/*

 * Copyright (c) 2005, 2008, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.  Oracle designates this

 * particular file as subject to the "Classpath" exception as provided

 * by Oracle in the LICENSE file that accompanied this code.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 */

package com.sun.jmx.mbeanserver;

import static com.sun.jmx.mbeanserver.Util.*;

import java.util.Iterator;

import java.util.Set;

import javax.management.InstanceAlreadyExistsException;

import javax.management.JMX;

import javax.management.MBeanServer;

import javax.management.NotCompliantMBeanException;

import javax.management.ObjectName;

/**

 * Base class for MXBeans.

 *

 * @since 1.6

 */

public class MXBeanSupport extends MBeanSupport<ConvertingMethod> {

    /**

       <p>Construct an MXBean that wraps the given resource using the

       given MXBean interface.</p>

       @param resource the underlying resource for the new MXBean.

       @param mxbeanInterface the interface to be used to determine

       the MXBean's management interface.

       @param <T> a type parameter that allows the compiler to check

       that {@code resource} implements {@code mxbeanInterface},

       provided that {@code mxbeanInterface} is a class constant like

       {@code SomeMXBean.class}.

       @throws IllegalArgumentException if {@code resource} is null or

       if it does not implement the class {@code mxbeanInterface} or if

       that class is not a valid MXBean interface.

    */

    public <T> MXBeanSupport(T resource, Class<T> mxbeanInterface)

            throws NotCompliantMBeanException {

        super(resource, mxbeanInterface);

    }

    @Override

    MBeanIntrospector<ConvertingMethod> getMBeanIntrospector() {

        return MXBeanIntrospector.getInstance();

    }

    @Override

    Object getCookie() {

        return mxbeanLookup;

    }

    static <T> Class<? super T> findMXBeanInterface(Class<T> resourceClass) {

        if (resourceClass == null)

            throw new IllegalArgumentException("Null resource class");

        final Set<Class<?>> intfs = transitiveInterfaces(resourceClass);

        final Set<Class<?>> candidates = newSet();

        for (Class<?> intf : intfs) {

            if (JMX.isMXBeanInterface(intf))

                candidates.add(intf);

        }

    reduce:

        while (candidates.size() > 1) {

            for (Class<?> intf : candidates) {

                for (Iterator<Class<?>> it = candidates.iterator(); it.hasNext();

                    ) {

                    final Class<?> intf2 = it.next();

                    if (intf != intf2 && intf2.isAssignableFrom(intf)) {

                        it.remove();

                        continue reduce;

                    }

                }

            }

            final String msg =

                "Class " + resourceClass.getName() + " implements more than " +

                "one MXBean interface: " + candidates;

            throw new IllegalArgumentException(msg);

        }

        if (candidates.iterator().hasNext()) {

            return Util.cast(candidates.iterator().next());

        } else {

            final String msg =

                "Class " + resourceClass.getName() +

                " is not a JMX compliant MXBean";

            throw new IllegalArgumentException(msg);

        }

    }

    /* Return all interfaces inherited by this class, directly or

     * indirectly through the parent class and interfaces.

     */

    private static Set<Class<?>> transitiveInterfaces(Class<?> c) {

        Set<Class<?>> set = newSet();

        transitiveInterfaces(c, set);

        return set;

    }

    private static void transitiveInterfaces(Class<?> c, Set<Class<?>> intfs) {

        if (c == null)

            return;

        if (c.isInterface())

            intfs.add(c);

        transitiveInterfaces(c.getSuperclass(), intfs);

        for (Class<?> sup : c.getInterfaces())

            transitiveInterfaces(sup, intfs);

    }

    /*

     * The sequence of events for tracking inter-MXBean references is

     * relatively complicated.  We use the magical preRegister2 method

     * which the MBeanServer knows about.  The steps during registration

     * are:

     * (1) Call user preRegister, if any.  If exception, abandon.

     * (2) Call preRegister2 and hence this register method.  If exception,

     * call postRegister(false) and abandon.

     * (3) Try to register the MBean.  If exception, call registerFailed()

     * which will call the unregister method.  (Also call postRegister(false).)

     * (4) If we get this far, we can call postRegister(true).

     *

     * When we are wrapped in an instance of javax.management.StandardMBean,

     * things are simpler.  That class calls this method from its preRegister,

     * and propagates any exception.  There is no user preRegister in this case.

     * If this method succeeds but registration subsequently fails,

     * StandardMBean calls unregister from its postRegister(false) method.

     */

    @Override

    public void register(MBeanServer server, ObjectName name)

            throws InstanceAlreadyExistsException {

        if (name == null)

            throw new IllegalArgumentException("Null object name");

        // eventually we could have some logic to supply a default name

        synchronized (lock) {

            this.mxbeanLookup = MXBeanLookup.lookupFor(server);

            this.mxbeanLookup.addReference(name, getResource());

            this.objectName = name;

        }

    }

    @Override

    public void unregister() {

        synchronized (lock) {

            if (mxbeanLookup != null) {

                if (mxbeanLookup.removeReference(objectName, getResource()))

                    objectName = null;

            }

        }

    }

    private final Object lock = new Object(); // for mxbeanLookup and objectName

    private MXBeanLookup mxbeanLookup;

    private ObjectName objectName;

}