import * as m from '$lib/paraglide/messages.js';

export function relativeTimeDe(from: Date, now: Date = new Date()): string {
	const minutes = Math.round((now.getTime() - from.getTime()) / 60_000);
	// Malformed input (e.g. Invalid Date from a broken backend string) must not
	// crash the dashboard — fall back to "0 Minuten" rather than render NaN.
	if (!Number.isFinite(minutes)) return m.comment_time_minutes({ count: 0 });
	if (minutes < 60) return m.comment_time_minutes({ count: minutes });
	if (minutes < 1440) return m.comment_time_hours({ count: Math.round(minutes / 60) });
	return m.comment_time_days({ count: Math.round(minutes / 1440) });
}

// "vor N Jahren" for a historical letter date relative to now. Computed from
// calendar fields (not a constant ms-per-year) so that a letter from exactly
// one year ago reports "vor 1 Jahr" rather than falling on the wrong side of
// a leap-year rounding. Returns "" for invalid or future dates — the caller
// should then hide the relative-time label rather than render a misleading
// "vor 0 Jahren".
export function relativeYearsDe(from: Date, now: Date = new Date()): string {
	if (Number.isNaN(from.getTime()) || Number.isNaN(now.getTime())) return '';
	if (from.getTime() > now.getTime()) return '';
	let years = now.getUTCFullYear() - from.getUTCFullYear();
	const beforeAnniversary =
		now.getUTCMonth() < from.getUTCMonth() ||
		(now.getUTCMonth() === from.getUTCMonth() && now.getUTCDate() < from.getUTCDate());
	if (beforeAnniversary) years -= 1;
	if (years < 1) return 'vor weniger als 1 Jahr';
	if (years === 1) return 'vor 1 Jahr';
	return `vor ${years} Jahren`;
}