/*
 * 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.beans.factory.generic;

import java.lang.annotation.Annotation;
import java.util.LinkedHashMap;
import java.util.Map;

import org.springframework.beans.BeansException;
import org.springframework.beans.factory.ListableBeanFactory;
import org.springframework.beans.factory.config.BeanDefinition;
import org.springframework.beans.factory.config.ConfigurableBeanFactory;
import org.springframework.beans.factory.support.AbstractBeanDefinition;
import org.springframework.core.annotation.AnnotationUtils;
import org.springframework.util.Assert;

/**
 * Simple wrapper around a {@link ListableBeanFactory} that provides typed, generics-based
 * access to key methods. This removes the need for casting in many cases and should
 * increase compile-time type safety.
 *
 * <p>Provides a simple mechanism for accessing all beans with a particular {@link Annotation}.
 *
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 2.0
 */
public class GenericBeanFactoryAccessor {

	/**
	 * The {@link ListableBeanFactory} being wrapped.
	 */
	private final ListableBeanFactory beanFactory;


	/**
	 * Constructs a <code>GenericBeanFactoryAccessor</code> that wraps the supplied {@link ListableBeanFactory}.
	 */
	public GenericBeanFactoryAccessor(ListableBeanFactory beanFactory) {
		Assert.notNull(beanFactory, "Bean factory must not be null");
		this.beanFactory = beanFactory;
	}

	/**
	 * Return the wrapped {@link ListableBeanFactory}.
	 */
	public final ListableBeanFactory getBeanFactory() {
		return this.beanFactory;
	}


	/**
	 * @see org.springframework.beans.factory.BeanFactory#getBean(String)
	 */
	public <T> T getBean(String name) throws BeansException {
		return (T) this.beanFactory.getBean(name);
	}

	/**
	 * @see org.springframework.beans.factory.BeanFactory#getBean(String, Class)
	 */
	public <T> T getBean(String name, Class<T> requiredType) throws BeansException {
		return (T) this.beanFactory.getBean(name, requiredType);
	}

	/**
	 * @see ListableBeanFactory#getBeansOfType(Class)
	 */
	public <T> Map<String, T> getBeansOfType(Class<T> type) throws BeansException {
		return this.beanFactory.getBeansOfType(type);
	}

	/**
	 * @see ListableBeanFactory#getBeansOfType(Class, boolean, boolean)
	 */
	public <T> Map<String, T> getBeansOfType(Class<T> type, boolean includeNonSingletons, boolean allowEagerInit)
			throws BeansException {

		return this.beanFactory.getBeansOfType(type, includeNonSingletons, allowEagerInit);
	}

	/**
	 * Find all beans whose <code>Class</code> has the supplied {@link Annotation} type.
	 * @param annotationType the type of annotation to look for
	 * @return a Map with the matching beans, containing the bean names as
	 * keys and the corresponding bean instances as values
	 */
	public Map<String, Object> getBeansWithAnnotation(Class<? extends Annotation> annotationType) {
		Map<String, Object> results = new LinkedHashMap<String, Object>();
		for (String beanName : this.beanFactory.getBeanNamesForType(Object.class)) {
			if (findAnnotationOnBean(beanName, annotationType) != null) {
				results.put(beanName, this.beanFactory.getBean(beanName));
			}
		}
		return results;
	}

	/**
	 * Find a {@link Annotation} of <code>annotationType</code> on the specified
	 * bean, traversing its interfaces and super classes if no annotation can be
	 * found on the given class itself, as well as checking its raw bean class
	 * if not found on the exposed bean reference (e.g. in case of a proxy).
	 * @param beanName the name of the bean to look for annotations on
	 * @param annotationType the annotation class to look for
	 * @return the annotation of the given type found, or <code>null</code>
	 * @see org.springframework.core.annotation.AnnotationUtils#findAnnotation(Class, Class)
	 */
	public <A extends Annotation> A findAnnotationOnBean(String beanName, Class<A> annotationType) {
		Class<?> handlerType = this.beanFactory.getType(beanName);
		A ann = AnnotationUtils.findAnnotation(handlerType, annotationType);
		if (ann == null && this.beanFactory instanceof ConfigurableBeanFactory &&
				this.beanFactory.containsBeanDefinition(beanName)) {
			ConfigurableBeanFactory cbf = (ConfigurableBeanFactory) this.beanFactory;
			BeanDefinition bd = cbf.getMergedBeanDefinition(beanName);
			if (bd instanceof AbstractBeanDefinition) {
				AbstractBeanDefinition abd = (AbstractBeanDefinition) bd;
				if (abd.hasBeanClass()) {
					Class<?> beanClass = abd.getBeanClass();
					ann = AnnotationUtils.findAnnotation(beanClass, annotationType);
				}
			}
		}
		return ann;
	}

}