/*
 * Copyright 2005-2011 the original author or authors.
 * 
 * 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 org.wamblee.xmlrouter.impl;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;

import org.wamblee.xmlrouter.common.Id;
import org.wamblee.xmlrouter.config.Identifiable;

/**
 * This proxy factory creates proxies for identifiable objects that add a prefix
 * to the ids.
 * 
 * @author Erik Brakkee
 * 
 * @param <T>
 */
public class IdentifiablePrefixProxyFactory<T> {

    public static final class IdPrefixInvocationHandler<T> implements
        InvocationHandler {

        private String prefix;
        private T service;

        public IdPrefixInvocationHandler(String aPrefix, T aService) {
            prefix = aPrefix;
            service = aService;
        }

        @Override
        public Object invoke(Object aProxy, final Method aMethod,
            final Object[] aArgs) throws Throwable {
            try {
                if (aMethod.getDeclaringClass().equals(Identifiable.class)) {
                    if (!aMethod.getName().equals("getId")) {
                        throw new RuntimeException(
                            "Programming error, Identifiable interface was modified");
                    }
                    Id id = (Id) aMethod.invoke(service, aArgs);
                    return new Id(prefix + id.getId());
                }
                return aMethod.invoke(service, aArgs);
            } catch (InvocationTargetException e) {
                throw e.getCause();
            }
        }
    }

    public static <T> T getProxy(String aPrefix, T aService,
        Class... aInterfaces) {
        InvocationHandler handler = new IdPrefixInvocationHandler<T>(aPrefix,
            aService);
        Class proxyClass = Proxy.getProxyClass(aService.getClass()
            .getClassLoader(), aInterfaces);
        T proxy;
        try {
            proxy = (T) proxyClass.getConstructor(
                new Class[] { InvocationHandler.class }).newInstance(
                new Object[] { handler });
            return proxy;
        } catch (Exception e) {
            throw new RuntimeException("Could not create proxy for " +
                aService.getClass().getName(), e);
        }
    }
}