/* Line breaking of UTF-8 strings.
   Copyright (C) 2001-2003, 2006-2009 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 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.

   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 <http://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 */
