import { describe, it, expect } from 'vitest';
import { Frequency } from './frequency';

// Branding is compile-time: construction and forgery must not type-check.
// Checked by `npm run check`, inert at runtime.
function _assertUnforgeable(): void {
	// @ts-expect-error — Frequency's constructor is private
	new Frequency('5/2w');
	// @ts-expect-error — the private brand makes object literals non-assignable
	const forged: Frequency = { count: 5, length: 2, unit: 'w' };
	void forged;
}
void _assertUnforgeable;

describe('Frequency grammar', () => {
	it('accepts interval specs', () => {
		for (const spec of ['1d', '2w', '3m', '1y', '7d', '07d', '180d']) {
			expect(Frequency.safeParse(spec)?.toSpec()).toBe(spec);
		}
	});

	it('accepts quota specs with an explicit period length', () => {
		for (const spec of ['5/2w', '5/1w', '1/1d', '2/3m', '1/1y', '5/14d']) {
			expect(Frequency.safeParse(spec)?.toSpec()).toBe(spec);
		}
	});

	it('normalizes case and surrounding whitespace only', () => {
		expect(Frequency.safeParse('  5/2W ')?.toSpec()).toBe('5/2w');
		expect(Frequency.safeParse('2W')?.toSpec()).toBe('2w');
		expect(Frequency.safeParse('07D')?.toSpec()).toBe('07d');
	});

	it('rejects invalid specs', () => {
		const invalid = [
			'',
			'2',
			'w',
			'2x',
			'-1d',
			'+2w',
			'1.5d',
			'0d',
			'00d',
			'5/w',
			'5/14',
			'5/2',
			'2w/5',
			'0/2w',
			'5/0w',
			'5 /2w',
			'1/2/3w',
			'２w',
		];
		for (const spec of invalid) {
			expect(Frequency.safeParse(spec), spec).toBeNull();
			expect(() => Frequency.parse(spec), spec).toThrow();
		}
	});
});

describe('spec round-trip', () => {
	it('keeps the spec exactly as written', () => {
		for (const spec of ['5/2w', '2w', '07d', '5/02w', '1/1y']) {
			expect(Frequency.parse(spec).toSpec()).toBe(spec);
		}
	});
});

describe('parsed fields', () => {
	it('extracts interval parts', () => {
		const freq = Frequency.parse('2w');
		expect(freq.count).toBeNull();
		expect(freq.length).toBe(2);
		expect(freq.unit).toBe('w');
	});

	it('extracts quota parts', () => {
		const freq = Frequency.parse('5/2w');
		expect(freq.count).toBe(5);
		expect(freq.length).toBe(2);
		expect(freq.unit).toBe('w');
	});
});

describe('branding', () => {
	it('returns branded instances', () => {
		expect(Frequency.parse('5/2w')).toBeInstanceOf(Frequency);
		expect(Frequency.safeParse('2w')).toBeInstanceOf(Frequency);
	});
});

describe('format', () => {
	it('keeps day-based interval labels (legacy display)', () => {
		expect(Frequency.parse('1d').format()).toBe('chaque jour');
		expect(Frequency.parse('7d').format()).toBe('chaque semaine');
		expect(Frequency.parse('1w').format()).toBe('chaque semaine');
		expect(Frequency.parse('30d').format()).toBe('chaque mois');
		expect(Frequency.parse('365d').format()).toBe('chaque année');
		expect(Frequency.parse('2w').format()).toBe('tous les 14 jours');
		expect(Frequency.parse('14d').format()).toBe('tous les 14 jours');
		expect(Frequency.parse('180d').format()).toBe('tous les 180 jours');
	});

	it('labels quotas as completions per period', () => {
		expect(Frequency.parse('5/2w').format()).toBe('5 fois par 2 semaines');
		expect(Frequency.parse('5/1w').format()).toBe('5 fois par semaine');
		expect(Frequency.parse('3/1d').format()).toBe('3 fois par jour');
		expect(Frequency.parse('2/3m').format()).toBe('2 fois par 3 mois');
		expect(Frequency.parse('1/1y').format()).toBe('1 fois par an');
		expect(Frequency.parse('4/2y').format()).toBe('4 fois par 2 ans');
		expect(Frequency.parse('5/14d').format()).toBe('5 fois par 14 jours');
	});
});

describe('periodDays', () => {
	it('extracts day counts for compute only', () => {
		expect(Frequency.parse('1d').periodDays()).toBe(1);
		expect(Frequency.parse('2w').periodDays()).toBe(14);
		expect(Frequency.parse('5/2w').periodDays()).toBe(14);
		expect(Frequency.parse('5/1m').periodDays()).toBe(30);
		expect(Frequency.parse('2/3w').periodDays()).toBe(21);
		expect(Frequency.parse('1y').periodDays()).toBe(365);
	});
});