package com.cwhelp.common.xss;

import javax.servlet.*;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * Xss防护过滤器
 * @author yan.y
 */
public class XssFilter implements Filter{

    /**
     * 忽略规则列表
     */
    private List<String> excludes = new ArrayList<>();

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {

        String temp = filterConfig.getInitParameter("excludes");
        if (temp != null) {
            String[] url = temp.split(",");
            for (int i = 0; url != null && i < url.length; i++) {
                excludes.add(url[i]);
            }
        }
    }

    @Override
    public void doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) throws IOException,ServletException {

        HttpServletRequest req = (HttpServletRequest) request;
        HttpServletResponse resp = (HttpServletResponse) response;
        if(handleExcludeURL(req, resp)){
            filterChain.doFilter(request, response);
            return;
        }

        XssHttpServletRequestWrapper xssRequest = new XssHttpServletRequestWrapper((HttpServletRequest) request);
        filterChain.doFilter(xssRequest, response);
    }

    private boolean handleExcludeURL(HttpServletRequest request, HttpServletResponse response) {

        if (excludes == null || excludes.isEmpty()) {
            return false;
        }

        String url = request.getServletPath();
        for (String pattern : excludes) {
            Pattern p = Pattern.compile("^" + pattern);
            Matcher m = p.matcher(url);
            if (m.find()) {
                return true;
            }
        }

        return false;
    }

    @Override
    public void destroy() {}
}
