import {
  CHINA_UTC_OFFSET,
  addDaysToDateOnly,
  getWeekDayFromDateOnly,
  isConsecutiveDates,
  parseChinaDateOnly,
} from './china-time';

describe('china-time', () => {
  it('exports UTC+8 offset', () => {
    expect(CHINA_UTC_OFFSET).toBe(8);
  });

  it('addDaysToDateOnly crosses month/year boundaries', () => {
    expect(addDaysToDateOnly('2026-02-28', 1)).toBe('2026-03-01');
    expect(addDaysToDateOnly('2026-12-31', 1)).toBe('2027-01-01');
    expect(addDaysToDateOnly('2026-01-01', -1)).toBe('2025-12-31');
    expect(addDaysToDateOnly('2026-08-09', 7)).toBe('2026-08-16');
  });

  it('getWeekDayFromDateOnly is timezone independent', () => {
    // 2026-08-09 是周日 → 7
    expect(getWeekDayFromDateOnly('2026-08-09')).toBe(7);
    // 2026-08-10 是周一 → 1
    expect(getWeekDayFromDateOnly('2026-08-10')).toBe(1);
  });

  it('parseChinaDateOnly anchors to UTC+8 midnight', () => {
    const d = parseChinaDateOnly('2026-08-09');
    expect(d.toISOString()).toBe('2026-08-08T16:00:00.000Z');
  });

  it('isConsecutiveDates detects adjacent dates', () => {
    expect(isConsecutiveDates('2026-08-09', '2026-08-10')).toBe(true);
    expect(isConsecutiveDates('2026-08-09', '2026-08-11')).toBe(false);
    expect(isConsecutiveDates('2026-08-09', '2026-08-09')).toBe(false);
  });
});