addto_lineno(&cur_line, -1);
                                        break;
                                case '9':  /* forward half-line feed */
                                        /* FALLTHROUGH */
                                case '\011':
                                        addto_lineno(&cur_line, 1);
                                        if (cur_line > max_line)
                                                max_line = cur_line;
                                }
                                continue;
                        case NL:
                                addto_lineno(&cur_line, 2);
                                if (cur_line > max_line)
                                        max_line = cur_line;
                                cur_col = 0;
                                continue;
                        case SPACE:
                                ++cur_col;
                                continue;
                        case SI:
                                cur_set = CS_NORMAL;
                                continue;
                        case SO:
                                cur_set = CS_ALTERNATE;
                                continue;
                        case TAB:               /* adjust column */
                                cur_col |= 7;
                                ++cur_col;
                                continue;
                        case VT:
                                addto_lineno(&cur_line, -2);
                                continue;
                        }
                        continue;
                }

                /* Must stuff ch in a line - are we at the right one? */
                if (cur_line + adjust != this_line) {
                        LINE *lnew;

                        /* round up to next line */
                        adjust = !fine && (cur_line & 1);

                        if (cur_line + adjust < this_line) {
                                while (cur_line + adjust < this_line &&
                                    l->l_prev != NULL) {
                                        l = l->l_prev;
                                        this_line--;
                                }
                                if (cur_line + adjust < this_line) {
                                        if (nflushd_lines == 0) {
                                                /*
                                                 * Allow backup past first
                                                 * line if nothing has been
                                                 * flushed yet.
                                                 */
                                                while (cur_line + adjust
                                                    < this_line) {
                                                        lnew = alloc_line();
                                                        l->l_prev = lnew;
                                                        lnew->l_next = l;
                                                        l = lines = lnew;
                                                        extra_lines++;
                                                        this_line--;
                                                }
                                        } else {
                                                if (!warned++)
                                                        dowarn(cur_line);
                                                cur_line = this_line - adjust;
                                        }
                                }
                        } else {
                                /* may need to allocate here */
                                while (cur_line + adjust > this_line) {
                                        if (l->l_next == NULL) {
                                                l->l_next = alloc_line();
                                                l->l_next->l_prev = l;
                                        }
                                        l = l->l_next;
                                        this_line++;
                                }
                        }
                        if (this_line > nflushd_lines &&
                            this_line - nflushd_lines >=
                            max_bufd_lines + BUFFER_MARGIN) {
                                if (extra_lines) {
                                        flush_lines(extra_lines);
                                        extra_lines = 0;
                                }
                                flush_lines(this_line - nflushd_lines -
                                    max_bufd_lines);
                                nflushd_lines = this_line - max_bufd_lines;
                        }
                }
                /* grow line's buffer? */
                if (l->l_line_len + 1 >= l->l_lsize) {
                        size_t need;

                        need = l->l_lsize ? l->l_lsize : 45;
                        l->l_line = xreallocarray(l->l_line,
                            need, 2 * sizeof(CHAR));
                        l->l_lsize = need * 2;
                }
                c = &l->l_line[l->l_line_len++];
                c->c_char = ch;
                c->c_set = cur_set;
                c->c_column = cur_col;
                /*
                 * If things are put in out of order, they will need sorting
                 * when it is flushed.
                 */
                if (cur_col < l->l_max_col)
                        l->l_needs_sort = 1;
                else
                        l->l_max_col = cur_col;
                cur_col++;
        }
        if (extra_lines)
                flush_lines(extra_lines);

        /* goto the last line that had a character on it */
        for (; l->l_next; l = l->l_next)
                this_line++;
        flush_lines(this_line - nflushd_lines + 1);

        /* make sure we leave things in a sane state */
        if (last_set != CS_NORMAL)
                PUTC(SI);

        /* flush out the last few blank lines */
        if (max_line > this_line)
                nblank_lines = max_line - this_line;
        if (max_line & 1)
                nblank_lines++;
        flush_blanks();
        exit(0);
}

void
flush_lines(int nflush)
{
        LINE *l;

        while (--nflush >= 0) {
                l = lines;
                lines = l->l_next;
                if (l->l_line) {
                        flush_blanks();
                        flush_line(l);
                }
                if (l->l_line || l->l_next)
                        nblank_lines++;
                if (l->l_line)
                        (void)free((void *)l->l_line);
                free_line(l);
        }
        if (lines)
                lines->l_prev = NULL;
}

