/*
 * 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.aop.config;

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

import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;

import org.springframework.aop.aspectj.AspectJAfterAdvice;
import org.springframework.aop.aspectj.AspectJAfterReturningAdvice;
import org.springframework.aop.aspectj.AspectJAfterThrowingAdvice;
import org.springframework.aop.aspectj.AspectJAroundAdvice;
import org.springframework.aop.aspectj.AspectJExpressionPointcut;
import org.springframework.aop.aspectj.AspectJMethodBeforeAdvice;
import org.springframework.aop.aspectj.AspectJPointcutAdvisor;
import org.springframework.aop.aspectj.DeclareParentsAdvisor;
import org.springframework.aop.support.DefaultBeanFactoryPointcutAdvisor;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.BeanReference;
import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.config.RuntimeBeanNameReference;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.parsing.CompositeComponentDefinition;
import org.springframework.beans.factory.parsing.ParseState;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionBuilder;
import org.springframework.beans.factory.support.BeanDefinitionRegistry;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.beans.factory.xml.BeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.lang.Nullable;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.DomUtils;

BeanDefinitionParser for the <aop:config> tag. 
Author:
Rob Harrop, Juergen Hoeller, Adrian Colyer, Mark Fisher, Ramnivas Laddad
Since:
2.0/**
 * {@link BeanDefinitionParser} for the {@code <aop:config>} tag.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @author Adrian Colyer
 * @author Mark Fisher
 * @author Ramnivas Laddad
 * @since 2.0
 */
class ConfigBeanDefinitionParser implements BeanDefinitionParser {

	private static final String ASPECT = "aspect";
	private static final String EXPRESSION = "expression";
	private static final String ID = "id";
	private static final String POINTCUT = "pointcut";
	private static final String ADVICE_BEAN_NAME = "adviceBeanName";
	private static final String ADVISOR = "advisor";
	private static final String ADVICE_REF = "advice-ref";
	private static final String POINTCUT_REF = "pointcut-ref";
	private static final String REF = "ref";
	private static final String BEFORE = "before";
	private static final String DECLARE_PARENTS = "declare-parents";
	private static final String TYPE_PATTERN = "types-matching";
	private static final String DEFAULT_IMPL = "default-impl";
	private static final String DELEGATE_REF = "delegate-ref";
	private static final String IMPLEMENT_INTERFACE = "implement-interface";
	private static final String AFTER = "after";
	private static final String AFTER_RETURNING_ELEMENT = "after-returning";
	private static final String AFTER_THROWING_ELEMENT = "after-throwing";
	private static final String AROUND = "around";
	private static final String RETURNING = "returning";
	private static final String RETURNING_PROPERTY = "returningName";
	private static final String THROWING = "throwing";
	private static final String THROWING_PROPERTY = "throwingName";
	private static final String ARG_NAMES = "arg-names";
	private static final String ARG_NAMES_PROPERTY = "argumentNames";
	private static final String ASPECT_NAME_PROPERTY = "aspectName";
	private static final String DECLARATION_ORDER_PROPERTY = "declarationOrder";
	private static final String ORDER_PROPERTY = "order";
	private static final int METHOD_INDEX = 0;
	private static final int POINTCUT_INDEX = 1;
	private static final int ASPECT_INSTANCE_FACTORY_INDEX = 2;

	private ParseState parseState = new ParseState();


	@Override
	@Nullable
	public BeanDefinition parse(Element element, ParserContext parserContext) {
		CompositeComponentDefinition compositeDef =
				new CompositeComponentDefinition(element.getTagName(), parserContext.extractSource(element));
		parserContext.pushContainingComponent(compositeDef);

		configureAutoProxyCreator(parserContext, element);

