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/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.spring;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Collections;
import java.util.List;
import java.util.Map;

import org.directwebremoting.Container;
import org.directwebremoting.impl.DefaultContainer;
import org.directwebremoting.util.Logger;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.BeanFactoryAware;
import org.springframework.beans.factory.InitializingBean;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.util.ClassUtils;

/**
 * A Container implementation that looks up all beans from the
 * configuration specified in a Spring context.
 * It loads the configuration from a Spring web application context.
 * @author Bram Smeets
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class SpringContainer extends DefaultContainer implements Container, BeanFactoryAware, InitializingBean
{
    /* (non-Javadoc)
     * @see org.springframework.beans.factory.BeanFactoryAware#setBeanFactory(org.springframework.beans.factory.BeanFactory)
     */
    public void setBeanFactory(BeanFactory beanFactory) throws BeansException
    {
        this.beanFactory = beanFactory;
    }

    public void addParameter(Object askFor, Object valueParam)
    throws InstantiationException, IllegalAccessException {
        try {
            Class clz = ClassUtils.forName((String)askFor);
            if (log.isDebugEnabled()) {
                log.debug("trying to resolve the following class from the Spring bean container: " + clz.getName());
            }

            Map beansOfType = ((ListableBeanFactory)beanFactory).getBeansOfType(clz);
            if (log.isDebugEnabled()) {
                log.debug("beans: " + beansOfType + " - " + beansOfType.size());
            }
            if (beansOfType.size() == 0) {
                log.debug("adding parameter the normal way");
                super.addParameter(askFor, valueParam);
            } else if (beansOfType.size() > 1) {
                // TODO: handle multiple declarations
                throw new InstantiationException("multiple beans of type '" + clz.getName() + "' were found in the spring configuration");
            } else {
                this.beans.put(askFor, beansOfType.values().iterator().next());
            }
        } catch (ClassNotFoundException e) {
            super.addParameter(askFor, valueParam);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.impl.DefaultContainer#getBean(java.lang.String)
     */
    public Object getBean(String id)
    {
        Object reply;
        try {
            reply = beanFactory.getBean(id);
        }
        catch (BeansException ex)
        {
            // Spring throws on not-found, we return null.
            reply = super.getBean(id);
        }

        return reply;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.impl.DefaultContainer#getBeanNames()
     */
    public Collection getBeanNames()
    {
        List names = new ArrayList();

        // Snarf the beans from Spring
        if (beanFactory instanceof ListableBeanFactory)
        {
            ListableBeanFactory listable = (ListableBeanFactory) beanFactory;
            names.addAll(Arrays.asList(listable.getBeanDefinitionNames()));
        }
        else
        {
            log.warn("List of beanNames does not include Spring beans since your BeanFactory is not a ListableBeanFactory.");
        }

        // And append the DWR ones
        names.addAll(super.getBeanNames());

        return Collections.unmodifiableCollection(names);
    }

    /* (non-Javadoc)
     * @see org.springframework.beans.factory.InitializingBean#afterPropertiesSet()
     */
    public void afterPropertiesSet() throws Exception
    {
        callInitializingBeans();
    }

    /**
     * The Spring BeanFactory that we read from
     */
    protected BeanFactory beanFactory;

    /**
     * The log stream
     */
    private static final Logger log = Logger.getLogger(SpringContainer.class);
}