/*
 * Copyright 2003,2004 The Apache Software Foundation
 *
 *  Licensed 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 net.sf.cglib.proxy;

import java.io.Serializable;
import java.lang.reflect.Method;
import java.lang.reflect.Member;
import net.sf.cglib.core.CodeGenerationException;

This class is meant to be used as replacement for
java.lang.reflect.Proxy under JDK 1.2. There are some known
subtle differences:

The exceptions returned by invoking getExceptionTypes
on the Method passed to the invoke method
are the exact set that can be thrown without resulting in an
UndeclaredThrowableException being thrown.
UndeclaredThrowableException is used instead of java.lang.reflect.UndeclaredThrowableException.


Version:
$Id: Proxy.java,v 1.6 2004/06/24 21:15:19 herbyderby Exp $/**
 * This class is meant to be used as replacement for
 * <code>java.lang.reflect.Proxy</code> under JDK 1.2. There are some known
 * subtle differences:
 * <ul>
 * <li>The exceptions returned by invoking <code>getExceptionTypes</code>
 * on the <code>Method</code> passed to the <code>invoke</code> method
 * <b>are</b> the exact set that can be thrown without resulting in an
 * <code>UndeclaredThrowableException</code> being thrown.
 * <li>{@link UndeclaredThrowableException} is used instead
 * of <code>java.lang.reflect.UndeclaredThrowableException</code>.
 * </ul>
 * <p>
 * @version $Id: Proxy.java,v 1.6 2004/06/24 21:15:19 herbyderby Exp $
 */
public class Proxy implements Serializable {
    protected InvocationHandler h;

    private static final CallbackFilter BAD_OBJECT_METHOD_FILTER = new CallbackFilter() {
        public int accept(Method method) {
            if (method.getDeclaringClass().getName().equals("java.lang.Object")) {
                String name = method.getName();
                if (!(name.equals("hashCode") ||
                      name.equals("equals") ||
                      name.equals("toString"))) {
                    return 1;
                }
            }
            return 0;
        }
    };

    protected Proxy(InvocationHandler h) {
        Enhancer.registerCallbacks(getClass(), new Callback[]{ h, null });
        this.h = h;
    }

    // private for security of isProxyClass
    private static class ProxyImpl extends Proxy {
        protected ProxyImpl(InvocationHandler h) {
            super(h);
        }
    }

    public static InvocationHandler getInvocationHandler(Object proxy) {
        if (!(proxy instanceof ProxyImpl)) {
            throw new IllegalArgumentException("Object is not a proxy");
        }
        return ((Proxy)proxy).h;
    }

    public static Class getProxyClass(ClassLoader loader, Class[] interfaces) {
        Enhancer e = new Enhancer();
        e.setSuperclass(ProxyImpl.class);
        e.setInterfaces(interfaces);
        e.setCallbackTypes(new Class[]{
            InvocationHandler.class,
            NoOp.class,
        });
        e.setCallbackFilter(BAD_OBJECT_METHOD_FILTER);
        e.setUseFactory(false);
        return e.createClass();
    }

    public static boolean isProxyClass(Class cl) {
        return cl.getSuperclass().equals(ProxyImpl.class);
    }

    public static Object newProxyInstance(ClassLoader loader, Class[] interfaces, InvocationHandler h) {
        try {
            Class clazz = getProxyClass(loader, interfaces);
            return clazz.getConstructor(new Class[]{ InvocationHandler.class }).newInstance(new Object[]{ h });
        } catch (RuntimeException e) {
            throw e;
        } catch (Exception e) {
            throw new CodeGenerationException(e);
        }
    }
}