cinny/src/app/utils/formatTimestamp.test.ts

import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import {
  formatDayDivider,
  formatRelativeAge,
  formatShortAge,
  formatTimestamp,
} from './formatTimestamp';

// Fri 18 Sep 2026 14:05 local.
const now = new Date(2026, 8, 18, 14, 5).getTime();
const at = (y: number, m: number, d: number, h = 21, min = 14) =>
  new Date(y, m - 1, d, h, min).getTime();
const p12 = { hour24Clock: false, dateFormatString: 'D MMM YYYY' };
const p24 = { hour24Clock: true, dateFormatString: 'YYYY-MM-DD' };

describe('formatTimestamp', () => {
  it('today → time only', () => {
    assert.equal(formatTimestamp(at(2026, 9, 18, 9, 3), p12, 'auto', now), '09:03 AM');
    assert.equal(formatTimestamp(at(2026, 9, 18, 9, 3), p24, 'auto', now), '09:03');
  });

  it('yesterday / tomorrow → day word + time', () => {
    assert.equal(formatTimestamp(at(2026, 9, 17), p24, 'auto', now), 'Yesterday 21:14');
    assert.equal(formatTimestamp(at(2026, 9, 19), p24, 'auto', now), 'Tomorrow 21:14');
    // Just before midnight yesterday is still yesterday, not "hours ago".
    assert.equal(formatTimestamp(at(2026, 9, 17, 23, 59), p24, 'auto', now), 'Yesterday 23:59');
  });

  it('within the last week → weekday + time', () => {
    assert.equal(formatTimestamp(at(2026, 9, 14), p24, 'auto', now), 'Mon 21:14');
    assert.equal(formatTimestamp(at(2026, 9, 12), p24, 'auto', now), 'Sat 21:14');
  });

  it('a week or more → date + time in the user format', () => {
    assert.equal(formatTimestamp(at(2026, 9, 11), p24, 'auto', now), '2026-09-11 21:14');
    assert.equal(formatTimestamp(at(2025, 1, 2), p12, 'auto', now), '2 Jan 2025 09:14 PM');
    assert.equal(formatTimestamp(at(2026, 9, 25), p12, 'auto', now), '25 Sep 2026 09:14 PM');
  });

  it('autoDate never shows the time', () => {
    assert.equal(formatTimestamp(at(2026, 9, 18), p12, 'autoDate', now), 'Today');
    assert.equal(formatTimestamp(at(2026, 9, 17), p12, 'autoDate', now), 'Yesterday');
    assert.equal(formatTimestamp(at(2026, 9, 15), p12, 'autoDate', now), 'Tue');
    assert.equal(formatTimestamp(at(2026, 1, 15), p12, 'autoDate', now), '15 Jan 2026');
  });

  it('fixed styles ignore the relative day', () => {
    assert.equal(formatTimestamp(at(2026, 9, 18), p12, 'time', now), '09:14 PM');
    assert.equal(formatTimestamp(at(2026, 9, 18), p12, 'date', now), '18 Sep 2026');
    assert.equal(formatTimestamp(at(2026, 9, 18), p24, 'dateTime', now), '2026-09-18 21:14');
  });

  it('falls back to a default date format when the preference is empty', () => {
    assert.equal(
      formatTimestamp(at(2026, 1, 15), { hour24Clock: true, dateFormatString: '' }, 'date', now),
      '15 Jan 2026',
    );
  });
});

describe('formatShortAge', () => {
  it('minutes and hours today', () => {
    assert.equal(formatShortAge(now - 20_000, p12, now), 'now');
    assert.equal(formatShortAge(now - 5 * 60_000, p12, now), '5m');
    assert.equal(formatShortAge(now - 3 * 3_600_000, p12, now), '3h');
  });

  it('day words, then a short date (year dropped when current)', () => {
    assert.equal(formatShortAge(at(2026, 9, 17, 23, 0), p12, now), 'Yesterday');
    assert.equal(formatShortAge(at(2026, 9, 14), p12, now), 'Mon');
    assert.equal(formatShortAge(at(2026, 3, 2), p12, now), '2 Mar');
    assert.equal(formatShortAge(at(2026, 3, 2), p24, now), '03-02');
    assert.equal(formatShortAge(at(2025, 3, 2), p12, now), '2 Mar 2025');
  });
});

describe('formatRelativeAge', () => {
  it('steps through minutes, hours, days, then the date', () => {
    assert.equal(formatRelativeAge(now - 10_000, p12, now), 'just now');
    assert.equal(formatRelativeAge(now - 7 * 60_000, p12, now), '7m ago');
    assert.equal(formatRelativeAge(now - 5 * 3_600_000, p12, now), '5h ago');
    assert.equal(formatRelativeAge(at(2026, 9, 17, 8), p12, now), 'yesterday');
    assert.equal(formatRelativeAge(at(2026, 9, 15, 8), p12, now), '3d ago');
    assert.equal(formatRelativeAge(at(2026, 9, 1, 8), p24, now), '2026-09-01');
  });
});

describe('formatDayDivider', () => {
  it('uses the full weekday inside the last week', () => {
    assert.equal(formatDayDivider(at(2026, 9, 18), p12, now), 'Today');
    assert.equal(formatDayDivider(at(2026, 9, 17), p12, now), 'Yesterday');
    assert.equal(formatDayDivider(at(2026, 9, 14), p12, now), 'Monday');
    assert.equal(formatDayDivider(at(2026, 9, 11), p12, now), '11 Sep 2026');
  });
});