package com.sitech.ismp.ice.syslog;

import java.io.IOException;
import java.net.DatagramPacket;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.SocketException;
import java.net.UnknownHostException;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Locale;
import java.util.TimeZone;

/**
 * The Syslog class implements the UNIX syslog protocol allowing Java to log
 * messages to a specified UNIX host. Care has been taken to preserve as much of
 * the UNIX implementation as possible. <br>
 * To use Syslog, simply create an instance, and use the Syslog() method to log
 * your message. The class provides all the expected syslog constants. For
 * example, LOG_ERR is Syslog.LOG_ERR. <br>
 * 
 * Written: <a href="http://www.ice.com/time/">Tim Endres</a><br>
 * Version: 1.2 - July 27, 1998<br>
 * Version: 1.0 - August 14, 1996<br>
 * Source: <a href="http://www.ice.com/java/syslog/index.shtml">Syslog.java</a>
 * 
 * @see DatagramSocket
 * @see InetAddress
 */

public class Syslog extends Object {
	static private Syslog logger = null;

	private String logName;
	private String hostName;
	private int portNum;
	private int flags;
	private boolean includeDate;

	private InetAddress boundAddress;
	private DatagramSocket socket;

	private SimpleDateFormat date1Format;
	private SimpleDateFormat date2Format;

	// CLASS METHODS

	/**
	 * Binds the Syslog class to a specified host for further logging. See the
	 * Syslog constructor for details on the parameters.
	 */
	static public void open(String hostname, String name, int flags)
			throws SyslogException {
		try {
			Syslog.logger = new Syslog(hostname, SyslogDefs.DEFAULT_PORT, name,
					flags);
		} catch (SyslogException ex) {
			throw ex;
		}
	}

	/**
	 * Performs a syslog to the currently bound syslog host.
	 */
	static public void log(int fac, int lvl, String msg) throws SyslogException {
		try {
			logger.syslog(fac, lvl, msg);
		} catch (SyslogException ex) {
			throw ex;
		}
	}

	/**
	 * Unbinds the current syslog host.
	 */
	static public void close() {
		logger = null;
	}

	/**
	 * Creates a Syslog object instance, targeted for the UNIX host with the
	 * hostname 'hostname' on the syslog port 'port'. The only flags recognized
	 * are 'LOG_PERROR', which will log the message to Java's 'System.err'.
	 */
	public Syslog(String name, int flags) throws SyslogException {
		super();

		this.logName = name;
		this.hostName = null;
		this.portNum = SyslogDefs.DEFAULT_PORT;
		this.flags = flags;

		this.initialize();
	}

	/**
	 * Creates a Syslog object instance, targeted for the UNIX host with the
	 * hostname 'hostname' on the syslog port 'port'. The only flags recognized
	 * are 'LOG_PERROR', which will log the message to Java's 'System.err'.
	 */
	public Syslog(String hostname, int port, String name, int flags)
			throws SyslogException {
		super();

		this.logName = name;
		this.hostName = hostname;
		this.portNum = port;
		this.flags = flags;

		try {
			this.boundAddress = InetAddress.getByName(hostname);
		} catch (UnknownHostException ex) {
			String message = "error locating host named '" + hostname + "': "
					+ ex.getMessage();

			throw new SyslogException(message);
		}

		this.initialize();
	}

	private void initialize() throws SyslogException {
		try {
			this.socket = new DatagramSocket();
		} catch (SocketException ex) {
			String message = "error creating syslog udp socket: "
					+ ex.getMessage();

			throw new SyslogException(message);
		}

		// This determines if the timestamp is added to the message
		// in this, the client, or if it is left off for the server
		// to fill in. Adding it in the client is the "standard" way,
		// but most servers support the "old style" (no timestamp)
		// messages as well. I leave this choice, since some servers
		// may not work without it, and because some JDK's may not
		// support SimpleDateFormat or TimeZone correctly.

		this.includeDate = true;

		if (this.includeDate) {
			// We need two separate formatters here, since there is
			// no way to get the single digit date (day of month) to
			// pad with a space instead of a zero.
			this.date1Format = new SimpleDateFormat("MMM  d HH:mm:ss ",
					Locale.US);

			this.date2Format = new SimpleDateFormat("MMM dd HH:mm:ss ",
					Locale.US);

			this.date1Format.setTimeZone(TimeZone.getDefault());

			this.date2Format.setTimeZone(TimeZone.getDefault());
		}
	}

	/**
	 * Use this method to log your syslog messages. The facility and level are
	 * the same as their UNIX counterparts, and the Syslog class provides
	 * constants for these fields. The msg is what is actually logged.
	 */
	public void syslog(int fac, int pri, String msg) throws SyslogException {
		this.syslog(this.boundAddress, this.portNum, fac, pri, msg);
	}

