import { HttpException, HttpStatus, Injectable } from '@nestjs/common';
import { RateLimitStore } from '@task-stream/api/tracker/application';

/** Proposals from one address within the window. */
const LIMIT = 5;
const WINDOW_MS = 15 * 60_000;

/**
 * Keeps one address from flooding a project with proposals. Counted in
 * Redis, so the limit holds across every instance of the API.
 */
@Injectable()
export class ProposalLimiter {
  constructor(private readonly store: RateLimitStore) {}

  async take(address: string): Promise<void> {
    const count = await this.store.hit(`proposals:${address}`, WINDOW_MS);
    if (count > LIMIT)
      throw new HttpException(
        'Too many proposals from here; try again in a few minutes',
        HttpStatus.TOO_MANY_REQUESTS,
      );
  }
}