/*      $NetBSD: fold.c,v 1.17 2011/09/04 20:24:59 joerg Exp $  */

/*-
 * 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. 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 <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1990, 1993\
 The Regents of the University of California.  All rights reserved.");
#endif /* not lint */

#ifndef lint
#if 0
static char sccsid[] = "@(#)fold.c      8.1 (Berkeley) 6/6/93";
#endif
__RCSID("$NetBSD: fold.c,v 1.17 2011/09/04 20:24:59 joerg Exp $");
#endif /* not lint */

#include <limits.h>
#include <locale.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <wchar.h>
#include <err.h>

#define DEFLINEWIDTH    80

static  void    fold(int);
static  int     new_column_position(int, wint_t);
__dead static   void    usage(void);

static int count_bytes = 0;
static int split_words = 0;

int
main(int argc, char **argv)
{
        int ch;
        int width;
        char *p;

        setlocale(LC_CTYPE, "");
        setprogname(argv[0]);

        width = -1;
        while ((ch = getopt(argc, argv, "0123456789bsw:")) != -1)
                switch (ch) {
                case 'b':
                        count_bytes = 1;
                        break;
                case 's':
                        split_words = 1;
                        break;
                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);
                        /* NOTREACHED */
                } else
                        fold(width);
        exit(0);
}

/*
 * Fold the contents of standard input to fit within WIDTH columns
 * (or bytes) and write to standard output.
 *
 * If split_words is set, split the line at the last space character
 * on the line.  This flag necessitates storing the line in a buffer
 * until the current column > width, or a newline or EOF is read.
 *
 * The buffer can grow larger than WIDTH due to backspaces and carriage
 * returns embedded in the input stream.
 */
static void
fold(int width)
{
        static wchar_t *buf = NULL;
        wchar_t *nbuf;
        static int   buf_max = 0;
        wint_t ch;
        int col, indx, i;

        col = indx = 0;
        while ((ch = getwchar()) != WEOF) {
                if (ch == L'\n') {
                        if (indx != 0) {
                                for (i = 0; i < indx; i++)
                                        putwchar(buf[i]);
                        }
                        putwchar(L'\n');
                        col = indx = 0;
                        continue;
                }

                col = new_column_position (col, ch);
                if (col > width) {
                        int last_space;

#ifdef __GNUC__
                        last_space = 0; /* XXX gcc */
#endif
                        if (split_words) {
                                for (i = 0, last_space = -1; i < indx; i++)
                                        if (buf[i] == L' ')
                                                last_space = i;
                        }

                        if (split_words && last_space != -1) {
                                for (i = 0; i < last_space; i++)
                                        putwchar(buf[i]);

                                /* increase last_space here, so we skip trailing whitespace */
                                last_space++;
                                wmemmove (buf, buf+last_space, indx-last_space);

                                indx -= last_space;
                                col = 0;
                                for (i = 0; i < indx; i++) {
                                        col = new_column_position (col, buf[i]);
                                }
                        } else {
                                for (i = 0; i < indx; i++)
                                        putwchar(buf[i]);
                                col = indx = 0;
                        }
                        putwchar('\n');

                        /* calculate the column position for the next line. */
                        col = new_column_position (col, ch);
                }

                if (indx + 1 > buf_max) {
                        /* Allocate buffer in LINE_MAX increments */
                        if ((nbuf = realloc (buf, buf_max + 2048)) == NULL) {
                                err (1, "realloc");
                                /* NOTREACHED */
                        }
                        buf = nbuf;
                        buf_max += 2048;
                }
                buf[indx++] = ch;
        }

        if (indx != 0) {
                for (i = 0; i < indx; i++)
                        putwchar(buf[i]);
        }
}

/*
 * calculate the column position 
 */
static int
new_column_position (int col, wint_t ch)
{
        int w;
        
        if (!count_bytes) {
                switch (ch) {
                case L'\b':
                        if (col > 0)
                                --col;
                        break;
                case L'\r':
                        col = 0;
                        break;
                case L'\t':
                        col = (col + 8) & ~7;
                        break;
                default:
                        w = wcwidth(ch);
                        if (w > 0)
                                col += w;
                        break;
                }
        } else {
                char dummy[MB_LEN_MAX];
                
                /* XXX: we assume stateless encoding */
                col += wcrtomb(dummy, ch, NULL);
        }

        return col;
}

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