/*
 * Copyright (c) 2006-2011 Nuxeo SA (http://nuxeo.com/) and others.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *     matic
 */

package org.eclipse.ecr.runtime.transaction;

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

/**
 * Start a user transaction if method or class is annotated for and if there is no
 * transaction active
 *
 * @author matic
 *
 * @param <T>
 */
public class TransactedInstanceHandler<T> implements InvocationHandler{

    protected final T object;

    public static <T> T newProxy(T object, Class<T> itf) {
         InvocationHandler h = new TransactedInstanceHandler<T>(object);
         return itf.cast(Proxy.newProxyInstance(Thread.currentThread().getContextClassLoader(), new Class<?>[] { itf }, h));
    }

    protected TransactedInstanceHandler(T object) {
        this.object = object;
    }

    protected boolean requireTransaction(Method m) {
        if (!m.isAnnotationPresent(Transacted.class) && !m.getClass().isAnnotationPresent(Transacted.class)) {
            return false;
        }
        return !TransactionHelper.isTransactionActive();
    }

    protected Object doInvoke(Method m, Object[] args) throws Throwable {
        try {
            return m.invoke(object, args);
        } catch (InvocationTargetException e) {
            throw e.getCause();
        }
    }

    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        if (!requireTransaction(method)) {
            return doInvoke(method, args);
        }
        TransactionHelper.startTransaction();
        try {
            return doInvoke(method, args);
        } catch (Throwable e) {
            TransactionHelper.setTransactionRollbackOnly();
            throw e;
        } finally {
            TransactionHelper.commitOrRollbackTransaction();
        }
    }

}