/*
 * Copyright 2002-2008 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.jsf.el;

import javax.el.ELContext;
import javax.faces.context.FacesContext;

import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.access.el.SpringBeanELResolver;
import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.jsf.FacesContextUtils;

/**
 * JSF 1.2 <code>ELResolver</code> that delegates to the Spring root
 * <code>WebApplicationContext</code>, resolving name references to
 * Spring-defined beans.
 *
 * <p>Configure this resolver in your <code>faces-config.xml</code> file as follows:
 *
 * <pre>
 * <application>
 *   ...
 *   <el-resolver>org.springframework.web.jsf.el.SpringBeanFacesELResolver</el-resolver>
 * </application></pre>
 *
 * All your JSF expressions can then implicitly refer to the names of
 * Spring-managed service layer beans, for example in property values of
 * JSF-managed beans:
 *
 * <pre>
 * <managed-bean>
 *   <managed-bean-name>myJsfManagedBean</managed-bean-name>
 *   <managed-bean-class>example.MyJsfManagedBean</managed-bean-class>
 *   <managed-bean-scope>session</managed-bean-scope>
 *   <managed-property>
 *     <property-name>mySpringManagedBusinessObject</property-name>
 *     <value>#{mySpringManagedBusinessObject}</value>
 *   </managed-property>
 * </managed-bean></pre>
 *
 * with "mySpringManagedBusinessObject" defined as Spring bean in
 * applicationContext.xml:
 *
 * <pre>
 * <bean id="mySpringManagedBusinessObject" class="example.MySpringManagedBusinessObject">
 *   ...
 * </bean></pre>
 *
 * @author Juergen Hoeller
 * @since 2.5
 * @see WebApplicationContextFacesELResolver
 * @see org.springframework.web.jsf.FacesContextUtils#getRequiredWebApplicationContext
 */
public class SpringBeanFacesELResolver extends SpringBeanELResolver {

	/**
	 * This implementation delegates to {@link #getWebApplicationContext}.
	 * Can be overridden to provide an arbitrary BeanFactory reference to resolve
	 * against; usually, this will be a full Spring ApplicationContext.
	 * @param elContext the current JSF ELContext
	 * @return the Spring BeanFactory (never <code>null</code>)
	 */
	protected BeanFactory getBeanFactory(ELContext elContext) {
		return getWebApplicationContext(elContext);
	}

	/**
	 * Retrieve the web application context to delegate bean name resolution to.
	 * <p>The default implementation delegates to FacesContextUtils.
	 * @param elContext the current JSF ELContext
	 * @return the Spring web application context (never <code>null</code>)
	 * @see org.springframework.web.jsf.FacesContextUtils#getRequiredWebApplicationContext
	 */
	protected WebApplicationContext getWebApplicationContext(ELContext elContext) {
		FacesContext facesContext = FacesContext.getCurrentInstance();
		return FacesContextUtils.getRequiredWebApplicationContext(facesContext);
	}

}