nostr-tools/filter.js

export function matchFilter(filter, event) {
  if (filter.ids && filter.ids.indexOf(event.id) === -1) return false
  if (filter.kinds && filter.kinds.indexOf(event.kind) === -1) return false
  if (filter.authors && filter.authors.indexOf(event.pubkey) === -1)
    return false

  for (let f in filter) {
    if (f[0] === '#') {
      if (
        filter[f] &&
        !event.tags.find(
          ([t, v]) => t === f.slice(1) && filter[f].indexOf(v) !== -1
        )
      )
        return false
    }
  }

  if (filter.since && event.created_at < filter.since) return false
  if (filter.until && event.created_at >= filter.until) return false

  return true
}

export function matchFilters(filters, event) {
  for (let i = 0; i < filters.length; i++) {
    if (matchFilter(filters[i], event)) return true
  }
  return false
}