ditto/src/kinds.ts

/** Events are **regular**, which means they're all expected to be stored by relays. */
function isRegularKind(kind: number) {
  return (1000 <= kind && kind < 10000) || [1, 2, 4, 5, 6, 7, 8, 16, 40, 41, 42, 43, 44].includes(kind);
}

/** Events are **replaceable**, which means that, for each combination of `pubkey` and `kind`, only the latest event is expected to (SHOULD) be stored by relays, older versions are expected to be discarded. */
function isReplaceableKind(kind: number) {
  return (10000 <= kind && kind < 20000) || [0, 3].includes(kind);
}

/** Events are **ephemeral**, which means they are not expected to be stored by relays. */
function isEphemeralKind(kind: number) {
  return 20000 <= kind && kind < 30000;
}

/** Events are **parameterized replaceable**, which means that, for each combination of `pubkey`, `kind` and the `d` tag, only the latest event is expected to be stored by relays, older versions are expected to be discarded. */
function isParameterizedReplaceableKind(kind: number) {
  return 30000 <= kind && kind < 40000;
}

/** These events are only valid if published by the server keypair. */
function isDittoInternalKind(kind: number) {
  return kind === 30361;
}

/** Classification of the event kind. */
type KindClassification = 'regular' | 'replaceable' | 'ephemeral' | 'parameterized' | 'unknown';

/** Determine the classification of this kind of event if known, or `unknown`. */
function classifyKind(kind: number): KindClassification {
  if (isRegularKind(kind)) return 'regular';
  if (isReplaceableKind(kind)) return 'replaceable';
  if (isEphemeralKind(kind)) return 'ephemeral';
  if (isParameterizedReplaceableKind(kind)) return 'parameterized';
  return 'unknown';
}

export {
  classifyKind,
  isDittoInternalKind,
  isEphemeralKind,
  isParameterizedReplaceableKind,
  isRegularKind,
  isReplaceableKind,
  type KindClassification,
};