/*

 * Copyright 2005-2006 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 static com.sun.jmx.mbeanserver.Util.*;

import java.lang.ref.WeakReference;

import java.lang.reflect.Array;

import java.lang.reflect.Constructor;

import java.lang.reflect.InvocationTargetException;

import java.lang.reflect.Method;

import java.lang.reflect.Type;

import java.util.Arrays;

import java.util.List;

import java.util.WeakHashMap;

import javax.management.Descriptor;

import javax.management.ImmutableDescriptor;

import javax.management.InvalidAttributeValueException;

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.NotCompliantMBeanException;

import javax.management.NotificationBroadcaster;

import javax.management.ReflectionException;

/**

 * An introspector for MBeans of a certain type.  There is one instance

 *

 * @param <M> the representation of methods for this kind of MBean:

 * Method for Standard MBeans, ConvertingMethod for MXBeans.

 *

 * @since 1.6

 */

/*

 * Using a type parameter <M> allows us to deal with the fact that

 * Method and ConvertingMethod have no useful common ancestor, on

 * which we could call getName, getGenericReturnType, etc.  A simpler approach

 * would be to wrap every Method in an object that does have a common

 * ancestor with ConvertingMethod.  But that would mean an extra object

 * for every Method in every Standard MBean interface.

 */

abstract class MBeanIntrospector<M> {

    static final class PerInterfaceMap<M>

            extends WeakHashMap<Class<?>, WeakReference<PerInterface<M>>> {}

    /** The map from interface to PerInterface for this type of MBean. */

    abstract PerInterfaceMap<M> getPerInterfaceMap();

    /**

     * The map from concrete implementation class and interface to

     * MBeanInfo for this type of MBean.

     */

    abstract MBeanInfoMap getMBeanInfoMap();

    /** Make an interface analyzer for this type of MBean. */

    abstract MBeanAnalyzer<M> getAnalyzer(Class<?> mbeanInterface)

    throws NotCompliantMBeanException;

    /** True if MBeans with this kind of introspector are MXBeans. */

    abstract boolean isMXBean();

    /** Find the M corresponding to the given Method. */

    abstract M mFrom(Method m);

    /** Get the name of this method. */

    abstract String getName(M m);

    /**

     * Get the return type of this method.  This is the return type

     * of a method in a Java interface, so for MXBeans it is the

     * declared Java type, not the mapped Open Type.

     */

    abstract Type getGenericReturnType(M m);

    /**

     * Get the parameter types of this method in the Java interface

     * it came from.

     */

    abstract Type[] getGenericParameterTypes(M m);

    /**

     * Get the signature of this method as a caller would have to supply

     * it in MBeanServer.invoke.  For MXBeans, the named types will be

     * the mapped Open Types for the parameters.

     */

    abstract String[] getSignature(M m);

    /**

     * Check that this method is valid.  For example, a method in an

     * MXBean interface is not valid if one of its parameters cannot be

     * mapped to an Open Type.

     */

    /**

     * Invoke the method with the given target and arguments.

     *

     * @param cookie Additional information about the target.  For an

     * MXBean, this is the MXBeanLookup associated with the MXBean.

     */

    /*

     * It would be cleaner if the type of the cookie were a

     * type parameter to this class, but that would involve a lot of

     * messy type parameter propagation just to avoid a couple of casts.

     */

    abstract Object invokeM2(M m, Object target, Object[] args, Object cookie)

    throws InvocationTargetException, IllegalAccessException,

            MBeanException;

    /**

     * Test whether the given value is valid for the given parameter of this

     * M.

     */

    abstract boolean validParameter(M m, Object value, int paramNo,

            Object cookie);

    /**

     * Construct an MBeanAttributeInfo for the given attribute based on the

     * given getter and setter.  One but not both of the getter and setter

     * may be null.

     */

    abstract MBeanAttributeInfo getMBeanAttributeInfo(String attributeName,

    /**

     * Construct an MBeanOperationInfo for the given operation based on

     * the M it was derived from.

     */

    abstract MBeanOperationInfo getMBeanOperationInfo(String operationName,

            M operation);

    /**

     * Get a Descriptor containing fields that MBeans of this kind will

     * always have.  For example, MXBeans will always have "mxbean=true".

     */

    abstract Descriptor getBasicMBeanDescriptor();

    /**

     * Get a Descriptor containing additional fields beyond the ones

     * from getBasicMBeanDescriptor that MBeans whose concrete class

     * is resourceClass will always have.

     */

    abstract Descriptor getMBeanDescriptor(Class<?> resourceClass);

    void checkCompliance(Class<?> mbeanType) throws NotCompliantMBeanException {

        if (!mbeanType.isInterface()) {

            throw new NotCompliantMBeanException("Not an interface: " +

                    mbeanType.getName());

        }

    }

    /**

     * Get the methods to be analyzed to build the MBean interface.

