/*
 * 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
 *
 *      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.scripting.config;

import java.util.List;

import org.w3c.dom.Element;

import org.springframework.beans.factory.config.ConstructorArgumentValues;
import org.springframework.beans.factory.config.RuntimeBeanReference;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.beans.factory.support.BeanDefinitionDefaults;
import org.springframework.beans.factory.support.GenericBeanDefinition;
import org.springframework.beans.factory.xml.AbstractBeanDefinitionParser;
import org.springframework.beans.factory.xml.BeanDefinitionParserDelegate;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.beans.factory.xml.XmlReaderContext;
import org.springframework.scripting.support.ScriptFactoryPostProcessor;
import org.springframework.util.StringUtils;
import org.springframework.util.xml.DomUtils;

/**
 * BeanDefinitionParser implementation for the '{@code <lang:groovy/>}',
 * '{@code <lang:std/>}' and '{@code <lang:bsh/>}' tags.
 * Allows for objects written using dynamic languages to be easily exposed with
 * the {@link org.springframework.beans.factory.BeanFactory}.
 *
 * <p>The script for each object can be specified either as a reference to the
 * resource containing it (using the '{@code script-source}' attribute) or inline
 * in the XML configuration itself (using the '{@code inline-script}' attribute.
 *
 * <p>By default, dynamic objects created with these tags are <strong>not</strong>
 * refreshable. To enable refreshing, specify the refresh check delay for each
 * object (in milliseconds) using the '{@code refresh-check-delay}' attribute.
 *
 * @author Rob Harrop
 * @author Rod Johnson
 * @author Juergen Hoeller
 * @author Mark Fisher
 * @since 2.0
 */
class ScriptBeanDefinitionParser extends AbstractBeanDefinitionParser {

	private static final String ENGINE_ATTRIBUTE = "engine";

	private static final String SCRIPT_SOURCE_ATTRIBUTE = "script-source";

	private static final String INLINE_SCRIPT_ELEMENT = "inline-script";

	private static final String SCOPE_ATTRIBUTE = "scope";

	private static final String AUTOWIRE_ATTRIBUTE = "autowire";

	private static final String DEPENDS_ON_ATTRIBUTE = "depends-on";

	private static final String INIT_METHOD_ATTRIBUTE = "init-method";

	private static final String DESTROY_METHOD_ATTRIBUTE = "destroy-method";

	private static final String SCRIPT_INTERFACES_ATTRIBUTE = "script-interfaces";

	private static final String REFRESH_CHECK_DELAY_ATTRIBUTE = "refresh-check-delay";

	private static final String PROXY_TARGET_CLASS_ATTRIBUTE = "proxy-target-class";

	private static final String CUSTOMIZER_REF_ATTRIBUTE = "customizer-ref";


	/**
	 * The {@link org.springframework.scripting.ScriptFactory} class that this
	 * parser instance will create bean definitions for.
	 */
	private final String scriptFactoryClassName;


	/**
	 * Create a new instance of this parser, creating bean definitions for the
	 * supplied {@link org.springframework.scripting.ScriptFactory} class.
	 * @param scriptFactoryClassName the ScriptFactory class to operate on
	 */
	public ScriptBeanDefinitionParser(String scriptFactoryClassName) {
		this.scriptFactoryClassName = scriptFactoryClassName;
	}


	/**
	 * Parses the dynamic object element and returns the resulting bean definition.
	 * Registers a {@link ScriptFactoryPostProcessor} if needed.
	 */
	@Override
	@SuppressWarnings("deprecation")
	protected AbstractBeanDefinition parseInternal(Element element, ParserContext parserContext) {
		// Engine attribute only supported for <lang:std>
		String engine = element.getAttribute(ENGINE_ATTRIBUTE);

		// Resolve the script source.
		String value = resolveScriptSource(element, parserContext.getReaderContext());
		if (value == null) {
			return null;
		}

		// Set up infrastructure.
		LangNamespaceUtils.registerScriptFactoryPostProcessorIfNecessary(parserContext.getRegistry());

		// Create script factory bean definition.
		GenericBeanDefinition bd = new GenericBeanDefinition();
		bd.setBeanClassName(this.scriptFactoryClassName);
		bd.setSource(parserContext.extractSource(element));
		bd.setAttribute(ScriptFactoryPostProcessor.LANGUAGE_ATTRIBUTE, element.getLocalName());

		// Determine bean scope.
		String scope = element.getAttribute(SCOPE_ATTRIBUTE);
		if (StringUtils.hasLength(scope)) {
			bd.setScope(scope);
		}

		// Determine autowire mode.
		String autowire = element.getAttribute(AUTOWIRE_ATTRIBUTE);
		int autowireMode = parserContext.getDelegate().getAutowireMode(autowire);
		// Only "byType" and "byName" supported, but maybe other default inherited...
		if (autowireMode == GenericBeanDefinition.AUTOWIRE_AUTODETECT) {
			autowireMode = GenericBeanDefinition.AUTOWIRE_BY_TYPE;
		}
		else if (autowireMode == GenericBeanDefinition.AUTOWIRE_CONSTRUCTOR) {
			autowireMode = GenericBeanDefinition.AUTOWIRE_NO;
		}
		bd.setAutowireMode(autowireMode);

