const MINUTE = 60;
const HOUR = 60 * MINUTE;
const DAY = 24 * HOUR;
const YEAR = 365 * DAY;
const MONTH = YEAR / 12;

/**
 * get readable string of time elapsed since date
 * @param {Date} date
 * @returns string
 */
export default function timeElapsed(date) {
	const now = new Date();
	const age = Math.floor((now.getTime() - date.getTime()) / 1000);

	const years = Math.floor(age / YEAR);
	let remainder = age % YEAR;
	const months = Math.floor(remainder / MONTH);
	remainder %= MONTH;
	const days = Math.floor(remainder / DAY);
	remainder %= DAY;
	const hours = Math.floor(remainder / HOUR);
	remainder %= HOUR;
	const minutes = Math.floor(remainder / MINUTE);
	const seconds = remainder % MINUTE;
	if (years > 0) return years === 1 ? 'vor 1 Jahr' : `vor ${years} Jahren`;
	if (months > 0) return months === 1 ? 'vor 1 Monat' : `vor ${months} Monaten`;
	if (days > 0) return days === 1 ? 'vor 1 Tag' : `vor ${days} Tagen`;
	if (hours > 0) return hours === 1 ? 'vor 1 Stunde' : `vor ${hours} Stunden`;
	if (minutes > 0) return minutes === 1 ? 'vor 1 Minute' : `vor ${minutes} Minuten`;

	return seconds === 1 ? 'vor 1 Sekunde' : `vor ${seconds} Sekunden`;
}