fix: recurrance recalulation with excemption

src/recurrence/recurrenceManager.js

@@ -812,14 +812,17 @@ export default class RecurrenceManager {
 			exdate.addDuration(difference)
 		}
 
-		for (const recurrenceException of this.getRecurrenceExceptionIterator()) {
-			// We don't edit RDATES, so don't update recurrence-ids if they
-			// are based on an RDATE
-			if (this.hasRecurrenceDate(false, recurrenceException.recurrenceId)) {
-				continue
-			}
-
+		// Snapshot the exceptions first because mutating the live Map while iterating it makes
+		// the iterator revisit reinserted items, causing an infinite loop.
+		const recurrenceExceptions = this.getRecurrenceExceptionList()
+		// Remove all rule-based exceptions before reinserting any shifted keys. This
+		// prevents adjacent exceptions from overwriting entries at still-occupied keys.
+		for (const recurrenceException of recurrenceExceptions.filter((recurrenceException) => !this.hasRecurrenceDate(false, recurrenceException.recurrenceId))) {
 			this.removeRecurrenceException(recurrenceException)
+		}
+		// Shift and relate the exceptions again under their new recurrence IDs, rebuilding
+		// the regular and range-exception indexes in the process.
+		for (const recurrenceException of recurrenceExceptions.filter((recurrenceException) => !this.hasRecurrenceDate(false, recurrenceException.recurrenceId))) {
 			recurrenceException.recurrenceId.addDuration(difference)
 			this.relateRecurrenceException(recurrenceException)
 		}

