import { redis } from '../redis.js';

export interface RateLimitResult {
  limited: boolean;
  retryAfter: number;
}

export async function checkRateLimit(
  ip: string,
  action: string,
  max: number,
  windowSeconds: number,
): Promise<RateLimitResult> {
  const key = `rl:${action}:${ip}`;
  const hits = await redis.incr(key);
  if (hits === 1) await redis.expire(key, windowSeconds);
  if (hits > max) {
    const ttl = await redis.ttl(key);
    return { limited: true, retryAfter: Math.max(ttl, 1) };
  }
  return { limited: false, retryAfter: 0 };
}

export async function checkRateLimitBySubject(
  subject: string,
  action: string,
  max: number,
  windowSeconds: number,
): Promise<RateLimitResult> {
  const key = `rl:${action}:${subject}`;
  const hits = await redis.incr(key);
  if (hits === 1) await redis.expire(key, windowSeconds);
  if (hits > max) {
    const ttl = await redis.ttl(key);
    return { limited: true, retryAfter: Math.max(ttl, 1) };
  }
  return { limited: false, retryAfter: 0 };
}

export function rateLimitResponse(reply: import('fastify').FastifyReply, retryAfter: number) {
  reply.header('Retry-After', String(retryAfter));
  return reply.code(429).send({ error: 'rate_limited', retryAfter });
}