/*
 * Copyright 2002-2016 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.aop.aspectj.annotation;

import java.io.Serializable;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.core.Ordered;
import org.springframework.core.annotation.OrderUtils;
import org.springframework.util.Assert;
import org.springframework.util.ClassUtils;

/**
 * {@link org.springframework.aop.aspectj.AspectInstanceFactory} implementation
 * backed by a Spring {@link org.springframework.beans.factory.BeanFactory}.
 *
 * <p>Note that this may instantiate multiple times if using a prototype,
 * which probably won't give the semantics you expect.
 * Use a {@link LazySingletonAspectInstanceFactoryDecorator}
 * to wrap this to ensure only one new aspect comes back.
 *
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @since 2.0
 * @see org.springframework.beans.factory.BeanFactory
 * @see LazySingletonAspectInstanceFactoryDecorator
 */
@SuppressWarnings("serial")
public class BeanFactoryAspectInstanceFactory implements MetadataAwareAspectInstanceFactory, Serializable {

        private final BeanFactory beanFactory;

        private final String name;

        private final AspectMetadata aspectMetadata;


        /**
         * Create a BeanFactoryAspectInstanceFactory. AspectJ will be called to
         * introspect to create AJType metadata using the type returned for the
         * given bean name from the BeanFactory.
         * @param beanFactory BeanFactory to obtain instance(s) from
         * @param name name of the bean
         */
        public BeanFactoryAspectInstanceFactory(BeanFactory beanFactory, String name) {
                this(beanFactory, name, beanFactory.getType(name));
        }

        /**
         * Create a BeanFactoryAspectInstanceFactory, providing a type that AspectJ should
         * introspect to create AJType metadata. Use if the BeanFactory may consider the type
         * to be a subclass (as when using CGLIB), and the information should relate to a superclass.
         * @param beanFactory BeanFactory to obtain instance(s) from
         * @param name the name of the bean
         * @param type the type that should be introspected by AspectJ
         */
        public BeanFactoryAspectInstanceFactory(BeanFactory beanFactory, String name, Class<?> type) {
                Assert.notNull(beanFactory, "BeanFactory must not be null");
                Assert.notNull(name, "Bean name must not be null");
                this.beanFactory = beanFactory;
                this.name = name;
                this.aspectMetadata = new AspectMetadata(type, name);
        }


        @Override
        public Object getAspectInstance() {
                return this.beanFactory.getBean(this.name);
        }

        @Override
        public ClassLoader getAspectClassLoader() {
                return (this.beanFactory instanceof ConfigurableBeanFactory ?
                                ((ConfigurableBeanFactory) this.beanFactory).getBeanClassLoader() :
                                ClassUtils.getDefaultClassLoader());
        }

        @Override
        public AspectMetadata getAspectMetadata() {
                return this.aspectMetadata;
        }

        @Override
        public Object getAspectCreationMutex() {
                if (this.beanFactory != null) {
                        if (this.beanFactory.isSingleton(name)) {
                                // Rely on singleton semantics provided by the factory -> no local lock.
                                return null;
                        }
                        else if (this.beanFactory instanceof ConfigurableBeanFactory) {
                                // No singleton guarantees from the factory -> let's lock locally but
                                // reuse the factory's singleton lock, just in case a lazy dependency
                                // of our advice bean happens to trigger the singleton lock implicitly...
                                return ((ConfigurableBeanFactory) this.beanFactory).getSingletonMutex();
                        }
                }
                return this;
        }

        /**
         * Determine the order for this factory's target aspect, either
         * an instance-specific order expressed through implementing the
         * {@link org.springframework.core.Ordered} interface (only
         * checked for singleton beans), or an order expressed through the
         * {@link org.springframework.core.annotation.Order} annotation
         * at the class level.
         * @see org.springframework.core.Ordered
         * @see org.springframework.core.annotation.Order
         */
        @Override
        public int getOrder() {
                Class<?> type = this.beanFactory.getType(this.name);
                if (type != null) {
                        if (Ordered.class.isAssignableFrom(type) && this.beanFactory.isSingleton(this.name)) {
                                return ((Ordered) this.beanFactory.getBean(this.name)).getOrder();
                        }
                        return OrderUtils.getOrder(type, Ordered.LOWEST_PRECEDENCE);
                }
                return Ordered.LOWEST_PRECEDENCE;
        }


        @Override
        public String toString() {
                return getClass().getSimpleName() + ": bean name '" + this.name + "'";
        }

}