package com.smppw.analysis.infrastructure.components;

import cn.hutool.core.util.StrUtil;
import cn.hutool.crypto.SignUtil;
import cn.hutool.json.JSONUtil;
import com.smppw.analysis.infrastructure.config.AnalysisProperty;
import com.smppw.common.pojo.ResultVo;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.http.MediaType;
import org.springframework.lang.NonNull;
import org.springframework.web.servlet.HandlerInterceptor;

import java.nio.charset.Charset;
import java.time.Duration;
import java.util.Map;

/**
 * @author wangzaijun
 * @date 2023/8/7 15:58
 * @description api验证签名拦截器
 */
public class ApiSignInterceptor implements HandlerInterceptor {
    private static final long MAX_TIMEOUT = 50000L;
    private final Logger logger = LoggerFactory.getLogger(this.getClass());
    private final AnalysisProperty property;

    public ApiSignInterceptor(AnalysisProperty property) {
        this.property = property;
    }

    @Override
    public boolean preHandle(@NonNull HttpServletRequest request, @NonNull HttpServletResponse response, @NonNull Object handler) throws Exception {
        if (logger.isInfoEnabled()) {
            logger.info(StrUtil.format("{} 接口正在被 {} 请求！", request.getRequestURI(), request.getRemoteAddr()));
        }
        if (!this.property.getEnableSign()) {
            if (logger.isDebugEnabled()) {
                logger.debug("接口不需要签名验证！");
            }
            return HandlerInterceptor.super.preHandle(request, response, handler);
        }
        String sign = request.getHeader("sign");
        if (StrUtil.isBlank(sign)) {
            this.writeFailJson(response, "sign 参数为空");
            return false;
        }
        String timestamp = request.getHeader("timestamp");
        if (StrUtil.isBlank(timestamp)) {
            this.writeFailJson(response, "timestamp 参数为空");
            return false;
        }
        String appKey = request.getParameter("appKey");
        AnalysisProperty.AppSign appSign = this.property.getAppSigns().stream()
                .filter(e -> appKey.equals(e.getAppKey())).findFirst().orElse(null);
        if (appSign == null) {
            this.writeFailJson(response, "appKey非法");
            return false;
        }
        if (!appSign.getEnabled()) {
            logger.warn(StrUtil.format("{} 应用未开启接口签名验证！", appKey));
            return HandlerInterceptor.super.preHandle(request, response, handler);
        }
        boolean flag = this.checkTimestamp(request, response, timestamp, appSign.getTimeout());
        if (!flag) {
            return false;
        }
        String appSecret = appSign.getAppSecret();
        Map<String, String[]> parameterMap = request.getParameterMap();
        parameterMap.entrySet().removeIf(next -> "appKey".equalsIgnoreCase(next.getKey()));
        String paramsSign = SignUtil.signParamsMd5(parameterMap, appSecret);
        if (!sign.equalsIgnoreCase(paramsSign)) {
            this.writeFailJson(response, "签名验证失败");
            return false;
        }
        return HandlerInterceptor.super.preHandle(request, response, handler);
    }

    private boolean checkTimestamp(HttpServletRequest request, HttpServletResponse response, String timestamp, Duration timeout) throws Exception {
        long millis = System.currentTimeMillis();
        long time = Long.parseLong(timestamp);
        long seconds = Math.min(timeout.getSeconds(), MAX_TIMEOUT);
        if (millis - time > seconds) {
            logger.error(StrUtil.format("接口有重放攻击，调用方：{}-{}"), request.getRemoteUser(), request.getRemoteAddr());
            this.writeFailJson(response, "请求失败！");
            return false;
        }
        return true;
    }

    private synchronized void writeFailJson(HttpServletResponse response, String msg) throws Exception {
        ResultVo<?> resultVo = ResultVo.fail(400, msg);
        response.setContentType(MediaType.APPLICATION_JSON_VALUE);
        response.setCharacterEncoding(Charset.defaultCharset().displayName());
        response.getWriter().write(JSONUtil.toJsonStr(resultVo));
        response.getWriter().flush();
    }
}