// Copyright (C) 1999-2005 Open Source Telecom Corporation.
//
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 2 of the License, or
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//
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
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// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
//
// As a special exception, you may use this file as part of a free software
// library without restriction.  Specifically, if other files instantiate
// templates or use macros or inline functions from this file, or you compile
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// file does not by itself cause the resulting executable to be covered by
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/**
 * @file slog.h
 * @short System logging facilities abstraction.
 **/

#ifndef	CCXX_SLOG_H_
#define	CCXX_SLOG_H_

#ifndef CCXX_MISSING_H_
#include <cc++/missing.h>
#endif

#ifndef	CCXX_THREAD_H_
#include <cc++/thread.h>
#endif

#ifndef	HAVE_SYSLOG_H
#include <cstdio>
#endif

#ifdef	CCXX_NAMESPACES
namespace ost {
#endif

/**
 * The slog class is used to stream messages to the system's logging facility (syslogd).
 * A default <code>slog</code> object is used to avoid confusion with the native syslog
 * facility and to imply a logical relationship to the C++ <code>clog()</code>.
 *
 * The key difference is that the <code>slog</code> object sends it's output to the
 * system logging daemon (typically syslogd) rather than through stderr.
 * <code>slog</code> can be streamed with the <code><<</code> operator just
 * like <code>clog</code>; a default slog object is pre-initialized, and you stream
 * character data to it.
 *
 * The <code>slog</code> allows one to specify logging levels and other properties through the <code>()</code> operators.
 * Hence, once can do:
 *
 * <code><pre>
 * slog("mydaemon", SLOG_DAEMON, SLOG_EMERGENCY) << I just died << endl; </pre></code>
 *
 * or things like:
 *
 * <code><pre>
 * slog("mydaemon", SLOG_DAEMON);
 * slog(SLOG_INFO) << "daemon initalized" << endl; </pre></code>
 *
 * The intent is to be as common-place and as convenient to use as the stderr based clog facility
 * found in C++, and this is especially useful for C++ daemons.
 *
 * The <code>std::flush</code> manipulator doesn't work.  Either the
 * <code>std::endl</code> or <code>std::ends</code> manipulators
 * must be used to cause the output to be sent to the daemon.
 *
 * When this class is used on a system that doesn't have the syslog headers
 * (i.e. a non-posix win32 box), the output goes to the a file with the same name
 * as the syslog identifier string with '.log' appended to it.  If the identifier string ends in
 * '.exe', the '.exe' is removed before the '.log' is appened. (e.g. the identifier foo.exe will
 * generate a log file named foo.log)
 *
 * @author David Sugar <dyfet@ostel.com>
 * <br>Minor docs & hacks by Jon Little <littlej@arlut.utexas.edu>
 *
 * @short system logging facility class.
 */
class __EXPORT Slog : protected std::streambuf, public std::ostream
{
public:
	typedef enum Class {
		classSecurity,
		classAudit,
		classDaemon,
		classUser,
		classDefault,
		classLocal0,
		classLocal1,
		classLocal2,
		classLocal3,
		classLocal4,
		classLocal5,
		classLocal6,
		classLocal7
	} Class;

	typedef enum Level {
		levelEmergency = 1,
		levelAlert,
		levelCritical,
		levelError,
		levelWarning,
		levelNotice,
		levelInfo,
		levelDebug
	} Level;

private:
#ifndef	HAVE_SYSLOG_H
	Mutex lock;
	FILE *syslog;
#endif
	int priority;
	Level  _level;
	bool _enable;
	bool _clogEnable;

	ThreadImpl *getPriv(void);

protected:
	/**
	 * This is the streambuf function that actually outputs the data
	 * to the device.  Since all output should be done with the standard
	 * ostream operators, this function should never be called directly.
	 */
	int overflow(int c);

public:
	/**
	 * Default (and only) constructor.  The default log level is set to
	 * SLOG_DEBUG.  There is no default log facility set.  One should be
	 * set before attempting any output.  This is done by the <code>open()</code> or the
	 * <code>operator()(const char*, Class, Level)</code>
	 * functions.
	 */
	Slog(void);

	virtual ~Slog(void);

	void close(void);

	/**
	 * (re)opens the output stream.
	 * @param ident The identifier portion of the message sent to the syslog daemon.
	 * @param grp The log facility the message is sent to
	 */
	void open(const char *ident, Class grp = classUser);

	/**
	 * Sets the log identifier, level, and class to use for subsequent output
	 * @param ident The identifier portion of the message
	 * @param grp The log facility the message is sent to
	 * @param level The log level of the message
	 */
	Slog &operator()(const char *ident, Class grp = classUser,
			 Level level = levelError);

	/**
	 * Changes the log level and class to use for subsequent output
	 * @param level The log level of the message
	 * @param grp The log facility the message is sent to
	 */
	Slog &operator()(Level level, Class grp = classDefault);

	/**
	 * Does nothing except return *this.
	 */
	Slog &operator()(void);

#ifdef	HAVE_SNPRINTF
	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void error(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void warn(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void debug(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void emerg(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void alert(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void critical(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void notice(const char *format, ...);

	/**
	 * Print a formatted syslog string.
	 *
	 * @param format string.
	 */
	void info(const char *format, ...);
#endif

	/**
	 * Sets the logging level.
	 * @param enable is the logging level to use for further output
	 */
	inline void level(Level enable)
		{_level = enable;};

	/**
	 * Enables or disables the echoing of the messages to clog in addition
	 * to the syslog daemon.  This is enabled by the default class constructor.
	 * @param f true to enable, false to disable clog output
	 */
	inline void clogEnable(bool f=true)
		{_clogEnable = f;};

	inline Slog &warn(void)
		{return operator()(Slog::levelWarning);};

	inline Slog &error(void)
		{return operator()(Slog::levelError);};

	inline Slog &debug(void)
		{return operator()(Slog::levelDebug);};

	inline Slog &emerg(void)
		{return operator()(Slog::levelEmergency);};

	inline Slog &alert(void)
		{return operator()(Slog::levelAlert);};

	inline Slog &critical(void)
		{return operator()(Slog::levelCritical);};

	inline Slog &notice(void)
		{return operator()(Slog::levelNotice);};

	inline Slog &info(void)
		{return operator()(Slog::levelInfo);};

};

//#ifdef	CYGWIN_IMPORTS
//extern __declspec(dllimport) Slog slog;
//#else
extern __EXPORT Slog	slog;
//#endif

#ifdef	CCXX_NAMESPACES
}
#endif

#endif

/** EMACS **
 * Local variables:
 * mode: c++
 * c-basic-offset: 8
 * End:
 */