     */

    List<Method> getMethods(final Class<?> mbeanType) throws Exception {

        return Arrays.asList(mbeanType.getMethods());

    }

    final PerInterface<M> getPerInterface(Class<?> mbeanInterface)

    throws NotCompliantMBeanException {

        PerInterfaceMap<M> map = getPerInterfaceMap();

        synchronized (map) {

            WeakReference<PerInterface<M>> wr = map.get(mbeanInterface);

            PerInterface<M> pi = (wr == null) ? null : wr.get();

            if (pi == null) {

                try {

                    MBeanAnalyzer<M> analyzer = getAnalyzer(mbeanInterface);

                    MBeanInfo mbeanInfo =

                            makeInterfaceMBeanInfo(mbeanInterface, analyzer);

                    pi = new PerInterface<M>(mbeanInterface, this, analyzer,

                            mbeanInfo);

                    wr = new WeakReference<PerInterface<M>>(pi);

                    map.put(mbeanInterface, wr);

                } catch (Exception x) {

                    throw Introspector.throwException(mbeanInterface,x);

                }

            }

            return pi;

        }

    }

    /**

     * Make the MBeanInfo skeleton for the given MBean interface using

     * the given analyzer.  This will never be the MBeanInfo of any real

     * MBean (because the getClassName() must be a concrete class), but

     * its MBeanAttributeInfo[] and MBeanOperationInfo[] can be inserted

     * into such an MBeanInfo, and its Descriptor can be the basis for

     * the MBeanInfo's Descriptor.

     */

    private MBeanInfo makeInterfaceMBeanInfo(Class<?> mbeanInterface,

        final MBeanInfoMaker maker = new MBeanInfoMaker();

        analyzer.visit(maker);

        final String description =

                "Information on the management interface of the MBean";

        return maker.makeMBeanInfo(mbeanInterface, description);

    }

    /** True if the given getter and setter are consistent. */

    final boolean consistent(M getter, M setter) {

        return (getter == null || setter == null ||

                getGenericReturnType(getter).equals(getGenericParameterTypes(setter)[0]));

    }

    /**

     * Invoke the given M on the given target with the given args and cookie.

     * Wrap exceptions appropriately.

     */

    final Object invokeM(M m, Object target, Object[] args, Object cookie)

    throws MBeanException, ReflectionException {

        try {

            return invokeM2(m, target, args, cookie);

        } catch (InvocationTargetException e) {

            unwrapInvocationTargetException(e);

            throw new RuntimeException(e); // not reached

        } catch (IllegalAccessException e) {

            throw new ReflectionException(e, e.toString());

        }

        /* We do not catch and wrap RuntimeException or Error,

         * because we're in a DynamicMBean, so the logic for DynamicMBeans

         * will do the wrapping.

         */

    }

    /**

     * Invoke the given setter on the given target with the given argument

     * and cookie.  Wrap exceptions appropriately.

     */

    /* If the value is of the wrong type for the method we are about to

     * invoke, we are supposed to throw an InvalidAttributeValueException.

     * Rather than making the check always, we invoke the method, then

     * if it throws an exception we check the type to see if that was

     * what caused the exception.  The assumption is that an exception

     * from an invalid type will arise before any user method is ever

     * called (either in reflection or in OpenConverter).

     */

    final void invokeSetter(String name, M setter, Object target, Object arg,

            Object cookie)

            throws MBeanException, ReflectionException,

            InvalidAttributeValueException {

        try {

            invokeM2(setter, target, new Object[] {arg}, cookie);

        } catch (IllegalAccessException e) {

            throw new ReflectionException(e, e.toString());

        } catch (RuntimeException e) {

            maybeInvalidParameter(name, setter, arg, cookie);

            throw e;

        } catch (InvocationTargetException e) {

            maybeInvalidParameter(name, setter, arg, cookie);

            unwrapInvocationTargetException(e);

        }

    }

    private void maybeInvalidParameter(String name, M setter, Object arg,

            Object cookie)

            throws InvalidAttributeValueException {

        if (!validParameter(setter, arg, 0, cookie)) {

            final String msg =

                    "Invalid value for attribute " + name + ": " + arg;

            throw new InvalidAttributeValueException(msg);

        }

    }

    static boolean isValidParameter(Method m, Object value, int paramNo) {

        Class<?> c = m.getParameterTypes()[paramNo];

        try {

            // Following is expensive but we only call this method to determine

            // if an exception is due to an incompatible parameter type.

            // Plain old c.isInstance doesn't work for primitive types.

            Object a = Array.newInstance(c, 1);

            Array.set(a, 0, value);

            return true;

        } catch (IllegalArgumentException e) {

            return false;

        }

    }

    private static void

            unwrapInvocationTargetException(InvocationTargetException e)

            throws MBeanException {

        Throwable t = e.getCause();

        if (t instanceof RuntimeException)

            throw (RuntimeException) t;

        else if (t instanceof Error)

            throw (Error) t;

        else

            throw new MBeanException((Exception) t,

                    (t == null ? null : t.toString()));

    }

    /** A visitor that constructs the per-interface MBeanInfo. */

        public void visitAttribute(String attributeName,

                M getter,

            MBeanAttributeInfo mbai =

                    getMBeanAttributeInfo(attributeName, getter, setter);

            attrs.add(mbai);

