/*

 * Copyright 2007-2008 Sun Microsystems, Inc.  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.  Sun designates this

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

 * by Sun 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

 * CA 95054 USA or visit www.sun.com if you need additional information or

 * have any questions.

 */

package com.sun.jmx.mbeanserver;

import java.lang.ref.WeakReference;

import java.security.PrivilegedAction;

import java.util.Map;

import java.util.WeakHashMap;

import javax.annotation.Resource;

import javax.management.MBeanServer;

import javax.management.NotCompliantMBeanException;

import javax.management.ObjectName;

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

import java.lang.reflect.AccessibleObject;

import java.lang.reflect.Field;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Modifier;

import java.security.AccessController;

import java.util.ArrayList;

import java.util.Collections;

import java.util.List;

import javax.management.SendNotification;

public class MBeanInjector {

    private static Class<?>[] injectedClasses = {

        MBeanServer.class, ObjectName.class, SendNotification.class,

    };

    public static void inject(Object mbean, MBeanServer mbs, ObjectName name)

    throws Exception {

        ClassInjector injector = injectorForClass(mbean.getClass());

        injector.inject(mbean, MBeanServer.class, mbs);

        injector.inject(mbean, ObjectName.class, name);

    }

    public static boolean injectsSendNotification(Object mbean)

    throws NotCompliantMBeanException {

        ClassInjector injector = injectorForClass(mbean.getClass());

        return injector.injects(SendNotification.class);

    }

    public static void injectSendNotification(Object mbean, SendNotification sn)

    throws Exception {

        ClassInjector injector = injectorForClass(mbean.getClass());

        injector.inject(mbean, SendNotification.class, sn);

    }

    public static void validate(Class<?> c) throws NotCompliantMBeanException {

        injectorForClass(c);

    }

    private static class ClassInjector {

        private Map<Class<?>, List<Field>> fields;

        private Map<Class<?>, List<Method>> methods;

        ClassInjector(Class<?> c) throws NotCompliantMBeanException {

            fields = newMap();

            methods = newMap();

            Class<?> sup = c.getSuperclass();

            ClassInjector supInjector;

            if (sup == null) {

                supInjector = null;

            } else {

                supInjector = injectorForClass(sup);

                fields.putAll(supInjector.fields);

                methods.putAll(supInjector.methods);

            }

            addMembers(c);

            eliminateOverriddenMethods();

            // If we haven't added any new fields or methods to what we

            // inherited, then we can share the parent's maps.

            if (supInjector != null) {

                if (fields.equals(supInjector.fields))

                    fields = supInjector.fields;

                if (methods.equals(supInjector.methods))

                    methods = supInjector.methods;

            }

        }

        boolean injects(Class<?> c) {

            return (fields.get(c) != null || methods.get(c) != null);

        }

        <T> void inject(Object instance, Class<T> type, T resource)

        throws Exception {

            List<Field> fs = fields.get(type);

            if (fs != null) {

                for (Field f : fs)

                    f.set(instance, resource);

            }

            List<Method> ms = methods.get(type);

            if (ms != null) {

                for (Method m : ms) {

                    try {

                        m.invoke(instance, resource);

                    } catch (InvocationTargetException e) {

                        Throwable cause = e.getCause();

                        if (cause instanceof Error)

                            throw (Error) cause;

                        else

                            throw (Exception) cause;

                    }

                }

            }

        }

        private void eliminateOverriddenMethods() {

            /* Covariant overriding is unlikely, but it is possible that the

             * parent has a @Resource method that we override with another

             * @Resource method.  We don't want to invoke both methods,

             * because polymorphism means we would actually invoke the same

             * method twice.

             */

            for (Map.Entry<Class<?>, List<Method>> entry : methods.entrySet()) {

                List<Method> list = entry.getValue();

                list = MBeanAnalyzer.eliminateCovariantMethods(list);

                entry.setValue(list);

            }

        }

        /*

         * Find Fields or Methods within the given Class that we can inject

         * resource references into.  Suppose we want to know if a Field can get

         * a reference to an ObjectName.  We'll accept fields like this:

         *

         * @Resource

         * private transient ObjectName name;

         *

         * or like this:

         *

         * @Resource(type = ObjectName.class)

         * private transient Object name;

         *

         * but not like this:

         *

         * @Resource

         * private transient Object name;

         *

         * (Plain @Resource is equivalent to @Resource(type = Object.class).)

