/* -*- 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
 *
 *	   Zhenkai Zhu <zhenkai@cs.ucla.edu>
 * Author: Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 */

#include "dispatcher.h"
#include "logging.h"
#include "ccnx-discovery.h"
#include "fetch-task-db.h"

#include <boost/make_shared.hpp>
#include <boost/lexical_cast.hpp>

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

INIT_LOGGER ("Dispatcher");

static const string CHRONOSHARE_APP = "chronoshare";
static const string BROADCAST_DOMAIN = "/ndn/broadcast";

static const int CONTENT_FRESHNESS = 1800;  // seconds
const static double DEFAULT_SYNC_INTEREST_INTERVAL = 10.0; // seconds;

Dispatcher::Dispatcher(const std::string &localUserName
                       , const std::string &sharedFolder
                       , const filesystem::path &rootDir
                       , Ccnx::CcnxWrapperPtr ccnx
                       , bool enablePrefixDiscovery
                       )
           : m_ccnx(ccnx)
           , m_core(NULL)
           , m_rootDir(rootDir)
           , m_executor(1) // creates problems with file assembly. need to ensure somehow that FinishExectute is called after all Segment_Execute finished
           , m_objectManager(ccnx, rootDir, CHRONOSHARE_APP)
           , m_localUserName(localUserName)
           , m_sharedFolder(sharedFolder)
           , m_server(NULL)
           , m_enablePrefixDiscovery(enablePrefixDiscovery)
{
  m_syncLog = make_shared<SyncLog>(m_rootDir, localUserName);
  m_actionLog = make_shared<ActionLog>(m_ccnx, m_rootDir, m_syncLog, sharedFolder, CHRONOSHARE_APP,
                                       // bind (&Dispatcher::Did_ActionLog_ActionApply_AddOrModify, this, _1, _2, _3, _4, _5, _6, _7),
                                       ActionLog::OnFileAddedOrChangedCallback (), // don't really need this callback
                                       bind (&Dispatcher::Did_ActionLog_ActionApply_Delete, this, _1));
  m_fileState = m_actionLog->GetFileState ();

  Name syncPrefix = Name(BROADCAST_DOMAIN)(CHRONOSHARE_APP)(sharedFolder);

  // m_server needs a different ccnx face
  m_server = new ContentServer(make_shared<CcnxWrapper>(), m_actionLog, rootDir, m_localUserName, m_sharedFolder, CHRONOSHARE_APP, CONTENT_FRESHNESS);
  m_server->registerPrefix(Name("/"));
  m_server->registerPrefix(Name(BROADCAST_DOMAIN));

  m_core = new SyncCore (m_syncLog, localUserName, Name("/"), syncPrefix,
                         bind(&Dispatcher::Did_SyncLog_StateChange, this, _1), ccnx, DEFAULT_SYNC_INTEREST_INTERVAL);

  FetchTaskDbPtr actionTaskDb = make_shared<FetchTaskDb>(m_rootDir, "action");
  m_actionFetcher = make_shared<FetchManager> (m_ccnx, bind (&SyncLog::LookupLocator, &*m_syncLog, _1),
                                               Name(BROADCAST_DOMAIN), // no appname suffix now
                                               3,
                                               bind (&Dispatcher::Did_FetchManager_ActionFetch, this, _1, _2, _3, _4), FetchManager::FinishCallback(), actionTaskDb);

  FetchTaskDbPtr fileTaskDb = make_shared<FetchTaskDb>(m_rootDir, "file");
  m_fileFetcher  = make_shared<FetchManager> (m_ccnx, bind (&SyncLog::LookupLocator, &*m_syncLog, _1),
                                              Name(BROADCAST_DOMAIN), // no appname suffix now
                                              3,
                                              bind (&Dispatcher::Did_FetchManager_FileSegmentFetch, this, _1, _2, _3, _4),
                                              bind (&Dispatcher::Did_FetchManager_FileFetchComplete, this, _1, _2),
                                              fileTaskDb);


  if (m_enablePrefixDiscovery)
  {
    _LOG_DEBUG("registering prefix discovery in Dispatcher");
    string tag = "dispatcher" + m_localUserName.toString();
    Ccnx::CcnxDiscovery::registerCallback (TaggedFunction (bind (&Dispatcher::Did_LocalPrefix_Updated, this, _1), tag));
  }

  m_executor.start ();
}

Dispatcher::~Dispatcher()
{
  _LOG_DEBUG ("Enter destructor of dispatcher");
  m_executor.shutdown ();

