/*
 * JBoss, Home of Professional Open Source
 * Copyright 2012, Red Hat, Inc., and individual contributors
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * 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.jboss.weld.module.jta;

import java.util.ArrayList;
import java.util.List;
import java.util.stream.Collectors;

import javax.enterprise.event.TransactionPhase;
import javax.enterprise.inject.spi.EventMetadata;
import javax.enterprise.inject.spi.ObserverMethod;
import javax.transaction.RollbackException;

import org.jboss.weld.bootstrap.api.ServiceRegistry;
import org.jboss.weld.event.ObserverNotifier;
import org.jboss.weld.module.ObserverNotifierFactory;
import org.jboss.weld.resolution.TypeSafeObserverResolver;
import org.jboss.weld.transaction.spi.TransactionServices;

/**
 * {@link ObserverNotifier} with support for transactional observer methods.
 *
 * @author Jozef Hartinger
 */
class TransactionalObserverNotifier extends ObserverNotifier {

    static final ObserverNotifierFactory FACTORY = new ObserverNotifierFactory() {
        @Override
        public ObserverNotifier create(String contextId, TypeSafeObserverResolver resolver, ServiceRegistry services, boolean strict) {
            return new TransactionalObserverNotifier(contextId, resolver, services, strict);
        }
    };

    private final TransactionServices transactionServices;
    private final String contextId;

    TransactionalObserverNotifier(String contextId, TypeSafeObserverResolver resolver, ServiceRegistry services, boolean strict) {
        super(contextId, resolver, services, strict);
        this.contextId = contextId;
        this.transactionServices = services.get(TransactionServices.class);
    }

    /**
     * Defers an event for processing in a later phase of the current
     * transaction.
     *
     * @param metadata The event object
     */
    private <T> void deferNotification(T event, final EventMetadata metadata, final ObserverMethod<? super T> observer,
            final List<DeferredEventNotification<?>> notifications) {
        TransactionPhase transactionPhase = observer.getTransactionPhase();
        boolean before = transactionPhase.equals(TransactionPhase.BEFORE_COMPLETION);
        Status status = Status.valueOf(transactionPhase);
        notifications.add(new DeferredEventNotification<T>(contextId, event, metadata, observer, currentEventMetadata, status, before));
    }

    @Override
    protected <T> void notifyTransactionObservers(List<ObserverMethod<? super T>> observers, T event, EventMetadata metadata,
            final ObserverExceptionHandler handler) {
        if (observers.isEmpty()) {
            return;
        }
        if (transactionServices == null || !transactionServices.isTransactionActive()) {
            // Transaction is not active - no deferred notifications
            notifySyncObservers(observers, event, metadata, handler);
        } else {
            List<DeferredEventNotification<?>> notifications = new ArrayList<DeferredEventNotification<?>>();
            for (ObserverMethod<? super T> observer : observers) {
                deferNotification(event, metadata, observer, notifications);
            }
            try {
                transactionServices.registerSynchronization(new TransactionNotificationSynchronization(notifications));
            } catch (Exception e) {
                if (e.getCause() instanceof RollbackException || e.getCause() instanceof IllegalStateException) {
                    List<ObserverMethod<? super T>> filteredObservers = observers.stream()
                            .filter(observerMethod -> !observerMethod.getTransactionPhase().equals(TransactionPhase.AFTER_SUCCESS))
                            .sorted((o1, o2) -> {
                                // using descending order since we only need to ensure that BEFORE_COMPLETION precedes AFTER_COMPLETION
                                return o2.getTransactionPhase().toString().compareTo(o1.getTransactionPhase().toString());
                            })
                            .collect(Collectors.toList());
                    notifySyncObservers(filteredObservers, event, metadata, handler);
                } else {
                    throw e;
                }

            }
        }
    }
}