import { Inject, Injectable } from "@nestjs/common";
import { RedisService } from "../redis/redis.service.js";

@Injectable()
export class ChatRateLimiter {
  constructor(@Inject(RedisService) private readonly redis: RedisService) {}
  async consume(accountId: string, sessionId: string): Promise<boolean> {
    const prefix = process.env.REDIS_KEY_PREFIX ?? "drift:auth:";
    const max = Number(process.env.CHAT_MESSAGE_RATE_LIMIT ?? 30);
    const ttl = Number(process.env.CHAT_MESSAGE_RATE_WINDOW_SECONDS ?? 60);
    const keys = [
      `${prefix}chat:account:${accountId}`,
      `${prefix}chat:session:${sessionId}`,
    ];
    const result = await this.redis.executeWithDeadline((client) =>
      client.eval(
        `for _,k in ipairs(KEYS) do if tonumber(redis.call('GET',k) or '0')+1>tonumber(ARGV[1]) then return 0 end end; for _,k in ipairs(KEYS) do local n=redis.call('INCR',k); if n==1 then redis.call('EXPIRE',k,ARGV[2]) end end; return 1`,
        { keys, arguments: [String(max), String(ttl)] },
      ),
    );
    return Number(result) === 1;
  }
}