		List<Element> childElts = DomUtils.getChildElements(element);
		for (Element elt: childElts) {
			String localName = parserContext.getDelegate().getLocalName(elt);
			if (POINTCUT.equals(localName)) {
				parsePointcut(elt, parserContext);
			}
			else if (ADVISOR.equals(localName)) {
				parseAdvisor(elt, parserContext);
			}
			else if (ASPECT.equals(localName)) {
				parseAspect(elt, parserContext);
			}
		}

		parserContext.popAndRegisterContainingComponent();
		return null;
	}

	
Configures the auto proxy creator needed to support the BeanDefinitions created by the '<aop:config/>' tag. Will force class proxying if the 'proxy-target-class' attribute is set to 'true'. 
See Also:
AopNamespaceUtils/**
	 * Configures the auto proxy creator needed to support the {@link BeanDefinition BeanDefinitions}
	 * created by the '{@code <aop:config/>}' tag. Will force class proxying if the
	 * '{@code proxy-target-class}' attribute is set to '{@code true}'.
	 * @see AopNamespaceUtils
	 */
	private void configureAutoProxyCreator(ParserContext parserContext, Element element) {
		AopNamespaceUtils.registerAspectJAutoProxyCreatorIfNecessary(parserContext, element);
	}

	
Parses the supplied <advisor> element and registers the resulting Advisor and any resulting Pointcut with the supplied BeanDefinitionRegistry. /**
	 * Parses the supplied {@code <advisor>} element and registers the resulting
	 * {@link org.springframework.aop.Advisor} and any resulting {@link org.springframework.aop.Pointcut}
	 * with the supplied {@link BeanDefinitionRegistry}.
	 */
	private void parseAdvisor(Element advisorElement, ParserContext parserContext) {
		AbstractBeanDefinition advisorDef = createAdvisorBeanDefinition(advisorElement, parserContext);
		String id = advisorElement.getAttribute(ID);

		try {
			this.parseState.push(new AdvisorEntry(id));
			String advisorBeanName = id;
			if (StringUtils.hasText(advisorBeanName)) {
				parserContext.getRegistry().registerBeanDefinition(advisorBeanName, advisorDef);
			}
			else {
				advisorBeanName = parserContext.getReaderContext().registerWithGeneratedName(advisorDef);
			}

			Object pointcut = parsePointcutProperty(advisorElement, parserContext);
			if (pointcut instanceof BeanDefinition) {
				advisorDef.getPropertyValues().add(POINTCUT, pointcut);
				parserContext.registerComponent(
						new AdvisorComponentDefinition(advisorBeanName, advisorDef, (BeanDefinition) pointcut));
			}
			else if (pointcut instanceof String) {
				advisorDef.getPropertyValues().add(POINTCUT, new RuntimeBeanReference((String) pointcut));
				parserContext.registerComponent(
						new AdvisorComponentDefinition(advisorBeanName, advisorDef));
			}
		}
		finally {
			this.parseState.pop();
		}
	}

	
Create a RootBeanDefinition for the advisor described in the supplied. Does not parse any associated 'pointcut' or 'pointcut-ref' attributes. /**
	 * Create a {@link RootBeanDefinition} for the advisor described in the supplied. Does <strong>not</strong>
	 * parse any associated '{@code pointcut}' or '{@code pointcut-ref}' attributes.
	 */
	private AbstractBeanDefinition createAdvisorBeanDefinition(Element advisorElement, ParserContext parserContext) {
		RootBeanDefinition advisorDefinition = new RootBeanDefinition(DefaultBeanFactoryPointcutAdvisor.class);
		advisorDefinition.setSource(parserContext.extractSource(advisorElement));

		String adviceRef = advisorElement.getAttribute(ADVICE_REF);
		if (!StringUtils.hasText(adviceRef)) {
			parserContext.getReaderContext().error(
					"'advice-ref' attribute contains empty value.", advisorElement, this.parseState.snapshot());
		}
		else {
			advisorDefinition.getPropertyValues().add(
					ADVICE_BEAN_NAME, new RuntimeBeanNameReference(adviceRef));
		}

		if (advisorElement.hasAttribute(ORDER_PROPERTY)) {
			advisorDefinition.getPropertyValues().add(
					ORDER_PROPERTY, advisorElement.getAttribute(ORDER_PROPERTY));
		}

		return advisorDefinition;
	}

	private void parseAspect(Element aspectElement, ParserContext parserContext) {
		String aspectId = aspectElement.getAttribute(ID);
		String aspectName = aspectElement.getAttribute(REF);

		try {
			this.parseState.push(new AspectEntry(aspectId, aspectName));
			List<BeanDefinition> beanDefinitions = new ArrayList<>();
			List<BeanReference> beanReferences = new ArrayList<>();