  // _LOG_DEBUG (">>");

  if (m_enablePrefixDiscovery)
  {
    _LOG_DEBUG("deregistering prefix discovery in Dispatcher");
    string tag = "dispatcher" + m_localUserName.toString();
    Ccnx::CcnxDiscovery::deregisterCallback (TaggedFunction (bind (&Dispatcher::Did_LocalPrefix_Updated, this, _1), tag));
  }

  if (m_core != NULL)
  {
    delete m_core;
    m_core = NULL;
  }

  if (m_server != NULL)
  {
    delete m_server;
    m_server = NULL;
  }
}

void
Dispatcher::Did_LocalPrefix_Updated (const Ccnx::Name &forwardingHint)
{
  Name effectiveForwardingHint;
  if (m_localUserName.size () >= forwardingHint.size () &&
      m_localUserName.getPartialName (0, forwardingHint.size ()) == forwardingHint)
    {
      effectiveForwardingHint = Name ("/"); // "directly" accesible
    }
  else
    {
      effectiveForwardingHint = forwardingHint;
    }

  Name oldLocalPrefix = m_syncLog->LookupLocalLocator ();

  if (oldLocalPrefix == effectiveForwardingHint)
    {
      _LOG_DEBUG ("Got notification about prefix change from " << oldLocalPrefix << " to: " << forwardingHint << ", but effective prefix didn't change");
      return;
    }

  if (effectiveForwardingHint == Name ("/") ||
      effectiveForwardingHint == Name (BROADCAST_DOMAIN))
    {
      _LOG_DEBUG ("Basic effective prefix [" << effectiveForwardingHint << "]. Updating local prefix, but don't reregister");
      m_syncLog->UpdateLocalLocator (effectiveForwardingHint);
      return;
    }

  _LOG_DEBUG ("LocalPrefix changed from: " << oldLocalPrefix << " to: " << effectiveForwardingHint);

  m_server->registerPrefix(effectiveForwardingHint);
  m_syncLog->UpdateLocalLocator (effectiveForwardingHint);

  if (oldLocalPrefix == Name ("/") ||
      oldLocalPrefix == Name (BROADCAST_DOMAIN))
    {
      _LOG_DEBUG ("Don't deregister basic prefix: " << oldLocalPrefix);
      return;
    }
  m_server->deregisterPrefix(oldLocalPrefix);
}

void
Dispatcher::Restore_LocalFile (FileItemPtr file)
{
  m_executor.execute (bind (&Dispatcher::Restore_LocalFile_Execute, this, file));
}

/////////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////

void
Dispatcher::Did_LocalFile_AddOrModify (const filesystem::path &relativeFilePath)
{
  m_executor.execute (bind (&Dispatcher::Did_LocalFile_AddOrModify_Execute, this, relativeFilePath));
}

void
Dispatcher::Did_LocalFile_AddOrModify_Execute (filesystem::path relativeFilePath)
{
  _LOG_DEBUG(m_localUserName << " calls LocalFile_AddOrModify_Execute");
  filesystem::path absolutePath = m_rootDir / relativeFilePath;
  if (!filesystem::exists(absolutePath))
    {
      //BOOST_THROW_EXCEPTION (Error::Dispatcher() << error_info_str("Update non exist file: " + absolutePath.string() ));
      _LOG_DEBUG("Update non exist file: " << absolutePath.string());
      return;
    }

