/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2013 University of California, Los Angeles
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
 *         Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#include "content-server.h"
#include "logging.h"
#include <boost/make_shared.hpp>
#include <utility>
#include "task.h"
#include "periodic-task.h"
#include "simple-interval-generator.h"
#include <boost/lexical_cast.hpp>

INIT_LOGGER ("ContentServer");

using namespace Ccnx;
using namespace std;
using namespace boost;

static const int DB_CACHE_LIFETIME = 60;

ContentServer::ContentServer(CcnxWrapperPtr ccnx, ActionLogPtr actionLog,
                             const boost::filesystem::path &rootDir,
                             const Ccnx::Name &deviceName, const std::string &sharedFolderName,
                             const std::string &appName,
                             int freshness)
  : m_ccnx(ccnx)
  , m_actionLog(actionLog)
  , m_dbFolder(rootDir / ".chronoshare")
  , m_freshness(freshness)
  , m_scheduler (new Scheduler())
  , m_deviceName (deviceName)
  , m_sharedFolderName (sharedFolderName)
  , m_appName (appName)
{
  m_scheduler->start ();
  TaskPtr flushStaleDbCacheTask = boost::make_shared<PeriodicTask>(boost::bind(&ContentServer::flushStaleDbCache, this), "flush-state-db-cache", m_scheduler, boost::make_shared<SimpleIntervalGenerator>(DB_CACHE_LIFETIME));
  m_scheduler->addTask(flushStaleDbCacheTask);
}

ContentServer::~ContentServer()
{
  m_scheduler->shutdown ();

  ScopedLock lock (m_mutex);
  for (PrefixIt it = m_prefixes.begin(); it != m_prefixes.end(); ++it)
  {
    m_ccnx->clearInterestFilter (*it);
  }

  m_prefixes.clear ();
}

void
ContentServer::registerPrefix(const Name &forwardingHint)
{
  // Format for files:   /<forwarding-hint>/<device_name>/<appname>/file/<hash>/<segment>
  // Format for actions: /<forwarding-hint>/<device_name>/<appname>/action/<shared-folder>/<action-seq>

  _LOG_DEBUG (">> content server: register " << forwardingHint);
  m_ccnx->setInterestFilter (forwardingHint, bind(&ContentServer::filterAndServe, this, forwardingHint, _1));

  ScopedLock lock (m_mutex);
  m_prefixes.insert(forwardingHint);
}

void
ContentServer::deregisterPrefix (const Name &forwardingHint)
{
  _LOG_DEBUG ("<< content server: deregister " << forwardingHint);
  m_ccnx->clearInterestFilter(forwardingHint);

  ScopedLock lock (m_mutex);
  m_prefixes.erase (forwardingHint);
}

void
ContentServer::filterAndServe (Name forwardingHint, const Name &interest)
{
  // Format for files:   /<forwarding-hint>/<device_name>/<appname>/file/<hash>/<segment>
  // Format for actions: /<forwarding-hint>/<device_name>/<appname>/action/<shared-folder>/<action-seq>

  Name name = interest.getPartialName (forwardingHint.size());
  // name for files:   /<device_name>/<appname>/file/<hash>/<segment>
  // name for actions: /<device_name>/<appname>/action/<shared-folder>/<action-seq>

  if (name.size() >= 4 && name.getCompFromBackAsString (3) == m_appName)
  {
    string type = name.getCompFromBackAsString (2);
    if (type == "file")
      {
        serve_File (forwardingHint, interest);
      }
    else if (type == "action")
      {
        serve_Action (forwardingHint, interest);
      }
  }
}

void
ContentServer::serve_Action (Name forwardingHint, Name interest)
{
  _LOG_DEBUG (">> content server serving ACTION, hint: " << forwardingHint << ", interest: " << interest);
  m_scheduler->scheduleOneTimeTask (m_scheduler, 0, bind (&ContentServer::serve_Action_Execute, this, forwardingHint, interest), boost::lexical_cast<string>(interest));
  // need to unlock ccnx mutex... or at least don't lock it
}

void
ContentServer::serve_File (Name forwardingHint, Name interest)
{
  _LOG_DEBUG (">> content server serving FILE, hint: " << forwardingHint << ", interest: " << interest);

  m_scheduler->scheduleOneTimeTask (m_scheduler, 0, bind (&ContentServer::serve_File_Execute, this, forwardingHint, interest), boost::lexical_cast<string>(interest));
  // need to unlock ccnx mutex... or at least don't lock it
}

void
ContentServer::serve_File_Execute (Name forwardingHint, Name interest)
{
  // forwardingHint: /<forwarding-hint>
  // interest:       /<forwarding-hint>/<device_name>/<appname>/file/<hash>/<segment>

