Event date and recurrence dates out of sync

[axtg]

I've been looking through the rrule repo for this as well, but so far haven't figured out where the discrepancy comes from that I am encountering. I have the following ics:

DTSTART;TZID=Europe/Amsterdam:20220622T190000
DTEND;TZID=Europe/Amsterdam:20220622T193000
RRULE:FREQ=DAILY;UNTIL=20220624T215959Z

event.start.utc() gives me 17 for the hour (true), while event.rrule.all()[0].getUTCHours() gives me 15.
The former is correct. It seems somehow that the rule UTC offset is applies twice? Could that be?

Tldr; example RRule from docs

Example code from the docs

const dates = event.rrule.between(new Date(2022, 0, 1, 0, 0, 0, 0), new Date(2022, 11, 31, 0, 0, 0, 0))
      if (dates.length === 0) continue;

      console.log('Summary:', event.summary);
      console.log('Original start:', event.start);
      console.log('RRule start:', `${event.rrule.origOptions.dtstart} [${event.rrule.origOptions.tzid}]`)

      dates.forEach(date => {
          let newDate
          if (event.rrule.origOptions.tzid) {
              // tzid present (calculate offset from recurrence start)
              const dateTimezone = moment.tz.zone('UTC')
              const localTimezone = moment.tz.guess()
              const tz = event.rrule.origOptions.tzid === localTimezone ? event.rrule.origOptions.tzid : localTimezone
              const timezone = moment.tz.zone(tz)
              const offset = timezone.utcOffset(date) - dateTimezone.utcOffset(date)
              newDate = moment(date).add(offset, 'minutes').toDate()
          } else {
              // tzid not present (calculate offset from original start)
              newDate = new Date(date.setHours(date.getHours() - ((event.start.getTimezoneOffset() - date.getTimezoneOffset()) / 60)))
          }
          const start = moment(newDate)
          console.log('Recurrence start:', start)
      })

Result

Here you see that the Original start and UTC RRule start are 22 June 17:00:00, yet the three recurrences start at 15:00:00 UTC.

2022-08-20T12:50:28.775Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	Summary: Test recurring end date
2022-08-20T12:50:28.776Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	Original start: 2022-06-22T17:00:00.000Z { tz: 'Europe/Amsterdam' }
2022-08-20T12:50:28.777Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	RRule start: Wed Jun 22 2022 17:00:00 GMT+0000 (Coordinated Universal Time) [Europe/Amsterdam]
2022-08-20T12:50:29.137Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	Recurrence start: Moment<2022-06-22T15:00:00+00:00>
2022-08-20T12:50:29.137Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	Recurrence start: Moment<2022-06-23T15:00:00+00:00>
2022-08-20T12:50:29.137Z	f63d18df-c840-418e-9389-8731a38f7b73	INFO	Recurrence start: Moment<2022-06-24T15:00:00+00:00>

Dump of event.rrule

2022-08-20T13:02:53.732Z	12a40880-be48-4393-ac31-28142c3eb329	INFO	RRule {
  _cache: Cache {
    all: [
      2022-06-22T15:00:00.000Z,
      2022-06-23T15:00:00.000Z,
      2022-06-24T15:00:00.000Z
    ],
    before: [],
    after: [],
    between: []
  },
  origOptions: {
    tzid: 'Europe/Amsterdam',
    dtstart: 2022-06-22T17:00:00.000Z,
    freq: 3,
    until: 2022-06-24T21:59:59.000Z
  },
  options: {
    freq: 3,
    dtstart: 2022-06-22T17:00:00.000Z,
    interval: 1,
    wkst: 0,
    count: null,
    until: 2022-06-24T21:59:59.000Z,
    tzid: 'Europe/Amsterdam',
    bysetpos: null,
    bymonth: null,
    bymonthday: [],
    bynmonthday: [],
    byyearday: null,
    byweekno: null,
    byweekday: null,
    bynweekday: null,
    byhour: [ 17 ],
    byminute: [ 0 ],
    bysecond: [ 0 ],
    byeaster: null
  }
}

[sdetweil]

no.. RRULE expects NON-TZ based dates.. and gets confused..

see #260 (comment)