/*
 * Copyright 2002-2004 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.view.tiles;

import org.apache.struts.tiles.DefinitionsFactory;
import org.apache.struts.tiles.DefinitionsFactoryConfig;
import org.apache.struts.tiles.DefinitionsFactoryException;
import org.apache.struts.tiles.TilesUtil;
import org.apache.struts.tiles.TilesUtilImpl;
import org.apache.struts.tiles.xmlDefinition.I18nFactorySet;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.util.StringUtils;
import org.springframework.web.context.support.WebApplicationObjectSupport;

/**
 * Helper class to configure Tiles for the Spring Framework. See
 * <a href="http://jakarta.apache.org/struts">http://jakarta.apache.org/struts</a>
 * for more information about Tiles, which basically is a templating mechanism
 * for JSP-based web applications.
 *
 * <p>The TilesConfigurer simply configures a Tiles DefinitionsFactory using a
 * set of files containing definitions, to be accessed by TilesView instances.
 * TilesViews can be managed by any ViewResolver.
 *
 * <p>A typical TilesConfigurer bean definition looks as follows:
 *
 * <pre>
 * <bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles.TilesConfigurer">
 *   <property name="definitions">
 *     <list>
 *       <value>/WEB-INF/defs/general.xml</value>
 *       <value>/WEB-INF/defs/widgets.xml</value>
 *       <value>/WEB-INF/defs/administrator.xml</value>
 *       <value>/WEB-INF/defs/customer.xml</value>
 *       <value>/WEB-INF/defs/templates.xml</value>
 *     </list>
 *   </property>
 * </bean></pre>
 *
 * The values in the list are the actual files containing the definitions.
 *
 * @author Alef Arendsen
 * @author Juergen Hoeller
 * @see TilesView
 * @see org.springframework.web.servlet.ViewResolver
 */
public class TilesConfigurer extends WebApplicationObjectSupport implements InitializingBean {

	/** factory class for Tiles */
	private Class factoryClass = I18nFactorySet.class;

	/** validate the Tiles definitions? */
	private boolean validateDefinitions = true;

	/** definition URLs mapped to descriptions */
	private String[] definitions;

	/**
	 * Set the factory class for Tiles. Default is I18nFactorySet.
	 * @see org.apache.struts.tiles.xmlDefinition.I18nFactorySet
	 */
	public void setFactoryClass(Class factoryClass) {
		this.factoryClass = factoryClass;
	}

	/**
	 * Validate the Tiles definitions? Default is false.
	 * @param validateDefinitions <code>true</code> to validate,
	 * <code>false</code> otherwise
	 */
	public void setValidateDefinitions(boolean validateDefinitions) {
		this.validateDefinitions = validateDefinitions;
	}

	/**
	 * Set the Tiles definitions, i.e. the list of files.
	 * @param definitions the files containing the definitions
	 */
	public void setDefinitions(String[] definitions) {
		this.definitions = definitions;
	}

	/**
	 * Initialize the Tiles definition factory.
	 * Delegates to createDefinitionsFactory for the actual creation.
	 * @throws DefinitionsFactoryException if an error occurs
	 * @see #createDefinitionsFactory
	 */
	public void afterPropertiesSet() throws DefinitionsFactoryException {
		logger.info("TilesConfigurer: initializion started");

		// initialize the configuration for the definitions factory
		DefinitionsFactoryConfig factoryConfig = new DefinitionsFactoryConfig();
		factoryConfig.setFactoryClassname(this.factoryClass.getName());
		factoryConfig.setParserValidate(this.validateDefinitions);

		if (this.definitions != null) {
			String defs = StringUtils.arrayToCommaDelimitedString(this.definitions);
			logger.info("TilesConfigurer: adding definitions [" + defs + "]");
			factoryConfig.setDefinitionConfigFiles(defs);
		}

		// initialize the definitions factory
		DefinitionsFactory factory = createDefinitionsFactory(factoryConfig);
		getServletContext().setAttribute(TilesUtilImpl.DEFINITIONS_FACTORY, factory);

		logger.info("TilesConfigurer: initialization completed");
	}

	/**
	 * Create the Tiles DefinitionsFactory.
	 * @param factoryConfig the configuration for the DefinitionsFactory
	 * @return the DefinitionsFactory
	 * @throws DefinitionsFactoryException if an error occurs
	 */
	protected DefinitionsFactory createDefinitionsFactory(DefinitionsFactoryConfig factoryConfig)
			throws DefinitionsFactoryException {
		return TilesUtil.createDefinitionsFactory(getServletContext(), factoryConfig);
	}

}