/*
 * 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.varia;

import java.io.DataInputStream;
import java.io.DataOutputStream;
import java.io.IOException;
import java.io.InterruptedIOException;
import java.net.ServerSocket;
import java.net.Socket;

import org.apache.log4j.RollingFileAppender;
import org.apache.log4j.helpers.LogLog;

/**
 * This appender listens on a socket on the port specified by the <b>Port</b> property for a "RollOver" message. When
 * such a message is received, the underlying log file is rolled over and an acknowledgment message is sent back to the
 * process initiating the roll over.
 *
 * <p>
 * This method of triggering roll over has the advantage of being operating system independent, fast and reliable.
 *
 * <p>
 * A simple application {@link Roller} is provided to initiate the roll over.
 *
 * <p>
 * Note that the initiator is not authenticated. Anyone can trigger a rollover. In production environments, it is
 * recommended that you add some form of protection to prevent undesired rollovers.
 *
 * @author Ceki G&uuml;lc&uuml;
 * @since version 0.9.0
 */
public class ExternallyRolledFileAppender extends RollingFileAppender {

    /**
     * The string constant sent to initiate a roll over. Current value of this string constant is <b>RollOver</b>.
     */
    static final public String ROLL_OVER = "RollOver";

    /**
     * The string constant sent to acknowledge a roll over. Current value of this string constant is <b>OK</b>.
     */
    static final public String OK = "OK";

    int port = 0;
    HUP hup;

    /**
     * The default constructor does nothing but calls its super-class constructor.
     */
    public ExternallyRolledFileAppender() {
    }

    /**
     * The <b>Port</b> [roperty is used for setting the port for listening to external roll over messages.
     */
    public void setPort(int port) {
        this.port = port;
    }

    /**
     * Returns value of the <b>Port</b> option.
     */
    public int getPort() {
        return port;
    }

    /**
     * Start listening on the port specified by a preceding call to {@link #setPort}.
     */
    public void activateOptions() {
        super.activateOptions();
        if (port != 0) {
            if (hup != null) {
                hup.interrupt();
            }
            hup = new HUP(this, port);
            hup.setDaemon(true);
            hup.start();
        }
    }
}

class HUP extends Thread {

    int port;
    ExternallyRolledFileAppender er;

    HUP(ExternallyRolledFileAppender er, int port) {
        this.er = er;
        this.port = port;
    }

    public void run() {
        while (!isInterrupted()) {
            try {
                ServerSocket serverSocket = new ServerSocket(port);
                while (true) {
                    Socket socket = serverSocket.accept();
                    LogLog.debug("Connected to client at " + socket.getInetAddress());
                    new Thread(new HUPNode(socket, er), "ExternallyRolledFileAppender-HUP").start();
                }
            } catch (InterruptedIOException e) {
                Thread.currentThread().interrupt();
                e.printStackTrace();
            } catch (IOException e) {
                e.printStackTrace();
            } catch (RuntimeException e) {
                e.printStackTrace();
            }
        }
    }
}

class HUPNode implements Runnable {

    Socket socket;
    DataInputStream dis;
    DataOutputStream dos;
    ExternallyRolledFileAppender er;

    public HUPNode(Socket socket, ExternallyRolledFileAppender er) {
        this.socket = socket;
        this.er = er;
        try {
            dis = new DataInputStream(socket.getInputStream());
            dos = new DataOutputStream(socket.getOutputStream());
        } catch (InterruptedIOException e) {
            Thread.currentThread().interrupt();
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (RuntimeException e) {
            e.printStackTrace();
        }
    }

    public void run() {
        try {
            String line = dis.readUTF();
            LogLog.debug("Got external roll over signal.");
            if (ExternallyRolledFileAppender.ROLL_OVER.equals(line)) {
                synchronized (er) {
                    er.rollOver();
                }
                dos.writeUTF(ExternallyRolledFileAppender.OK);
            } else {
                dos.writeUTF("Expecting [RollOver] string.");
            }
            dos.close();
        } catch (InterruptedIOException e) {
            Thread.currentThread().interrupt();
            LogLog.error("Unexpected exception. Exiting HUPNode.", e);
        } catch (IOException e) {
            LogLog.error("Unexpected exception. Exiting HUPNode.", e);
        } catch (RuntimeException e) {
            LogLog.error("Unexpected exception. Exiting HUPNode.", e);
        }
    }
}
