#include <Python.h>

#include <locale.h>

/* ascii character tests (as opposed to locale tests) */
#define ISSPACE(c)  ((c) == ' ' || (c) == '\f' || (c) == '\n' || \
                     (c) == '\r' || (c) == '\t' || (c) == '\v')
#define ISDIGIT(c)  ((c) >= '0' && (c) <= '9')
#define ISXDIGIT(c) (ISDIGIT(c) || ((c) >= 'a' && (c) <= 'f') || ((c) >= 'A' && (c) <= 'F'))


/**
 * g_ascii_strtod:
 * @nptr:    the string to convert to a numeric value.
 * @endptr:  if non-%NULL, it returns the character after
 *           the last character used in the conversion.
 * 
 * Converts a string to a #gdouble value.
 * This function behaves like the standard strtod() function
 * does in the C locale. It does this without actually
 * changing the current locale, since that would not be
 * thread-safe.
 *
 * This function is typically used when reading configuration
 * files or other non-user input that should be locale independent.
 * To handle input from the user you should normally use the
 * locale-sensitive system strtod() function.
 *
 * To convert from a #gdouble to a string in a locale-insensitive
 * way, use g_ascii_dtostr().
 *
 * If the correct value would cause overflow, plus or minus %HUGE_VAL
 * is returned (according to the sign of the value), and %ERANGE is
 * stored in %errno. If the correct value would cause underflow,
 * zero is returned and %ERANGE is stored in %errno.
 * 
 * This function resets %errno before calling strtod() so that
 * you can reliably detect overflow and underflow.
 *
 * Return value: the #gdouble value.
 **/
double
PyOS_ascii_strtod (const char *nptr,
		     char      **endptr)
{
  char *fail_pos;
  double val;
  struct lconv *locale_data;
  const char *decimal_point;
  int decimal_point_len;
  const char *p, *decimal_point_pos;
  const char *end = NULL; /* Silence gcc */

  //g_return_val_if_fail (nptr != NULL, 0);
  assert (nptr != NULL);

  fail_pos = NULL;

  locale_data = localeconv ();
  decimal_point = locale_data->decimal_point;
  decimal_point_len = strlen (decimal_point);

  assert (decimal_point_len != 0);
  
  decimal_point_pos = NULL;
  if (decimal_point[0] != '.' ||
      decimal_point[1] != 0)
    {
      p = nptr;
      /* Skip leading space */
      while (ISSPACE (*p))
	p++;
      
      /* Skip leading optional sign */
      if (*p == '+' || *p == '-')
	p++;
      
      if (p[0] == '0' &&
	  (p[1] == 'x' || p[1] == 'X'))
	{
	  p += 2;
	  /* HEX - find the (optional) decimal point */
	  
	  while (ISXDIGIT (*p))
	    p++;
	  
	  if (*p == '.')
	    {
	      decimal_point_pos = p++;
	      
	      while (ISXDIGIT (*p))
		p++;
	      
	      if (*p == 'p' || *p == 'P')
		p++;
	      if (*p == '+' || *p == '-')
		p++;
	      while (ISDIGIT (*p))
		p++;
	      end = p;
	    }
	}
      else
	{
	  while (ISDIGIT (*p))
	    p++;
	  
	  if (*p == '.')
	    {
	      decimal_point_pos = p++;
	      
	      while (ISDIGIT (*p))
		p++;
	      
	      if (*p == 'e' || *p == 'E')
		p++;
	      if (*p == '+' || *p == '-')
		p++;
	      while (ISDIGIT (*p))
		p++;
	      end = p;
	    }
	}
      /* For the other cases, we need not convert the decimal point */
    }

  /* Set errno to zero, so that we can distinguish zero results
     and underflows */
  errno = 0;
  
  if (decimal_point_pos)
    {
      char *copy, *c;

