/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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.apache.camel.component.jpa;

import java.util.Map;
import java.util.concurrent.ExecutorService;
import javax.persistence.EntityManagerFactory;

import org.apache.camel.Endpoint;
import org.apache.camel.spi.Metadata;
import org.apache.camel.spi.annotations.Component;
import org.apache.camel.support.DefaultComponent;
import org.apache.camel.util.ObjectHelper;
import org.springframework.transaction.PlatformTransactionManager;
import org.springframework.transaction.support.TransactionTemplate;

/**
 * A JPA Component
 */
@Component("jpa")
public class JpaComponent extends DefaultComponent {

    private ExecutorService pollingConsumerExecutorService;

    private EntityManagerFactory entityManagerFactory;
    private PlatformTransactionManager transactionManager;
    @Metadata(defaultValue = "true")
    private boolean joinTransaction = true;
    private boolean sharedEntityManager;

    public JpaComponent() {
    }

    // Properties
    //-------------------------------------------------------------------------
    public EntityManagerFactory getEntityManagerFactory() {
        return entityManagerFactory;
    }

    /**
     * To use the {@link EntityManagerFactory}. This is strongly recommended to configure.
     */
    public void setEntityManagerFactory(EntityManagerFactory entityManagerFactory) {
        this.entityManagerFactory = entityManagerFactory;
    }

    public PlatformTransactionManager getTransactionManager() {
        return transactionManager;
    }

    /**
     * To use the {@link PlatformTransactionManager} for managing transactions.
     */
    public void setTransactionManager(PlatformTransactionManager transactionManager) {
        this.transactionManager = transactionManager;
    }

    public boolean isJoinTransaction() {
        return joinTransaction;
    }

    /**
     * The camel-jpa component will join transaction by default.
     * You can use this option to turn this off, for example if you use LOCAL_RESOURCE and join transaction
     * doesn't work with your JPA provider. This option can also be set globally on the JpaComponent,
     * instead of having to set it on all endpoints.
     */
    public void setJoinTransaction(boolean joinTransaction) {
        this.joinTransaction = joinTransaction;
    }

    public boolean isSharedEntityManager() {
        return sharedEntityManager;
    }

    /**
     * Whether to use Spring's SharedEntityManager for the consumer/producer.
     * Note in most cases joinTransaction should be set to false as this is not an EXTENDED EntityManager.
     */
    public void setSharedEntityManager(boolean sharedEntityManager) {
        this.sharedEntityManager = sharedEntityManager;
    }

    synchronized ExecutorService getOrCreatePollingConsumerExecutorService() {
        if (pollingConsumerExecutorService == null) {
            log.debug("Creating thread pool for JpaPollingConsumer to support polling using timeout");
            pollingConsumerExecutorService = getCamelContext().getExecutorServiceManager().newDefaultThreadPool(this, "JpaPollingConsumer");
        }
        return pollingConsumerExecutorService;
    }

    // Implementation methods
    //-------------------------------------------------------------------------

    @Override
    protected Endpoint createEndpoint(String uri, String path, Map<String, Object> options) throws Exception {
        JpaEndpoint endpoint = new JpaEndpoint(uri, this);
        endpoint.setJoinTransaction(isJoinTransaction());
        endpoint.setSharedEntityManager(isSharedEntityManager());

        // lets interpret the next string as a class
        if (ObjectHelper.isNotEmpty(path)) {
            // provide the class loader of this component to work in OSGi environments as camel-jpa must be able
            // to resolve the entity classes
            Class<?> type = getCamelContext().getClassResolver().resolveClass(path, JpaComponent.class.getClassLoader());
            if (type != null) {
                endpoint.setEntityType(type);
            }
        }
        setProperties(endpoint, options);
        return endpoint;
    }

    @Override
    protected void doStart() throws Exception {
        super.doStart();

        // lookup entity manager factory and use it if only one provided
        if (entityManagerFactory == null) {
            Map<String, EntityManagerFactory> map = getCamelContext().getRegistry().findByTypeWithName(EntityManagerFactory.class);
            if (map != null) {
                if (map.size() == 1) {
                    entityManagerFactory = map.values().iterator().next();
                    log.info("Using EntityManagerFactory found in registry with id ["
                            + map.keySet().iterator().next() + "] " + entityManagerFactory);
                } else {
                    log.debug("Could not find a single EntityManagerFactory in registry as there was {} instances.", map.size());
                }
            }
        } else {
            log.info("Using EntityManagerFactory configured: {}", entityManagerFactory);
        }

        // lookup transaction manager and use it if only one provided
        if (transactionManager == null) {
            Map<String, PlatformTransactionManager> map = getCamelContext().getRegistry().findByTypeWithName(PlatformTransactionManager.class);
            if (map != null) {
                if (map.size() == 1) {
                    transactionManager = map.values().iterator().next();
                    log.info("Using TransactionManager found in registry with id ["
                            + map.keySet().iterator().next() + "] " + transactionManager);
                } else {
                    log.debug("Could not find a single TransactionManager in registry as there was {} instances.", map.size());
                }
            }
        } else {
            log.info("Using TransactionManager configured on this component: {}", transactionManager);
        }

        // transaction manager could also be hidden in a template
        if (transactionManager == null) {
            Map<String, TransactionTemplate> map = getCamelContext().getRegistry().findByTypeWithName(TransactionTemplate.class);
            if (map != null) {
                if (map.size() == 1) {
                    transactionManager = map.values().iterator().next().getTransactionManager();
                    log.info("Using TransactionManager found in registry with id ["
                            + map.keySet().iterator().next() + "] " + transactionManager);
                } else {
                    log.debug("Could not find a single TransactionTemplate in registry as there was {} instances.", map.size());
                }
            }
        }

        // warn about missing configuration
        if (entityManagerFactory == null) {
            log.warn("No EntityManagerFactory has been configured on this JpaComponent. Each JpaEndpoint will auto create their own EntityManagerFactory.");
        }
        if (transactionManager == null) {
            log.warn("No TransactionManager has been configured on this JpaComponent. Each JpaEndpoint will auto create their own JpaTransactionManager.");
        }
    }

    @Override
    protected void doStop() throws Exception {
        super.doStop();

        if (pollingConsumerExecutorService != null) {
            getCamelContext().getExecutorServiceManager().shutdown(pollingConsumerExecutorService);
            pollingConsumerExecutorService = null;
        }
    }
}