  FileItemPtr currentFile = m_fileState->LookupFile (relativeFilePath.generic_string ());
  if (currentFile &&
      *Hash::FromFileContent (absolutePath) == Hash (currentFile->file_hash ().c_str (), currentFile->file_hash ().size ())
      // The following two are commented out to prevent front end from reporting intermediate files
      // should enable it if there is other way to prevent this
      // && last_write_time (absolutePath) == currentFile->mtime ()
      // && status (absolutePath).permissions () == static_cast<filesystem::perms> (currentFile->mode ())
      )
    {
      _LOG_ERROR ("Got notification about the same file [" << relativeFilePath << "]");
      return;
    }

  if (currentFile &&
      !currentFile->is_complete ())
    {
      _LOG_ERROR ("Got notification about incomplete file [" << relativeFilePath << "]");
      return;
    }


  int seg_num;
  HashPtr hash;
  tie (hash, seg_num) = m_objectManager.localFileToObjects (absolutePath, m_localUserName);

  try
    {
      m_actionLog->AddLocalActionUpdate (relativeFilePath.generic_string(),
                                         *hash,
                                         last_write_time (absolutePath), status (absolutePath).permissions (), seg_num);

      // notify SyncCore to propagate the change
      m_core->localStateChangedDelayed ();
    }
  catch (filesystem::filesystem_error &error)
    {
      _LOG_ERROR ("File operations failed on [" << relativeFilePath << "] (ignoring)");
    }
}

void
Dispatcher::Did_LocalFile_Delete (const filesystem::path &relativeFilePath)
{
  m_executor.execute (bind (&Dispatcher::Did_LocalFile_Delete_Execute, this, relativeFilePath));
}

void
Dispatcher::Did_LocalFile_Delete_Execute (filesystem::path relativeFilePath)
{
  filesystem::path absolutePath = m_rootDir / relativeFilePath;
  if (filesystem::exists(absolutePath))
    {
      //BOOST_THROW_EXCEPTION (Error::Dispatcher() << error_info_str("Delete notification but file exists: " + absolutePath.string() ));
      _LOG_ERROR("DELETE command, but file still exists: " << absolutePath.string());
      return;
    }

  FileItemPtr currentFile = m_fileState->LookupFile (relativeFilePath.generic_string ());
  if (!currentFile)
    {
      _LOG_ERROR ("File already deleted [" << relativeFilePath << "]");
      return;
    }

  m_actionLog->AddLocalActionDelete (relativeFilePath.generic_string());
  // notify SyncCore to propagate the change
  m_core->localStateChangedDelayed();
}

/////////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////
/////////////////////////////////////////////////////////////////////////////////////////////////////

/**
 * Callbacks:
 *
 * - from SyncLog: when state changes -> to fetch missing actions
 *
 * - from FetchManager/Actions: when action is fetched -> to request a file, specified by the action
 *                                                     -> to add action to the action log
 *
 * - from ActionLog/Delete:      when action applied (file state changed, file deleted)           -> to delete local file
 *
 * - from ActionLog/AddOrUpdate: when action applied (file state changes, file added or modified) -> do nothing?
 *
 * - from FetchManager/Files: when file segment is retrieved -> save it in ObjectDb
 *                            when file fetch is completed   -> if file belongs to FileState, then assemble it to filesystem. Don't do anything otherwise
 */

void
Dispatcher::Did_SyncLog_StateChange (SyncStateMsgPtr stateMsg)
{
  m_executor.execute (bind (&Dispatcher::Did_SyncLog_StateChange_Execute, this, stateMsg));
}

void
Dispatcher::Did_SyncLog_StateChange_Execute (SyncStateMsgPtr stateMsg)
{
  int size = stateMsg->state_size();
  int index = 0;
  // iterate and fetch the actions
  for (; index < size; index++)
  {
    SyncState state = stateMsg->state (index);
    if (state.has_old_seq() && state.has_seq())
    {
      uint64_t oldSeq = state.old_seq();
      uint64_t newSeq = state.seq();
      Name userName (reinterpret_cast<const unsigned char *> (state.name ().c_str ()), state.name ().size ());

      // fetch actions with oldSeq + 1 to newSeq (inclusive)
      Name actionNameBase = Name ("/")(userName)(CHRONOSHARE_APP)("action")(m_sharedFolder);

      m_actionFetcher->Enqueue (userName, actionNameBase,
                                std::max<uint64_t> (oldSeq + 1, 1), newSeq, FetchManager::PRIORITY_HIGH);
    }
  }
}


void
Dispatcher::Did_FetchManager_ActionFetch (const Ccnx::Name &deviceName, const Ccnx::Name &actionBaseName, uint32_t seqno, Ccnx::PcoPtr actionPco)
{
  /// @todo Errors and exception checking
  _LOG_DEBUG ("Received action deviceName: " << deviceName << ", actionBaseName: " << actionBaseName << ", seqno: " << seqno);

