/* 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. */

/******************************************************************************************
 * $Id: configcpp.cpp 3899 2013-06-17 20:54:10Z rdempsey $
 *
 ******************************************************************************************/
#include "mcsconfig.h"

#include <string>
#include <stdexcept>
#include <iostream>
#include <sstream>
#include <fstream>
#include <vector>
#include <string>
using namespace std;

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

#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <stdio.h>
#include <libxml/xmlmemory.h>
#include <libxml/parser.h>
#include <fcntl.h>
#include <errno.h>
#include <stdlib.h>
#ifdef HAVE_ALLOCA_H
#include <alloca.h>
#endif
#include <cstring>
//#define NDEBUG
#include <cassert>
#include <atomic>

#include "configcpp.h"

#include "exceptclasses.h"
#include "installdir.h"
#include <tr1/unordered_map>

#include "bytestream.h"

namespace
{
static const std::string configDefaultFileName("Columnstore.xml");
const fs::path defaultConfigFilePath(configDefaultFileName);
}  // namespace

namespace config
{
Config* globConfigInstancePtr = nullptr;
Config::configMap_t Config::fInstanceMap;
boost::mutex Config::fInstanceMapMutex;
// duplicate to that in the Config class
boost::mutex Config::fXmlLock;
// duplicate to that in the Config class
boost::mutex Config::fWriteXmlLock;
std::atomic_bool globHasConfig;

void Config::checkAndReloadConfig()
{
  struct stat statbuf;

  if (stat(fConfigFile.c_str(), &statbuf) == 0)
  {
    if (statbuf.st_mtime != fMtime)
    {
      closeConfig();
      fMtime = statbuf.st_mtime;
      parseDoc();
    }
  }
}

Config* Config::makeConfig(const string& cf)
{
  if (cf.empty() || cf == configDefaultFileName)
  {
    if (!globHasConfig.load(std::memory_order_relaxed))
    {
      // To save against the moment zero race when multiple threads hits
      // this scope.
      boost::mutex::scoped_lock lk(fInstanceMapMutex);
      if (globConfigInstancePtr)
      {
        globConfigInstancePtr->checkAndReloadConfig();
        return globConfigInstancePtr;
      }

      // Make this configurable at least at compile-time.
      std::string configFilePath =
          std::string(MCSSYSCONFDIR) + std::string("/columnstore/") + configDefaultFileName;
      globConfigInstancePtr = new Config(configFilePath);
      globHasConfig.store(true, std::memory_order_relaxed);
      return globConfigInstancePtr;
    }

    boost::mutex::scoped_lock lk(fInstanceMapMutex);
    globConfigInstancePtr->checkAndReloadConfig();
    return globConfigInstancePtr;
  }

  boost::mutex::scoped_lock lk(fInstanceMapMutex);

  if (fInstanceMap.find(cf) == fInstanceMap.end())
  {
    fInstanceMap[cf] = new Config(cf);
  }
  else
  {
    fInstanceMap[cf]->checkAndReloadConfig();
  }

  return fInstanceMap[cf];
}

Config* Config::makeConfig(const char* cf)
{
  return cf ? makeConfig(std::string(cf)) : makeConfig(std::string(""));
}

Config::Config(const string& configFile) : fDoc(0), fConfigFile(configFile), fMtime(0), fParser()
{
  int i = 0;
  for (; i < 2; i++)
  {
    if (access(fConfigFile.c_str(), R_OK) == 0)
      break;
    sleep(1);
  }

  if (i == 2)
    throw runtime_error("Config::Config: error accessing config file " + fConfigFile);

  struct stat statbuf;

  if (stat(configFile.c_str(), &statbuf) == 0)
    fMtime = statbuf.st_mtime;

  parseDoc();
}

Config::~Config()
{
  if (fDoc != 0)
    closeConfig();
}

void Config::parseDoc(void)
{
  struct flock fl;
  int fd;

  memset(&fl, 0, sizeof(fl));
  fl.l_type = F_RDLCK;  // read lock
  fl.l_whence = SEEK_SET;
  fl.l_start = 0;
  fl.l_len = 0;  // lock whole file