  Name name = interest.getPartialName (forwardingHint.size());
  // name:           /<device_name>/<appname>/file/<hash>/<segment>

  int64_t segment = name.getCompFromBackAsInt (0);
  Name deviceName = name.getPartialName (0, name.size () - 4);
  Hash hash (head(name.getCompFromBack (1)), name.getCompFromBack (1).size());

  _LOG_DEBUG (" server FILE for device: " << deviceName << ", file_hash: " << hash.shortHash () << " segment: " << segment);

  string hashStr = lexical_cast<string> (hash);

  ObjectDbPtr db;

  ScopedLock(m_dbCacheMutex);
  {
    DbCache::iterator it = m_dbCache.find(hash);
    if (it != m_dbCache.end())
    {
      db = it->second;
    }
    else
    {
      if (ObjectDb::DoesExist (m_dbFolder, deviceName, hashStr)) // this is kind of overkill, as it counts available segments
        {
         db = boost::make_shared<ObjectDb>(m_dbFolder, hashStr);
         m_dbCache.insert(make_pair(hash, db));
        }
      else
        {
          _LOG_ERROR ("ObjectDd doesn't exist for device: " << deviceName << ", file_hash: " << hash.shortHash ());
        }
    }
  }

  if (db)
  {
    BytesPtr co = db->fetchSegment (deviceName, segment);
    if (co)
      {
        if (forwardingHint.size () == 0)
          {
            _LOG_DEBUG (ParsedContentObject (*co).name ());
            m_ccnx->putToCcnd (*co);
          }
        else
          {
            if (m_freshness > 0)
              {
                m_ccnx->publishData(interest, *co, m_freshness);
              }
            else
              {
                m_ccnx->publishData(interest, *co);
              }
          }

      }
    else
      {
        _LOG_ERROR ("ObjectDd exists, but no segment " << segment << " for device: " << deviceName << ", file_hash: " << hash.shortHash ());
      }

  }
}

void
ContentServer::serve_Action_Execute (Name forwardingHint, Name interest)
{
  // forwardingHint: /<forwarding-hint>
  // interest:       /<forwarding-hint>/<device_name>/<appname>/action/<shared-folder>/<action-seq>

  Name name = interest.getPartialName (forwardingHint.size());
  // name for actions: /<device_name>/<appname>/action/<shared-folder>/<action-seq>

  int64_t seqno = name.getCompFromBackAsInt (0);
  Name deviceName = name.getPartialName (0, name.size () - 4);

  _LOG_DEBUG (" server ACTION for device: " << deviceName << " and seqno: " << seqno);

  PcoPtr pco = m_actionLog->LookupActionPco (deviceName, seqno);
  if (pco)
    {
      if (forwardingHint.size () == 0)
        {
          m_ccnx->putToCcnd (pco->buf ());
        }
      else
        {
          const Bytes &content = pco->buf ();
          if (m_freshness > 0)
            {
              m_ccnx->publishData(interest, content, m_freshness);
            }
          else
            {
              m_ccnx->publishData(interest, content);
            }
        }
    }
  else
    {
      _LOG_ERROR ("ACTION not found for device: " << deviceName << " and seqno: " << seqno);
    }
}

void
ContentServer::flushStaleDbCache()
{
  ScopedLock(m_dbCacheMutex);
  DbCache::iterator it = m_dbCache.begin();
  while (it != m_dbCache.end())
  {
    ObjectDbPtr db = it->second;
    if (db->secondsSinceLastUse() >= DB_CACHE_LIFETIME)
    {
      m_dbCache.erase(it++);
    }
    else
    {
      ++it;
    }
  }
}