package com.nbclass.shiro.filter;

import java.io.IOException;
import java.io.PrintWriter;
import java.io.Serializable;
import java.util.Deque;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.Map;

import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;

import org.apache.shiro.cache.Cache;
import org.apache.shiro.cache.CacheManager;
import org.apache.shiro.session.Session;
import org.apache.shiro.session.mgt.DefaultSessionKey;
import org.apache.shiro.session.mgt.SessionManager;
import org.apache.shiro.subject.Subject;
import org.apache.shiro.web.filter.AccessControlFilter;
import org.apache.shiro.web.util.WebUtils;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import com.alibaba.fastjson.JSON;
import com.nbclass.system.model.User;

/**
 * @author superzheng
 * @date 2018-07-18
 */
public class KickoutSessionControlFilter extends AccessControlFilter {

	protected static Logger logger = LoggerFactory.getLogger(KickoutSessionControlFilter.class);
	
    /**
     * 踢出后到的地址
     */
    private String kickoutUrl;
    /**
     * 踢出之前登录的/之后登录的用户 默认踢出之前登录的用户
     */
    private boolean kickoutAfter = false;
    /**
     * 同一个帐号最大会话数 默认5
     */
    private int maxSession = 5;

    private SessionManager sessionManager;
    private Cache<String, Deque<Serializable>> cache;

    public void setKickoutUrl(String kickoutUrl) {
        this.kickoutUrl = kickoutUrl;
    }

    public void setKickoutAfter(boolean kickoutAfter) {
        this.kickoutAfter = kickoutAfter;
    }

    public void setMaxSession(int maxSession) {
        this.maxSession = maxSession;
    }

    public void setSessionManager(SessionManager sessionManager) {
        this.sessionManager = sessionManager;
    }

    public void setCacheManager(CacheManager cacheManager) {
        this.cache = cacheManager.getCache("shiro_redis_cache");
    }

    @Override
    protected boolean isAccessAllowed(ServletRequest request, ServletResponse response, Object mappedValue) throws Exception {
        return false;
    }

    @Override
    protected boolean onAccessDenied(ServletRequest request, ServletResponse response) throws Exception {
    //	HttpServletRequest req = (HttpServletRequest) request;
    	
        Subject subject = getSubject(request, response);
        if(!subject.isAuthenticated() && !subject.isRemembered()) {
            //如果没有登录，直接进行之后的流程
            return true;
        }
        

        Session session = subject.getSession();
        User user = (User) subject.getPrincipal();
        String username = user.getUsername();
        Serializable sessionId = session.getId();

        //读取缓存   没有就存入
        Deque<Serializable> deque = cache.get(username);
        
        //如果此用户没有session队列，也就是还没有登录过，缓存中没有
        //就new一个空队列，不然deque对象为空，会报空指针
        if(deque==null){
        	deque = new LinkedList<Serializable>();
        }
        
        //如果队列里没有此sessionId，且用户没有被踢出；放入队列
        if(!deque.contains(sessionId) && session.getAttribute("kickout") == null) {
            //将sessionId存入队列
        	deque.push(sessionId);
        	//将用户的sessionId队列缓存
            cache.put(username, deque);
        }

        //如果队列里的sessionId数超出最大会话数，开始踢人
        while(deque.size() > maxSession) {
            Serializable kickoutSessionId = null;
            //如果踢出后者
            if(kickoutAfter) {
                kickoutSessionId = deque.removeFirst();
                //踢出后再更新下缓存队列
                cache.put(username, deque);
            } else { //否则踢出前者
                kickoutSessionId = deque.removeLast();
                //踢出后再更新下缓存队列
                cache.put(username, deque);
            }
            
            
            
            try {
            	//获取被踢出的sessionId的session对象
                Session kickoutSession = sessionManager.getSession(new DefaultSessionKey(kickoutSessionId));
                if(kickoutSession != null) {
                    //设置会话的kickout属性表示踢出了
                    kickoutSession.setAttribute("kickout", true);
                }
            } catch (Exception e) {//ignore exception
            }
        }

        //如果被踢出了，直接退出，重定向到踢出后的地址
        if ((Boolean)session.getAttribute("kickout")!=null&&(Boolean)session.getAttribute("kickout") == true) {
            //会话被踢出了
            try {
            	//退出登录
                subject.logout();
            } catch (Exception e) { //ignore
            }
            saveRequest(request);
            
            Map<String, String> resultMap = new HashMap<String, String>(2);
			//判断是不是Ajax请求
			if ("XMLHttpRequest".equalsIgnoreCase(((HttpServletRequest) request).getHeader("X-Requested-With"))) {
				resultMap.put("user_status", "300");
				resultMap.put("message", "您已经在其他地方登录，请重新登录！");
				//输出json串
				out(response, resultMap);
			}else{
				//重定向
				WebUtils.issueRedirect(request, response, kickoutUrl);
			}
            return false;
        }
        return true;
    }
    private void out(ServletResponse hresponse, Map<String, String> resultMap)
			throws IOException {
		try {
			hresponse.setCharacterEncoding("UTF-8");
			PrintWriter out = hresponse.getWriter();
			out.println(JSON.toJSONString(resultMap));
			out.flush();
			out.close();
		} catch (Exception e) {
			System.err.println("KickoutSessionFilter.class 输出JSON异常，可以忽略。");
		}
	}
}
