type BirthDateRow = Readonly<{
  birth_date?: unknown;
  date?: unknown;
  active_birth_date?: unknown;
  activeDate?: unknown;
  birth_time_status?: unknown;
  birthTimeStatus?: unknown;
}>;

export function birthCalendarDate(value: unknown): string | undefined {
  if (value instanceof Date && Number.isFinite(value.getTime())) return value.toISOString().slice(0, 10);
  if (typeof value !== "string") return undefined;
  const date = value.trim().slice(0, 10);
  return /^\d{4}-\d{2}-\d{2}$/.test(date) ? date : undefined;
}

// Declaration date remains immutable input; adoption is a separate server-owned output.
export function effectiveBirthDate(row: BirthDateRow, useActive = true): string | undefined {
  const declared = birthCalendarDate(row.birth_date ?? row.date);
  const status = row.birth_time_status ?? row.birthTimeStatus;
  if (useActive && (status === "accepted" || status === "confirmed")) {
    return birthCalendarDate(row.active_birth_date ?? row.activeDate) ?? declared;
  }
  return declared;
}