package im.zhaojun.common.util;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.BeansException;
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.lang.NonNull;
import org.springframework.stereotype.Service;

/**
 * @author zhaojun
 */
@Service
@Lazy(false)
public class SpringContextHolder implements ApplicationContextAware, DisposableBean {

    private static ApplicationContext applicationContext = null;

    private static Logger logger = LoggerFactory.getLogger(SpringContextHolder.class);

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

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

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

    @Override
    public void setApplicationContext(@NonNull ApplicationContext applicationContext) throws BeansException {
        SpringContextHolder.applicationContext = applicationContext;
    }

}