/* Line breaking of UTF-8 strings.
   Copyright (C) 2001-2003, 2006-2017 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2001.

   This program is free software: you can redistribute it and/or
   modify it under the terms of either:

     * the GNU Lesser General Public License as published by the Free
       Software Foundation; either version 3 of the License, or (at your
       option) any later version.

   or

     * the GNU General Public License as published by the Free
       Software Foundation; either version 2 of the License, or (at your
       option) any later version.

   or both in parallel, as here.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include "unilbrk.h"

#include <stdlib.h>
#include <string.h>

#include "unilbrk/lbrktables.h"
#include "uniwidth/cjk.h"
#include "unistr.h"

void
u8_possible_linebreaks (const uint8_t *s, size_t n, const char *encoding, char *p)
{
  int LBP_AI_REPLACEMENT = (is_cjk_encoding (encoding) ? LBP_ID : LBP_AL);
  const uint8_t *s_end = s + n;
  int last_prop = LBP_BK; /* line break property of last non-space character */
  char *seen_space = NULL; /* Was a space seen after the last non-space character? */
  char *seen_space2 = NULL; /* At least two spaces after the last non-space? */

  /* Don't break inside multibyte characters.  */
  memset (p, UC_BREAK_PROHIBITED, n);

  while (s < s_end)
    {
      ucs4_t uc;
      int count = u8_mbtouc_unsafe (&uc, s, s_end - s);
      int prop = unilbrkprop_lookup (uc);

      if (prop == LBP_BK)
        {
          /* Mandatory break.  */
          *p = UC_BREAK_MANDATORY;
          last_prop = LBP_BK;
          seen_space = NULL;
          seen_space2 = NULL;
        }
      else
        {
          char *q;

          /* Resolve property values whose behaviour is not fixed.  */
          switch (prop)
            {
            case LBP_AI:
              /* Resolve ambiguous.  */
              prop = LBP_AI_REPLACEMENT;
              break;
            case LBP_CB:
              /* This is arbitrary.  */
              prop = LBP_ID;
              break;
            case LBP_SA:
              /* We don't handle complex scripts yet.
                 Treat LBP_SA like LBP_XX.  */
            case LBP_XX:
              /* This is arbitrary.  */
              prop = LBP_AL;
              break;
            }

          /* Deal with spaces and combining characters.  */
          q = p;
          if (prop == LBP_SP)
            {
              /* Don't break just before a space.  */
              *p = UC_BREAK_PROHIBITED;
              seen_space2 = seen_space;
              seen_space = p;
            }
          else if (prop == LBP_ZW)
            {
              /* Don't break just before a zero-width space.  */
              *p = UC_BREAK_PROHIBITED;
              last_prop = LBP_ZW;
              seen_space = NULL;
              seen_space2 = NULL;
            }
          else if (prop == LBP_CM)
            {
              /* Don't break just before a combining character, except immediately after a
                 zero-width space.  */
              if (last_prop == LBP_ZW)
                {
                  /* Break after zero-width space.  */
                  *p = UC_BREAK_POSSIBLE;
                  /* A combining character turns a preceding space into LBP_ID.  */
                  last_prop = LBP_ID;
                }
              else
                {
                  *p = UC_BREAK_PROHIBITED;
                  /* A combining character turns a preceding space into LBP_ID.  */
                  if (seen_space != NULL)
                    {
                      q = seen_space;
                      seen_space = seen_space2;
                      prop = LBP_ID;
                      goto lookup_via_table;
                    }
                }
            }
          else
            {
             lookup_via_table:
              /* prop must be usable as an index for table 7.3 of UTR #14.  */
              if (!(prop >= 0 && prop < sizeof (unilbrk_table) / sizeof (unilbrk_table[0])))
                abort ();

              if (last_prop == LBP_BK)
                {
                  /* Don't break at the beginning of a line.  */
                  *q = UC_BREAK_PROHIBITED;
                }
              else if (last_prop == LBP_ZW)
                {
                  /* Break after zero-width space.  */
                  *q = UC_BREAK_POSSIBLE;
                }
              else
                {
                  switch (unilbrk_table [last_prop] [prop])
                    {
                    case D:
                      *q = UC_BREAK_POSSIBLE;
                      break;
                    case I:
                      *q = (seen_space != NULL ? UC_BREAK_POSSIBLE : UC_BREAK_PROHIBITED);
                      break;
                    case P:
                      *q = UC_BREAK_PROHIBITED;
                      break;
                    default:
                      abort ();
                    }
                }
              last_prop = prop;
              seen_space = NULL;
              seen_space2 = NULL;
            }
        }

      s += count;
      p += count;
    }
}


#ifdef TEST

#include <stdio.h>
#include <string.h>

/* Read the contents of an input stream, and return it, terminated with a NUL
   byte. */
char *
read_file (FILE *stream)
{
#define BUFSIZE 4096
  char *buf = NULL;
  int alloc = 0;
  int size = 0;
  int count;

  while (! feof (stream))
    {
      if (size + BUFSIZE > alloc)
        {
          alloc = alloc + alloc / 2;
          if (alloc < size + BUFSIZE)
            alloc = size + BUFSIZE;
          buf = realloc (buf, alloc);
          if (buf == NULL)
            {
              fprintf (stderr, "out of memory\n");
              exit (1);
            }
        }
      count = fread (buf + size, 1, BUFSIZE, stream);
      if (count == 0)
        {
          if (ferror (stream))
            {
              perror ("fread");
              exit (1);
            }
        }
      else
        size += count;
    }
  buf = realloc (buf, size + 1);
  if (buf == NULL)
    {
      fprintf (stderr, "out of memory\n");
      exit (1);
    }
  buf[size] = '\0';
  return buf;
#undef BUFSIZE
}

int
main (int argc, char * argv[])
{
  if (argc == 1)
    {
      /* Display all the break opportunities in the input string.  */
      char *input = read_file (stdin);
      int length = strlen (input);
      char *breaks = malloc (length);
      int i;

      u8_possible_linebreaks ((uint8_t *) input, length, "UTF-8", breaks);

      for (i = 0; i < length; i++)
        {
          switch (breaks[i])
            {
            case UC_BREAK_POSSIBLE:
              /* U+2027 in UTF-8 encoding */
              putc (0xe2, stdout); putc (0x80, stdout); putc (0xa7, stdout);
              break;
            case UC_BREAK_MANDATORY:
              /* U+21B2 (or U+21B5) in UTF-8 encoding */
              putc (0xe2, stdout); putc (0x86, stdout); putc (0xb2, stdout);
              break;
            case UC_BREAK_PROHIBITED:
              break;
            default:
              abort ();
            }
          putc (input[i], stdout);
        }

      free (breaks);

      return 0;
    }
  else
    return 1;
}

#endif /* TEST */
