anchorage_layer_simple/userwallet/src/utils/bloom.ts

import bloomFilters from 'bloom-filters';
import { getBloom } from './relay';

type BloomFilterInstance = ReturnType<typeof bloomFilters.BloomFilter.fromJSON>;

/**
 * Fetch Bloom filter from relay and load from JSON.
 * Returns null on fetch or parse failure (e.g. relay without /bloom).
 */
export async function fetchAndLoadBloom(
  relay: string,
): Promise<BloomFilterInstance | null> {
  try {
    const json = await getBloom(relay);
    const { BloomFilter } = bloomFilters;
    const filter = BloomFilter.fromJSON(
      json as Parameters<typeof BloomFilter.fromJSON>[0],
    );
    return filter;
  } catch {
    return null;
  }
}