/*
 * 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
 *
 *      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.springframework.context.annotation;

import java.util.Collections;
import java.util.LinkedHashSet;
import java.util.Map;
import java.util.Set;

import org.springframework.beans.factory.annotation.AnnotatedBeanDefinition;
import org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanDefinitionHolder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.DefaultListableBeanFactory;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.context.event.DefaultEventListenerFactory;
import org.springframework.context.event.EventListenerMethodProcessor;
import org.springframework.context.support.GenericApplicationContext;
import org.springframework.core.annotation.AnnotationAttributes;
import org.springframework.core.annotation.AnnotationAwareOrderComparator;
import org.springframework.core.type.AnnotatedTypeMetadata;
import org.springframework.core.type.AnnotationMetadata;
import org.springframework.lang.Nullable;
import org.springframework.util.ClassUtils;

Utility class that allows for convenient registration of common BeanPostProcessor and BeanFactoryPostProcessor definitions for annotation-based configuration. Also registers a common AutowireCandidateResolver. 
Author:
Mark Fisher, Juergen Hoeller, Chris Beams, Phillip Webb, Stephane Nicoll
See Also:
ContextAnnotationAutowireCandidateResolver
ConfigurationClassPostProcessor
CommonAnnotationBeanPostProcessor
AutowiredAnnotationBeanPostProcessor
PersistenceAnnotationBeanPostProcessor
Since:
2.5/**
 * Utility class that allows for convenient registration of common
 * {@link org.springframework.beans.factory.config.BeanPostProcessor} and
 * {@link org.springframework.beans.factory.config.BeanFactoryPostProcessor}
 * definitions for annotation-based configuration. Also registers a common
 * {@link org.springframework.beans.factory.support.AutowireCandidateResolver}.
 *
 * @author Mark Fisher
 * @author Juergen Hoeller
 * @author Chris Beams
 * @author Phillip Webb
 * @author Stephane Nicoll
 * @since 2.5
 * @see ContextAnnotationAutowireCandidateResolver
 * @see ConfigurationClassPostProcessor
 * @see CommonAnnotationBeanPostProcessor
 * @see org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor
 * @see org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor
 */
public abstract class AnnotationConfigUtils {

	
The bean name of the internally managed Configuration annotation processor.
/**
	 * The bean name of the internally managed Configuration annotation processor.
	 */
	public static final String CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME =
			"org.springframework.context.annotation.internalConfigurationAnnotationProcessor";

	
The bean name of the internally managed BeanNameGenerator for use when processing Configuration classes. Set by AnnotationConfigApplicationContext and AnnotationConfigWebApplicationContext during bootstrap in order to make any custom name generation strategy available to the underlying ConfigurationClassPostProcessor. 
Since:
3.1.1/**
	 * The bean name of the internally managed BeanNameGenerator for use when processing
	 * {@link Configuration} classes. Set by {@link AnnotationConfigApplicationContext}
	 * and {@code AnnotationConfigWebApplicationContext} during bootstrap in order to make
	 * any custom name generation strategy available to the underlying
	 * {@link ConfigurationClassPostProcessor}.
	 * @since 3.1.1
	 */
	public static final String CONFIGURATION_BEAN_NAME_GENERATOR =
			"org.springframework.context.annotation.internalConfigurationBeanNameGenerator";

	
The bean name of the internally managed Autowired annotation processor.
/**
	 * The bean name of the internally managed Autowired annotation processor.
	 */
	public static final String AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME =
			"org.springframework.context.annotation.internalAutowiredAnnotationProcessor";

	
The bean name of the internally managed Required annotation processor.
Deprecated:
as of 5.1, since no Required processor is registered by default anymore/**
	 * The bean name of the internally managed Required annotation processor.
	 * @deprecated as of 5.1, since no Required processor is registered by default anymore
	 */
	@Deprecated
	public static final String REQUIRED_ANNOTATION_PROCESSOR_BEAN_NAME =
			"org.springframework.context.annotation.internalRequiredAnnotationProcessor";

	
The bean name of the internally managed JSR-250 annotation processor.
/**
	 * The bean name of the internally managed JSR-250 annotation processor.
	 */
	public static final String COMMON_ANNOTATION_PROCESSOR_BEAN_NAME =
			"org.springframework.context.annotation.internalCommonAnnotationProcessor";

