package com.nuvole.rateLimit;

import com.alibaba.fastjson.JSONObject;
import com.google.common.collect.Maps;
import com.google.common.util.concurrent.RateLimiter;
import com.nuvole.common.domain.emnu.CommonResultEmnu;
import com.nuvole.common.domain.result.CommonResult;
import jakarta.servlet.http.HttpServletResponse;
import lombok.extern.slf4j.Slf4j;
import org.aspectj.lang.ProceedingJoinPoint;
import org.aspectj.lang.annotation.Around;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.reflect.MethodSignature;
import org.springframework.stereotype.Component;
import org.springframework.web.context.request.RequestContextHolder;
import org.springframework.web.context.request.ServletRequestAttributes;

import java.io.IOException;
import java.io.PrintWriter;
import java.lang.reflect.Method;
import java.util.Map;


@Slf4j
@Aspect
@Component
public class ApiRateLimitAop {
    /**
     * 不同的接口，不同的流量控制
     * map的key为 Limiter.key
     */
    private final Map<String, RateLimiter> limitMap = Maps.newConcurrentMap();

    @Around("@annotation(com.nuvole.rateLimit.ApiRateLimit)")
    public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
        MethodSignature signature = (MethodSignature) joinPoint.getSignature();
        Method method = signature.getMethod();
        //拿limit的注解
        ApiRateLimit limit = method.getAnnotation(ApiRateLimit.class);
        if (limit != null) {
            //key作用：不同的接口，不同的流量控制
            String key = limit.key();
            RateLimiter rateLimiter = null;
            //验证缓存是否有命中key
            if (!limitMap.containsKey(key)) {
                // 创建令牌桶
                rateLimiter = RateLimiter.create(limit.permitsPerSecond());
                limitMap.put(key, rateLimiter);
                log.info("新建了令牌桶={}，容量={}", key, limit.permitsPerSecond());
            }
            rateLimiter = limitMap.get(key);
            // 拿令牌
            boolean acquire = rateLimiter.tryAcquire(limit.timeout(), limit.timeunit());
            // 拿不到命令，直接返回异常提示
            if (!acquire) {
                log.debug("令牌桶={}，获取令牌失败", key);
                this.responseFail(limit.msg());
                return null;
            }
        }
        return joinPoint.proceed();
    }

    /**
     * @param msg 提示信息
     */
    private void responseFail(String msg) {
        HttpServletResponse response = ((ServletRequestAttributes) RequestContextHolder.getRequestAttributes()).getResponse();
        CommonResult resultData = new CommonResult(CommonResultEmnu.REQUEST_LIMIT_ERR, msg);
        response.setContentType("application/json;charset=UTF-8");
        PrintWriter out = null;
        try {
            out = response.getWriter();
        } catch (IOException e) {
            e.printStackTrace();
        }
        out.print(JSONObject.toJSONString(resultData));
        out.flush();
        out.close();
    }
}