/*
 * Print a number of newline/half newlines.  If fine flag is set, nblank_lines
 * is the number of half line feeds, otherwise it is the number of whole line
 * feeds.
 */
void
flush_blanks(void)
{
        int half, i, nb;

        half = 0;
        nb = nblank_lines;
        if (nb & 1) {
                if (fine)
                        half = 1;
                else
                        nb++;
        }
        nb /= 2;
        for (i = nb; --i >= 0;)
                PUTC('\n');
        if (half) {
                /*
                 * In the output stream, always generate
                 * escape sequences conforming to XPG5.
                 */
                PUTC(ESC);
                PUTC('9');
                if (!nb)
                        PUTC('\r');
        }
        nblank_lines = 0;
}

/*
 * Write a line to stdout taking care of space to tab conversion (-h flag)
 * and character set shifts.
 */
void
flush_line(LINE *l)
{
        CHAR *c, *endc;
        size_t nchars, last_col, this_col;

        last_col = 0;
        nchars = l->l_line_len;

        if (l->l_needs_sort) {
                static CHAR *sorted;
                static size_t count_size, i, sorted_size;
                static int *count, save, tot;

                /*
                 * Do an O(n) sort on l->l_line by column being careful to
                 * preserve the order of characters in the same column.
                 */
                if (l->l_lsize > sorted_size) {
                        sorted_size = l->l_lsize;
                        sorted = xreallocarray(sorted,
                            sorted_size, sizeof(CHAR));
                }
                if (l->l_max_col >= count_size) {
                        count_size = l->l_max_col + 1;
                        count = xreallocarray(count,
                            count_size, sizeof(int));
                }
                memset(count, 0, sizeof(*count) * (l->l_max_col + 1));
                for (i = nchars, c = l->l_line; i-- > 0; c++)
                        count[c->c_column]++;

                /*
                 * calculate running total (shifted down by 1) to use as
                 * indices into new line.
                 */
                for (tot = 0, i = 0; i <= l->l_max_col; i++) {
                        save = count[i];
                        count[i] = tot;
                        tot += save;
                }

                for (i = nchars, c = l->l_line; i-- > 0; c++)
                        sorted[count[c->c_column]++] = *c;
                c = sorted;
        } else
                c = l->l_line;
        while (nchars > 0) {
                this_col = c->c_column;
                endc = c;
                do {
                        ++endc;
                } while (--nchars > 0 && this_col == endc->c_column);

                /* if -b only print last character */
                if (no_backspaces)
                        c = endc - 1;

                if (this_col > last_col) {
                        size_t nspace = this_col - last_col;

                        if (compress_spaces && nspace > 1) {
                                size_t ntabs;

                                ntabs = ((last_col % 8) + nspace) / 8;
                                if (ntabs) {
                                        nspace -= (ntabs * 8) - (last_col % 8);
                                        while (ntabs-- > 0)
                                                PUTC('\t');
                                }
                        }
                        while (nspace-- > 0)
                                PUTC(' ');
                        last_col = this_col;
                }
                last_col++;

                for (;;) {
                        if (c->c_set != last_set) {
                                switch (c->c_set) {
                                case CS_NORMAL:
                                        PUTC(SI);
                                        break;
                                case CS_ALTERNATE:
                                        PUTC(SO);
                                }
                                last_set = c->c_set;
                        }
                        PUTC(c->c_char);
                        if (++c >= endc)
                                break;
                        PUTC('\b');
                }
        }
}

/*
 * Increment or decrement a line number, checking for overflow.
 * Stop one below INT_MAX such that the adjust variable is safe.
 */
void
addto_lineno(int *lno, int offset)
{
        if (offset > 0) {
                if (*lno >= INT_MAX - offset)
                        errx(1, "too many lines");
        } else {
                if (*lno < INT_MIN - offset)
                        errx(1, "too many reverse line feeds");
        }
        *lno += offset;
}

#define NALLOC 64

static LINE *line_freelist;

LINE *
alloc_line(void)
{
        LINE *l;
        int i;

        if (!line_freelist) {
                l = xreallocarray(NULL, NALLOC, sizeof(LINE));
                line_freelist = l;
                for (i = 1; i < NALLOC; i++, l++)
                        l->l_next = l + 1;
                l->l_next = NULL;
        }
        l = line_freelist;
        line_freelist = l->l_next;

        memset(l, 0, sizeof(LINE));
        return (l);
}

void
free_line(LINE *l)
{

        l->l_next = line_freelist;
        line_freelist = l;
}

void *
xreallocarray(void *p, size_t n, size_t size)
{

        if (!(p = reallocarray(p, n, size)))
                err(1, "realloc failed");
        return (p);
}

void
usage(void)
{
        (void)fprintf(stderr, "usage: col [-bfhx] [-l num]\n");
        exit(1);
}

void
dowarn(int line)
{

        warnx("warning: can't back up %s",
                line < 0 ? "past first line" : "-- line already flushed");
}