  // lock file if exist
  if ((fd = open(fConfigFile.c_str(), O_RDONLY)) >= 0)
  {
    if (fcntl(fd, F_SETLKW, &fl) != 0)
    {
      ostringstream oss;
      oss << "Config::parseDoc: error locking file " << fConfigFile << ": " << strerror(errno)
          << ", proceding anyway.";
      cerr << oss.str() << endl;
    }

    fXmlLock.lock();
    fDoc = xmlParseFile(fConfigFile.c_str());
    fXmlLock.unlock();

    fl.l_type = F_UNLCK;  // unlock
    fcntl(fd, F_SETLK, &fl);

    close(fd);
  }
  else
  {
    ostringstream oss;
    oss << "Config::parseDoc: error opening file " << fConfigFile << ": " << strerror(errno);
    throw runtime_error(oss.str());
  }

  if (fDoc == 0)
  {
    throw runtime_error("Config::parseDoc: error parsing config file " + fConfigFile);
  }

  xmlNodePtr cur = xmlDocGetRootElement(fDoc);

  if (cur == NULL)
  {
    xmlFreeDoc(fDoc);
    fDoc = 0;
    throw runtime_error("Config::parseDoc: error parsing config file " + fConfigFile);
  }

  if (xmlStrcmp(cur->name, (const xmlChar*)"Columnstore"))
  {
    xmlFreeDoc(fDoc);
    fDoc = 0;
    throw runtime_error("Config::parseDoc: error parsing config file " + fConfigFile);
  }

  return;
}

void Config::closeConfig(void)
{
  xmlFreeDoc(fDoc);
  fDoc = 0;
}

const string Config::getConfig(const string& section, const string& name)
{
  if (section.length() == 0 || name.length() == 0)
    throw invalid_argument("Config::getConfig: both section and name must have a length");

  if (fDoc == 0)
  {
    throw runtime_error("Config::getConfig: no XML document!");
  }

  return fParser.getConfig(fDoc, section, name);
}

void Config::getConfig(const string& section, const string& name, vector<string>& values)
{
  if (section.length() == 0)
    throw invalid_argument("Config::getConfig: section must have a length");

  if (fDoc == 0)
    throw runtime_error("Config::getConfig: no XML document!");

  fParser.getConfig(fDoc, section, name, values);
}

const string Config::getFromActualConfig(const string& section, const string& name)
{
  if (section.length() == 0 || name.length() == 0)
    throw invalid_argument("Config::getFromActualConfig: both section and name must have a length");

  if (fDoc == 0)
  {
    throw runtime_error("Config::getFromActualConfig: no XML document!");
  }

  struct stat statbuf;

  if (stat(fConfigFile.c_str(), &statbuf) == 0)
  {
    // Config was changed on disk since last read.
    if (statbuf.st_mtime != fMtime)
    {
      boost::recursive_mutex::scoped_lock lk(fLock);
      // To protect the potential race that happens right after
      // the config was changed.
      checkAndReloadConfig();
    }
  }

  return fParser.getConfig(fDoc, section, name);
}

// NB The only utility that uses setConfig is setConfig binary.
// !!!Don't ever ever use this in the engine code b/c it might result in a race
// b/w getConfig and setConfig methods.!!!
void Config::setConfig(const string& section, const string& name, const string& value)
{
  boost::recursive_mutex::scoped_lock lk(fLock);

  if (section.length() == 0 || name.length() == 0)
    throw invalid_argument("Config::setConfig: all of section and name must have a length");

  if (fDoc == 0)
  {
    throw runtime_error("Config::setConfig: no XML document!");
  }

  struct stat statbuf;

  memset(&statbuf, 0, sizeof(statbuf));
  if (stat(fConfigFile.c_str(), &statbuf) == 0)
  {
    if (statbuf.st_mtime != fMtime)
    {
      closeConfig();
      fMtime = statbuf.st_mtime;
      parseDoc();
    }
  }

  fParser.setConfig(fDoc, section, name, value);
  return;
}

void Config::delConfig(const string& section, const string& name)
{
  boost::recursive_mutex::scoped_lock lk(fLock);

