<?php
namespace app\api\middleware;

use think\Request;
use think\Response;
use think\exception\HttpResponseException;
use app\common\server\RedisHelper;

class RateLimit
{
    // 默认配置：每60秒最多20次
    protected $limit = 20;
    protected $ttl = 60;

    /**
     * 限流处理入口
     * @param Request $request
     * @param \Closure $next
     * @param string $keyPrefix 可传入 'ip' 或 'token' 等标识字段
     * @return Response
     */
    public function handle($request, \Closure $next, $keyPrefix = 'ip')
    {
        $identifier = $this->getIdentifier($request, $keyPrefix);

        $redisKey = "rate_limit:{$keyPrefix}:" . $identifier;
        $redis = (new RedisHelper())->getRedis();

        $count = $redis->incr($redisKey);

        if ($count == 1) {
            // 第一次设置过期时间
            $redis->expire($redisKey, $this->ttl);
        }

        if ($count > $this->limit) {
            $this->error("请求频率过高，请稍后再试");
        }

        return $next($request);
    }

    /**
     * 获取请求标识符（支持IP/token）
     */
    protected function getIdentifier(Request $request, string $keyPrefix)
    {
        switch ($keyPrefix) {
            case 'token':
                return $request->header('token') ?? $request->param('token') ?? 'guest';
            case 'ip':
            default:
                return $request->ip();
        }
    }

    /**
     * 错误输出统一格式
     */
    protected function error($msg, $code = 429)
    {
        $result = [
            'status' => 0,
            'msg' => $msg,
            'data' => null
        ];
        $response = Response::create($result, 'json', $code);
        throw new HttpResponseException($response);
    }
}