		// Parse depends-on list of bean names.
		String dependsOn = element.getAttribute(DEPENDS_ON_ATTRIBUTE);
		if (StringUtils.hasLength(dependsOn)) {
			bd.setDependsOn(StringUtils.tokenizeToStringArray(
					dependsOn, BeanDefinitionParserDelegate.MULTI_VALUE_ATTRIBUTE_DELIMITERS));
		}

		// Retrieve the defaults for bean definitions within this parser context
		BeanDefinitionDefaults beanDefinitionDefaults = parserContext.getDelegate().getBeanDefinitionDefaults();

		// Determine init method and destroy method.
		String initMethod = element.getAttribute(INIT_METHOD_ATTRIBUTE);
		if (StringUtils.hasLength(initMethod)) {
			bd.setInitMethodName(initMethod);
		}
		else if (beanDefinitionDefaults.getInitMethodName() != null) {
			bd.setInitMethodName(beanDefinitionDefaults.getInitMethodName());
		}

		if (element.hasAttribute(DESTROY_METHOD_ATTRIBUTE)) {
			String destroyMethod = element.getAttribute(DESTROY_METHOD_ATTRIBUTE);
			bd.setDestroyMethodName(destroyMethod);
		}
		else if (beanDefinitionDefaults.getDestroyMethodName() != null) {
			bd.setDestroyMethodName(beanDefinitionDefaults.getDestroyMethodName());
		}

		// Attach any refresh metadata.
		String refreshCheckDelay = element.getAttribute(REFRESH_CHECK_DELAY_ATTRIBUTE);
		if (StringUtils.hasText(refreshCheckDelay)) {
			bd.setAttribute(ScriptFactoryPostProcessor.REFRESH_CHECK_DELAY_ATTRIBUTE, Long.valueOf(refreshCheckDelay));
		}

		// Attach any proxy target class metadata.
		String proxyTargetClass = element.getAttribute(PROXY_TARGET_CLASS_ATTRIBUTE);
		if (StringUtils.hasText(proxyTargetClass)) {
			bd.setAttribute(ScriptFactoryPostProcessor.PROXY_TARGET_CLASS_ATTRIBUTE, Boolean.valueOf(proxyTargetClass));
		}

		// Add constructor arguments.
		ConstructorArgumentValues cav = bd.getConstructorArgumentValues();
		int constructorArgNum = 0;
		if (StringUtils.hasLength(engine)) {
			cav.addIndexedArgumentValue(constructorArgNum++, engine);
		}
		cav.addIndexedArgumentValue(constructorArgNum++, value);
		if (element.hasAttribute(SCRIPT_INTERFACES_ATTRIBUTE)) {
			cav.addIndexedArgumentValue(
					constructorArgNum++, element.getAttribute(SCRIPT_INTERFACES_ATTRIBUTE), "java.lang.Class[]");
		}

		// This is used for Groovy. It's a bean reference to a customizer bean.
		if (element.hasAttribute(CUSTOMIZER_REF_ATTRIBUTE)) {
			String customizerBeanName = element.getAttribute(CUSTOMIZER_REF_ATTRIBUTE);
			if (!StringUtils.hasText(customizerBeanName)) {
				parserContext.getReaderContext().error("Attribute 'customizer-ref' has empty value", element);
			}
			else {
				cav.addIndexedArgumentValue(constructorArgNum++, new RuntimeBeanReference(customizerBeanName));
			}
		}

		// Add any property definitions that need adding.
		parserContext.getDelegate().parsePropertyElements(element, bd);

		return bd;
	}

	/**
	 * Resolves the script source from either the '{@code script-source}' attribute or
	 * the '{@code inline-script}' element. Logs and {@link XmlReaderContext#error} and
	 * returns {@code null} if neither or both of these values are specified.
	 */
	private String resolveScriptSource(Element element, XmlReaderContext readerContext) {
		boolean hasScriptSource = element.hasAttribute(SCRIPT_SOURCE_ATTRIBUTE);
		List<Element> elements = DomUtils.getChildElementsByTagName(element, INLINE_SCRIPT_ELEMENT);
		if (hasScriptSource && !elements.isEmpty()) {
			readerContext.error("Only one of 'script-source' and 'inline-script' should be specified.", element);
			return null;
		}
		else if (hasScriptSource) {
			return element.getAttribute(SCRIPT_SOURCE_ATTRIBUTE);
		}
		else if (!elements.isEmpty()) {
			Element inlineElement = elements.get(0);
			return "inline:" + DomUtils.getTextValue(inlineElement);
		}
		else {
			readerContext.error("Must specify either 'script-source' or 'inline-script'.", element);
			return null;
		}
	}

	/**
	 * Scripted beans may be anonymous as well.
	 */
	@Override
	protected boolean shouldGenerateIdAsFallback() {
		return true;
	}

}