        }

        public void visitOperation(String operationName,

                M operation) {

            MBeanOperationInfo mboi =

                    getMBeanOperationInfo(operationName, operation);

            ops.add(mboi);

        }

        /** Make an MBeanInfo based on the attributes and operations

         *  found in the interface. */

        MBeanInfo makeMBeanInfo(Class<?> mbeanInterface,

                String description) {

            final MBeanAttributeInfo[] attrArray =

                    attrs.toArray(new MBeanAttributeInfo[0]);

            final MBeanOperationInfo[] opArray =

                    ops.toArray(new MBeanOperationInfo[0]);

            final String interfaceClassName =

                    "interfaceClassName=" + mbeanInterface.getName();

                    new ImmutableDescriptor(interfaceClassName);

            final Descriptor mbeanDescriptor = getBasicMBeanDescriptor();

            final Descriptor annotatedDescriptor =

                    Introspector.descriptorForElement(mbeanInterface);

            final Descriptor descriptor =

                    mbeanDescriptor,

                    annotatedDescriptor);

            return new MBeanInfo(mbeanInterface.getName(),

                    description,

                    attrArray,

                    null,

                    opArray,

                    null,

                    descriptor);

        }

        private final List<MBeanAttributeInfo> attrs = newList();

        private final List<MBeanOperationInfo> ops = newList();

    }

    /*

     * Looking up the MBeanInfo for a given base class (implementation class)

     * is complicated by the fact that we may use the same base class with

     * several different explicit MBean interfaces via the

     * javax.management.StandardMBean class.  It is further complicated

     * by the fact that we have to be careful not to retain a strong reference

     * to any Class object for fear we would prevent a ClassLoader from being

     * garbage-collected.  So we have a first lookup from the base class

     * to a map for each interface that base class might specify giving

     * the MBeanInfo constructed for that base class and interface.

     */

    static class MBeanInfoMap

            extends WeakHashMap<Class<?>, WeakHashMap<Class<?>, MBeanInfo>> {

    }

    /**

     * Return the MBeanInfo for the given resource, based on the given

     * per-interface data.

     */

        MBeanInfo mbi =

                getClassMBeanInfo(resource.getClass(), perInterface);

        MBeanNotificationInfo[] notifs = findNotifications(resource);

            return mbi;

        else {

            return new MBeanInfo(mbi.getClassName(),

                    mbi.getDescription(),

                    mbi.getAttributes(),

                    mbi.getConstructors(),

                    mbi.getOperations(),

                    notifs,

        }

    }

    /**

     * Return the basic MBeanInfo for resources of the given class and

     * per-interface data.  This MBeanInfo might not be the final MBeanInfo

     * for instances of the class, because if the class is a

     * NotificationBroadcaster then each instance gets to decide what

     * MBeanNotificationInfo[] to put in its own MBeanInfo.

     */

    final MBeanInfo getClassMBeanInfo(Class<?> resourceClass,

            PerInterface<M> perInterface) {

        MBeanInfoMap map = getMBeanInfoMap();

        synchronized (map) {

            WeakHashMap<Class<?>, MBeanInfo> intfMap = map.get(resourceClass);

            if (intfMap == null) {

                intfMap = new WeakHashMap<Class<?>, MBeanInfo>();

                map.put(resourceClass, intfMap);

            }

            Class<?> intfClass = perInterface.getMBeanInterface();

            MBeanInfo mbi = intfMap.get(intfClass);

            if (mbi == null) {

                MBeanInfo imbi = perInterface.getMBeanInfo();

                Descriptor descriptor =

                        ImmutableDescriptor.union(imbi.getDescriptor(),

                        getMBeanDescriptor(resourceClass));

                mbi = new MBeanInfo(resourceClass.getName(),

                        imbi.getDescription(),

                        imbi.getAttributes(),

                        findConstructors(resourceClass),

                        imbi.getOperations(),

                        (MBeanNotificationInfo[]) null,

                        descriptor);

                intfMap.put(intfClass, mbi);

            }

            return mbi;

        }

    }

    static MBeanNotificationInfo[] findNotifications(Object moi) {

        if (!(moi instanceof NotificationBroadcaster))

            return null;

        MBeanNotificationInfo[] mbn =

                ((NotificationBroadcaster) moi).getNotificationInfo();

            return null;

        MBeanNotificationInfo[] result =

                new MBeanNotificationInfo[mbn.length];

        for (int i = 0; i < mbn.length; i++) {

            MBeanNotificationInfo ni = mbn[i];

            if (ni.getClass() != MBeanNotificationInfo.class)

                ni = (MBeanNotificationInfo) ni.clone();

            result[i] = ni;

        }

        return result;

    }

    private static MBeanConstructorInfo[] findConstructors(Class<?> c) {

        Constructor[] cons = c.getConstructors();

        MBeanConstructorInfo[] mbc = new MBeanConstructorInfo[cons.length];

        for (int i = 0; i < cons.length; i++) {

            final String descr = "Public constructor of the MBean";

            mbc[i] = new MBeanConstructorInfo(descr, cons[i]);

        }

        return mbc;

    }

}