			List<Element> declareParents = DomUtils.getChildElementsByTagName(aspectElement, DECLARE_PARENTS);
			for (int i = METHOD_INDEX; i < declareParents.size(); i++) {
				Element declareParentsElement = declareParents.get(i);
				beanDefinitions.add(parseDeclareParents(declareParentsElement, parserContext));
			}

			// We have to parse "advice" and all the advice kinds in one loop, to get the
			// ordering semantics right.
			NodeList nodeList = aspectElement.getChildNodes();
			boolean adviceFoundAlready = false;
			for (int i = 0; i < nodeList.getLength(); i++) {
				Node node = nodeList.item(i);
				if (isAdviceNode(node, parserContext)) {
					if (!adviceFoundAlready) {
						adviceFoundAlready = true;
						if (!StringUtils.hasText(aspectName)) {
							parserContext.getReaderContext().error(
									"<aspect> tag needs aspect bean reference via 'ref' attribute when declaring advices.",
									aspectElement, this.parseState.snapshot());
							return;
						}
						beanReferences.add(new RuntimeBeanReference(aspectName));
					}
					AbstractBeanDefinition advisorDefinition = parseAdvice(
							aspectName, i, aspectElement, (Element) node, parserContext, beanDefinitions, beanReferences);
					beanDefinitions.add(advisorDefinition);
				}
			}

			AspectComponentDefinition aspectComponentDefinition = createAspectComponentDefinition(
					aspectElement, aspectId, beanDefinitions, beanReferences, parserContext);
			parserContext.pushContainingComponent(aspectComponentDefinition);

			List<Element> pointcuts = DomUtils.getChildElementsByTagName(aspectElement, POINTCUT);
			for (Element pointcutElement : pointcuts) {
				parsePointcut(pointcutElement, parserContext);
			}

			parserContext.popAndRegisterContainingComponent();
		}
		finally {
			this.parseState.pop();
		}
	}

	private AspectComponentDefinition createAspectComponentDefinition(
			Element aspectElement, String aspectId, List<BeanDefinition> beanDefs,
			List<BeanReference> beanRefs, ParserContext parserContext) {

		BeanDefinition[] beanDefArray = beanDefs.toArray(new BeanDefinition[0]);
		BeanReference[] beanRefArray = beanRefs.toArray(new BeanReference[0]);
		Object source = parserContext.extractSource(aspectElement);
		return new AspectComponentDefinition(aspectId, beanDefArray, beanRefArray, source);
	}

	
Return true if the supplied node describes an advice type. May be one of: 'before', 'after', 'after-returning', 'after-throwing' or 'around'. /**
	 * Return {@code true} if the supplied node describes an advice type. May be one of:
	 * '{@code before}', '{@code after}', '{@code after-returning}',
	 * '{@code after-throwing}' or '{@code around}'.
	 */
	private boolean isAdviceNode(Node aNode, ParserContext parserContext) {
		if (!(aNode instanceof Element)) {
			return false;
		}
		else {
			String name = parserContext.getDelegate().getLocalName(aNode);
			return (BEFORE.equals(name) || AFTER.equals(name) || AFTER_RETURNING_ELEMENT.equals(name) ||
					AFTER_THROWING_ELEMENT.equals(name) || AROUND.equals(name));
		}
	}

