duration.ts

type Duration = {
  years?: number
  months?: number
  weeks?: number
  days?: number
  hours?: number
  minutes?: number
  seconds?: number
}

export const Duration = {
  MS_IN_DAY: milliseconds({ days: 1 }),
  MS_IN_HOUR: milliseconds({ hours: 1 }),
  MS_IN_MINUTE: milliseconds({ minutes: 1 }),
  MS_IN_SECOND: milliseconds({ seconds: 1 }),
  add(d1: Duration, d2: Duration): Duration {
    return Duration.ofMilliseconds(milliseconds(d1) + milliseconds(d2))
  },
  equals(d1: Duration, d2: Duration): boolean {
    return milliseconds(d1) === milliseconds(d2)
  },
  gt(d1: Duration, d2: Duration): boolean {
    return milliseconds(d1) > milliseconds(d2)
  },
  gte(d1: Duration, d2: Duration): boolean {
    return milliseconds(d1) >= milliseconds(d2)
  },
  lt(d1: Duration, d2: Duration): boolean {
    return milliseconds(d1) < milliseconds(d2)
  },
  lte(d1: Duration, d2: Duration): boolean {
    return milliseconds(d1) <= milliseconds(d2)
  },
  ofMilliseconds(ms: number): Duration {
    const days = Math.floor(ms / Duration.MS_IN_DAY)
    ms -= days * Duration.MS_IN_DAY

    const hours = Math.floor(ms / Duration.MS_IN_HOUR)
    ms -= hours * Duration.MS_IN_HOUR

    const minutes = Math.floor(ms / Duration.MS_IN_MINUTE)
    ms -= minutes * Duration.MS_IN_MINUTE

    const seconds = Math.floor(ms / Duration.MS_IN_SECOND)
    ms -= seconds * Duration.MS_IN_SECOND

    return {
      days,
      hours,
      minutes,
      seconds,
    }
  },
  subtract(d1: Duration, d2: Duration): Duration {
    const delta = milliseconds(d1) - milliseconds(d2)

    if (delta < 0) {
      throw new Error(
        "d1 is smaller than d2, can't produce a negative duration"
      )
    }

    return Duration.ofMilliseconds(delta)
  },
  toHumanString(d: Duration): string {
    const formattedDuration = formatDuration(d, { delimiter: ', ' })
    const lastCommaIndex = formattedDuration.lastIndexOf(',')

    if (lastCommaIndex === -1) {
      return formattedDuration
    }

    return (
      formattedDuration.substring(0, lastCommaIndex) +
      ' and' +
      formattedDuration.substring(lastCommaIndex + 1)
    )
  },
  toMilliseconds(d: Duration): number {
    return milliseconds(d)
  },
}