import { describe, it, expect } from 'vitest'
import { expandOccurrences, intervalDays } from '../src/lib/recur.js'

describe('intervalDays', () => {
  it('returns 7 for WEEKLY interval=1', () => {
    const ev = { rrule: { freq: 'WEEKLY', interval: 1 } }
    expect(intervalDays(ev)).toBe(7)
  })

  it('returns 14 for WEEKLY interval=2', () => {
    const ev = { rrule: { freq: 'WEEKLY', interval: 2 } }
    expect(intervalDays(ev)).toBe(14)
  })

  it('returns interval for DAILY', () => {
    const ev = { rrule: { freq: 'DAILY', interval: 3 } }
    expect(intervalDays(ev)).toBe(3)
  })
})

describe('expandOccurrences', () => {
  it('returns single occurrence for non-recurring event', () => {
    const ev = { dtstartDate: '2026-07-27', rrule: null, exdates: [] }
    const occs = expandOccurrences(ev)
    expect(occs).toHaveLength(1)
    expect(occs[0]).toEqual({ date: '2026-07-27', skipped: false })
  })

  it('expands weekly event from Jul 27 to Oct 19', () => {
    const ev = {
      dtstartDate: '2026-07-27',
      rrule: { freq: 'WEEKLY', interval: 1, byday: 'MO', untilDate: '2026-10-19' },
      exdates: ['2026-09-21'],
    }
    const occs = expandOccurrences(ev)
    // Jul 27 + 12 weeks = Oct 19 -> 13 occurrences
    expect(occs).toHaveLength(13)
    expect(occs[0].date).toBe('2026-07-27')
    expect(occs[12].date).toBe('2026-10-19')
    // Sep 21 is skipped
    const sep21 = occs.find(o => o.date === '2026-09-21')
    expect(sep21.skipped).toBe(true)
    // Others not skipped
    expect(occs[0].skipped).toBe(false)
  })

  it('respects exdates set', () => {
    const ev = {
      dtstartDate: '2026-07-27',
      rrule: { freq: 'WEEKLY', interval: 1, byday: 'MO', untilDate: '2026-08-24' },
      exdates: ['2026-08-03', '2026-08-17'],
    }
    const occs = expandOccurrences(ev)
    expect(occs).toHaveLength(5) // Jul27, Aug3, Aug10, Aug17, Aug24
    expect(occs[1].skipped).toBe(true)  // Aug 3
    expect(occs[2].skipped).toBe(false) // Aug 10
    expect(occs[3].skipped).toBe(true)  // Aug 17
  })

  it('caps at 500 occurrences', () => {
    const ev = {
      dtstartDate: '2020-01-01',
      rrule: { freq: 'DAILY', interval: 1, untilDate: '2030-12-31' },
      exdates: [],
    }
    const occs = expandOccurrences(ev)
    expect(occs.length).toBeLessThanOrEqual(500)
  })
})