      /* We need to convert the '.' to the locale specific decimal point */
      copy = malloc (end - nptr + 1 + decimal_point_len);
      
      c = copy;
      memcpy (c, nptr, decimal_point_pos - nptr);
      c += decimal_point_pos - nptr;
      memcpy (c, decimal_point, decimal_point_len);
      c += decimal_point_len;
      memcpy (c, decimal_point_pos + 1, end - (decimal_point_pos + 1));
      c += end - (decimal_point_pos + 1);
      *c = 0;

      val = strtod (copy, &fail_pos);

      if (fail_pos)
	{
	  if (fail_pos > decimal_point_pos)
	    fail_pos = (char *)nptr + (fail_pos - copy) - (decimal_point_len - 1);
	  else
	    fail_pos = (char *)nptr + (fail_pos - copy);
	}
      
      free (copy);
	  
    }
  else
    val = strtod (nptr, &fail_pos);

  if (endptr)
    *endptr = fail_pos;
  
  return val;
}


/**
 * g_ascii_formatd:
 * @buffer: A buffer to place the resulting string in
 * @buf_len: The length of the buffer.
 * @format: The printf()-style format to use for the
 *          code to use for converting. 
 * @d: The #gdouble to convert
 *
 * Converts a #gdouble to a string, using the '.' as
 * decimal point. To format the number you pass in
 * a printf()-style format string. Allowed conversion
 * specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'. 
 * 
 * If you just want to want to serialize the value into a
 * string, use g_ascii_dtostr().
 *
 * Return value: The pointer to the buffer with the converted string.
 **/
char *
PyOS_ascii_formatd (char       *buffer,
		      int         buf_len,
		      const char *format,
		      double      d)
{
  struct lconv *locale_data;
  const char *decimal_point;
  int decimal_point_len;
  char *p;
  int rest_len;
  char format_char;

  //g_return_val_if_fail (buffer != NULL, NULL);
  //g_return_val_if_fail (format[0] == '%', NULL);
  //g_return_val_if_fail (strpbrk (format + 1, "'l%") == NULL, NULL);
 
  format_char = format[strlen (format) - 1];
  
  //g_return_val_if_fail (format_char == 'e' || format_char == 'E' ||
  //			format_char == 'f' || format_char == 'F' ||
  //			format_char == 'g' || format_char == 'G',
  //			NULL);

  if (format[0] != '%')
    return NULL;

  if (strpbrk (format + 1, "'l%"))
    return NULL;

  if (!(format_char == 'e' || format_char == 'E' ||
	format_char == 'f' || format_char == 'F' ||
	format_char == 'g' || format_char == 'G'))
    return NULL;

      
  PyOS_snprintf (buffer, buf_len, format, d);

  locale_data = localeconv ();
  decimal_point = locale_data->decimal_point;
  decimal_point_len = strlen (decimal_point);

  assert (decimal_point_len != 0);

  if (decimal_point[0] != '.' ||
      decimal_point[1] != 0)
    {
      p = buffer;

      if (*p == '+' || *p == '-')
	p++;

      while (isdigit ((unsigned char)*p))
	p++;

      if (strncmp (p, decimal_point, decimal_point_len) == 0)
	{
	  *p = '.';
	  p++;
	  if (decimal_point_len > 1) {
	    rest_len = strlen (p + (decimal_point_len-1));
	    memmove (p, p + (decimal_point_len-1),
		     rest_len);
	    p[rest_len] = 0;
	    
	  }
	}
    }
  
  return buffer;
}

int
main(int argc, char **argv)
{
  char buf[80], *endptr;
  const double number = 42.54321;
  const char string[] = "42.543";

  setlocale(LC_ALL, "");

  printf("LC_NUMERIC = %s\n\n", setlocale(LC_NUMERIC, NULL));

  printf("Format of 42.54321:\n");
  PyOS_snprintf(buf, sizeof(buf), "%.5f", number);
  printf("Locale: %s\n", buf);

  PyOS_ascii_formatd(buf, sizeof(buf), "%.5f", number);
  printf("ASCII:  %s\n\n", buf);

  printf("Parse %s:\n", string);
  printf("Locale: %g", strtod(string, &endptr));
  printf("\t(endptr == '%s')\n", endptr);
  printf("ASCII:  %g", PyOS_ascii_strtod(string, &endptr));
  printf("\t(endptr == '%s')\n", endptr);

  return 0;
}