import {afterEach, beforeEach, describe, expect, it, vi} from 'vitest'
import {ref} from 'vue'
import {useMonthMatrix} from './useMonthMatrix'

describe('useMonthMatrix', () => {
  it('always produces 6 weeks of 7 days', () => {
    const {weeks} = useMonthMatrix(ref(4), ref(2026)) // mai 2026
    expect(weeks.value).toHaveLength(6)
    weeks.value.forEach(week => expect(week.days).toHaveLength(7))
  })

  it('starts every week on a Monday', () => {
    const {weeks} = useMonthMatrix(ref(4), ref(2026))
    weeks.value.forEach(week => {
      const first = new Date(`${week.days[0].isoDate}T00:00:00`)
      expect(first.getDay()).toBe(1) // 1 = lundi
    })
  })

  it('flags exactly the days of the current month', () => {
    const {weeks} = useMonthMatrix(ref(4), ref(2026)) // mai = 31 jours
    const currentMonthDays = weeks.value
      .flatMap(w => w.days)
      .filter(d => d.isCurrentMonth)
    expect(currentMonthDays).toHaveLength(31)
    expect(currentMonthDays.every(d => d.isoDate.startsWith('2026-05'))).toBe(true)
  })

  it('handles leap year February (29 days)', () => {
    const {weeks} = useMonthMatrix(ref(1), ref(2024)) // février 2024
    const days = weeks.value.flatMap(w => w.days).filter(d => d.isCurrentMonth)
    expect(days).toHaveLength(29)
  })

  it('assigns ISO week 1 to the week containing Jan 4th', () => {
    const {weeks} = useMonthMatrix(ref(0), ref(2026)) // janvier 2026
    const weekWithJan4 = weeks.value.find(w =>
      w.days.some(d => d.isoDate === '2026-01-04'),
    )
    expect(weekWithJan4?.weekNumber).toBe(1)
  })

  it('reacts to month/year changes', () => {
    const month = ref(4)
    const year = ref(2026)
    const {weeks} = useMonthMatrix(month, year)
    const mayCount = weeks.value.flatMap(w => w.days).filter(d => d.isCurrentMonth).length
    month.value = 1 // février
    year.value = 2024
    const febCount = weeks.value.flatMap(w => w.days).filter(d => d.isCurrentMonth).length
    expect(mayCount).toBe(31)
    expect(febCount).toBe(29)
  })

  describe('isToday', () => {
    beforeEach(() => {
      vi.useFakeTimers()
      vi.setSystemTime(new Date(2026, 4, 19)) // 19 mai 2026
    })
    afterEach(() => vi.useRealTimers())

    it('flags only today', () => {
      const {weeks} = useMonthMatrix(ref(4), ref(2026))
      const todays = weeks.value.flatMap(w => w.days).filter(d => d.isToday)
      expect(todays).toHaveLength(1)
      expect(todays[0].isoDate).toBe('2026-05-19')
    })
  })
})