Event: improved local handling of exceptions of recurring events

src/main/java/at/bitfire/ical4android/AndroidEvent.kt

@@ -254,9 +254,7 @@ abstract class AndroidEvent(
 
         // exceptions from recurring events
         row.getAsLong(Events.ORIGINAL_INSTANCE_TIME)?.let { originalInstanceTime ->
-            var originalAllDay = false
-            row.getAsInteger(Events.ORIGINAL_ALL_DAY)?.let { originalAllDay = it != 0 }
-
+            val originalAllDay = (row.getAsInteger(Events.ORIGINAL_ALL_DAY) ?: 0) != 0
             val originalDate = if (originalAllDay)
                     Date(originalInstanceTime) else
                     DateTime(originalInstanceTime)

src/main/java/at/bitfire/ical4android/DateUtils.kt

@@ -15,6 +15,7 @@ import net.fortuna.ical4j.model.TimeZone
 import net.fortuna.ical4j.model.component.VTimeZone
 import net.fortuna.ical4j.model.parameter.Value
 import net.fortuna.ical4j.model.property.DateListProperty
+import net.fortuna.ical4j.model.property.DateProperty
 import net.fortuna.ical4j.model.property.ExDate
 import net.fortuna.ical4j.model.property.RDate
 import java.io.StringReader
@@ -74,6 +75,14 @@ object DateUtils {
         return deviceTZ
     }
 
+    /**
+     * Determines whether a given date represents a DATE-TIME value.
+     * @param date date property to check
+     * @return *true* if the date is a DATE-TIME value; *false* otherwise (for instance, when the
+     * date is a DATE value or null)
+     */
+    fun isDateTime(date: DateProperty?) = date != null && date.date is DateTime
+
     /**
      * Parses a VTIMEZONE definition to a VTimeZone object.
      * @param timezoneDef VTIMEZONE definition

src/main/java/at/bitfire/ical4android/Event.kt

@@ -8,6 +8,7 @@
 
 package at.bitfire.ical4android
 
+import at.bitfire.ical4android.DateUtils.isDateTime
 import at.bitfire.ical4android.ICalendar.Companion.CALENDAR_NAME
 import net.fortuna.ical4j.data.CalendarOutputter
 import net.fortuna.ical4j.data.ParserException
@@ -206,24 +207,37 @@ class Event: ICalendar() {
 
         // recurrence exceptions
         for (exception in exceptions) {
-            // make sure that
-            //     - exceptions have the same UID as the main event and
-            //     - RECURRENCE-IDs have the same timezone as the main event's DTSTART
+            // exceptions must always have the same UID as the main event
             exception.uid = uid
-            exception.recurrenceId?.let { recurrenceId ->
-                if (recurrenceId.timeZone != dtStart.timeZone) {
-                    recurrenceId.timeZone = dtStart.timeZone
-                    exception.recurrenceId = recurrenceId
-                }
 
-                // create VEVENT for exception
-                val vException = exception.toVEvent()
-                components += vException
+            val recurrenceId = exception.recurrenceId
+            if (recurrenceId == null) {
+                Constants.log.warning("Ignoring exception without recurrenceId")
+                continue
+            }
+
+            /* Exceptions must always have the same value type as DTSTART [RFC 5545 3.8.4.4].
+               If this is not the case, we don't add the exception to the event because we're
+               strict in what we send (and servers may reject such a case).
+             */
+            if (isDateTime(recurrenceId) != isDateTime(dtStart)) {
+                Constants.log.warning("Ignoring exception $recurrenceId with other date type than dtStart: $dtStart")
+                continue
+            }
 
-                // remember used time zones
-                exception.dtStart?.timeZone?.let(usedTimeZones::add)
-                exception.dtEnd?.timeZone?.let(usedTimeZones::add)
+            // for simplicity and compatibility, rewrite date-time exceptions to the same time zone as DTSTART
+            if (isDateTime(recurrenceId) && recurrenceId.timeZone != dtStart.timeZone) {
+                Constants.log.fine("Changing timezone of $recurrenceId to same time zone as dtStart: $dtStart")
+                recurrenceId.timeZone = dtStart.timeZone
             }
+
+            // create and add VEVENT for exception
+            val vException = exception.toVEvent()
+            components += vException
+
+            // remember used time zones
+            exception.dtStart?.timeZone?.let(usedTimeZones::add)
+            exception.dtEnd?.timeZone?.let(usedTimeZones::add)
         }
 
