Create fake main event for exceptions of recurring events where the main event is missing

* fixes bitfireAT/icsx5#27
* fixes bitfireAT/davx5#58

4 files changed, 48 insertions, 7 deletions

diff --git a/src/main/java/at/bitfire/ical4android/AndroidEvent.kt b/src/main/java/at/bitfire/ical4android/AndroidEvent.kt
index 3005d30..a465c06 100644
--- a/src/main/java/at/bitfire/ical4android/AndroidEvent.kt
+++ b/src/main/java/at/bitfire/ical4android/AndroidEvent.kt
@@ -573,10 +573,10 @@ abstract class AndroidEvent(
                (it checks for RRULE and aborts if no RRULE is found).
                So I have chosen the method of inserting the exception event manually.
 
-               It's also noteworthy that the link between the main event and the exception is not
-               between ID and ORIGINAL_ID (as one could assume), but between _SYNC_ID and ORIGINAL_SYNC_ID.
-               So, if you don't set _SYNC_ID in the master event and ORIGINAL_SYNC_ID in the exception,
-               the exception will appear additionally (and not *instead* of the instance).
+               It's also noteworthy that linking the main event to the exception only works using _SYNC_ID
+               and ORIGINAL_SYNC_ID (and not ID and ORIGINAL_ID, as one could assume). So, if you don't
+               set _SYNC_ID in the main event and ORIGINAL_SYNC_ID in the exception, the exception will
+               appear additionally (and not *instead* of the instance).
              */
 
             val recurrenceId = exception.recurrenceId
diff --git a/src/main/java/at/bitfire/ical4android/Event.kt b/src/main/java/at/bitfire/ical4android/Event.kt
index d96ac73..fcbb67f 100644
--- a/src/main/java/at/bitfire/ical4android/Event.kt
+++ b/src/main/java/at/bitfire/ical4android/Event.kt
@@ -94,7 +94,6 @@ class Event: ICalendar() {
             Ical4Android.log.fine("Assigning exceptions to main events")
             val mainEvents = mutableMapOf<String /* UID */,VEvent>()
             val exceptions = mutableMapOf<String /* UID */,MutableMap<String /* RECURRENCE-ID */,VEvent>>()
-
             for (vEvent in vEvents) {
                 val uid = vEvent.uid.value
                 val sequence = vEvent.sequence?.sequenceNo ?: 0
@@ -124,11 +123,17 @@ class Event: ICalendar() {
                 }
             }
 
+            /* There may be UIDs which have only RECURRENCE-ID entries and not a main entry (for instance, a recurring
+            event with an exception where the current user has been invited only to this exception. In this case,
+            the UID will not appear in mainEvents but only in exceptions. */
+
             val events = mutableListOf<Event>()
             for ((uid, vEvent) in mainEvents) {
                 val event = fromVEvent(vEvent)
-                exceptions[uid]?.let { eventExceptions ->
-                    event.exceptions.addAll(eventExceptions.map { (_,it) -> fromVEvent(it) })
+
+                // assign exceptions to main event and then remove them from exceptions array
+                exceptions.remove(uid)?.let { eventExceptions ->
+                    event.exceptions.addAll(eventExceptions.values.map { fromVEvent(it) })
                 }
 
                 // make sure that exceptions have at least a SUMMARY
@@ -137,6 +142,16 @@ class Event: ICalendar() {
                 events += event
             }
 
+            for ((uid, onlyExceptions) in exceptions) {
+                Ical4Android.log.info("UID $uid doesn't have a main event but only exceptions: $onlyExceptions")
+
+                // create a fake main event from the first exception
+                val fakeEvent = fromVEvent(onlyExceptions.values.first())
+                fakeEvent.exceptions.addAll(onlyExceptions.values.map { fromVEvent(it) })
+
+                events += fakeEvent
+            }
+
             return events
         }
 
diff --git a/src/test/java/at/bitfire/ical4android/EventTest.kt b/src/test/java/at/bitfire/ical4android/EventTest.kt
index e4d25c8..6842974 100644
--- a/src/test/java/at/bitfire/ical4android/EventTest.kt
+++ b/src/test/java/at/bitfire/ical4android/EventTest.kt
@@ -158,6 +158,21 @@ class EventTest {
     }
 
     @Test
+    fun testRecurringOnlyException() {
+        val event = parseCalendar("recurring-only-exception.ics").first()
+
+        assertEquals(1, event.exceptions.size)
+        val exception = event.exceptions.first
+        assertEquals("20150503T010203Z", exception.recurrenceId!!.value)
+        assertEquals("This is an exception", exception.summary)
+
+        // fake main event
+        assertEquals(event.summary, exception.summary)
+        assertEquals(event.dtStart, exception.dtStart)
+        assertEquals(event.dtEnd, exception.dtEnd)
+    }
+
+    @Test
     fun testStartEndTimes() {
         // event with start+end date-time
         val eViennaEvolution = parseCalendar("vienna-evolution.ics").first()
diff --git a/src/test/resources/events/recurring-only-exception.ics b/src/test/resources/events/recurring-only-exception.ics
new file mode 100644
index 0000000..26012e1
--- /dev/null
+++ b/src/test/resources/events/recurring-only-exception.ics
@@ -0,0 +1,11 @@
+BEGIN:VCALENDAR
+VERSION:2.0
+BEGIN:VEVENT
+UID:fcb42e4d-bc6e-4499-97f0-6616a02da7bc
+RECURRENCE-ID:20150503T010203Z
+DTSTART:20150503T010203Z
+DTEND:20150504T010203Z
+SUMMARY:This is an exception
+DESCRIPTION:The main event is not visible for us.
+END:VEVENT
+END:VCALENDAR