//
// UUIDGenerator.h
//
// Library: Foundation
// Package: UUID
// Module:  UUID
//
// Definition of the UUIDGenerator class.
//
// Copyright (c) 2004-2006, Applied Informatics Software Engineering GmbH.
// and Contributors.
//
// SPDX-License-Identifier:	BSL-1.0
//


#ifndef Foundation_UUIDGenerator_INCLUDED
#define Foundation_UUIDGenerator_INCLUDED


#include "Poco/Foundation.h"
#include "Poco/UUID.h"
#include "Poco/Mutex.h"
#include "Poco/Random.h"
#include "Poco/Timestamp.h"
#include "Poco/Environment.h"


namespace Poco {


class DigestEngine;


class Foundation_API UUIDGenerator
	/// This class implements a generator for Universal Unique Identifiers,
	/// as specified in Appendix A of the DCE 1.1 Remote Procedure
	/// Call Specification (http://www.opengroup.org/onlinepubs/9629399/),
	/// RFC 2518 (WebDAV), section 6.4.1 and the UUIDs and GUIDs internet
	/// draft by Leach/Salz from February, 1998
	/// (http://ftp.ics.uci.edu/pub/ietf/webdav/uuid-guid/draft-leach-uuids-guids-01.txt)
{
public:
	UUIDGenerator();
		/// Creates the UUIDGenerator.

	~UUIDGenerator();
		/// Destroys the UUIDGenerator.

	UUID create();
		/// Creates a new time-based UUID, using the MAC address of
		/// one of the system's ethernet adapters.
		///
		/// Throws a SystemException if no MAC address can be
		/// obtained.

	UUID createFromName(const UUID& nsid, const std::string& name);
		/// Creates a name-based UUID.

	UUID createFromName(const UUID& nsid, const std::string& name, DigestEngine& de);
		/// Creates a name-based UUID, using the given digest engine.
		///
		/// Note: in order to create a standard-compliant UUID, the given DigestEngine
		/// must be either an instance of MD5Engine or SHA1Engine. The version field of
		/// the UUID will be set accordingly.

	UUID createFromName(const UUID& nsid, const std::string& name, DigestEngine& de, UUID::Version version);
		/// Creates a name-based UUID, using the given digest engine and version.

	UUID createRandom();
		/// Creates a random UUID.

	UUID createOne();
		/// Tries to create and return a time-based UUID (see create()), and,
		/// if that does not work due to the unavailability of a MAC address,
		/// creates and returns a random UUID (see createRandom()).
		///
		/// The UUID::version() method can be used to determine the actual kind of
		/// the UUID generated.

	void seed(UInt32 n);
		/// Seeds the internal pseudo random generator for time-based UUIDs with the given seed.

	void seed();
		/// Seeds the internal pseudo random generator used for time-based UUIDs
		/// with a random seed obtained from a RandomInputStream.

	static UUIDGenerator& defaultGenerator();
		/// Returns a reference to the default UUIDGenerator.

protected:
	Timestamp::UtcTimeVal timeStamp();
	void getNode();

private:
	FastMutex           _mutex;
	Random              _random;
	Timestamp           _lastTime;
	int                 _ticks;
	Environment::NodeId _node;
	bool                _haveNode;

	UUIDGenerator(const UUIDGenerator&);
	UUIDGenerator& operator = (const UUIDGenerator&);
};


} // namespace Poco


#endif // Foundation_UUIDGenerator_INCLUDED