/*	$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.
 */

#define _XOPEN_SOURCE

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

#define DEFLINEWIDTH 80

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

static int count_bytes = 0;
static int split_words = 0;
static const char *__progname;

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

  setlocale(LC_CTYPE, "");
  __progname = basename(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;

      last_space = 0;
      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", __progname);
  exit(1);
}