         *

         * We don't want to inject into everything that might possibly accept

         * an ObjectName reference, because examples like the last one above

         * could also accept an MBeanServer reference or any other sort of

         * reference.

         *

         * So we accept a Field if it has a @Resource annotation and either

         * (a) its type is exactly ObjectName and its @Resource type is

         * compatible with ObjectName (e.g. it is Object); or

         * (b) its type is compatible with ObjectName and its @Resource type

         * is exactly ObjectName.  Fields that meet these criteria will not

         * meet the same criteria with respect to other types such as MBeanServer.

         *

         * The same logic applies mutatis mutandis to Methods such as this:

         *

         * @Resource

         * private void setObjectName1(ObjectName name)

         * @Resource(type = Object.class)

         * private void setObjectName2(Object name)

         */

        private void addMembers(final Class<?> c)

        throws NotCompliantMBeanException {

            AccessibleObject[][] memberArrays =

                AccessController.doPrivileged(

                    new PrivilegedAction<AccessibleObject[][]>() {

                        public AccessibleObject[][] run() {

                            return new AccessibleObject[][] {

                                c.getDeclaredFields(), c.getDeclaredMethods()

                            };

                        }

                    });

            for (AccessibleObject[] members : memberArrays) {

                for (final AccessibleObject member : members) {

                    Resource res = member.getAnnotation(Resource.class);

                    if (res == null)

                        continue;

                    final Field field;

                    final Method method;

                    final Class<?> memberType;

                    final int modifiers;

                    if (member instanceof Field) {

                        field = (Field) member;

                        memberType = field.getType();

                        modifiers = field.getModifiers();

                        method = null;

                    } else {

                        field = null;

                        method = (Method) member;

                        Class<?>[] paramTypes = method.getParameterTypes();

                        if (paramTypes.length != 1) {

                            throw new NotCompliantMBeanException(

                                    "@Resource method must have exactly 1 " +

                                    "parameter: " + method);

                        }

                        if (method.getReturnType() != void.class) {

                            throw new NotCompliantMBeanException(

                                    "@Resource method must return void: " +

                                    method);

                        }

                        memberType = paramTypes[0];

                        modifiers = method.getModifiers();

                    }

                    if (Modifier.isStatic(modifiers)) {

                        throw new NotCompliantMBeanException(

                                "@Resource method or field cannot be static: " +

                                member);

                    }

                    for (Class<?> injectedClass : injectedClasses) {

                        Class<?>[] types = {memberType, res.type()};

                        boolean accept = false;

                        for (int i = 0; i < 2; i++) {

                            if (types[i] == injectedClass &&

                                    types[1 - i].isAssignableFrom(injectedClass)) {

                                accept = true;

                                break;

                            }

                        }

                        if (accept) {

                            AccessController.doPrivileged(new PrivilegedAction<Void>() {

                                public Void run() {

                                    member.setAccessible(true);

                                    return null;

                                }

                            });

                            addToMap(fields, injectedClass, field);

                            addToMap(methods, injectedClass, method);

                        }

                    }

                }

            }

        }

        private static <K, V> void addToMap(Map<K, List<V>> map, K key, V value) {

            if (value == null)

                return;

            List<V> list = map.get(key);

            if (list == null)

                list = Collections.singletonList(value);

            else {

                if (list.size() == 1)

                    list = new ArrayList<V>(list);

                list.add(value);

            }

            map.put(key, list);

        }

    }

    private static synchronized ClassInjector injectorForClass(Class<?> c)

    throws NotCompliantMBeanException {

        WeakReference<ClassInjector> wr = injectorMap.get(c);

        ClassInjector ci = (wr == null) ? null : wr.get();

        if (ci == null) {

            ci = new ClassInjector(c);

            injectorMap.put(c, new WeakReference<ClassInjector>(ci));

        }

        return ci;

    }

    private static Map<Class<?>, WeakReference<ClassInjector>> injectorMap =

            new WeakHashMap<Class<?>, WeakReference<ClassInjector>>();

}