/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.log4j.helpers;

import java.io.Writer;
import java.net.DatagramSocket;
import java.net.InetAddress;
import java.net.DatagramPacket;
import java.net.UnknownHostException;
import java.net.SocketException;
import java.io.IOException;
import java.net.URL;
import java.net.MalformedURLException;

/**
 * SyslogWriter is a wrapper around the java.net.DatagramSocket class so that it
 * behaves like a java.io.Writer.
 * 
 * @since 0.7.3
 */
public class SyslogWriter extends Writer {

    final int SYSLOG_PORT = 514;
    /**
     * Host string from last constructed SyslogWriter.
     * 
     * @deprecated
     */
    static String syslogHost;

    private InetAddress address;
    private final int port;
    private DatagramSocket ds;

    /**
     * Constructs a new instance of SyslogWriter.
     * 
     * @param syslogHost host name, may not be null. A port may be specified by
     *                   following the name or IPv4 literal address with a colon and
     *                   a decimal port number. To specify a port with an IPv6
     *                   address, enclose the IPv6 address in square brackets before
     *                   appending the colon and decimal port number.
     */
    public SyslogWriter(final String syslogHost) {
	SyslogWriter.syslogHost = syslogHost;
	if (syslogHost == null) {
	    throw new NullPointerException("syslogHost");
	}

	String host = syslogHost;
	int urlPort = -1;

	//
	// If not an unbracketed IPv6 address then
	// parse as a URL
	//
	if (host.indexOf("[") != -1 || host.indexOf(':') == host.lastIndexOf(':')) {
	    try {
		URL url = new URL("http://" + host);
		if (url.getHost() != null) {
		    host = url.getHost();
		    // if host is a IPv6 literal, strip off the brackets
		    if (host.startsWith("[") && host.charAt(host.length() - 1) == ']') {
			host = host.substring(1, host.length() - 1);
		    }
		    urlPort = url.getPort();
		}
	    } catch (MalformedURLException e) {
		LogLog.error("Malformed URL: will attempt to interpret as InetAddress.", e);
	    }
	}

	if (urlPort == -1) {
	    urlPort = SYSLOG_PORT;
	}
	port = urlPort;

	try {
	    this.address = InetAddress.getByName(host);
	} catch (UnknownHostException e) {
	    LogLog.error("Could not find " + host + ". All logging will FAIL.", e);
	}

	try {
	    this.ds = new DatagramSocket();
	} catch (SocketException e) {
	    e.printStackTrace();
	    LogLog.error("Could not instantiate DatagramSocket to " + host + ". All logging will FAIL.", e);
	}

    }

    public void write(char[] buf, int off, int len) throws IOException {
	this.write(new String(buf, off, len));
    }

    public void write(final String string) throws IOException {

	if (this.ds != null && this.address != null) {
	    byte[] bytes = string.getBytes();
	    //
	    // syslog packets must be less than 1024 bytes
	    //
	    int bytesLength = bytes.length;
	    if (bytesLength >= 1024) {
		bytesLength = 1024;
	    }
	    DatagramPacket packet = new DatagramPacket(bytes, bytesLength, address, port);
	    ds.send(packet);
	}

    }

    public void flush() {
    }

    public void close() {
	if (ds != null) {
	    ds.close();
	}
    }
}
