/*
 * Copyright 2002-2013 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.web.servlet.config;

import java.util.Arrays;
import java.util.Map;

import org.w3c.dom.Element;

import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.parsing.BeanComponentDefinition;
import org.springframework.beans.factory.support.ManagedList;
import org.springframework.beans.factory.support.ManagedMap;
import org.springframework.beans.factory.support.RootBeanDefinition;
import org.springframework.beans.factory.xml.BeanDefinitionParser;
import org.springframework.beans.factory.xml.ParserContext;
import org.springframework.core.Ordered;
import org.springframework.util.StringUtils;
import org.springframework.web.servlet.handler.SimpleUrlHandlerMapping;
import org.springframework.web.servlet.mvc.HttpRequestHandlerAdapter;
import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;

/**
 * {@link org.springframework.beans.factory.xml.BeanDefinitionParser} that parses a
 * {@code resources} element to register a {@link ResourceHttpRequestHandler}.
 * Will also register a {@link SimpleUrlHandlerMapping} for mapping resource requests,
 * and a {@link HttpRequestHandlerAdapter}.
 *
 * @author Keith Donald
 * @author Jeremy Grelle
 * @since 3.0.4
 */
class ResourcesBeanDefinitionParser implements BeanDefinitionParser {

	public BeanDefinition parse(Element element, ParserContext parserContext) {
		Object source = parserContext.extractSource(element);

		String resourceHandlerName = registerResourceHandler(parserContext, element, source);
		if (resourceHandlerName == null) {
			return null;
		}

		Map<String, String> urlMap = new ManagedMap<String, String>();
		String resourceRequestPath = element.getAttribute("mapping");
		if (!StringUtils.hasText(resourceRequestPath)) {
			parserContext.getReaderContext().error("The 'mapping' attribute is required.", parserContext.extractSource(element));
			return null;
		}
		urlMap.put(resourceRequestPath, resourceHandlerName);

		RootBeanDefinition handlerMappingDef = new RootBeanDefinition(SimpleUrlHandlerMapping.class);
		handlerMappingDef.setSource(source);
		handlerMappingDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		handlerMappingDef.getPropertyValues().add("urlMap", urlMap);

		String order = element.getAttribute("order");
		// use a default of near-lowest precedence, still allowing for even lower precedence in other mappings
		handlerMappingDef.getPropertyValues().add("order", StringUtils.hasText(order) ? order : Ordered.LOWEST_PRECEDENCE - 1);

		String beanName = parserContext.getReaderContext().generateBeanName(handlerMappingDef);
		parserContext.getRegistry().registerBeanDefinition(beanName, handlerMappingDef);
		parserContext.registerComponent(new BeanComponentDefinition(handlerMappingDef, beanName));

		// Ensure BeanNameUrlHandlerMapping (SPR-8289) and default HandlerAdapters are not "turned off"
		// Register HttpRequestHandlerAdapter
		MvcNamespaceUtils.registerDefaultComponents(parserContext, source);

		return null;
	}

	private String registerResourceHandler(ParserContext parserContext, Element element, Object source) {
		String locationAttr = element.getAttribute("location");
		if (!StringUtils.hasText(locationAttr)) {
			parserContext.getReaderContext().error("The 'location' attribute is required.", parserContext.extractSource(element));
			return null;
		}

		ManagedList<String> locations = new ManagedList<String>();
		locations.addAll(Arrays.asList(StringUtils.commaDelimitedListToStringArray(locationAttr)));

		RootBeanDefinition resourceHandlerDef = new RootBeanDefinition(ResourceHttpRequestHandler.class);
		resourceHandlerDef.setSource(source);
		resourceHandlerDef.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
		resourceHandlerDef.getPropertyValues().add("locations", locations);

		String cacheSeconds = element.getAttribute("cache-period");
		if (StringUtils.hasText(cacheSeconds)) {
			resourceHandlerDef.getPropertyValues().add("cacheSeconds", cacheSeconds);
		}

		String beanName = parserContext.getReaderContext().generateBeanName(resourceHandlerDef);
		parserContext.getRegistry().registerBeanDefinition(beanName, resourceHandlerDef);
		parserContext.registerComponent(new BeanComponentDefinition(resourceHandlerDef, beanName));
		return beanName;
	}

}
