How many weeks between now and…

export const take = [
  { type: "date" },
  {
    type: "dropdown",
    label: "Week starts",
    options: [
      { value: 0, label: "Sunday" },
      { value: 1, label: "Monday" },
      { value: 2, label: "Tuesday" },
      { value: 3, label: "Wednesday" },
      { value: 4, label: "Thursday" },
      { value: 5, label: "Friday" },
      { value: 6, label: "Saturday" },
    ],
  },
]

export const make = ([target, offset]) => {
  if (!target) return

  const day = 1000 * 60 * 60 * 24
  const now = Date.now()
  const current = new Date(now - (now % day))

  const delta = Math.floor((target - current) / day)
  const major = Math.floor(Math.abs(delta / 7))
  const minor = Math.abs(delta % 7)
  const weeks = Math.floor((delta + ((current.getDay() + 7 - offset) % 7)) / 7)

  const formatNumber = new Intl.NumberFormat().format
  const formatDate = new Intl.DateTimeFormat(undefined, {
    year: "numeric",
    day: "numeric",
    month: "long",
    weekday: "long",
    era: target.getFullYear() < 1200 ? "short" : undefined,
  }).format

  const majCount = (n) =>
    n > 0 ? `${formatNumber(n)} ${n > 1 ? "weeks" : "week"}` : ""

  const minCount = (n) =>
    n > 0 ? `${formatNumber(n)} ${n > 1 ? "days" : "day"}` : ""

  let value
  let detail = formatDate(target)

  if (weeks === 0) {
    value = "This week"
  } else if (weeks === 1) {
    value = "Next week"
  } else if (weeks === -1) {
    value = "Last week"
  } else if (weeks > 0) {
    value = `${majCount(major)} left`
  } else {
    value = `${majCount(major)} ago`
  }

  if (delta === 0) {
    detail += " is today!"
  } else if (delta === 1) {
    detail += " is tomorrow."
  } else if (delta === -1) {
    detail += " was yesterday."
  } else {
    const count = [majCount(major), minCount(minor)]
      .filter((f) => f)
      .join(" and ")

    detail += delta > 0 ? ` is in ${count}.` : ` was ${count} ago.`
  }

  return {
    type: "card",
    value,
    detail,
  }
}