const formatters = new Map<string, Intl.NumberFormat>();

export function formatCents(cents: number, currency = "USD"): string {
	let fmt = formatters.get(currency);
	if (!fmt) {
		fmt = new Intl.NumberFormat(undefined, { style: "currency", currency });
		formatters.set(currency, fmt);
	}
	return fmt.format(cents / 100);
}

const dateFmt = new Intl.DateTimeFormat(undefined, {
	month: "short",
	day: "numeric",
});
const dateFmtFull = new Intl.DateTimeFormat(undefined, {
	year: "numeric",
	month: "short",
	day: "numeric",
});

export function formatDay(unixSeconds: number): string {
	const date = new Date(unixSeconds * 1000);
	const now = new Date();
	return date.getFullYear() === now.getFullYear()
		? dateFmt.format(date)
		: dateFmtFull.format(date);
}

export function formatMonth(month: string): string {
	const [y, m] = month.split("-").map(Number);
	return new Intl.DateTimeFormat(undefined, { month: "long", year: "numeric" })
		.format(
			new Date(Date.UTC(y, m - 1, 15)),
		);
}