	
The bean name of the internally managed JPA annotation processor.
/**
	 * The bean name of the internally managed JPA annotation processor.
	 */
	public static final String PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME =
			"org.springframework.context.annotation.internalPersistenceAnnotationProcessor";

	private static final String PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME =
			"org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor";

	
The bean name of the internally managed @EventListener annotation processor.
/**
	 * The bean name of the internally managed @EventListener annotation processor.
	 */
	public static final String EVENT_LISTENER_PROCESSOR_BEAN_NAME =
			"org.springframework.context.event.internalEventListenerProcessor";

	
The bean name of the internally managed EventListenerFactory.
/**
	 * The bean name of the internally managed EventListenerFactory.
	 */
	public static final String EVENT_LISTENER_FACTORY_BEAN_NAME =
			"org.springframework.context.event.internalEventListenerFactory";

	private static final boolean jsr250Present;

	private static final boolean jpaPresent;

	static {
		ClassLoader classLoader = AnnotationConfigUtils.class.getClassLoader();
		jsr250Present = ClassUtils.isPresent("javax.annotation.Resource", classLoader);
		jpaPresent = ClassUtils.isPresent("javax.persistence.EntityManagerFactory", classLoader) &&
				ClassUtils.isPresent(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, classLoader);
	}


	
Register all relevant annotation post processors in the given registry.
Params:
registry – the registry to operate on/**
	 * Register all relevant annotation post processors in the given registry.
	 * @param registry the registry to operate on
	 */
	public static void registerAnnotationConfigProcessors(BeanDefinitionRegistry registry) {
		registerAnnotationConfigProcessors(registry, null);
	}

	
Register all relevant annotation post processors in the given registry.
Params:
registry – the registry to operate on
source – the configuration source element (already extracted) that this registration was triggered from. May be null.
Returns:
a Set of BeanDefinitionHolders, containing all bean definitions
that have actually been registered by this call/**
	 * Register all relevant annotation post processors in the given registry.
	 * @param registry the registry to operate on
	 * @param source the configuration source element (already extracted)
	 * that this registration was triggered from. May be {@code null}.
	 * @return a Set of BeanDefinitionHolders, containing all bean definitions
	 * that have actually been registered by this call
	 */
	public static Set<BeanDefinitionHolder> registerAnnotationConfigProcessors(
			BeanDefinitionRegistry registry, @Nullable Object source) {

		DefaultListableBeanFactory beanFactory = unwrapDefaultListableBeanFactory(registry);
		if (beanFactory != null) {
			if (!(beanFactory.getDependencyComparator() instanceof AnnotationAwareOrderComparator)) {
				beanFactory.setDependencyComparator(AnnotationAwareOrderComparator.INSTANCE);
			}
			if (!(beanFactory.getAutowireCandidateResolver() instanceof ContextAnnotationAutowireCandidateResolver)) {
				beanFactory.setAutowireCandidateResolver(new ContextAnnotationAutowireCandidateResolver());
			}
		}

		Set<BeanDefinitionHolder> beanDefs = new LinkedHashSet<>(8);

		if (!registry.containsBeanDefinition(CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(ConfigurationClassPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, CONFIGURATION_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(AutowiredAnnotationBeanPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, AUTOWIRED_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		// Check for JSR-250 support, and if present add the CommonAnnotationBeanPostProcessor.
		if (jsr250Present && !registry.containsBeanDefinition(COMMON_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(CommonAnnotationBeanPostProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, COMMON_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		// Check for JPA support, and if present add the PersistenceAnnotationBeanPostProcessor.
		if (jpaPresent && !registry.containsBeanDefinition(PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition();
			try {
				def.setBeanClass(ClassUtils.forName(PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME,
						AnnotationConfigUtils.class.getClassLoader()));
			}
			catch (ClassNotFoundException ex) {
				throw new IllegalStateException(
						"Cannot load optional framework class: " + PERSISTENCE_ANNOTATION_PROCESSOR_CLASS_NAME, ex);
			}
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, PERSISTENCE_ANNOTATION_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(EVENT_LISTENER_PROCESSOR_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(EventListenerMethodProcessor.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_PROCESSOR_BEAN_NAME));
		}

		if (!registry.containsBeanDefinition(EVENT_LISTENER_FACTORY_BEAN_NAME)) {
			RootBeanDefinition def = new RootBeanDefinition(DefaultEventListenerFactory.class);
			def.setSource(source);
			beanDefs.add(registerPostProcessor(registry, def, EVENT_LISTENER_FACTORY_BEAN_NAME));
		}

		return beanDefs;
	}

	private static BeanDefinitionHolder registerPostProcessor(
			BeanDefinitionRegistry registry, RootBeanDefinition definition, String beanName) {

		definition.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		registry.registerBeanDefinition(beanName, definition);
		return new BeanDefinitionHolder(definition, beanName);
	}

