import { describe, expect, it } from 'vitest';

import { dateTimeFormat, lazy, numberFormat, pluralRules } from './runtime.ts';

describe('lazy', () => {
	it('computes once on first access and caches the result', () => {
		let calls = 0;
		const holder = lazy(() => {
			calls++;
			return { id: calls };
		});
		expect(holder.value).toBe(holder.value);
		expect(holder.value.id).toBe(1);
		expect(calls).toBe(1);
	});
});

describe('Intl shorthands', () => {
	it('builds an Intl.PluralRules', () => {
		const rules = pluralRules('en', { type: 'cardinal' });
		expect(rules).toBeInstanceOf(Intl.PluralRules);
		expect(rules.select(1)).toBe('one');
	});

	it('builds an Intl.NumberFormat', () => {
		const format = numberFormat('en', { style: 'percent' });
		expect(format).toBeInstanceOf(Intl.NumberFormat);
		expect(format.format(0.5)).toBe('50%');
	});

	it('builds an Intl.DateTimeFormat', () => {
		const format = dateTimeFormat('en', { timeZone: 'UTC', year: 'numeric' });
		expect(format).toBeInstanceOf(Intl.DateTimeFormat);
		expect(format.format(new Date('2026-06-28T00:00:00Z'))).toBe('2026');
	});
});