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/*
 * 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.jmx;

import org.apache.log4j.Appender;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.apache.log4j.helpers.OptionConverter;

import javax.management.Attribute;
import javax.management.AttributeNotFoundException;
import javax.management.InvalidAttributeValueException;
import javax.management.JMException;
import javax.management.MBeanAttributeInfo;
import javax.management.MBeanConstructorInfo;
import javax.management.MBeanException;
import javax.management.MBeanInfo;
import javax.management.MBeanNotificationInfo;
import javax.management.MBeanOperationInfo;
import javax.management.MBeanParameterInfo;
import javax.management.MalformedObjectNameException;
import javax.management.Notification;
import javax.management.NotificationListener;
import javax.management.ObjectName;
import javax.management.ReflectionException;
import javax.management.RuntimeOperationsException;
import java.lang.reflect.Constructor;
import java.util.Enumeration;
import java.util.Vector;

public class LoggerDynamicMBean extends AbstractDynamicMBean implements NotificationListener {

    private MBeanConstructorInfo[] dConstructors = new MBeanConstructorInfo[1];
    private MBeanOperationInfo[] dOperations = new MBeanOperationInfo[1];

    private Vector dAttributes = new Vector();
    private String dClassName = this.getClass().getName();

    private String dDescription = "This MBean acts as a management facade for a org.apache.log4j.Logger instance.";

    // This Logger instance is for logging.
    private static Logger cat = Logger.getLogger(LoggerDynamicMBean.class);

    // We wrap this Logger instance.
    private Logger logger;

    public LoggerDynamicMBean(Logger logger) {
	this.logger = logger;
	buildDynamicMBeanInfo();
    }

    public void handleNotification(Notification notification, Object handback) {
	cat.debug("Received notification: " + notification.getType());
	registerAppenderMBean((Appender) notification.getUserData());

    }

    private void buildDynamicMBeanInfo() {
	Constructor[] constructors = this.getClass().getConstructors();
	dConstructors[0] = new MBeanConstructorInfo(
		"HierarchyDynamicMBean(): Constructs a HierarchyDynamicMBean instance", constructors[0]);

	dAttributes.add(
		new MBeanAttributeInfo("name", "java.lang.String", "The name of this Logger.", true, false, false));

	dAttributes.add(new MBeanAttributeInfo("priority", "java.lang.String", "The priority of this logger.", true,
		true, false));

	MBeanParameterInfo[] params = new MBeanParameterInfo[2];
	params[0] = new MBeanParameterInfo("class name", "java.lang.String", "add an appender to this logger");
	params[1] = new MBeanParameterInfo("appender name", "java.lang.String", "name of the appender");

	dOperations[0] = new MBeanOperationInfo("addAppender", "addAppender(): add an appender", params, "void",
		MBeanOperationInfo.ACTION);
    }

    protected Logger getLogger() {
	return logger;
    }

    public MBeanInfo getMBeanInfo() {
	// cat.debug("getMBeanInfo called.");

	MBeanAttributeInfo[] attribs = new MBeanAttributeInfo[dAttributes.size()];
	dAttributes.toArray(attribs);

	MBeanInfo mb = new MBeanInfo(dClassName, dDescription, attribs, dConstructors, dOperations,
		new MBeanNotificationInfo[0]);
	// cat.debug("getMBeanInfo exit.");
	return mb;
    }

    public Object invoke(String operationName, Object params[], String signature[])
	    throws MBeanException, ReflectionException {

	if (operationName.equals("addAppender")) {
	    addAppender((String) params[0], (String) params[1]);
	    return "Hello world.";
	}

	return null;
    }

    public Object getAttribute(String attributeName)
	    throws AttributeNotFoundException, MBeanException, ReflectionException {

	// Check attributeName is not null to avoid NullPointerException later on
	if (attributeName == null) {
	    throw new RuntimeOperationsException(new IllegalArgumentException("Attribute name cannot be null"),
		    "Cannot invoke a getter of " + dClassName + " with null attribute name");
	}

	// Check for a recognized attributeName and call the corresponding getter
	if (attributeName.equals("name")) {
	    return logger.getName();
	} else if (attributeName.equals("priority")) {
	    Level l = logger.getLevel();
	    if (l == null) {
		return null;
	    } else {
		return l.toString();
	    }
	} else if (attributeName.startsWith("appender=")) {
	    try {
		return new ObjectName("log4j:" + attributeName);
	    } catch (MalformedObjectNameException e) {
		cat.error("Could not create ObjectName" + attributeName);
	    } catch (RuntimeException e) {
		cat.error("Could not create ObjectName" + attributeName);
	    }
	}

	// If attributeName has not been recognized throw an AttributeNotFoundException
	throw (new AttributeNotFoundException("Cannot find " + attributeName + " attribute in " + dClassName));

    }

    void addAppender(String appenderClass, String appenderName) {
	cat.debug("addAppender called with " + appenderClass + ", " + appenderName);
	Appender appender = (Appender) OptionConverter.instantiateByClassName(appenderClass,
		org.apache.log4j.Appender.class, null);
	appender.setName(appenderName);
	logger.addAppender(appender);

	// appenderMBeanRegistration();

    }

    public void setAttribute(Attribute attribute)
	    throws AttributeNotFoundException, InvalidAttributeValueException, MBeanException, ReflectionException {

	// Check attribute is not null to avoid NullPointerException later on
	if (attribute == null) {
	    throw new RuntimeOperationsException(new IllegalArgumentException("Attribute cannot be null"),
		    "Cannot invoke a setter of " + dClassName + " with null attribute");
	}
	String name = attribute.getName();
	Object value = attribute.getValue();

	if (name == null) {
	    throw new RuntimeOperationsException(new IllegalArgumentException("Attribute name cannot be null"),
		    "Cannot invoke the setter of " + dClassName + " with null attribute name");
	}

	if (name.equals("priority")) {
	    if (value instanceof String) {
		String s = (String) value;
		Level p = logger.getLevel();
		if (s.equalsIgnoreCase("NULL")) {
		    p = null;
		} else {
		    p = OptionConverter.toLevel(s, p);
		}
		logger.setLevel(p);
	    }
	} else {
	    throw (new AttributeNotFoundException("Attribute " + name + " not found in " + this.getClass().getName()));
	}
    }

    void appenderMBeanRegistration() {
	Enumeration enumeration = logger.getAllAppenders();
	while (enumeration.hasMoreElements()) {
	    Appender appender = (Appender) enumeration.nextElement();
	    registerAppenderMBean(appender);
	}
    }

    void registerAppenderMBean(Appender appender) {
	String name = getAppenderName(appender);
	cat.debug("Adding AppenderMBean for appender named " + name);
	ObjectName objectName = null;
	try {
	    AppenderDynamicMBean appenderMBean = new AppenderDynamicMBean(appender);
	    objectName = new ObjectName("log4j", "appender", name);
	    if (!server.isRegistered(objectName)) {
		registerMBean(appenderMBean, objectName);
		dAttributes.add(new MBeanAttributeInfo("appender=" + name, "javax.management.ObjectName",
			"The " + name + " appender.", true, true, false));
	    }

	} catch (JMException e) {
	    cat.error("Could not add appenderMBean for [" + name + "].", e);
	} catch (java.beans.IntrospectionException e) {
	    cat.error("Could not add appenderMBean for [" + name + "].", e);
	} catch (RuntimeException e) {
	    cat.error("Could not add appenderMBean for [" + name + "].", e);
	}
    }

    public void postRegister(java.lang.Boolean registrationDone) {
	appenderMBeanRegistration();
    }
}