<?php
/**
 *  +----------------------------------------------------------------------
 *  | CRMEB [ CRMEB赋能开发者，助力企业发展 ]
 *  +----------------------------------------------------------------------
 *  | Copyright (c) 2016~2022 https://www.crmeb.com All rights reserved.
 *  +----------------------------------------------------------------------
 *  | Licensed CRMEB并不是自由软件，未经许可不能去掉CRMEB相关版权
 *  +----------------------------------------------------------------------
 *  | Author: CRMEB Team <admin@crmeb.com>
 *  +----------------------------------------------------------------------
 */

namespace app\http\middleware\api;


use app\Request;
use Closure;
use Redis;
use think\exception\ValidateException;
use think\facade\Cache;

/**
 * 限流中间件
 * Class RateLimiterMiddleware
 * @author 等风来
 * @email 136327134@qq.com
 * @date 2023/1/4
 * @package app\http\middleware\api
 */
class RateLimiterMiddleware
{

    /**
     * @param Request $request
     * @param Closure $next
     * @return mixed
     * @author 等风来
     * @email 136327134@qq.com
     * @date 2023/1/4
     */
    public function handle(Request $request, Closure $next)
    {

        $option = $request->rule()->getOption();

        //是否开启限流
        if (isset($option['rateLimiter']) && $option['rateLimiter']) {
            $rule = trim(strtolower($request->rule()->getRule()));
            $uid = 0;
            if ($request->uid() && !empty($option['isUser'])) {
                $uid = $request->uid();
            }
            $key = md5($rule . $uid);
            $this->createLimit($key, $option['limitNum'], $option['expire']);
        }
        return $next($request);
    }

    /**
     * @param string $key
     * @param int $initNum
     * @param int $expire
     * @return bool
     * @author 等风来
     * @email 136327134@qq.com
     * @date 2023/1/4
     */
    protected function createLimit(string $key, int $initNum, int $expire)
    {
        $nowTime = time();

        /** @var Redis $redis */
        $redis = Cache::store('redis')->handler();

        $script = <<<LUA
    local key = KEYS[1]
    local initNum = tonumber(ARGV[1])
    local expire = tonumber(ARGV[2])
    local nowTime = tonumber(ARGV[3])

    local limitVal = redis.call('get', key)

    if limitVal then
        limitVal = cjson.decode(limitVal)
        local newNum = math.min(initNum, (limitVal.num - 1) + ((initNum / expire) * (nowTime - limitVal.time)))
        if newNum <= 0 then
            return 0
        else
            local redisVal = {num = newNum, time = nowTime}
            redis.call('set', key, cjson.encode(redisVal))
            redis.call('expire', key, expire)
            return 1
        end
    else
        local redisVal = {num = initNum, time = nowTime}
        redis.call('set', key, cjson.encode(redisVal))
        redis.call('expire', key, expire)
        return 1
    end
LUA;

        $result = $redis->eval($script, [$key, $initNum, $expire, $nowTime], 1);
        if (!$result) {
            throw new ValidateException('访问频次过多！');
        }

        return true;
    }
}