/*
 * Copyright (c) 2012-2013 Yubico AB
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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 COPYRIGHT
 * OWNER 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.
 */

#include <ykclient_version.h>
#include <stddef.h>

#define _GNU_SOURCE
#include <string.h>

/* From http://article.gmane.org/gmane.os.freebsd.devel.hackers/23606 */
int
my_strverscmp (const char *s1, const char *s2)
{
  static const char *digits = "0123456789";
  int ret, lz1, lz2;
  size_t p1, p2;

  p1 = strcspn (s1, digits);
  p2 = strcspn (s2, digits);
  while (p1 == p2 && s1[p1] != '\0' && s2[p2] != '\0')
    {
      /* Different prefix */
      if ((ret = strncmp (s1, s2, p1)) != 0)
	return ret;

      s1 += p1;
      s2 += p2;

      lz1 = lz2 = 0;
      if (*s1 == '0')
	lz1 = 1;
      if (*s2 == '0')
	lz2 = 1;

      if (lz1 > lz2)
	return -1;
      else if (lz1 < lz2)
	return 1;
      else if (lz1 == 1)
	{
	  /*
	   * If the common prefix for s1 and s2 consists only of zeros, then the
	   * "longer" number has to compare less. Otherwise the comparison needs
	   * to be numerical (just fallthrough). See
	   * http://refspecs.freestandards.org/LSB_2.0.1/LSB-generic/
	   *                                 LSB-generic/baselib-strverscmp.html
	   */
	  while (*s1 == '0' && *s2 == '0')
	    {
	      ++s1;
	      ++s2;
	    }

	  p1 = strspn (s1, digits);
	  p2 = strspn (s2, digits);

	  /* Catch empty strings */
	  if (p1 == 0 && p2 > 0)
	    return 1;
	  else if (p2 == 0 && p1 > 0)
	    return -1;

	  /* Prefixes are not same */
	  if (*s1 != *s2 && *s1 != '0' && *s2 != '0')
	    {
	      if (p1 < p2)
		return 1;
	      else if (p1 > p2)
		return -1;
	    }
	  else
	    {
	      if (p1 < p2)
		ret = strncmp (s1, s2, p1);
	      else if (p1 > p2)
		ret = strncmp (s1, s2, p2);
	      if (ret != 0)
		return ret;
	    }
	}

      p1 = strspn (s1, digits);
      p2 = strspn (s2, digits);

      if (p1 < p2)
	return -1;
      else if (p1 > p2)
	return 1;
      else if ((ret = strncmp (s1, s2, p1)) != 0)
	return ret;

      /* Numbers are equal or not present, try with next ones. */
      s1 += p1;
      s2 += p2;
      p1 = strcspn (s1, digits);
      p2 = strcspn (s2, digits);
    }

  return strcmp (s1, s2);
}

const char *
ykclient_check_version (const char *req_version)
{
  if (!req_version
      || my_strverscmp (req_version, YKCLIENT_VERSION_STRING) <= 0)
    return YKCLIENT_VERSION_STRING;

  return NULL;
}