  if (section.length() == 0 || name.length() == 0)
    throw invalid_argument("Config::delConfig: both section and name must have a length");

  if (fDoc == 0)
  {
    throw runtime_error("Config::delConfig: no XML document!");
  }

  checkAndReloadConfig();

  fParser.delConfig(fDoc, section, name);
  return;
}

void Config::writeConfig(const string& configFile) const
{
  boost::recursive_mutex::scoped_lock lk(fLock);
  FILE* fi;

  if (fDoc == 0)
    throw runtime_error("Config::writeConfig: no XML document!");


  const fs::path defaultConfigFilePathTemp("Columnstore.xml.temp");
  const fs::path saveCalpontConfigFileTemp("Columnstore.xml.columnstoreSave");
  const fs::path tmpCalpontConfigFileTemp("Columnstore.xml.temp1");

  fs::path etcdir = fs::path(MCSSYSCONFDIR) / fs::path("columnstore");

  fs::path dcf = etcdir / fs::path(defaultConfigFilePath);
  fs::path dcft = etcdir / fs::path(defaultConfigFilePathTemp);
  fs::path scft = etcdir / fs::path(saveCalpontConfigFileTemp);
  fs::path tcft = etcdir / fs::path(tmpCalpontConfigFileTemp);

  // perform a temp write first if Columnstore.xml file to prevent possible corruption
  if (configFile == dcf)
  {
    if (exists(dcft))
      fs::remove(dcft);

    if ((fi = fopen(dcft.string().c_str(), "w+")) == NULL)
      throw runtime_error("Config::writeConfig: error writing config file " + configFile);

    int rc;
    rc = xmlDocDump(fi, fDoc);

    if (rc < 0)
    {
      throw runtime_error("Config::writeConfig: error writing config file " + configFile);
      // cout << "xmlDocDump " << rc << " " << errno << endl;
    }

    fclose(fi);

    // check temp file
    try
    {
      Config* c1 = makeConfig(dcft.string().c_str());

      string value;
      value = c1->getConfig("SystemConfig", "SystemName");

      // good read, save copy, copy temp file tp tmp then to Columnstore.xml
      // move to get around a 'same file error' in mv command
      try
      {
        if (exists(scft))
          fs::remove(scft);
      }
      catch (fs::filesystem_error&)
      {
      }

      fs::copy_file(dcf, scft, fs::copy_option::overwrite_if_exists);

      try
      {
        fs::permissions(scft, fs::add_perms | fs::owner_read | fs::owner_write | fs::group_read |
                                  fs::group_write | fs::others_read | fs::others_write);
      }
      catch (fs::filesystem_error&)
      {
      }

      if (exists(tcft))
        fs::remove(tcft);

      fs::rename(dcft, tcft);

      if (exists(dcf))
        fs::remove(dcf);

      fs::rename(tcft, dcf);
    }
    catch (...)
    {
      throw runtime_error("Config::writeConfig: error writing config file " + configFile);
    }
  }
  else
  {
    // non Columnstore.xml, perform update
    if ((fi = fopen(configFile.c_str(), "w")) == NULL)
      throw runtime_error("Config::writeConfig: error writing config file " + configFile);

    xmlDocDump(fi, fDoc);

    fclose(fi);
  }

  return;
}

void Config::write(void) const
{
  boost::mutex::scoped_lock lk(fWriteXmlLock);
  write(fConfigFile);
}

void Config::write(const string& configFile) const
{
  struct flock fl;
  int fd;

  fl.l_type = F_WRLCK;  // write lock
  fl.l_whence = SEEK_SET;
  fl.l_start = 0;
  fl.l_len = 0;
  fl.l_pid = getpid();

  // lock file if it exists
  if ((fd = open(configFile.c_str(), O_WRONLY)) >= 0)
  {
    if (fcntl(fd, F_SETLKW, &fl) == -1)
      throw runtime_error("Config::write: file lock error " + configFile);

    try
    {
      writeConfig(configFile);
    }
    catch (...)
    {
      fl.l_type = F_UNLCK;  // unlock

      if (fcntl(fd, F_SETLK, &fl) == -1)
        throw runtime_error("Config::write: file unlock error after exception in writeConfig " + configFile);

      throw;
    }

    fl.l_type = F_UNLCK;  // unlock

    if (fcntl(fd, F_SETLK, &fl) == -1)
      throw runtime_error("Config::write: file unlock error " + configFile);

    close(fd);
  }
  else
  {
    writeConfig(configFile);
  }
}

void Config::writeConfigFile(messageqcpp::ByteStream msg) const
{
  struct flock fl;
  int fd;

