package com.lxzn.auth;

import com.alibaba.fastjson.JSON;
import com.lxzn.framework.utils.ValidateUtil;
import lombok.extern.slf4j.Slf4j;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
import org.springframework.security.jwt.Jwt;
import org.springframework.security.jwt.JwtHelper;
import org.springframework.security.jwt.crypto.sign.RsaVerifier;
import org.springframework.web.context.request.RequestAttributes;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import javax.servlet.http.HttpServletRequest;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Map;
import java.util.stream.Collectors;

@Slf4j
public class JwtUtil {

    //公钥
    private static final String PUBLIC_KEY = "publickey.txt";

    /**
     * 获取非对称加密公钥 Key
     * @return 公钥 Key
     */
    public static String getPubKey() {
        Resource resource = new ClassPathResource(PUBLIC_KEY);
        BufferedReader br = null;
        try {
            InputStreamReader inputStreamReader = new InputStreamReader(resource.getInputStream());
            br = new BufferedReader(inputStreamReader);
            return br.lines().collect(Collectors.joining("\n"));
        } catch (IOException ioe) {
            log.error(ioe.getMessage(), ioe.getStackTrace());
            return null;
        }finally {
            if(br != null) {
                try {
                    br.close();
                } catch (IOException e) {
                    log.error(e.getMessage(), e.getStackTrace());
                    return null;
                }
            }
        }
    }

    public static Map<String, String> parseJwtToken(String jwtToken) {
        String pubKey = getPubKey();
        Jwt jwt = JwtHelper.decodeAndVerify(jwtToken, new RsaVerifier(pubKey));
        if(jwt == null)
            return null;
        String claims = jwt.getClaims();
        if(!ValidateUtil.validateString(claims))
            return null;
        Map<String, String> map = JSON.parseObject(claims, Map.class);
        return map;
    }

    public static String getUserId() {
        RequestAttributes requestAttributes = RequestContextHolder.getRequestAttributes();
        if(requestAttributes == null)
            return null;
        HttpServletRequest request = ((ServletRequestAttributes)requestAttributes).getRequest();
        if(request == null)
            return null;
        String header = request.getHeader("Authorization");
        if(ValidateUtil.validateString(header) && header.toLowerCase().startsWith("bearer ")) {
            String token = header.substring("bearer ".length());
            Map<String, String> map = parseJwtToken(token);
            if(map != null && map.containsKey("userId")){
                return map.get("userId");
            }
        }
        return null;
    }
}