tests/integration/editing/updateMasterStartDate.test.js

@@ -0,0 +1,190 @@
+/**
+ * SPDX-FileCopyrightText: 2026 Nextcloud GmbH and Nextcloud contributors
+ * SPDX-License-Identifier: AGPL-3.0-or-later
+ */
+
+import { getParserManager } from '../../../src/index.js'
+import DurationValue from '../../../src/values/durationValue.js'
+
+jest.mock('../../../src/factories/dateFactory.js')
+
+/**
+ * Parse a calendar and return its recurring master item.
+ *
+ * @param {string} ics iCalendar data
+ * @return {AbstractRecurringComponent}
+ */
+function getMasterItem(ics) {
+	const parser = getParserManager().getParserForFileType('text/calendar')
+	parser.parse(ics)
+	const calendarComponent = parser.getItemIterator().next().value
+
+	return Array.from(calendarComponent.getComponentIterator())
+		.find(component => component.name === 'VEVENT' && !component.hasProperty('RECURRENCE-ID'))
+}
+
+/**
+ * Build a minimal recurring calendar from VEVENT property arrays.
+ *
+ * @param {string[]} masterProperties Properties of the master VEVENT
+ * @param {string[][]} exceptionProperties Properties of exception VEVENTs
+ * @return {string}
+ */
+function buildCalendar(masterProperties, exceptionProperties = []) {
+	const event = properties => ['BEGIN:VEVENT', 'UID:update-start-test', ...properties, 'END:VEVENT']
+
+	return [
+		'BEGIN:VCALENDAR',
+		'VERSION:2.0',
+		'PRODID:-//Nextcloud Tests//calendar-js//EN',
+		...event(masterProperties),
+		...exceptionProperties.flatMap(event),
+		'END:VCALENDAR',
+	].join('\r\n')
+}
+
+/**
+ * Shift a master item by a number of seconds through its public setter.
+ *
+ * @param {AbstractRecurringComponent} masterItem Master event
+ * @param {number} seconds Number of seconds to shift
+ */
+function shiftMaster(masterItem, seconds) {
+	const shiftedStart = masterItem.startDate.clone()
+	shiftedStart.addDuration(DurationValue.fromSeconds(seconds))
+	masterItem.startDate = shiftedStart
+}
+
+const asICALString = value => value.toICALJs().toString()
+
+describe('updateStartDateOfMasterItem', () => {
+	it('shifts an existing recurrence exception once without hanging', () => {
+		const masterItem = getMasterItem(getAsset('weekly-recurring-with-exception'))
+		const recurrenceManager = masterItem.recurrenceManager
+		const originalExceptionRecurrenceId = recurrenceManager.getRecurrenceExceptionList()[0].recurrenceId.clone()
+
+		shiftMaster(masterItem, 24 * 60 * 60)
+
+		const exceptionsAfter = recurrenceManager.getRecurrenceExceptionList()
+		expect(exceptionsAfter).toHaveLength(1)
+
+		const expectedShiftedRecurrenceId = originalExceptionRecurrenceId.clone()
+		expectedShiftedRecurrenceId.addDuration(DurationValue.fromSeconds(24 * 60 * 60))
+		expect(exceptionsAfter[0].recurrenceId.compare(expectedShiftedRecurrenceId)).toEqual(0)
+	})
+
+	it('preserves every exception when adjacent recurrence IDs shift onto occupied map keys', () => {
+		const masterItem = getMasterItem(buildCalendar(
+			['DTSTART:20240101T090000Z', 'RRULE:FREQ=DAILY;COUNT=10'],
+			[
+				['DTSTART:20240102T100000Z', 'RECURRENCE-ID:20240102T090000Z'],
+				['DTSTART:20240103T100000Z', 'RECURRENCE-ID;RANGE=THISANDFUTURE:20240103T090000Z'],
+				['DTSTART:20240104T100000Z', 'RECURRENCE-ID:20240104T090000Z'],
+			],
+		))
+		const recurrenceManager = masterItem.recurrenceManager
+
+		shiftMaster(masterItem, 24 * 60 * 60)
+
+		expect(recurrenceManager.getRecurrenceExceptionList()
+			.map(exception => asICALString(exception.recurrenceId))
+			.sort()).toEqual([
+			'2024-01-03T09:00:00Z',
+			'2024-01-04T09:00:00Z',
+			'2024-01-05T09:00:00Z',
+		])
+		const rangeException = recurrenceManager.getRecurrenceExceptionList()
+			.find(exception => exception.modifiesFuture())
+		expect(recurrenceManager.getRangeRecurrenceExceptionForId(
+			recurrenceManager.getRecurrenceExceptionList().at(-1).recurrenceId,
+		)).toEqual(rangeException)
+	})
+
+	it.each([
+		['forward across a month boundary', 36 * 60 * 60, '2024-02-02T21:00:00Z'],
+		['backward across a month boundary', -12 * 60 * 60, '2024-01-31T21:00:00Z'],
+		['by a zero-length duration', 0, '2024-02-01T09:00:00Z'],
+	])('shifts recurrence IDs %s', (_scenario, seconds, expectedRecurrenceId) => {
+		const masterItem = getMasterItem(buildCalendar(
+			['DTSTART:20240131T090000Z', 'RRULE:FREQ=DAILY;COUNT=5'],
+			[['DTSTART:20240201T100000Z', 'RECURRENCE-ID:20240201T090000Z']],
+		))
+
+		shiftMaster(masterItem, seconds)
+
+		expect(asICALString(masterItem.recurrenceManager.getRecurrenceExceptionList()[0].recurrenceId))
+			.toEqual(expectedRecurrenceId)
+	})
+
+	it('shifts EXDATE values except those that also match an unchanged RDATE', () => {
+		const masterItem = getMasterItem(buildCalendar([
+			'DTSTART:20240101T090000Z',
+			'RRULE:FREQ=DAILY;COUNT=10',
+			'RDATE:20240105T090000Z',
+			'EXDATE:20240103T090000Z,20240105T090000Z',
+		]))
+
+		shiftMaster(masterItem, 24 * 60 * 60)
+
+		expect(masterItem.recurrenceManager.listAllRecurrenceDates(false).map(asICALString))
+			.toEqual(['2024-01-05T09:00:00Z'])
+		expect(masterItem.recurrenceManager.listAllRecurrenceDates(true).map(asICALString).sort())
+			.toEqual(['2024-01-04T09:00:00Z', '2024-01-05T09:00:00Z'])
+	})
+
+	it('leaves an RDATE-based exception unchanged while shifting a rule-based exception', () => {
+		const masterItem = getMasterItem(buildCalendar(
+			['DTSTART:20240101T090000Z', 'RRULE:FREQ=DAILY;COUNT=10', 'RDATE:20240110T090000Z'],
+			[
+				['DTSTART:20240103T100000Z', 'RECURRENCE-ID:20240103T090000Z'],
+				['DTSTART:20240110T100000Z', 'RECURRENCE-ID:20240110T090000Z'],
+			],
+		))
+
+		shiftMaster(masterItem, 24 * 60 * 60)
+
+		expect(masterItem.recurrenceManager.getRecurrenceExceptionList()
+			.map(exception => asICALString(exception.recurrenceId))
+			.sort()).toEqual(['2024-01-04T09:00:00Z', '2024-01-10T09:00:00Z'])
+	})
+
+	it('shifts RRULE UNTIL while leaving a COUNT-based rule unchanged', () => {
+		const untilMaster = getMasterItem(buildCalendar([
+			'DTSTART:20240101T090000Z',
+			'RRULE:FREQ=DAILY;UNTIL=20240131T090000Z',
+		]))
+		const countMaster = getMasterItem(buildCalendar([
+			'DTSTART:20240101T090000Z',
+			'RRULE:FREQ=DAILY;COUNT=10',
+		]))
+
+		shiftMaster(untilMaster, 2 * 24 * 60 * 60)
+		shiftMaster(countMaster, 2 * 24 * 60 * 60)
+
+		const untilRule = untilMaster.recurrenceManager.getRecurrenceRuleList()[0]
+		const countRule = countMaster.recurrenceManager.getRecurrenceRuleList()[0]
+		expect(asICALString(untilRule.until)).toEqual('2024-02-02T09:00:00Z')
+		expect(countRule.until).toBeNull()
+		expect(countRule.count).toEqual(10)
+	})
+
+	it('shifts all-day recurrence metadata by whole days', () => {
+		const masterItem = getMasterItem(buildCalendar(
+			[
+				'DTSTART;VALUE=DATE:20240228',
+				'RRULE:FREQ=DAILY;UNTIL=20240305',
+				'EXDATE;VALUE=DATE:20240301',
+			],
+			[['DTSTART;VALUE=DATE:20240303', 'RECURRENCE-ID;VALUE=DATE:20240302']],
+		))
+
+		shiftMaster(masterItem, 2 * 24 * 60 * 60)
+
+		expect(asICALString(masterItem.recurrenceManager.listAllRecurrenceDates(true)[0]))
+			.toEqual('2024-03-03')
+		expect(asICALString(masterItem.recurrenceManager.getRecurrenceExceptionList()[0].recurrenceId))
+			.toEqual('2024-03-04')
+		expect(asICALString(masterItem.recurrenceManager.getRecurrenceRuleList()[0].until))
+			.toEqual('2024-03-07')
+	})
+})

