/* IRI related functions.
   Copyright (C) 2008 Free Software Foundation, Inc.

This file is part of GNU Wget.

GNU Wget is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at
your option) any later version.

GNU Wget 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 General Public License for more details.

You should have received a copy of the GNU General Public License
along with Wget.  If not, see <http://www.gnu.org/licenses/>.

Additional permission under GNU GPL version 3 section 7

If you modify this program, or any covered work, by linking or
combining it with the OpenSSL project's OpenSSL library (or a
modified version of that library), containing parts covered by the
terms of the OpenSSL or SSLeay licenses, the Free Software Foundation
grants you additional permission to convey the resulting work.
Corresponding Source for a non-source form of such a combination
shall include the source code for the parts of OpenSSL used as well
as that of the covered work.  */

#include "wget.h"

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include <iconv.h>
#include <stringprep.h>
#include <idna.h>
#include <errno.h>

#include "utils.h"
#include "iri.h"


static iconv_t locale2utf8;


static bool open_locale_to_utf8 (void);
static bool do_conversion (iconv_t cd, char *in, size_t inlen, char **out);


/* Given a string containing "charset=XXX", return the encoding if found,
   or NULL otherwise */
char *
parse_charset (char *str)
{
  char *charset;

  if (!str || !*str)
    return NULL;

  str = strcasestr (str, "charset=");
  if (!str)
    return NULL;

  str += 8;
  charset = str;

  /* sXXXav: which chars should be banned ??? */
  while (*charset && !c_isspace (*charset))
    charset++;

  /* sXXXav: could strdupdelim return NULL ? */
  charset = strdupdelim (str, charset);

  /* Do a minimum check on the charset value */
  if (!check_encoding_name (charset))
    {
      xfree (charset);
      return NULL;
    }

  logprintf (LOG_VERBOSE, "parse_charset: %s\n", quote (charset));

  return charset;
}

/* Find the locale used, or fall back on a default value */
char *
find_locale (void)
{
  /* sXXXav, made our own function or use libidn one ?! */
  return (char *) stringprep_locale_charset ();
}

/* Basic check of an encoding name. */
bool
check_encoding_name (char *encoding)
{
  char *s = encoding;

  while (*s)
    {
      if (!c_isascii (*s) || c_isspace (*s))
        {
          logprintf (LOG_VERBOSE, "Encoding %s isn't valid\n", quote (encoding));
          return false;
        }

      s++;
    }

  return true;
}

/* Try opening an iconv_t descriptor for conversion from locale to UTF-8 */
static bool
open_locale_to_utf8 (void)
{
  if (locale2utf8)
    return true;

  /* sXXXav : That shouldn't happen, just in case */
  if (!opt.locale)
    {
      logprintf (LOG_VERBOSE, "open_locale_to_utf8: locale is unset\n");
      opt.locale = find_locale ();
    }

  if (!opt.locale)
    return false;

  locale2utf8 = iconv_open ("UTF-8", opt.locale);
  if (locale2utf8 != (iconv_t)(-1))
    return true;

  logprintf (LOG_VERBOSE, "Conversion from %s to %s isn't supported\n",
             quote (opt.locale), quote ("UTF-8"));
  locale2utf8 = NULL;
  return false;
}

/* Return a new string */
const char *
locale_to_utf8 (const char *str)
{
  char *new;

  if (!strcasecmp (opt.locale, "utf-8"))
    return str;

  if (!open_locale_to_utf8 ())
    return str;

  if (do_conversion (locale2utf8, (char *) str, strlen ((char *) str), &new))
    return (const char *) new;

  return str;
}

/* */
static bool
do_conversion (iconv_t cd, char *in, size_t inlen, char **out)
{
  /* sXXXav : hummm hard to guess... */
  size_t len, done, outlen = inlen * 2;
  int invalid = 0, tooshort = 0;
  char *s;

  s = xmalloc (outlen + 1);
  *out = s;
  len = outlen;
  done = 0;

  /* sXXXav : put a maximum looping factor ??? */
  for (;;)
    {
      if (iconv (cd, &in, &inlen, out, &outlen) != (size_t)(-1))
        {
          *out = s;
          *(s + len - outlen - done) = '\0';
          return true;
        }

      /* Incomplete or invalid multibyte sequence */
      if (errno == EINVAL || errno == EILSEQ)
        {
          invalid++;
          **out = *in;
          in++;
          inlen--;
          (*out)++;
          outlen--;
        }
      else if (errno == E2BIG) /* Output buffer full */ 
        {
          char *new;

          tooshort++;
          done = len;
          outlen = done + inlen * 2;
          new = xmalloc (outlen + 1);
          memcpy (new, s, done);
          xfree (s);
          s = new;
          len = outlen;
          *out = s + done;
        }
      else /* Weird, we got an unspecified error */
        {
          logprintf (LOG_VERBOSE, "Unhandled errno %d\n", errno);
          break;
        }
    }

    return false;
}

/* Try to encode UTF-8 host to ASCII. Return the new domain on success or NULL
   on error. */
char *idn_encode (char *host)
{
  char *new;
  int ret;

  /* toASCII UTF-8 NULL terminated string */
  ret = idna_to_ascii_8z (host, &new, 0);
  if (ret != IDNA_SUCCESS)
    {
      logprintf (LOG_VERBOSE, "idn_encode failed (%d): %s\n", ret,
                 quote (idna_strerror (ret)));
      return NULL;
    }

  return new;
}