/**
 * Copyright &copy; 2015 <a href="https://git.oschina.net/luckyben/webook">WeBook</a> All rights reserved.
 */
package com.qihoo.finance.chronus.context;


import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.DisposableBean;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.annotation.Lazy;
import org.springframework.stereotype.Component;
import org.springframework.util.Assert;

/**
 * 以静态变量保存Spring ApplicationContext, 可在任何代码任何地方任何时候取出ApplicaitonContext.
 *
 * @author Zaric
 * @date 2013-5-29 下午1:25:40
 */
@Slf4j
@Component("applicationContextHolder")
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

    private static ApplicationContext applicationContext = null;

    public SpringContextHolder() {
    }

    public SpringContextHolder(ApplicationContext applicationContext) {
        SpringContextHolder.applicationContext = applicationContext;
    }
    /**
     * 实现ApplicationContextAware接口, 注入Context到静态变量中.
     */
    @Override
    public void setApplicationContext(ApplicationContext applicationContext) {
        log.debug("注入ApplicationContext到SpringContextHolder:{}", applicationContext);
        if (SpringContextHolder.applicationContext != null) {
            log.info("SpringContextHolder中的ApplicationContext被覆盖, 原有ApplicationContext为:" + SpringContextHolder.applicationContext);
        }
        SpringContextHolder.applicationContext = applicationContext;
    }


    /**
     * 取得存储在静态变量中的ApplicationContext.
     */
    public static ApplicationContext getApplicationContext() {
        assertContextInjected();
        return applicationContext;
    }


    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    @SuppressWarnings("unchecked")
    public static <T> T getBean(String name) {
        assertContextInjected();
        return (T) applicationContext.getBean(name);
    }

    public static boolean containsBean(String name) {
        assertContextInjected();
        return applicationContext.containsBean(name);
    }

    /**
     * 从静态变量applicationContext中取得Bean, 自动转型为所赋值对象的类型.
     */
    public static <T> T getBean(Class<T> requiredType) {
        assertContextInjected();
        return applicationContext.getBean(requiredType);
    }

    /**
     * 清除SpringContextHolder中的ApplicationContext为Null.
     */
    public static void clearHolder() {
        if (log.isDebugEnabled()) {
            log.debug("清除SpringContextHolder中的ApplicationContext:" + applicationContext);
        }
        applicationContext = null;
    }

    /**
     * 检查ApplicationContext不为空.
     */
    private static void assertContextInjected() {
        Assert.notNull(applicationContext, "applicaitonContext属性未注入!");
    }

    /**
     * 实现DisposableBean接口, 在Context关闭时清理静态变量.
     */
    @Override
    public void destroy() throws Exception {
        SpringContextHolder.clearHolder();
    }
}