export async function createReservation(
  req: CreateReservationRequest,
  ctx: RequestContext,
): Promise<Reservation> {
  const id = ulid();
  const now = new Date().toISOString();
  await assertResourceAvailable(req.resourceId, req.start, req.end);
  const record = {
    id, tenantId: ctx.tenantId, status: "PENDING",
    resourceId: req.resourceId, start: req.start, end: req.end,
    createdAt: now, updatedAt: now, version: 0,
  };
  await ddb.put({
    TableName: RESERVATIONS_TABLE,
    Item: record,
    ConditionExpression: "attribute_not_exists(id)",
  });
  await publishEvent("reservation.created", record);
  await scheduleExpiryTask(id, req.expiresAt);
  return toReservationDto(record);
}

val reservationConfig = EntityConfig(
  name          = "Reservation",
  accessMode    = EntityAccessMode.OWNER,
  fragments     = Seq("resourceId", "status"),
  externalKeys  = Seq("confirmationCode"),
  sortKeys      = Seq("start"),
).withLifecycle(
  LifecycleConfig(
    initial     = "Pending",
    transitions = Seq(
      Transition("Confirm", from = "Pending", to = "Confirmed"),
      Transition("Cancel",  from = Set("Pending", "Confirmed"), to = "Cancelled"),
    ),
    expiry      = Some(ExpiryRule(after = 30.minutes, transitionTo = "Cancelled")),
  ),
)