  ActionItemPtr action = m_actionLog->AddRemoteAction (deviceName, seqno, actionPco);
  if (!action)
    {
      _LOG_ERROR ("AddRemoteAction did not insert action, ignoring");
      return;
    }
  // trigger may invoke Did_ActionLog_ActionApply_Delete or Did_ActionLog_ActionApply_AddOrModify callbacks

  if (action->action () == ActionItem::UPDATE)
    {
      Hash hash (action->file_hash ().c_str(), action->file_hash ().size ());

      Name fileNameBase = Name ("/")(deviceName)(CHRONOSHARE_APP)("file")(hash.GetHash (), hash.GetHashBytes ());

      string hashStr = lexical_cast<string> (hash);
      if (ObjectDb::DoesExist (m_rootDir / ".chronoshare",  deviceName, hashStr))
        {
          _LOG_DEBUG ("File already exists in the database. No need to refetch, just directly applying the action");
          Did_FetchManager_FileFetchComplete (deviceName, fileNameBase);
        }
      else
        {
          if (m_objectDbMap.find (hash) == m_objectDbMap.end ())
            {
              _LOG_DEBUG ("create ObjectDb for " << hash);
              m_objectDbMap [hash] = make_shared<ObjectDb> (m_rootDir / ".chronoshare", hashStr);
            }

          m_fileFetcher->Enqueue (deviceName, fileNameBase,
                                  0, action->seg_num () - 1, FetchManager::PRIORITY_NORMAL);
        }
    }
  // if necessary (when version number is the highest) delete will be applied through the trigger in m_actionLog->AddRemoteAction call
}

void
Dispatcher::Did_ActionLog_ActionApply_Delete (const std::string &filename)
{
  m_executor.execute (bind (&Dispatcher::Did_ActionLog_ActionApply_Delete_Execute, this, filename));
}

void
Dispatcher::Did_ActionLog_ActionApply_Delete_Execute (std::string filename)
{
  _LOG_DEBUG ("Action to delete " << filename);

  filesystem::path absolutePath = m_rootDir / filename;
  if (filesystem::exists(absolutePath))
    {
      // need some protection from local detection of removal
      remove (absolutePath);
    }
  // don't exist
}

void
Dispatcher::Did_FetchManager_FileSegmentFetch (const Ccnx::Name &deviceName, const Ccnx::Name &fileSegmentBaseName, uint32_t segment, Ccnx::PcoPtr fileSegmentPco)
{
  m_executor.execute (bind (&Dispatcher::Did_FetchManager_FileSegmentFetch_Execute, this, deviceName, fileSegmentBaseName, segment, fileSegmentPco));
}

void
Dispatcher::Did_FetchManager_FileSegmentFetch_Execute (Ccnx::Name deviceName, Ccnx::Name fileSegmentBaseName, uint32_t segment, Ccnx::PcoPtr fileSegmentPco)
{
  // fileSegmentBaseName:  /<device_name>/<appname>/file/<hash>

  const Bytes &hashBytes = fileSegmentBaseName.getCompFromBack (0);
  Hash hash (head(hashBytes), hashBytes.size());

  _LOG_DEBUG ("Received segment deviceName: " << deviceName << ", segmentBaseName: " << fileSegmentBaseName << ", segment: " << segment);

  // _LOG_DEBUG ("Looking up objectdb for " << hash);

  map<Hash, ObjectDbPtr>::iterator db = m_objectDbMap.find (hash);
  if (db != m_objectDbMap.end())
  {
    db->second->saveContentObject(deviceName, segment, fileSegmentPco->buf ());
  }
  else
  {
    _LOG_ERROR ("no db available for this content object: " << fileSegmentBaseName << ", size: " << fileSegmentPco->buf ().size());
  }

