import { describe, it, expect } from 'vitest'
import { readFileSync } from 'node:fs'
import { fileURLToPath } from 'node:url'
import { dirname, join } from 'node:path'
import { parseICS } from '../src/lib/ical-io.js'
import { serializeICS } from '../src/lib/ical-io.js'

const __dirname = dirname(fileURLToPath(import.meta.url))
const GOLDEN = readFileSync(join(__dirname, 'golden-org.ics'), 'utf-8')

describe('parseICS', () => {
  const { meta, events } = parseICS(GOLDEN)

  it('parses calendar meta', () => {
    expect(meta.prodid).toBe('-//Allocate//iCal4j 1.0//EN')
    expect(meta.version).toBe('2.0')
    expect(meta.calscale).toBe('GREGORIAN')
    expect(meta.vtimezones.length).toBe(1)
  })

  it('parses all 61 events', () => {
    expect(events).toHaveLength(61)
  })

  it('parses first event fields correctly', () => {
    const e = events[0]
    expect(e.summary).toBe('ACC INFO SYS, Tutorial')
    expect(e.location).toBe('CA_B_B471')
    expect(e.dtstartDate).toBe('2026-07-27')
    expect(e.dtstartTime).toBe('18:00')
    expect(e.dtendTime).toBe('20:00')
    expect(e.tzid).toBe('Australia/Melbourne')
    expect(e.rrule).toBeNull()
    expect(e.exdates).toEqual([])
  })

  it('preserves description with escaped commas', () => {
    const e = events[0]
    expect(e.description).toContain('ACF2400_CA_S2_ON-CAMPUS')
    expect(e.description).toContain('ACC INFO SYS')
  })

  it('captures dtstamp in _raw', () => {
    expect(events[0]._raw.dtstamp).toBe('20260711T085008Z')
  })

  it('events have UIDs', () => {
    expect(events[0].uid).toBe('uid0')
    expect(events[60].uid).toBe('uid60')
  })
})

describe('serializeICS round-trip', () => {
  it('round-trips: parse(serialize(parse(x))) equals parse(x)', () => {
    const original = parseICS(GOLDEN)
    const text = serializeICS(original)
    const reparsed = parseICS(text)

    expect(reparsed.events).toHaveLength(original.events.length)
    // Spot-check first event
    const e0 = reparsed.events[0]
    expect(e0.summary).toBe(original.events[0].summary)
    expect(e0.dtstartDate).toBe(original.events[0].dtstartDate)
    expect(e0.dtstartTime).toBe(original.events[0].dtstartTime)
    expect(e0.tzid).toBe(original.events[0].tzid)
    expect(e0._raw.dtstamp).toBe(original.events[0]._raw.dtstamp)
  })

  it('preserves VTIMEZONE in output', () => {
    const { meta } = parseICS(serializeICS(parseICS(GOLDEN)))
    expect(meta.vtimezones).toHaveLength(1)
  })

  it('serializes a manually-built recurring event', () => {
    const ev = {
      uid: 'test-1',
      summary: 'Test Event',
      location: 'Room A',
      description: 'Desc',
      dtstartDate: '2026-07-27',
      dtstartTime: '09:00',
      dtendTime: '10:30',
      tzid: 'UTC',
      rrule: { freq: 'WEEKLY', interval: 1, byday: 'MO', untilDate: '2026-10-19' },
      exdates: ['2026-09-21'],
      _raw: { dtstamp: '20260711T085008Z' },
    }
    const text = serializeICS({
      meta: {
        prodid: '-//Test//EN', version: '2.0', calscale: 'GREGORIAN',
        method: null, xWrCalname: null, xWrTimezone: null, vtimezones: [],
      },
      events: [ev],
    })
    expect(text).toContain('BEGIN:VEVENT')
    expect(text).toContain('SUMMARY:Test Event')
    expect(text).toContain('RRULE:FREQ=WEEKLY')
    expect(text).toContain('BYDAY=MO')
    expect(text).toContain('EXDATE')
    expect(text).toContain('DTSTART:20260727T090000Z')

    // Re-parse and verify
    const reparsed = parseICS(text)
    expect(reparsed.events[0].rrule.freq).toBe('WEEKLY')
    expect(reparsed.events[0].rrule.byday).toBe('MO')
    expect(reparsed.events[0].exdates).toContain('2026-09-21')
  })
})