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/**
 * Copyright (c) 2013-2015 by The SeedStack authors. All rights reserved.
 *
 * This file is part of SeedStack, An enterprise-oriented full development stack.
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 */
package org.seedstack.seed.transaction.utils;

import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

import javassist.util.proxy.MethodFilter;
import javassist.util.proxy.MethodHandler;
import javassist.util.proxy.ProxyFactory;

import org.seedstack.seed.core.api.SeedException;
import org.seedstack.seed.transaction.internal.TransactionErrorCode;
import org.seedstack.seed.transaction.spi.TransactionalLink;

/**
 * This class proxy takes a {@link org.seedstack.seed.transaction.spi.TransactionalLink}. It intercepts method calls and
 * apply them to the instance retrieved from {@link org.seedstack.seed.transaction.spi.TransactionalLink}.get().
 *
 * @author [email protected]
 * @param  the type of the transactional object.
 */
public class TransactionalClassProxy implements MethodHandler {
	private TransactionalLink transactionalLink;

	private TransactionalClassProxy(TransactionalLink transactionalLink) {
		super();
		this.transactionalLink = transactionalLink;
	}

	@Override
	public Object invoke(Object self, Method thisMethod, Method proceed,
			Object[] args) throws Throwable { // NOSONAR
		if (thisMethod.getDeclaringClass().equals(Object.class)) {
			return thisMethod.invoke(transactionalLink, args);
		}

		try {
			return thisMethod.invoke(transactionalLink.get(), args);
		} catch (InvocationTargetException e) { // NOSONAR
			throw e.getCause();
		}
	}

	/**
	 * Create a transactional proxy around the provided {@link TransactionalLink}.
	 *
	 * @param  the interface used to create the proxy.
	 * @param clazz the class representing the transacted resource.
	 * @param transactionalLink the link to access the instance of the transacted resource.
	 * @return the proxy.
	 */
	@SuppressWarnings("unchecked")
	public static  T create(Class clazz, final TransactionalLink transactionalLink) {
		try {
			ProxyFactory factory = new ProxyFactory();
			factory.setSuperclass(clazz);
			factory.setFilter(new MethodFilter() {
				@Override
				public boolean isHandled(Method method) {
					return Modifier.isAbstract(method.getModifiers());
				}
			});
			return (T) factory.create(new Class[0], new Object[0], new TransactionalClassProxy(transactionalLink));
		} catch (Exception e) {
			throw SeedException.wrap(e, TransactionErrorCode.UNABLE_TO_CREATE_TRANSACTIONAL_PROXY).put("class", clazz.getName());
		}
	}
}