nostr-tools/lib/esm/filter.js

Tools for making a Nostr client.

// kinds.ts
function isReplaceableKind(kind) {
  return [0, 3].includes(kind) || 1e4 <= kind && kind < 2e4;
}
function isAddressableKind(kind) {
  return 3e4 <= kind && kind < 4e4;
}

// filter.ts
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] === "#") {
      let tagName = f.slice(1);
      let values = filter[`#${tagName}`];
      if (values && !event.tags.find(([t, v]) => t === f.slice(1) && values.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;
}
function matchFilters(filters, event) {
  for (let i = 0; i < filters.length; i++) {
    if (matchFilter(filters[i], event)) {
      return true;
    }
  }
  return false;
}
function mergeFilters(...filters) {
  let result = {};
  for (let i = 0; i < filters.length; i++) {
    let filter = filters[i];
    Object.entries(filter).forEach(([property, values]) => {
      if (property === "kinds" || property === "ids" || property === "authors" || property[0] === "#") {
        result[property] = result[property] || [];
        for (let v = 0; v < values.length; v++) {
          let value = values[v];
          if (!result[property].includes(value))
            result[property].push(value);
        }
      }
    });
    if (filter.limit && (!result.limit || filter.limit > result.limit))
      result.limit = filter.limit;
    if (filter.until && (!result.until || filter.until > result.until))
      result.until = filter.until;
    if (filter.since && (!result.since || filter.since < result.since))
      result.since = filter.since;
  }
  return result;
}
function getFilterLimit(filter) {
  if (filter.ids && !filter.ids.length)
    return 0;
  if (filter.kinds && !filter.kinds.length)
    return 0;
  if (filter.authors && !filter.authors.length)
    return 0;
  for (const [key, value] of Object.entries(filter)) {
    if (key[0] === "#" && Array.isArray(value) && !value.length)
      return 0;
  }
  return Math.min(
    Math.max(0, filter.limit ?? Infinity),
    filter.ids?.length ?? Infinity,
    filter.authors?.length && filter.kinds?.every((kind) => isReplaceableKind(kind)) ? filter.authors.length * filter.kinds.length : Infinity,
    filter.authors?.length && filter.kinds?.every((kind) => isAddressableKind(kind)) && filter["#d"]?.length ? filter.authors.length * filter.kinds.length * filter["#d"].length : Infinity
  );
}
export {
  getFilterLimit,
  matchFilter,
  matchFilters,
  mergeFilters
};