import { describe, expect, it } from 'vitest';
import { monthsAgo, computeLastActivity } from '../../src/lib/staleSpaces.ts';

describe('monthsAgo', () => {
    it('subtracts calendar months', () => {
        const now = new Date('2026-07-06T12:00:00Z');
        const back = monthsAgo(24, now);
        expect(back.getUTCFullYear()).toBe(2024);
        expect(back.getUTCMonth()).toBe(6); // July (0-indexed)
    });

    it('handles month-boundary edge without throwing (Mar 31 → Feb 28/Mar 3)', () => {
        const now = new Date('2026-03-31T00:00:00Z');
        expect(() => monthsAgo(1, now)).not.toThrow();
    });

    it('is idempotent for months=0', () => {
        const now = new Date('2026-01-15T00:00:00Z');
        expect(monthsAgo(0, now).toISOString()).toBe(now.toISOString());
    });
});

describe('computeLastActivity', () => {
    const older = new Date('2024-01-01T00:00:00Z');
    const newer = new Date('2025-06-01T00:00:00Z');

    it('returns spaceCreatedAt when there are no messages', () => {
        expect(computeLastActivity(older, null).toISOString()).toBe(older.toISOString());
        expect(computeLastActivity(older, undefined).toISOString()).toBe(older.toISOString());
    });

    it('returns the message date when it is newer', () => {
        expect(computeLastActivity(older, newer).toISOString()).toBe(newer.toISOString());
    });

    it('returns spaceCreatedAt when the message is older (defensive)', () => {
        expect(computeLastActivity(newer, older).toISOString()).toBe(newer.toISOString());
    });
});