/**
 * Human readable elapsed or remaining time (example: 3 minutes ago)
 * @author github.com/victornpb
 * @see https://stackoverflow.com/a/67338038/938822
 */
export function ago(
	/** A Date object, timestamp or string parsable with Date.parse() */
	date: string | number | Date,
	/** A Date object, timestamp or string parsable with Date.parse() */
	nowDate: string | number | Date = Date.now(),
	/** A Intl formater */
	rft: Intl.RelativeTimeFormat = new Intl.RelativeTimeFormat(undefined, { numeric: 'auto' })
): string {
	const SECOND = 1000;
	const MINUTE = 60 * SECOND;
	const HOUR = 60 * MINUTE;
	const DAY = 24 * HOUR;
	const WEEK = 7 * DAY;
	const MONTH = 30 * DAY;
	const YEAR = 365 * DAY;
	const intervals = [
		{ ge: YEAR, divisor: YEAR, unit: 'year' },
		{ ge: MONTH, divisor: MONTH, unit: 'month' },
		{ ge: WEEK, divisor: WEEK, unit: 'week' },
		{ ge: DAY, divisor: DAY, unit: 'day' },
		{ ge: HOUR, divisor: HOUR, unit: 'hour' },
		{ ge: MINUTE, divisor: MINUTE, unit: 'minute' },
		{ ge: 30 * SECOND, divisor: SECOND, unit: 'seconds' },
		{ ge: 0, divisor: 1, text: 'just now' },
	];
	const now = typeof nowDate === 'object' ? nowDate.getTime() : new Date(nowDate).getTime();
	const diff = now - (typeof date === 'object' ? date : new Date(date)).getTime();
	const diffAbs = Math.abs(diff);
	for (const interval of intervals) {
		if (diffAbs >= interval.ge) {
			const x = Math.round(Math.abs(diff) / interval.divisor);
			const isFuture = diff < 0;
			return interval.unit ? rft.format(isFuture ? x : -x, interval.unit as Unit) : interval.text;
		}
	}
}

type Unit =
	| 'second'
	| 'seconds'
	| 'minute'
	| 'minutes'
	| 'hour'
	| 'hours'
	| 'day'
	| 'days'
	| 'week'
	| 'weeks'
	| 'month'
	| 'months'
	| 'year'
	| 'years';