/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
/*
 * Copyright (c) 2012-2013 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: Jared Lindblom <lindblom@cs.ucla.edu>
 *         Alexander Afanasyev <alexander.afanasyev@ucla.edu>
 *         Zhenkai Zhu <zhenkai@cs.ucla.edu>
 */
#ifndef FS_WATCHER_H
#define FS_WATCHER_H

#include <vector>
#include <QFileSystemWatcher>
#include <boost/filesystem.hpp>
#include <sqlite3.h>

#include "scheduler.h"

class FsWatcher : public QObject
{
  Q_OBJECT

public:
  typedef boost::function<void (const boost::filesystem::path &)> LocalFile_Change_Callback;

  // constructor
  FsWatcher (QString dirPath,
             LocalFile_Change_Callback onChange, LocalFile_Change_Callback onDelete,
             QObject* parent = 0);

  // destructor
  ~FsWatcher ();

private slots:
  // handle callback from watcher
  void
  DidDirectoryChanged (QString dirPath);

  /**
   * @brief This even will be triggered either by actual file change or via directory change event
   * (i.e., can happen twice in a row, as well as trigger false alarm)
   */
  void
  DidFileChanged (QString filePath);

private:
  // handle callback from the watcher
  // scan directory and notify callback about any file changes
  void
  ScanDirectory_NotifyUpdates_Execute (QString dirPath);

  void
  ScanDirectory_NotifyRemovals_Execute (QString dirPath);

  void
  initFileStateDb();

  bool
  fileExists(const boost::filesystem::path &filename);

  void
  addFile(const boost::filesystem::path &filename);

  void
  deleteFile(const boost::filesystem::path &filename);

  void
  getFilesInDir(const boost::filesystem::path &dir, std::vector<std::string> &files);

private:
  QFileSystemWatcher* m_watcher; // filesystem watcher
  SchedulerPtr m_scheduler;

  QString m_dirPath; // monitored path

  LocalFile_Change_Callback m_onChange;
  LocalFile_Change_Callback m_onDelete;

  sqlite3 *m_db;
};

#endif // FILESYSTEMWATCHER_H