tests/integration/parser/parser.test.js

@@ -2252,7 +2252,7 @@ it ('edit first occurrence - this and future', () => {
 		'DTSTAMP:20190703T172836Z\r\n' +
 		'DTSTART;TZID=Europe/Berlin:20190717T090000\r\n' +
 		'SEQUENCE:0\r\n' +
-		'RECURRENCE-ID;TZID=Europe/Berlin:20190719T080000\r\n' +
+		'RECURRENCE-ID;TZID=Europe/Berlin:20190715T100000\r\n' +
 		'END:VEVENT\r\n' +
 		'BEGIN:VEVENT\r\n' +
 		'CREATED:20190703T172822Z\r\n' +
@@ -2265,7 +2265,7 @@ it ('edit first occurrence - this and future', () => {
 		'DTSTAMP:20190703T172836Z\r\n' +
 		'DTSTART;TZID=Europe/Berlin:20190731T090000\r\n' +
 		'SEQUENCE:0\r\n' +
-		'RECURRENCE-ID;TZID=Europe/Berlin:20190801T090000\r\n' +
+		'RECURRENCE-ID;TZID=Europe/Berlin:20190729T100000\r\n' +
 		'END:VEVENT\r\n' +
 		'BEGIN:VEVENT\r\n' +
 		'CREATED:20190703T172822Z\r\n' +
@@ -2279,7 +2279,7 @@ it ('edit first occurrence - this and future', () => {
 		'DTSTAMP:20190703T172836Z\r\n' +
 		'DTSTART;TZID=Europe/Berlin:20190714T090000\r\n' +
 		'SEQUENCE:0\r\n' +
-		'RECURRENCE-ID;TZID=Europe/Berlin:20190719T080000\r\n' +
+		'RECURRENCE-ID;TZID=Europe/Berlin:20190703T100000\r\n' +
 		'END:VEVENT\r\n' +
 		'BEGIN:VEVENT\r\n' +
 		'CREATED:20190703T172822Z\r\n' +