/* Copyright (C) 2014 InfiniDB, Inc.

   This program 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; version 2 of
   the License.

   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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
   MA 02110-1301, USA. */

#include <unistd.h>
#include <string>
//#define NDEBUG
#include <cassert>
#include <climits>
using namespace std;

#include <boost/tokenizer.hpp>
#include <boost/filesystem.hpp>
using namespace boost;
namespace fs = boost::filesystem;

#include "fsutils.h"
#include "exceptclasses.h"

namespace
{
const string resolveInDir(const string& dir, const string& name)
{
  idbassert(!dir.empty() && !name.empty());
  string ret;
  fs::path path(dir);

  if (!fs::exists(path))
    return ret;

  idbassert(fs::exists(path));
  path /= name;

  if (!fs::exists(path))
    return ret;

  idbassert(fs::exists(path));

  if (!fs::is_symlink(path))
    return ret;

  idbassert(fs::is_symlink(path));
  char* realname = (char*)alloca(PATH_MAX + 1);
  ssize_t realnamelen = readlink(path.string().c_str(), realname, PATH_MAX);

  if (realnamelen <= 0)
    return ret;

  realname[realnamelen] = 0;
  fs::path linkname(realname);
  fs::path realpath("/dev");
  realpath /= linkname.filename();
  ret = realpath.string();
  return ret;
}

inline const string label2dev(const string& name)
{
  return resolveInDir("/dev/disk/by-label", name);
}

inline const string uuid2dev(const string& name)
{
  return resolveInDir("/dev/disk/by-uuid", name);
}

}  // namespace

namespace fsutils
{
const string symname2devname(const string& sympath)
{
  string ret;
  typedef boost::tokenizer<boost::char_separator<char> > tokenizer;
  boost::char_separator<char> sep("=");
  tokenizer tokens(sympath, sep);
  tokenizer::iterator tok_iter = tokens.begin();

  idbassert(tok_iter != tokens.end());
  string symtype = *tok_iter;

  if (symtype != "LABEL" && symtype != "UUID")
    return ret;

  idbassert(symtype == "LABEL" || symtype == "UUID");

  ++tok_iter;
  idbassert(tok_iter != tokens.end());
  string symname = *tok_iter;

  ++tok_iter;
  idbassert(tok_iter == tokens.end());

  if (symtype == "LABEL")
    ret = label2dev(symname);
  else if (symtype == "UUID")
    ret = uuid2dev(symname);

  return ret;
}

}  // namespace fsutils