Function useCalendarView

packages/emcn/src/components/calendar/calendar.tsx:222–253

(seed: Date | null)

}

function useCalendarView(seed: Date | null) {
  const today = useMemo(() => new Date(), [])
  const [view, setView] = useState(() => {
    const base = seed ?? today
    return { month: base.getMonth(), year: base.getFullYear() }
  })

  const goToPrevMonth = () =>
    setView((prev) =>
      prev.month === 0
        ? { month: 11, year: prev.year - 1 }
        : { month: prev.month - 1, year: prev.year }
    )

  const goToNextMonth = () =>
    setView((prev) =>
      prev.month === 11
        ? { month: 0, year: prev.year + 1 }
        : { month: prev.month + 1, year: prev.year }
    )

  const cells = useMemo<(number | null)[]>(() => {
    const leading = getFirstDayOfMonth(view.year, view.month)
    const total = getDaysInMonth(view.year, view.month)
    const result: (number | null)[] = []
    for (let i = 0; i < leading; i++) result.push(null)
    for (let day = 1; day <= total; day++) result.push(day)
    return result
  }, [view])

  return { today, view, setView, goToPrevMonth, goToNextMonth, cells }
}

function CalendarHeader({
  month,