/*
 * This file is part of LibrePlan
 *
 * Copyright (C) 2009-2010 Fundación para o Fomento da Calidade Industrial e
 *                         Desenvolvemento Tecnolóxico de Galicia
 * Copyright (C) 2010-2011 Igalia, S.L.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program 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 Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package org.libreplan.web.common.concurrentdetection;

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

import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Pointcut;
import org.springframework.core.annotation.Order;
import org.springframework.dao.OptimisticLockingFailureException;

/**
 * Responsible of handling {@link OptimisticLockingFailureException} on Spring beans
 * marked with {@link OnConcurrentModification}.
 *
 * @author Óscar González Fernández <ogonzalez@igalia.com>
 */
@Aspect
@Order(0)
public class ConcurrentModificationHandling {

    public ConcurrentModificationHandling() {
    }

    public static <T> T addHandling(final String goToPage, Class<T> interfaceKlass, T toBeWrapped) {
        Class<?>[] classesToProxy = { interfaceKlass };

        Object result =
                Proxy.newProxyInstance(interfaceKlass.getClassLoader(), classesToProxy, handler(toBeWrapped, goToPage));

        return interfaceKlass.cast(result);
    }

    private static InvocationHandler handler(final Object toBeWraped, final String goToPage) {
        return (proxy, method, args) -> {
            try {
                return method.invoke(toBeWraped, args);
            } catch (InvocationTargetException e) {
                Throwable cause = e.getCause();
                if ( cause instanceof OptimisticLockingFailureException ) {

                    OptimisticLockingFailureException optimisticLockingFailureException =
                            (OptimisticLockingFailureException) cause;

                    ConcurrentModificationController.showException(optimisticLockingFailureException, goToPage);
                }
                throw cause;
            }
        };
    }

    @SuppressWarnings("unused")
    @Pointcut(value = "@within(onConcurrentModification))")
    private void methodWithinConcurrentModificationMarkedType(OnConcurrentModification onConcurrentModification) {
    }

    /**
     * It intercepts the calls to public methods of Spring beans marked with {@link OnConcurrentModification}.
     *
     * When an {@link OptimisticLockingFailureException} happens the page for concurrent
     * modification is shown and the user is returned to the page specified by {@link OnConcurrentModification}.
     *
     * @param jointPoint
     * @param onConcurrentModification
     *            the annotation applied to object's type
     * @return the object that would be originally returned
     */
    @Around("methodWithinConcurrentModificationMarkedType(onConcurrentModification) && execution(public * * (..))")
    public Object whenConcurrentModification(ProceedingJoinPoint jointPoint,
                                             OnConcurrentModification onConcurrentModification) throws Throwable {

        try {
            return jointPoint.proceed(jointPoint.getArgs());
        } catch (OptimisticLockingFailureException e) {
            ConcurrentModificationController.showException(e, onConcurrentModification.goToPage());
            throw e;
        }
    }
}