	
Parse a 'declare-parents' element and register the appropriate DeclareParentsAdvisor with the BeanDefinitionRegistry encapsulated in the supplied ParserContext. /**
	 * Parse a '{@code declare-parents}' element and register the appropriate
	 * DeclareParentsAdvisor with the BeanDefinitionRegistry encapsulated in the
	 * supplied ParserContext.
	 */
	private AbstractBeanDefinition parseDeclareParents(Element declareParentsElement, ParserContext parserContext) {
		BeanDefinitionBuilder builder = BeanDefinitionBuilder.rootBeanDefinition(DeclareParentsAdvisor.class);
		builder.addConstructorArgValue(declareParentsElement.getAttribute(IMPLEMENT_INTERFACE));
		builder.addConstructorArgValue(declareParentsElement.getAttribute(TYPE_PATTERN));

		String defaultImpl = declareParentsElement.getAttribute(DEFAULT_IMPL);
		String delegateRef = declareParentsElement.getAttribute(DELEGATE_REF);

		if (StringUtils.hasText(defaultImpl) && !StringUtils.hasText(delegateRef)) {
			builder.addConstructorArgValue(defaultImpl);
		}
		else if (StringUtils.hasText(delegateRef) && !StringUtils.hasText(defaultImpl)) {
			builder.addConstructorArgReference(delegateRef);
		}
		else {
			parserContext.getReaderContext().error(
					"Exactly one of the " + DEFAULT_IMPL + " or " + DELEGATE_REF + " attributes must be specified",
					declareParentsElement, this.parseState.snapshot());
		}

		AbstractBeanDefinition definition = builder.getBeanDefinition();
		definition.setSource(parserContext.extractSource(declareParentsElement));
		parserContext.getReaderContext().registerWithGeneratedName(definition);
		return definition;
	}

	
Parses one of 'before', 'after', 'after-returning', 'after-throwing' or 'around' and registers the resulting BeanDefinition with the supplied BeanDefinitionRegistry. 
Returns:
the generated advice RootBeanDefinition/**
	 * Parses one of '{@code before}', '{@code after}', '{@code after-returning}',
	 * '{@code after-throwing}' or '{@code around}' and registers the resulting
	 * BeanDefinition with the supplied BeanDefinitionRegistry.
	 * @return the generated advice RootBeanDefinition
	 */
	private AbstractBeanDefinition parseAdvice(
			String aspectName, int order, Element aspectElement, Element adviceElement, ParserContext parserContext,
			List<BeanDefinition> beanDefinitions, List<BeanReference> beanReferences) {

		try {
			this.parseState.push(new AdviceEntry(parserContext.getDelegate().getLocalName(adviceElement)));

			// create the method factory bean
			RootBeanDefinition methodDefinition = new RootBeanDefinition(MethodLocatingFactoryBean.class);
			methodDefinition.getPropertyValues().add("targetBeanName", aspectName);
			methodDefinition.getPropertyValues().add("methodName", adviceElement.getAttribute("method"));
			methodDefinition.setSynthetic(true);

			// create instance factory definition
			RootBeanDefinition aspectFactoryDef =
					new RootBeanDefinition(SimpleBeanFactoryAwareAspectInstanceFactory.class);
			aspectFactoryDef.getPropertyValues().add("aspectBeanName", aspectName);
			aspectFactoryDef.setSynthetic(true);

			// register the pointcut
			AbstractBeanDefinition adviceDef = createAdviceDefinition(
					adviceElement, parserContext, aspectName, order, methodDefinition, aspectFactoryDef,
					beanDefinitions, beanReferences);

			// configure the advisor
			RootBeanDefinition advisorDefinition = new RootBeanDefinition(AspectJPointcutAdvisor.class);
			advisorDefinition.setSource(parserContext.extractSource(adviceElement));
			advisorDefinition.getConstructorArgumentValues().addGenericArgumentValue(adviceDef);
			if (aspectElement.hasAttribute(ORDER_PROPERTY)) {
				advisorDefinition.getPropertyValues().add(
						ORDER_PROPERTY, aspectElement.getAttribute(ORDER_PROPERTY));
			}

