import crypto from 'node:crypto';

export function buildEventEnvelope({
  eventType,
  venue,
  payload,
  source,
  eventId = crypto.randomUUID(),
  schemaVersion = 1,
  observedAt = null,
  ingestedAt = new Date(),
  raw = null,
}) {
  if (!eventType) throw new Error('Missing eventType');
  if (!venue) throw new Error('Missing venue');
  if (payload == null) throw new Error('Missing payload');

  return {
    event_id: String(eventId),
    event_type: String(eventType),
    venue: String(venue),
    source: source ? String(source) : null,
    schema_version: Number(schemaVersion),
    observed_at: toIsoStringOrNull(observedAt),
    ingested_at: toIsoStringOrNull(ingestedAt) ?? new Date().toISOString(),
    payload,
    raw,
  };
}

export function parseEventMessage(value) {
  const event = typeof value === 'string' ? JSON.parse(value) : value;
  if (!event || typeof event !== 'object') throw new Error('Event must be an object');
  return event;
}

function toIsoStringOrNull(value) {
  if (value == null) return null;
  const date = value instanceof Date ? value : new Date(value);
  return Number.isNaN(date.getTime()) ? null : date.toISOString();
}