package com.nitpro.school.servlet;

import java.io.IOException;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;

import javax.servlet.Filter;
import javax.servlet.FilterChain;
import javax.servlet.FilterConfig;
import javax.servlet.RequestDispatcher;
import javax.servlet.ServletException;
import javax.servlet.ServletRequest;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

public class LoginFilter implements Filter {
	Map<String, String> patternmap = new HashMap<String, String>();

	public void init(FilterConfig config) throws ServletException {
		Enumeration names = config.getInitParameterNames();
		while(names.hasMoreElements()){
			String name = (String)names.nextElement();
			String value = config.getInitParameter(name);
			patternmap.put(name, value);
		}
	}

	public void doFilter(ServletRequest req, ServletResponse resp,
			FilterChain chain) throws IOException, ServletException {
		HttpServletRequest request = (HttpServletRequest)req;
		HttpSession session = request.getSession();
		
		String url = request.getRequestURI();
		String qString = request.getQueryString();
		if((qString != null)&&(!"".equals(qString))){
			url = url + "?" + qString;
		}
		
		boolean pass = true;
		
		Set<Map.Entry<String, String>> patternset = patternmap.entrySet();
		for(Map.Entry<String, String> entry:patternset){
			if(url.startsWith(entry.getKey())){
				boolean hasUser = session.getAttribute("user") != null;
				boolean isRightUser = false;
				if(hasUser){
					String classNameInSession = session.getAttribute("user").getClass().getName();
					String classNameInPatternMap = entry.getValue();
					isRightUser = classNameInSession.equals(classNameInPatternMap);
				}
				if (!(hasUser&&isRightUser)){
				    pass = false;
				}
			}
		}
		
		if(pass){
			chain.doFilter(req, resp);
			return;
		}else{
			String requestUri = request.getRequestURI();
			String queryString = request.getQueryString();
			if(queryString != null){
				requestUri = requestUri + "?" + queryString; 
			}
			req.setAttribute("nextUrl", requestUri);
			req.setAttribute("msg", "您剛才所訪問的頁面先登錄才可以訪問");
			RequestDispatcher rd = request.getRequestDispatcher("/index.jsp");
            rd.forward(req, resp);	
		}
	}


	public void destroy() {
	}

}