Prevent duplicate CalDAV availability slots for recurring slots

If there is the same time slot for more than one day, then we wrote two
recurring AVAILABILITY components before. With this patch equal blocks
are combined into one recurring component. This makes the generated
rules more compact and easier to work with.

Signed-off-by: Christoph Wurst <christoph@winzerhof-wurst.at>

.gitattributes

@@ -7,6 +7,8 @@
 /apps/comments/js/*.js.map binary
 /apps/dashboard/js/*.js binary
 /apps/dashboard/js/*.js.map binary
+/apps/dav/js/*.js binary
+/apps/dav/js/*.js.map binary
 /apps/files/js/dist/*.js binary
 /apps/files/js/dist/*.js.map binary
 /apps/files_sharing/js/dist/*.js binary

apps/dav/src/service/CalendarService.js

@@ -100,15 +100,37 @@ export async function saveScheduleInboxAvailability(slots, timezoneId) {
 	})))]
 
 	const vavailabilityComp = new ICAL.Component('vavailability')
-	// TODO: deduplicate slots that occur on more than one day
-	all.map(slot => {
+
+	// Deduplicate by start and end time
+	const deduplicated = all.reduce((acc, slot) => {
+		const key = [
+			slot.start.getHours(),
+			slot.start.getMinutes(),
+			slot.end.getHours(),
+			slot.end.getMinutes(),
+		].join('-')
+
+		return {
+			...acc,
+			[key]: [...(acc[key] ?? []), slot],
+		}
+	}, {})
+
+	// Create an AVAILABILITY component for every recurring slot
+	Object.keys(deduplicated).map(key => {
+		const slots = deduplicated[key]
+		const start = slots[0].start
+		const end = slots[0].end
+		// Combine days but make them also unique
+		const days = slots.map(slot => slot.day).filter((day, index, self) => self.indexOf(day) === index)
+
 		const availableComp = new ICAL.Component('available')
 
 		// Define DTSTART and DTEND
 		// TODO: tz? moment.tz(dateTime, timezone).toDate()
-		const startTimeProp = availableComp.addPropertyWithValue('dtstart', ICAL.Time.fromJSDate(slot.start, false))
+		const startTimeProp = availableComp.addPropertyWithValue('dtstart', ICAL.Time.fromJSDate(start, false))
 		startTimeProp.setParameter('tzid', timezoneId)
-		const endTimeProp = availableComp.addPropertyWithValue('dtend', ICAL.Time.fromJSDate(slot.end, false))
+		const endTimeProp = availableComp.addPropertyWithValue('dtend', ICAL.Time.fromJSDate(end, false))
 		endTimeProp.setParameter('tzid', timezoneId)
 
 		// Add mandatory UID
@@ -119,7 +141,7 @@ export async function saveScheduleInboxAvailability(slots, timezoneId) {
 		// Define RRULE
 		availableComp.addPropertyWithValue('rrule', {
 			freq: 'WEEKLY',
-			byday: slot.day,
+			byday: days,
 		})
 
 		return availableComp