	@Nullable
	private static DefaultListableBeanFactory unwrapDefaultListableBeanFactory(BeanDefinitionRegistry registry) {
		if (registry instanceof DefaultListableBeanFactory) {
			return (DefaultListableBeanFactory) registry;
		}
		else if (registry instanceof GenericApplicationContext) {
			return ((GenericApplicationContext) registry).getDefaultListableBeanFactory();
		}
		else {
			return null;
		}
	}

	public static void processCommonDefinitionAnnotations(AnnotatedBeanDefinition abd) {
		processCommonDefinitionAnnotations(abd, abd.getMetadata());
	}

	static void processCommonDefinitionAnnotations(AnnotatedBeanDefinition abd, AnnotatedTypeMetadata metadata) {
		AnnotationAttributes lazy = attributesFor(metadata, Lazy.class);
		if (lazy != null) {
			abd.setLazyInit(lazy.getBoolean("value"));
		}
		else if (abd.getMetadata() != metadata) {
			lazy = attributesFor(abd.getMetadata(), Lazy.class);
			if (lazy != null) {
				abd.setLazyInit(lazy.getBoolean("value"));
			}
		}

		if (metadata.isAnnotated(Primary.class.getName())) {
			abd.setPrimary(true);
		}
		AnnotationAttributes dependsOn = attributesFor(metadata, DependsOn.class);
		if (dependsOn != null) {
			abd.setDependsOn(dependsOn.getStringArray("value"));
		}

		AnnotationAttributes role = attributesFor(metadata, Role.class);
		if (role != null) {
			abd.setRole(role.getNumber("value").intValue());
		}
		AnnotationAttributes description = attributesFor(metadata, Description.class);
		if (description != null) {
			abd.setDescription(description.getString("value"));
		}
	}

	static BeanDefinitionHolder applyScopedProxyMode(
			ScopeMetadata metadata, BeanDefinitionHolder definition, BeanDefinitionRegistry registry) {

		ScopedProxyMode scopedProxyMode = metadata.getScopedProxyMode();
		if (scopedProxyMode.equals(ScopedProxyMode.NO)) {
			return definition;
		}
		boolean proxyTargetClass = scopedProxyMode.equals(ScopedProxyMode.TARGET_CLASS);
		return ScopedProxyCreator.createScopedProxy(definition, registry, proxyTargetClass);
	}

	@Nullable
	static AnnotationAttributes attributesFor(AnnotatedTypeMetadata metadata, Class<?> annotationClass) {
		return attributesFor(metadata, annotationClass.getName());
	}

	@Nullable
	static AnnotationAttributes attributesFor(AnnotatedTypeMetadata metadata, String annotationClassName) {
		return AnnotationAttributes.fromMap(metadata.getAnnotationAttributes(annotationClassName, false));
	}

	static Set<AnnotationAttributes> attributesForRepeatable(AnnotationMetadata metadata,
			Class<?> containerClass, Class<?> annotationClass) {

		return attributesForRepeatable(metadata, containerClass.getName(), annotationClass.getName());
	}

	@SuppressWarnings("unchecked")
	static Set<AnnotationAttributes> attributesForRepeatable(
			AnnotationMetadata metadata, String containerClassName, String annotationClassName) {

		Set<AnnotationAttributes> result = new LinkedHashSet<>();

		// Direct annotation present?
		addAttributesIfNotNull(result, metadata.getAnnotationAttributes(annotationClassName, false));

		// Container annotation present?
		Map<String, Object> container = metadata.getAnnotationAttributes(containerClassName, false);
		if (container != null && container.containsKey("value")) {
			for (Map<String, Object> containedAttributes : (Map<String, Object>[]) container.get("value")) {
				addAttributesIfNotNull(result, containedAttributes);
			}
		}

		// Return merged result
		return Collections.unmodifiableSet(result);
	}

	private static void addAttributesIfNotNull(
			Set<AnnotationAttributes> result, @Nullable Map<String, Object> attributes) {

		if (attributes != null) {
			result.add(AnnotationAttributes.fromMap(attributes));
		}
	}

}