/*
 * Copyright 2002-2018 the original author or authors.
 *
 * 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
 *
 *      https://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.springframework.jms.config;

import java.util.ArrayList;
import java.util.List;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.lang.Nullable;
import org.springframework.messaging.handler.annotation.support.DefaultMessageHandlerMethodFactory;
import org.springframework.messaging.handler.annotation.support.MessageHandlerMethodFactory;
import org.springframework.util.Assert;

/**
 * Helper bean for registering {@link JmsListenerEndpoint} with a {@link JmsListenerEndpointRegistry}.
 *
 * @author Stephane Nicoll
 * @author Juergen Hoeller
 * @since 4.1
 * @see org.springframework.jms.annotation.JmsListenerConfigurer
 */
public class JmsListenerEndpointRegistrar implements BeanFactoryAware, InitializingBean {

        @Nullable
        private JmsListenerEndpointRegistry endpointRegistry;

        @Nullable
        private MessageHandlerMethodFactory messageHandlerMethodFactory;

        @Nullable
        private JmsListenerContainerFactory<?> containerFactory;

        @Nullable
        private String containerFactoryBeanName;

        @Nullable
        private BeanFactory beanFactory;

        private final List<JmsListenerEndpointDescriptor> endpointDescriptors = new ArrayList<>();

        private boolean startImmediately;

        private Object mutex = this.endpointDescriptors;


        /**
         * Set the {@link JmsListenerEndpointRegistry} instance to use.
         */
        public void setEndpointRegistry(@Nullable JmsListenerEndpointRegistry endpointRegistry) {
                this.endpointRegistry = endpointRegistry;
        }

        /**
         * Return the {@link JmsListenerEndpointRegistry} instance for this
         * registrar, may be {@code null}.
         */
        @Nullable
        public JmsListenerEndpointRegistry getEndpointRegistry() {
                return this.endpointRegistry;
        }

        /**
         * Set the {@link MessageHandlerMethodFactory} to use to configure the message
         * listener responsible to serve an endpoint detected by this processor.
         * <p>By default, {@link DefaultMessageHandlerMethodFactory} is used and it
         * can be configured further to support additional method arguments
         * or to customize conversion and validation support. See
         * {@link DefaultMessageHandlerMethodFactory} javadoc for more details.
         */
        public void setMessageHandlerMethodFactory(@Nullable MessageHandlerMethodFactory messageHandlerMethodFactory) {
                this.messageHandlerMethodFactory = messageHandlerMethodFactory;
        }

        /**
         * Return the custom {@link MessageHandlerMethodFactory} to use, if any.
         */
        @Nullable
        public MessageHandlerMethodFactory getMessageHandlerMethodFactory() {
                return this.messageHandlerMethodFactory;
        }

        /**
         * Set the {@link JmsListenerContainerFactory} to use in case a {@link JmsListenerEndpoint}
         * is registered with a {@code null} container factory.
         * <p>Alternatively, the bean name of the {@link JmsListenerContainerFactory} to use
         * can be specified for a lazy lookup, see {@link #setContainerFactoryBeanName}.
         */
        public void setContainerFactory(JmsListenerContainerFactory<?> containerFactory) {
                this.containerFactory = containerFactory;
        }

        /**
         * Set the bean name of the {@link JmsListenerContainerFactory} to use in case
         * a {@link JmsListenerEndpoint} is registered with a {@code null} container factory.
         * Alternatively, the container factory instance can be registered directly:
         * see {@link #setContainerFactory(JmsListenerContainerFactory)}.
         * @see #setBeanFactory
         */
        public void setContainerFactoryBeanName(String containerFactoryBeanName) {
                this.containerFactoryBeanName = containerFactoryBeanName;
        }

        /**
         * A {@link BeanFactory} only needs to be available in conjunction with
         * {@link #setContainerFactoryBeanName}.
         */
        @Override
        public void setBeanFactory(BeanFactory beanFactory) {
                this.beanFactory = beanFactory;
                if (beanFactory instanceof ConfigurableBeanFactory) {
                        this.mutex = ((ConfigurableBeanFactory) beanFactory).getSingletonMutex();
                }
        }


        @Override
        public void afterPropertiesSet() {
                registerAllEndpoints();
        }

        protected void registerAllEndpoints() {
                Assert.state(this.endpointRegistry != null, "No JmsListenerEndpointRegistry set");
                synchronized (this.mutex) {
                        for (JmsListenerEndpointDescriptor descriptor : this.endpointDescriptors) {
                                this.endpointRegistry.registerListenerContainer(
                                                descriptor.endpoint, resolveContainerFactory(descriptor));
                        }
                        this.startImmediately = true;  // trigger immediate startup
                }
        }

        private JmsListenerContainerFactory<?> resolveContainerFactory(JmsListenerEndpointDescriptor descriptor) {
                if (descriptor.containerFactory != null) {
                        return descriptor.containerFactory;
                }
                else if (this.containerFactory != null) {
                        return this.containerFactory;
                }
                else if (this.containerFactoryBeanName != null) {
                        Assert.state(this.beanFactory != null, "BeanFactory must be set to obtain container factory by bean name");
                        // Consider changing this if live change of the factory is required...
                        this.containerFactory = this.beanFactory.getBean(
                                        this.containerFactoryBeanName, JmsListenerContainerFactory.class);
                        return this.containerFactory;
                }
                else {
                        throw new IllegalStateException("Could not resolve the " +
                                        JmsListenerContainerFactory.class.getSimpleName() + " to use for [" +
                                        descriptor.endpoint + "] no factory was given and no default is set.");
                }
        }

        /**
         * Register a new {@link JmsListenerEndpoint} alongside the
         * {@link JmsListenerContainerFactory} to use to create the underlying container.
         * <p>The {@code factory} may be {@code null} if the default factory has to be
         * used for that endpoint.
         */
        public void registerEndpoint(JmsListenerEndpoint endpoint, @Nullable JmsListenerContainerFactory<?> factory) {
                Assert.notNull(endpoint, "Endpoint must not be null");
                Assert.hasText(endpoint.getId(), "Endpoint id must be set");

                // Factory may be null, we defer the resolution right before actually creating the container
                JmsListenerEndpointDescriptor descriptor = new JmsListenerEndpointDescriptor(endpoint, factory);

                synchronized (this.mutex) {
                        if (this.startImmediately) {  // register and start immediately
                                Assert.state(this.endpointRegistry != null, "No JmsListenerEndpointRegistry set");
                                this.endpointRegistry.registerListenerContainer(descriptor.endpoint,
                                                resolveContainerFactory(descriptor), true);
                        }
                        else {
                                this.endpointDescriptors.add(descriptor);
                        }
                }
        }

        /**
         * Register a new {@link JmsListenerEndpoint} using the default
         * {@link JmsListenerContainerFactory} to create the underlying container.
         * @see #setContainerFactory(JmsListenerContainerFactory)
         * @see #registerEndpoint(JmsListenerEndpoint, JmsListenerContainerFactory)
         */
        public void registerEndpoint(JmsListenerEndpoint endpoint) {
                registerEndpoint(endpoint, null);
        }


        private static class JmsListenerEndpointDescriptor {

                public final JmsListenerEndpoint endpoint;

                @Nullable
                public final JmsListenerContainerFactory<?> containerFactory;

                public JmsListenerEndpointDescriptor(JmsListenerEndpoint endpoint,
                                @Nullable JmsListenerContainerFactory<?> containerFactory) {

                        this.endpoint = endpoint;
                        this.containerFactory = containerFactory;
                }
        }

}