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Module providing Spring specific helper functionality to ease configuration / set-up of an Axon application, as well as some Spring specific infrastructure components.
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/*
 * Copyright (c) 2010-2017. Axon Framework
 * 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.axonframework.spring.eventsourcing;

import org.axonframework.common.transaction.TransactionManager;
import org.axonframework.eventsourcing.AggregateFactory;
import org.axonframework.eventsourcing.AggregateSnapshotter;
import org.axonframework.eventsourcing.EventSourcingRepository;
import org.axonframework.eventsourcing.eventstore.EventStore;
import org.axonframework.messaging.annotation.ClasspathParameterResolverFactory;
import org.axonframework.messaging.annotation.ParameterResolverFactory;
import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

import java.util.Collections;
import java.util.Objects;
import java.util.Optional;
import java.util.concurrent.Executor;

/**
 * Snapshotter implementation that uses the AggregateRoot as state for the snapshot. Unlike the
 * {@link AggregateSnapshotter}, this implementation lazily retrieves AggregateFactories from the Application
 * Context when snapshot requests are made.
 * 
 * Instead of configuring directly, consider using the {@link SpringAggregateSnapshotterFactoryBean}, which
 * configures this class using values available in the application context.
 *
 * @see SpringAggregateSnapshotterFactoryBean
 */
public class SpringAggregateSnapshotter extends AggregateSnapshotter implements ApplicationContextAware {

    private ApplicationContext applicationContext;

    /**
     * Initializes a snapshotter using the ParameterResolverFactory instances available on the classpath.
     * The given Aggregate Factories are lazily retrieved from the application context.
     *
     * @param eventStore               The Event Store to store snapshots in
     * @param parameterResolverFactory The parameterResolverFactory used to reconstruct aggregates
     * @param executor                 The executor that processes the snapshotting requests
     * @param txManager                The transaction manager to manage the persistence transactions with
     * @see ClasspathParameterResolverFactory
     */
    public SpringAggregateSnapshotter(EventStore eventStore, ParameterResolverFactory parameterResolverFactory, Executor executor, TransactionManager txManager) {
        super(eventStore, Collections.emptyList(), parameterResolverFactory, executor, txManager);
    }

    @Override
    protected AggregateFactory getAggregateFactory(Class aggregateType) {
        AggregateFactory aggregateFactory = super.getAggregateFactory(aggregateType);
        if (aggregateFactory == null) {
            Optional factory = applicationContext.getBeansOfType(AggregateFactory.class)
                    .values().stream()
                    .filter(af -> Objects.equals(af.getAggregateType(), aggregateType))
                    .findFirst();
            if (!factory.isPresent()) {
                factory = applicationContext.getBeansOfType(EventSourcingRepository.class)
                        .values().stream()
                        .map(EventSourcingRepository::getAggregateFactory)
                        .filter(af -> Objects.equals(af.getAggregateType(), aggregateType))
                        .findFirst();
                if (factory.isPresent()) {
                    aggregateFactory = factory.get();
                    registerAggregateFactory(aggregateFactory);
                }
            }

            if (factory.isPresent()) {
                aggregateFactory = factory.get();
                registerAggregateFactory(aggregateFactory);
            }
        }
        return aggregateFactory;
    }

    @Override
    public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
        this.applicationContext = applicationContext;
    }
}