import { describe, it, expect } from 'vitest'
import { DOW, DOW_EN, BYDAY_TO_INDEX, bydayFromDate, dowLabel } from '../src/lib/weekday.js'

describe('weekday', () => {
  it('DOW has 7 entries starting Sunday', () => {
    expect(DOW).toHaveLength(7)
    expect(DOW[0]).toBe('周日')
    expect(DOW[6]).toBe('周六')
  })

  it('DOW_EN indexed by JS getDay (0=Sunday)', () => {
    expect(DOW_EN).toEqual(['SU', 'MO', 'TU', 'WE', 'TH', 'FR', 'SA'])
  })

  it('BYDAY_TO_INDEX maps SU..SA to 0..6', () => {
    expect(BYDAY_TO_INDEX.SU).toBe(0)
    expect(BYDAY_TO_INDEX.SA).toBe(6)
  })

  it('bydayFromDate returns BYDAY code for a Date', () => {
    // 2026-07-27 is a Monday -> getDay()=1 -> 'MO'
    expect(bydayFromDate(new Date(2026, 6, 27))).toBe('MO')
    // 2026-08-01 is a Saturday -> getDay()=6 -> 'SA'
    expect(bydayFromDate(new Date(2026, 7, 1))).toBe('SA')
  })

  it('dowLabel returns Chinese label for a Date', () => {
    expect(dowLabel(new Date(2026, 6, 27))).toBe('周一')
    expect(dowLabel(new Date(2026, 6, 26))).toBe('周日')
  })
})