import { dt } from "@scandic-hotels/common/dt"

import type { Lang } from "@scandic-hotels/common/constants/language"
import type { IntlShape } from "react-intl"

export function getDaysUntilText(
  checkinDate: string,
  lang: Lang,
  intl: IntlShape
): string {
  const checkInDateTime = dt(checkinDate).locale(lang).startOf("day")
  const now = dt().locale(lang).startOf("day")
  const daysUntil = checkInDateTime.diff(now, "days")

  // Handle past dates edge case.
  if (daysUntil < 0) {
    return dt(checkinDate).locale(lang).format("D MMM YYYY")
  }

  if (daysUntil === 0) {
    return intl.formatMessage({
      id: "nextStay.today",
      defaultMessage: "Today",
    })
  }

  if (daysUntil === 1) {
    return intl.formatMessage({
      id: "nextStay.tomorrow",
      defaultMessage: "Tomorrow",
    })
  }

  if (daysUntil > 1 && daysUntil <= 30) {
    return intl.formatMessage(
      {
        id: "nextStay.inXDays",
        defaultMessage: "In {days} days",
      },
      {
        days: daysUntil,
      }
    )
  }

  // Use proper month calculation for dates beyond 30 days
  const monthsUntil = checkInDateTime.diff(now, "months")
  return intl.formatMessage(
    {
      id: "nextStay.inXMonths",
      defaultMessage: "In {months} month{months, plural, =1 {} other {s}}",
    },
    {
      months: monthsUntil,
    }
  )
}