export type DateRangeValue = {start: string; end: string}

export function normalizeRange(a: string, b: string): DateRangeValue {
  return a <= b ? {start: a, end: b} : {start: b, end: a}
}

export function resolveRangeBounds(
  start: string | null,
  end: string | null,
  preview: string | null,
): {lo: string; hi: string} | null {
  if (!start) return null
  const other = end ?? preview
  if (!other) return {lo: start, hi: start}
  return start <= other ? {lo: start, hi: other} : {lo: other, hi: start}
}

export type DayRangeRole = 'none' | 'single' | 'start' | 'end' | 'in-range'

export function dayRangeRole(
  iso: string,
  bounds: {lo: string; hi: string} | null,
): DayRangeRole {
  if (!bounds) return 'none'
  const {lo, hi} = bounds
  if (lo === hi) return iso === lo ? 'single' : 'none'
  if (iso === lo) return 'start'
  if (iso === hi) return 'end'
  if (iso > lo && iso < hi) return 'in-range'
  return 'none'
}