/*      $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);
}