export function parseRange(
  header: string | null,
  size: number,
): { start: number; end: number } | null {
  if (!Number.isSafeInteger(size) || size <= 0) return null
  if (header === null) return { start: 0, end: size - 1 }
  const match = /^bytes=(\d*)-(\d*)$/.exec(header)
  if (!match || (!match[1] && !match[2])) return null
  const start = match[1] ? Number(match[1]) : Math.max(0, size - Number(match[2]))
  const end = match[1] && match[2] ? Math.min(Number(match[2]), size - 1) : size - 1
  if (
    !Number.isSafeInteger(start) ||
    !Number.isSafeInteger(end) ||
    start > end ||
    start >= size ||
    end < 0
  )
    return null
  return { start, end }
}