/*
 * Copyright (c) MuleSoft, Inc.  All rights reserved.  http://www.mulesoft.com
 * The software in this package is published under the terms of the CPAL v1.0
 * license, a copy of which has been included with this distribution in the
 * LICENSE.txt file.
 */
package org.mule.runtime.config.spring.util;

import org.mule.runtime.core.api.MuleContext;
import org.mule.runtime.core.api.construct.FlowConstructAware;
import org.mule.runtime.api.lifecycle.InitialisationException;
import org.mule.runtime.api.i18n.I18nMessageFactory;
import org.mule.runtime.core.object.AbstractObjectFactory;

import org.springframework.beans.BeansException;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;

/**
 * This is an implementation of the ObjectFactory interface which simply delegates to the Spring ApplicationContext. Since the
 * delegation happens each time a call to getOrCreate() is made, this will correctly handle Spring beans which are non-singletons
 * (factory beans, etc.)
 * 
 * Singleton usage:
 * 
 * <model> <service name="myOrangeService"> <service> <spring-object bean="myBean"/> </service> </service> </model>
 *
 * <spring:bean id="myBean" class="com.foo.Bar"/>
 * 
 * Non-singleton usage:
 * 
 * <model> <service name="myOrangeService"> <service> <spring-object bean="myFactoryBean"/> </service> </service> </model>
 *
 * <spring:bean id="myFactoryBean" class="com.foo.BarFactory" factory-method="getNewBar"/>
 */
public class SpringBeanLookup extends AbstractObjectFactory implements ApplicationContextAware {

  private ApplicationContext applicationContext;
  private String bean;

  @Override
  public void initialise() throws InitialisationException {
    if (bean == null) {
      throw new InitialisationException(I18nMessageFactory.createStaticMessage("Bean name has not been set."), this);
    }
    if (applicationContext == null) {
      throw new InitialisationException(I18nMessageFactory.createStaticMessage("ApplicationContext has not been injected."),
                                        this);
    }

    // Get instance of spring bean to determine bean type.
    // We do this because the result of org.springframework.beans.factory.BeanFactory.getType(String) when
    // used before bean initialization does not always return the same type as afterwards. One specific
    // case when AOP is used, and the actual bean class is returned before initialization but a proxy
    // afterwards. This affects both prototype beans and lazy-init singletons.
    objectClass = applicationContext.getBean(bean).getClass();
  }

  @Override
  public void dispose() {
    // Not implemented for Spring Beans
  }

  @Override
  public Object getInstance(MuleContext muleContext) throws Exception {
    Object instance = applicationContext.getBean(bean);
    if (instance instanceof FlowConstructAware) {
      // The servie cannot be autowired from within Spring, so we do it here
      ((FlowConstructAware) instance).setFlowConstruct(flowConstruct);
    }
    fireInitialisationCallbacks(instance);
    return instance;
  }

  public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
    this.applicationContext = applicationContext;
  }

  public String getBean() {
    return bean;
  }

  public void setBean(String bean) {
    this.bean = bean;
  }

  @Override
  public boolean isSingleton() {
    return applicationContext.isSingleton(bean);
  }

  @Override
  public boolean isExternallyManagedLifecycle() {
    return true;
  }

  public boolean isAutoWireObject() {
    // Spring does the wiring
    return false;
  }
}