import {
  CUSTOMER_RATE_LIMIT,
  CUSTOMER_RATE_WINDOW_SECONDS,
} from "@/lib/constants/cache";
import { withBoundedRedis } from "@/lib/redis";

export type RateLimitResult =
  | { allowed: true }
  | { allowed: false; errorCode: "RATE_LIMITED" };

function customerKey(customerId: string): string {
  return `ratelimit:customer:${customerId}`;
}

/** 令牌桶：60 次/分钟/customer，超限返回 RATE_LIMITED */
export async function checkRateLimit(
  customerId: string,
): Promise<RateLimitResult> {
  const key = customerKey(customerId);
  const result = await withBoundedRedis(async (redis) => {
    const count = await redis.incr(key);
    if (count === 1) {
      await redis.expire(key, CUSTOMER_RATE_WINDOW_SECONDS);
    }
    if (count > CUSTOMER_RATE_LIMIT) {
      return { allowed: false as const, errorCode: "RATE_LIMITED" as const };
    }
    return { allowed: true as const };
  });

  if (!result) {
    return { allowed: true };
  }
  return result;
}