			// register the final advisor
			parserContext.getReaderContext().registerWithGeneratedName(advisorDefinition);

			return advisorDefinition;
		}
		finally {
			this.parseState.pop();
		}
	}

	
Creates the RootBeanDefinition for a POJO advice bean. Also causes pointcut
parsing to occur so that the pointcut may be associate with the advice bean.
This same pointcut is also configured as the pointcut for the enclosing
Advisor definition using the supplied MutablePropertyValues.
/**
	 * Creates the RootBeanDefinition for a POJO advice bean. Also causes pointcut
	 * parsing to occur so that the pointcut may be associate with the advice bean.
	 * This same pointcut is also configured as the pointcut for the enclosing
	 * Advisor definition using the supplied MutablePropertyValues.
	 */
	private AbstractBeanDefinition createAdviceDefinition(
			Element adviceElement, ParserContext parserContext, String aspectName, int order,
			RootBeanDefinition methodDef, RootBeanDefinition aspectFactoryDef,
			List<BeanDefinition> beanDefinitions, List<BeanReference> beanReferences) {

		RootBeanDefinition adviceDefinition = new RootBeanDefinition(getAdviceClass(adviceElement, parserContext));
		adviceDefinition.setSource(parserContext.extractSource(adviceElement));

		adviceDefinition.getPropertyValues().add(ASPECT_NAME_PROPERTY, aspectName);
		adviceDefinition.getPropertyValues().add(DECLARATION_ORDER_PROPERTY, order);

		if (adviceElement.hasAttribute(RETURNING)) {
			adviceDefinition.getPropertyValues().add(
					RETURNING_PROPERTY, adviceElement.getAttribute(RETURNING));
		}
		if (adviceElement.hasAttribute(THROWING)) {
			adviceDefinition.getPropertyValues().add(
					THROWING_PROPERTY, adviceElement.getAttribute(THROWING));
		}
		if (adviceElement.hasAttribute(ARG_NAMES)) {
			adviceDefinition.getPropertyValues().add(
					ARG_NAMES_PROPERTY, adviceElement.getAttribute(ARG_NAMES));
		}

		ConstructorArgumentValues cav = adviceDefinition.getConstructorArgumentValues();
		cav.addIndexedArgumentValue(METHOD_INDEX, methodDef);

		Object pointcut = parsePointcutProperty(adviceElement, parserContext);
		if (pointcut instanceof BeanDefinition) {
			cav.addIndexedArgumentValue(POINTCUT_INDEX, pointcut);
			beanDefinitions.add((BeanDefinition) pointcut);
		}
		else if (pointcut instanceof String) {
			RuntimeBeanReference pointcutRef = new RuntimeBeanReference((String) pointcut);
			cav.addIndexedArgumentValue(POINTCUT_INDEX, pointcutRef);
			beanReferences.add(pointcutRef);
		}

		cav.addIndexedArgumentValue(ASPECT_INSTANCE_FACTORY_INDEX, aspectFactoryDef);

		return adviceDefinition;
	}

	
Gets the advice implementation class corresponding to the supplied Element. /**
	 * Gets the advice implementation class corresponding to the supplied {@link Element}.
	 */
	private Class<?> getAdviceClass(Element adviceElement, ParserContext parserContext) {
		String elementName = parserContext.getDelegate().getLocalName(adviceElement);
		if (BEFORE.equals(elementName)) {
			return AspectJMethodBeforeAdvice.class;
		}
		else if (AFTER.equals(elementName)) {
			return AspectJAfterAdvice.class;
		}
		else if (AFTER_RETURNING_ELEMENT.equals(elementName)) {
			return AspectJAfterReturningAdvice.class;
		}
		else if (AFTER_THROWING_ELEMENT.equals(elementName)) {
			return AspectJAfterThrowingAdvice.class;
		}
		else if (AROUND.equals(elementName)) {
			return AspectJAroundAdvice.class;
		}
		else {
			throw new IllegalArgumentException("Unknown advice kind [" + elementName + "].");
		}
	}

