rateLimitAnonAndLogin.ts

import { MiddlewareFn } from "type-graphql";
import { redis } from "./redis";
import { MyContext } from "./types/MyContext";

const ONE_DAY = 60 * 60 * 24;

export const rateLimit: (limit?: number) => MiddlewareFn<MyContext> = (
  limitForAnonUser = 50,
  limitForUser = 100
) => async ({ context: { req }, info }, next) => {
  const isAnon = !req.session!.userId;
  const key = `rate-limit:${info.fieldName}:${
    isAnon ? req.ip : req.session!.userId
  }`;

  const current = await redis.incr(key);
  if (
    (isAnon && current > limitForAnonUser) ||
    (!isAnon && current > limitForUser)
  ) {
    throw new Error("you're doing that too much");
  } else if (current === 1) {
    await redis.expire(key, ONE_DAY);
  }

  return next();
};