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Fix timezone handling for recurring events #178

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Merged
muness merged 1 commit into from
Jun 3, 2025
Merged

Fix timezone handling for recurring events #178

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39 changes: 22 additions & 17 deletions src/icalUtils.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -27,15 +27,14 @@ export function extractMeetingInfo(e: any): { callUrl: string, callType: string
}

function applyRecurrenceDateAndTimezone(originalDate: Date, currentDate: Date, tzid: string): Date {
const momentOriginal = tz(originalDate, tzid);
const momentCurrent = tz(currentDate, tzid);
const originalMoment = tz(originalDate, tzid);

// Calculate the difference in hours and minutes between the original and current
const hourOffset = momentOriginal.hour() - momentCurrent.hour();
const minuteOffset = momentOriginal.minute() - momentCurrent.minute();
// Create a moment in the target timezone using just the date components of currentDate
// This avoids timezone conversion issues with the recurrence date
const currentDateMoment = moment.utc(currentDate);
const adjustedMoment = tz(`${currentDateMoment.format('YYYY-MM-DD')} ${originalMoment.format('HH:mm:ss')}`, tzid);

// Adjust the current date by the offset to keep the local time constant
return momentCurrent.add(hourOffset, 'hours').add(minuteOffset, 'minutes').toDate();
return adjustedMoment.toDate();
}

function isExcluded(recurrenceDate: moment.Moment, exdateArray: moment.Moment[]): boolean {
Expand Down Expand Up @@ -65,29 +64,35 @@ function processRecurrenceOverrides(event: any, sortedDaysToMatch: string[], exc
}

function processRecurringRules(event: any, sortedDaysToMatch: string[], excludedDates: moment.Moment[], matchingEvents: any[]) {
const localStartOfRange = moment(sortedDaysToMatch.first()).subtract(1, 'day').startOf('day').toDate();
const localEndOfRange = moment(sortedDaysToMatch.last()).add(1, 'day').endOf('day').toDate();
const tzid = event.rrule.origOptions.tzid || 'UTC';

// Use UTC for rrule calculations to avoid timezone offset issues
const startOfRange = moment.utc(sortedDaysToMatch.first()).subtract(1, 'day').startOf('day').toDate();
const endOfRange = moment.utc(sortedDaysToMatch.last()).add(1, 'day').endOf('day').toDate();

// Get recurrence dates within the range
const recurrenceDates = event.rrule.between(localStartOfRange, localEndOfRange, true);
const recurrenceDates = event.rrule.between(startOfRange, endOfRange, true);

recurrenceDates.forEach(recurrenceDate => {
const recurrenceMoment = tz(recurrenceDate, event.rrule.origOptions.tzid || 'UTC');

// Clone the event and use the recurrence date directly if start and end times are present
const clonedEvent = { ...event };
clonedEvent.start = applyRecurrenceDateAndTimezone(event.start, recurrenceDate, event.rrule.origOptions.tzid);
clonedEvent.end = applyRecurrenceDateAndTimezone(event.end, recurrenceDate, event.rrule.origOptions.tzid);
const recurrenceMoment = tz(recurrenceDate, tzid).startOf('day');

if (isExcluded(recurrenceMoment, excludedDates)) {
console.debug(`Skipping excluded recurrence: ${event.summary} on ${recurrenceMoment.format('YYYY-MM-DD')}`);
return;
}

// Clone the event and apply proper timezone-aware date/time calculation
const clonedEvent = { ...event };
clonedEvent.start = applyRecurrenceDateAndTimezone(event.start, recurrenceDate, tzid);
clonedEvent.end = applyRecurrenceDateAndTimezone(event.end, recurrenceDate, tzid);

delete clonedEvent.rrule;
clonedEvent.recurrent = true;

if (moment(clonedEvent.start).isBetween(sortedDaysToMatch.first(), sortedDaysToMatch.last(), 'day', '[]')) {
// Check if the recurrence falls within the requested date range using timezone-aware comparison
const eventStartMoment = tz(clonedEvent.start, tzid);
const eventStartDate = eventStartMoment.format('YYYY-MM-DD');
if (sortedDaysToMatch.includes(eventStartDate)) {
console.debug(`Adding recurring event: ${clonedEvent.summary} ${clonedEvent.start} - ${clonedEvent.end}`);
console.debug("Excluded dates:", excludedDates.map(date => date.format('YYYY-MM-DD')));

Expand Down