// -*- C++ -*-
/**
 * \file FileMonitor.h
 * This file is part of LyX, the document processor.
 * Licence details can be found in the file COPYING.
 *
 * \author Angus Leeming
 *
 * Full author contact details are available in file CREDITS.
 *
 * FileMonitor monitors a file and informs a listener when that file has
 * changed.
 */

#ifndef FILEMONITOR_H
#define FILEMONITOR_H

#include <boost/utility.hpp>
#include <boost/scoped_ptr.hpp>
#include <boost/signals/signal0.hpp>

namespace lyx {
namespace support {

class FileMonitor : boost::noncopyable {
public:
	/** Once monitoring begins, the file will be monitored every
	 *  interval ms.
	 */
	FileMonitor(std::string const & file_with_path, int interval);

	/// Define an empty d-tor out-of-line to keep boost::scoped_ptr happy.
	~FileMonitor();

	///
	void reset(std::string const & file_with_path) const;

	///
	std::string const & filename() const;

	/// Begin monitoring the file
	void start() const;
	///
	void stop() const;
	///
	bool monitoring() const;

	/** The checksum is recomputed whenever the file is modified.
	 *  If the file is not being monitored, then the checksum will be
	 *  recomputed each time this function is called.
	 */
	unsigned long checksum() const;

	/// Connect and you'll be informed when the file has changed.
	typedef boost::signal0<void>::slot_type slot_type;
	///
	boost::signals::connection connect(slot_type const &) const;

private:
	/// Use the Pimpl idiom to hide the internals.
	class Impl;

	/// The pointer never changes although *pimpl_'s contents may.
	boost::scoped_ptr<Impl> const pimpl_;
};

} // namespace support
} // namespace lyx

#endif // FILEMONITOR_H