	
Parses the supplied <pointcut> and registers the resulting Pointcut with the BeanDefinitionRegistry. /**
	 * Parses the supplied {@code <pointcut>} and registers the resulting
	 * Pointcut with the BeanDefinitionRegistry.
	 */
	private AbstractBeanDefinition parsePointcut(Element pointcutElement, ParserContext parserContext) {
		String id = pointcutElement.getAttribute(ID);
		String expression = pointcutElement.getAttribute(EXPRESSION);

		AbstractBeanDefinition pointcutDefinition = null;

		try {
			this.parseState.push(new PointcutEntry(id));
			pointcutDefinition = createPointcutDefinition(expression);
			pointcutDefinition.setSource(parserContext.extractSource(pointcutElement));

			String pointcutBeanName = id;
			if (StringUtils.hasText(pointcutBeanName)) {
				parserContext.getRegistry().registerBeanDefinition(pointcutBeanName, pointcutDefinition);
			}
			else {
				pointcutBeanName = parserContext.getReaderContext().registerWithGeneratedName(pointcutDefinition);
			}

			parserContext.registerComponent(
					new PointcutComponentDefinition(pointcutBeanName, pointcutDefinition, expression));
		}
		finally {
			this.parseState.pop();
		}

		return pointcutDefinition;
	}

	
Parses the pointcut or pointcut-ref attributes of the supplied Element and add a pointcut property as appropriate. Generates a BeanDefinition for the pointcut if necessary and returns its bean name, otherwise returns the bean name of the referred pointcut. /**
	 * Parses the {@code pointcut} or {@code pointcut-ref} attributes of the supplied
	 * {@link Element} and add a {@code pointcut} property as appropriate. Generates a
	 * {@link org.springframework.beans.factory.config.BeanDefinition} for the pointcut if  necessary
	 * and returns its bean name, otherwise returns the bean name of the referred pointcut.
	 */
	@Nullable
	private Object parsePointcutProperty(Element element, ParserContext parserContext) {
		if (element.hasAttribute(POINTCUT) && element.hasAttribute(POINTCUT_REF)) {
			parserContext.getReaderContext().error(
					"Cannot define both 'pointcut' and 'pointcut-ref' on <advisor> tag.",
					element, this.parseState.snapshot());
			return null;
		}
		else if (element.hasAttribute(POINTCUT)) {
			// Create a pointcut for the anonymous pc and register it.
			String expression = element.getAttribute(POINTCUT);
			AbstractBeanDefinition pointcutDefinition = createPointcutDefinition(expression);
			pointcutDefinition.setSource(parserContext.extractSource(element));
			return pointcutDefinition;
		}
		else if (element.hasAttribute(POINTCUT_REF)) {
			String pointcutRef = element.getAttribute(POINTCUT_REF);
			if (!StringUtils.hasText(pointcutRef)) {
				parserContext.getReaderContext().error(
						"'pointcut-ref' attribute contains empty value.", element, this.parseState.snapshot());
				return null;
			}
			return pointcutRef;
		}
		else {
			parserContext.getReaderContext().error(
					"Must define one of 'pointcut' or 'pointcut-ref' on <advisor> tag.",
					element, this.parseState.snapshot());
			return null;
		}
	}

	
Creates a BeanDefinition for the AspectJExpressionPointcut class using the supplied pointcut expression. /**
	 * Creates a {@link BeanDefinition} for the {@link AspectJExpressionPointcut} class using
	 * the supplied pointcut expression.
	 */
	protected AbstractBeanDefinition createPointcutDefinition(String expression) {
		RootBeanDefinition beanDefinition = new RootBeanDefinition(AspectJExpressionPointcut.class);
		beanDefinition.setScope(BeanDefinition.SCOPE_PROTOTYPE);
		beanDefinition.setSynthetic(true);
		beanDefinition.getPropertyValues().add(EXPRESSION, expression);
		return beanDefinition;
	}

}