import com.alibaba.fastjson.JSONObject;
import io.swagger.annotations.Api;
import io.swagger.annotations.ApiOperation;
import lombok.RequiredArgsConstructor;
import lombok.extern.slf4j.Slf4j;
import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.util.encoders.Base64;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import javax.crypto.Cipher;
import javax.crypto.spec.IvParameterSpec;
import javax.crypto.spec.SecretKeySpec;
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;
import java.nio.charset.StandardCharsets;
import java.security.AlgorithmParameters;
import java.security.Security;
import java.util.Arrays;

/**
 * @author xiegege
 * @date 2021/3/2 11:16
 */
@RequestMapping("/wechat/login")
@RestController
@RequiredArgsConstructor(onConstructor = @__(@Autowired))
@Slf4j
public class WechatLoginController {

    private static final String APP_ID = "你的appId";
    private static final String SECRET = "你的secret";

    @ApiOperation(value = "微信授权登录")
    @PostMapping("wechat-login")
    public String wechatLogin(String encryptedData, String iv, String code) {
        String errMsg = "解析失败！";
        try {
            String url = "https://api.weixin.qq.com/sns/jscode2session?appid=" + APP_ID + "&secret=" + SECRET + "&js_code=" + code + "&grant_type=authorization_code";
            JSONObject res = getJsonObject(url);
            log.info("res: " + res);
            if (res == null) {
                return errMsg;
            }
            if (res.get("errcode") != null) {
                return errMsg;
            }
            // 获取openid
            String openid = res.getString("openid");
            log.info("openid：" + openid);
            // 根据微信openid查询用户，如果有查到用户数据则生成token登录。如果没有查询到用户数据则新增一条用户，并把openid存入
            // 解析用户信息
            JSONObject res1 = getUserInfo(encryptedData, String.valueOf(res.get("session_key")), iv);
            if (res1 == null) {
                return errMsg;
            }
            // todo：通过openid查找用户信息
            /*WeChatUser user = userService.findUserByOpenId(openid);
            if (user == null) {
                // 新增用户

            } else {
                // 用户存在，更新用户信息，如昵称、头像、性别等...

            }*/
            log.info("昵称：" + res1.getString("nickName"));
            log.info("头像：" + res1.getString("avatarUrl"));
            log.info("性别：" + res1.getByte("gender"));

            return "openid：" + openid;
        } catch (Exception e) {
            e.printStackTrace();
            return errMsg;
        }
    }

    /**
     * 解密用户敏感数据获取用户信息
     *
     * @param sessionKey    数据进行加密签名的密钥
     * @param encryptedData 包括敏感数据在内的完整用户信息的加密数据
     * @param iv            加密算法的初始向量
     */
    public static JSONObject getUserInfo(String encryptedData, String sessionKey, String iv) {
        // 被加密的数据
        byte[] dataByte = Base64.decode(encryptedData);
        // 加密秘钥
        byte[] keyByte = Base64.decode(sessionKey);
        // 偏移量
        byte[] ivByte = Base64.decode(iv);

        try {
            // 如果密钥不足16位，那么就补足.  这个if 中的内容很重要
            int base = 16;
            if (keyByte.length % base != 0) {
                int groups = keyByte.length / base + (keyByte.length % base != 0 ? 1 : 0);
                byte[] temp = new byte[groups * base];
                Arrays.fill(temp, (byte) 0);
                System.arraycopy(keyByte, 0, temp, 0, keyByte.length);
                keyByte = temp;
            }
            // 初始化
            Security.addProvider(new BouncyCastleProvider());
            Cipher cipher = Cipher.getInstance("AES/CBC/PKCS7Padding", "BC");
            SecretKeySpec spec = new SecretKeySpec(keyByte, "AES");
            AlgorithmParameters parameters = AlgorithmParameters.getInstance("AES");
            parameters.init(new IvParameterSpec(ivByte));
            // 初始化
            cipher.init(Cipher.DECRYPT_MODE, spec, parameters);
            byte[] resultByte = cipher.doFinal(dataByte);
            if (null != resultByte && resultByte.length > 0) {
                String result = new String(resultByte, StandardCharsets.UTF_8);
                return JSONObject.parseObject(result);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    private JSONObject getJsonObject(String url) throws IOException {
        URL serverUrl = new URL(url);
        HttpURLConnection conn = (HttpURLConnection) serverUrl.openConnection();
        conn.setRequestMethod("GET");
        conn.setRequestProperty("Content-type", "application/json");
        // 必须设置false，否则会自动redirect到重定向后的地址
        conn.setInstanceFollowRedirects(false);