  // ObjectDb objectDb (m_rootDir / ".chronoshare", lexical_cast<string> (hash));
  // objectDb.saveContentObject(deviceName, segment, fileSegmentPco->buf ());
}

void
Dispatcher::Did_FetchManager_FileFetchComplete (const Ccnx::Name &deviceName, const Ccnx::Name &fileBaseName)
{
  m_executor.execute (bind (&Dispatcher::Did_FetchManager_FileFetchComplete_Execute, this, deviceName, fileBaseName));
}

void
Dispatcher::Did_FetchManager_FileFetchComplete_Execute (Ccnx::Name deviceName, Ccnx::Name fileBaseName)
{
  // fileBaseName:  /<device_name>/<appname>/file/<hash>

  _LOG_DEBUG ("Finished fetching " << deviceName << ", fileBaseName: " << fileBaseName);

  const Bytes &hashBytes = fileBaseName.getCompFromBack (0);
  Hash hash (head (hashBytes), hashBytes.size ());
  _LOG_DEBUG ("Extracted hash: " << hash.shortHash ());

  if (m_objectDbMap.find (hash) != m_objectDbMap.end())
  {
    // remove the db handle
    m_objectDbMap.erase (hash); // to commit write
  }
  else
  {
    _LOG_ERROR ("no db available for this file: " << hash);
  }

  FileItemsPtr filesToAssemble = m_fileState->LookupFilesForHash (hash);

  for (FileItems::iterator file = filesToAssemble->begin ();
       file != filesToAssemble->end ();
       file++)
    {
      boost::filesystem::path filePath = m_rootDir / file->filename ();

      try
        {
          if (filesystem::exists (filePath) &&
              filesystem::last_write_time (filePath) == file->mtime () &&
              filesystem::status (filePath).permissions () == static_cast<filesystem::perms> (file->mode ()) &&
              *Hash::FromFileContent (filePath) == hash)
            {
              _LOG_DEBUG ("Asking to assemble a file, but file already exists on a filesystem");
              continue;
            }
        }
      catch (filesystem::filesystem_error &error)
        {
          _LOG_ERROR ("File operations failed on [" << filePath << "] (ignoring)");
        }

      if (ObjectDb::DoesExist (m_rootDir / ".chronoshare",  deviceName, boost::lexical_cast<string>(hash)))
      {
        bool ok = m_objectManager.objectsToLocalFile (deviceName, hash, filePath);
        if (ok)
          {
            last_write_time (filePath, file->mtime ());
            permissions (filePath, static_cast<filesystem::perms> (file->mode ()));

            m_fileState->SetFileComplete (file->filename ());
          }
        else
          {
            _LOG_ERROR ("Notified about complete fetch, but file cannot be restored from the database: [" << filePath << "]");
          }
      }
      else
      {
        _LOG_ERROR (filePath << " supposed to have all segments, but not");
        // should abort for debugging
      }
    }
}

void
Dispatcher::Restore_LocalFile_Execute (FileItemPtr file)
{
  _LOG_DEBUG ("Got request to restore local file [" << file->filename () << "]");
  // the rest will gracefully fail if object-db is missing or incomplete

  boost::filesystem::path filePath = m_rootDir / file->filename ();
  Name deviceName (file->device_name ().c_str (), file->device_name ().size ());
  Hash hash (file->file_hash ().c_str (), file->file_hash ().size ());

  try
    {
      if (filesystem::exists (filePath) &&
          filesystem::last_write_time (filePath) == file->mtime () &&
          filesystem::status (filePath).permissions () == static_cast<filesystem::perms> (file->mode ()) &&
          *Hash::FromFileContent (filePath) == hash)
        {
          _LOG_DEBUG ("Asking to assemble a file, but file already exists on a filesystem");
          return;
        }
    }
  catch (filesystem::filesystem_error &error)
    {
      _LOG_ERROR ("File operations failed on [" << filePath << "] (ignoring)");
    }

  m_objectManager.objectsToLocalFile (deviceName, hash, filePath);

  last_write_time (filePath, file->mtime ());
  permissions (filePath, static_cast<filesystem::perms> (file->mode ()));

}