	/**
	 * Use this method to log your syslog messages. The facility and level are
	 * the same as their UNIX counterparts, and the Syslog class provides
	 * constants for these fields. The msg is what is actually logged.
	 */
	public void syslog(InetAddress addr, int fac, int pri, String msg)
			throws SyslogException {
		this.syslog(addr, this.portNum, fac, pri, msg);
	}

	/**
	 * Use this method to log your syslog messages. The facility and level are
	 * the same as their UNIX counterparts, and the Syslog class provides
	 * constants for these fields. The msg is what is actually logged.
	 */
	public void syslog(String hostname, int fac, int pri, String msg)
			throws SyslogException {
		try {
			InetAddress address = InetAddress.getByName(hostname);
			this.syslog(address, this.portNum, fac, pri, msg);
		} catch (UnknownHostException ex) {
			String message = "error locating host named '" + hostname + "': "
					+ ex.getMessage();

			throw new SyslogException(message);
		}
	}

	/**
	 * Use this method to log your syslog messages. The facility and level are
	 * the same as their UNIX counterparts, and the Syslog class provides
	 * constants for these fields. The msg is what is actually logged.
	 */
	public void syslog(String hostname, int port, int fac, int pri, String msg)
			throws SyslogException {
		try {
			InetAddress address = InetAddress.getByName(hostname);
			this.syslog(address, port, fac, pri, msg);
		} catch (UnknownHostException ex) {
			String message = "error locating host named '" + hostname + "': "
					+ ex.getMessage();

			throw new SyslogException(message);
		}
	}

	/**
	 * Use this method to log your syslog messages. The facility and level are
	 * the same as their UNIX counterparts, and the Syslog class provides
	 * constants for these fields. The msg is what is actually logged.
	 */
	public void syslog(InetAddress addr, int port, int fac, int pri, String msg)
			throws SyslogException {
		int pricode;
		int length;
		int idx, sidx, nidx;
		StringBuffer buffer;
		byte[] data;
		byte[] sBytes;
		byte[] numbuf = new byte[32];
		String nmObj;
		String strObj;

		pricode = SyslogDefs.computeCode(fac, pri);
		Integer priObj = new Integer(pricode);

		if (this.logName != null) {
			nmObj = new String(this.logName);
		} else {
			nmObj = new String(Thread.currentThread().getName());
		}

		length = 4 + nmObj.length() + msg.length() + 1;
		length += (pricode > 99) ? 3 : ((pricode > 9) ? 2 : 1);

		String dStr = null;
		if (this.includeDate) {
			// See note above on why we have two formats...
			Calendar now = Calendar.getInstance();
			if (now.get(Calendar.DAY_OF_MONTH) < 10)
				dStr = this.date1Format.format(now.getTime());
			else
				dStr = this.date2Format.format(now.getTime());

			length += dStr.length();
		}

		data = new byte[length];

		idx = 0;
		data[idx++] = '<';

		strObj = priObj.toString(priObj.intValue());
		sBytes = strObj.getBytes();
		System.arraycopy(sBytes, 0, data, idx, sBytes.length);
		idx += sBytes.length;

		data[idx++] = '>';

		if (this.includeDate) {
			sBytes = dStr.getBytes();
			System.arraycopy(sBytes, 0, data, idx, sBytes.length);
			idx += sBytes.length;
		}

		sBytes = nmObj.getBytes();
		System.arraycopy(sBytes, 0, data, idx, sBytes.length);
		idx += sBytes.length;

		data[idx++] = ':';
		data[idx++] = ' ';

		sBytes = msg.getBytes();
		System.arraycopy(sBytes, 0, data, idx, sBytes.length);
		idx += sBytes.length;

		data[idx] = 0;

		DatagramPacket packet = new DatagramPacket(data, length, addr, port);

		try {
			socket.send(packet);
		} catch (IOException ex) {
			String message = "error sending message: '" + ex.getMessage() + "'";

			System.err.println(message);
			throw new SyslogException(message);
		}

		if ((this.flags & SyslogDefs.LOG_PERROR) != 0) {
			if (this.logName != null) {
				System.err.print(this.logName + ": ");
			} else {
				System.err.print(Thread.currentThread().getName() + ": ");
			}

			System.err.println(msg);
		}
	}
}