package com.fdkankan.site.aspectj;

import cn.hutool.core.util.ObjectUtil;
import cn.hutool.core.util.StrUtil;
import com.fdkankan.site.annotation.RateLimiter;
import com.fdkankan.site.common.ResultCode;
import com.fdkankan.site.enums.LimitType;
import com.fdkankan.site.exception.BusinessException;
import com.fdkankan.site.util.IpUtils;
import com.fdkankan.site.util.ServletUtils;
import org.aspectj.lang.JoinPoint;
import org.aspectj.lang.annotation.Aspect;
import org.aspectj.lang.annotation.Before;
import org.aspectj.lang.reflect.MethodSignature;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.core.io.ClassPathResource;
import org.springframework.data.redis.core.RedisTemplate;
import org.springframework.data.redis.core.script.DefaultRedisScript;
import org.springframework.data.redis.core.script.RedisScript;
import org.springframework.scripting.support.ResourceScriptSource;
import org.springframework.stereotype.Component;

import java.lang.reflect.Method;
import java.util.Collections;
import java.util.List;

/**
 * 限流处理
 *
 * @author fdkk
 */
@Aspect
@Configuration
public class RateLimiterAspect
{
    private static final Logger log = LoggerFactory.getLogger(RateLimiterAspect.class);

    @Autowired
    private RedisTemplate redisTemplate;

    private RedisScript<Long> limitScript;


    @Autowired
    public void setLimitScript(RedisScript<Long> limitScript)
    {
        this.limitScript = limitScript;
    }

    @Before("@annotation(rateLimiter)")
    public void doBefore(JoinPoint point, RateLimiter rateLimiter) throws Throwable
    {
        String key = rateLimiter.key();
        int time = rateLimiter.time();
        int count = rateLimiter.count();

        String combineKey = getCombineKey(rateLimiter, point);
        List<Object> keys = Collections.singletonList(combineKey);
        try
        {
            Long number = (Long) redisTemplate.execute(limitScript, keys, String.valueOf(count), String.valueOf(time));
            if (ObjectUtil.isNull(number) || number.intValue() > count)
            {
                throw new BusinessException(ResultCode.RATE_LIMITER);

            }
            log.info("限制请求'{}',当前请求'{}',缓存key'{}'", count, number.intValue(), key);
        }
        catch (BusinessException e)
        {
            throw e;
        }
        catch (Exception e)
        {
            throw new RuntimeException("服务器限流异常，请稍后再试");
        }
    }

    public String getCombineKey(RateLimiter rateLimiter, JoinPoint point)
    {
        StringBuffer stringBuffer = new StringBuffer(rateLimiter.key());
        if (rateLimiter.limitType() == LimitType.IP)
        {
            stringBuffer.append(IpUtils.getIpAddr(ServletUtils.getRequest())).append("-");
        }
        MethodSignature signature = (MethodSignature) point.getSignature();
        Method method = signature.getMethod();
        Class<?> targetClass = method.getDeclaringClass();
        stringBuffer.append(targetClass.getName()).append("-").append(method.getName());
        return stringBuffer.toString();
    }
    /**
     * 限流脚本
     */
    @Bean("limitRedisScript")
    public RedisScript<Long> limitRedisScript() {
        DefaultRedisScript<Long> redisScript = new DefaultRedisScript<>();
        redisScript.setScriptText(limitScriptText());
        redisScript.setResultType(Long.class);
        return redisScript;
    }
    /**
     * 限流脚本
     */
    private String limitScriptText()
    {
        return "local key = KEYS[1]\n" +
                "local count = tonumber(ARGV[1])\n" +
                "local time = tonumber(ARGV[2])\n" +
                "local current = redis.call('get', key);\n" +
                "if current and tonumber(current) > count then\n" +
                "    return tonumber(current);\n" +
                "end\n" +
                "current = redis.call('incr', key)\n" +
                "if tonumber(current) == 1 then\n" +
                "    redis.call('expire', key, time)\n" +
                "end\n" +
                "return tonumber(current);";
    }
}