  // get config file name being udated
  string fileName;
  msg >> fileName;

  fl.l_type = F_WRLCK;  // write lock
  fl.l_whence = SEEK_SET;
  fl.l_start = 0;
  fl.l_len = 0;
  fl.l_pid = getpid();

  // lock file if it exists
  if ((fd = open(fileName.c_str(), O_WRONLY)) >= 0)
  {
    if (fcntl(fd, F_SETLKW, &fl) == -1)
      throw runtime_error("Config::write: file lock error " + fileName);

    ofstream out(fileName.c_str());
    out << msg;

    fl.l_type = F_UNLCK;  // unlock

    if (fcntl(fd, F_SETLK, &fl) == -1)
      throw runtime_error("Config::write: file unlock error " + fileName);

    close(fd);
  }
  else
  {
    ofstream out(fileName.c_str());
    out << msg;
  }
}

/* static */
void Config::deleteInstanceMap()
{
  boost::mutex::scoped_lock lk(fInstanceMapMutex);

  for (Config::configMap_t::iterator iter = fInstanceMap.begin(); iter != fInstanceMap.end(); ++iter)
  {
    Config* instance = iter->second;
    delete instance;
  }

  fInstanceMap.clear();

  if (globConfigInstancePtr)
  {
    delete globConfigInstancePtr;
    globConfigInstancePtr = nullptr;
  }
}

/* static */
int64_t Config::fromText(const std::string& text)
{
  if (text.length() == 0)
    return 0;

  int64_t val = 0;
  char* ctext = static_cast<char*>(alloca(text.length() + 1));
  strcpy(ctext, text.c_str());
  char* cptr;

  val = strtoll(ctext, &cptr, 0);

  switch (*cptr)
  {
    case 'T':
    case 't': val *= 1024;

    /* fallthru */
    case 'G':
    case 'g': val *= 1024;

    /* fallthru */
    case 'M':
    case 'm': val *= 1024;

    /* fallthru */
    case 'K':
    case 'k': val *= 1024;

    /* fallthru */
    case '\0': break;

    default:
      ostringstream oss;
      oss << "Invalid character '" << *cptr << "' found in numeric parameter '" << text
          << "'. Since this will not do what you want it is fatal." << endl;
      throw runtime_error(oss.str());
      break;
  }

  return val;
}

time_t Config::getCurrentMTime()
{
  struct stat statbuf;

  if (stat(fConfigFile.c_str(), &statbuf) == 0)
    return statbuf.st_mtime;
  else
    return 0;
}

// Utilized by getConfig only
const vector<string> Config::enumConfig()
{
  boost::recursive_mutex::scoped_lock lk(fLock);

  if (fDoc == 0)
  {
    throw runtime_error("Config::getConfig: no XML document!");
  }

  checkAndReloadConfig();

  return fParser.enumConfig(fDoc);
}

// Utilized by getConfig only
const vector<string> Config::enumSection(const string& section)
{
  boost::recursive_mutex::scoped_lock lk(fLock);

  if (fDoc == 0)
  {
    throw runtime_error("Config::getConfig: no XML document!");
  }

  checkAndReloadConfig();

  return fParser.enumSection(fDoc, section);
}
std::string Config::getTempFileDir(Config::TempDirPurpose what)
{
  std::string prefix = getConfig("SystemConfig", "SystemTempFileDir");
  if (prefix.empty())
  {
    prefix.assign("/tmp/columnstore_tmp_files");
  }
  prefix.append("/");
  switch (what)
  {
    case TempDirPurpose::Joins: return prefix.append("joins/");
    case TempDirPurpose::Aggregates: return prefix.append("aggregates/");
  }
  // NOTREACHED
  return {};
}

}  // namespace config