/*
 * 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.chainsaw;

import org.apache.log4j.Appender;
import org.apache.log4j.AppenderSkeleton;
import org.apache.log4j.helpers.Constants;
import org.apache.log4j.helpers.OptionConverter;
import org.apache.log4j.spi.LoggingEvent;

import java.net.InetAddress;
import java.net.UnknownHostException;


/**
 * ChainsawAppender receives LoggingEvents from the local
 * Log4J environment, and appends them into a model that
 * can be used inside a Swing GUI
 *
 * @author Paul Smith
 * @version 1.0
 */
public class ChainsawAppender
    extends AppenderSkeleton {

    private Appender appender;

    /**
     * The in-JVM singleton instance of the ChainsawAppender.
     * <p>
     * If somehow Log4j initialises more than one, then the first one to
     * initialise wins!
     */
    private static ChainsawAppender sSharedAppender = null;

    /**
     * The classname of the viewer to create to view the events.
     */
    private String viewerClassname;
    private String hostname = "localhost";
    private String application = "app";

    /**
     * Constructor, initialises the singleton instance of the appender
     */
    public ChainsawAppender() {
        super(false);
        synchronized (ChainsawAppender.class) {
            if (sSharedAppender == null) {
                sSharedAppender = this;
            }
        }
    }

    /**
     * Return the singleton instance of the ChainsawAppender, it should only
     * be initialised once.
     *
     * @return the One and only instance of the ChainsawAppender that is
     * allowed to be referenced by the GUI
     */
    static ChainsawAppender getInstance() {
        return sSharedAppender;
    }

    /**
     * This appender does not require layout and so return false
     *
     * @return false and only false
     */
    public boolean requiresLayout() {
        return false;
    }

    public Appender getAppender() {
        return appender;
    }

    public void setAppender(Appender appender) {
        this.appender = appender;
    }

    /**
     * Appends the event
     *
     * @param aEvent the LoggingEvent to append
     */
    protected void append(LoggingEvent aEvent) {
        if (hostname != null) {
            aEvent.setProperty(Constants.HOSTNAME_KEY, hostname);
        }

        if (application != null) {
            aEvent.setProperty(Constants.APPLICATION_KEY, application);
        }

        appender.doAppend(aEvent);
    }

    /**
     * Instantiates and activates an instance of a ChainsawViewer
     * to view the contents of this appender.
     */
    public void activateOptions() {
        if (viewerClassname == null) {
            viewerClassname = "org.apache.log4j.chainsaw.DefaultViewer";
        }

        ChainsawViewer viewer =
            (ChainsawViewer) OptionConverter.instantiateByClassName(viewerClassname,
                ChainsawViewer.class, null);

        if (viewer != null) {
            viewer.activateViewer(this);
        }
        try {
            hostname = InetAddress.getLocalHost().getHostName();
        } catch (UnknownHostException uhe) {
            try {
                hostname = InetAddress.getLocalHost().getHostAddress();
            } catch (UnknownHostException uhe2) {
            }
        }
    }

    /**
     * Close does nothing
     */
    public void close() {
    }

    /**
     * Sets the viewer class to use to view the events.  The class must
     * implement the ChainsawViewer interface.
     *
     * @param classname The class name of the viewer class.
     */
    public void setViewerClass(String classname) {
        viewerClassname = classname;
    }

    /**
     * Gets the viewer class to use to view the events.
     *
     * @return The class name of the viewer class.
     */
    public String getViewerClass() {
        return viewerClassname;
    }

    /**
     * The <b>Application</b> option takes a string value which should be the
     * name of the application getting logged
     */
    public void setApplication(String lapp) {
        this.application = lapp;
    }

    /**
     * Returns value of the <b>Application</b> option.
     */
    public String getApplication() {
        return application;
    }


}