         // add VTIMEZONE components
@@ -243,7 +257,7 @@ class Event: ICalendar() {
      * @return generated VEvent
      */
     private fun toVEvent(): VEvent {
-        val event = VEvent(true /* generates DTSTAMP */)
+        val event = VEvent(/* generates DTSTAMP */)
         val props = event.properties
         props += Uid(uid)
 
@@ -258,7 +272,7 @@ class Event: ICalendar() {
         description?.let { props += Description(it) }
         color?.let { props += Color(null, it.name) }
 
-        props += dtStart
+        dtStart?.let { props += it }
         dtEnd?.let { props += it }
         duration?.let { props += it }
 

src/main/java/at/bitfire/ical4android/ICalendar.kt

@@ -99,8 +99,6 @@ open class ICalendar {
 
         // time zone helpers
 
-        fun isDateTime(date: DateProperty?) = date != null && date.date is DateTime
-
         /**
          * Minifies a VTIMEZONE so that only components after [start] are kept.
          * Doesn't return the smallest possible VTIMEZONE at the moment, but

src/main/java/at/bitfire/ical4android/MiscUtils.kt

@@ -11,7 +11,7 @@ package at.bitfire.ical4android
 import android.content.ContentValues
 import android.database.Cursor
 import android.database.DatabaseUtils
-import net.fortuna.ical4j.model.TextList
+import at.bitfire.ical4android.DateUtils.isDateTime
 import net.fortuna.ical4j.model.property.DateProperty
 import net.fortuna.ical4j.util.TimeZones
 import java.lang.reflect.Modifier
@@ -25,7 +25,7 @@ object MiscUtils {
      * @param date DateProperty to validate. Values which are not DATE-TIME will be ignored.
      */
     fun androidifyTimeZone(date: DateProperty?) {
-        if (ICalendar.isDateTime(date)) {
+        if (isDateTime(date)) {
             val tz = date!!.timeZone ?: return
             val tzID = tz.id ?: return
             val deviceTzID = DateUtils.findAndroidTimezoneID(tzID)
@@ -47,7 +47,7 @@ object MiscUtils {
      *         - the currently set default time zone ID for floating date-times
      */
     fun getTzId(date: DateProperty): String =
-            if (ICalendar.isDateTime(date)) {
+            if (isDateTime(date)) {
                 when {
                     date.isUtc ->
                         // DATE-TIME in UTC format

src/test/java/at/bitfire/ical4android/EventTest.kt

@@ -7,10 +7,14 @@
  */
 package at.bitfire.ical4android
 
+import net.fortuna.ical4j.model.Date
+import net.fortuna.ical4j.model.DateTime
 import net.fortuna.ical4j.model.Dur
 import net.fortuna.ical4j.model.TimeZoneRegistryFactory
 import net.fortuna.ical4j.model.component.VAlarm
 import net.fortuna.ical4j.model.property.DtStart
+import net.fortuna.ical4j.model.property.RRule
+import net.fortuna.ical4j.model.property.RecurrenceId
 import org.junit.Assert.*
 import org.junit.Test
 import java.io.ByteArrayOutputStream
@@ -91,6 +95,44 @@ class EventTest {
         assertEquals("Unknown Value", unknown.value)
     }
 
+    @Test
+    fun testRecurringWriteFullDayException() {
+        val event = Event().apply {
+            uid = "test1"
+            dtStart = DtStart("20190117T083000", DateUtils.tzRegistry.getTimeZone("Europe/Berlin"))
+            summary = "Main event"
+            rRule = RRule("FREQ=DAILY;COUNT=5")
+            exceptions += arrayOf(
+                    Event().apply {
+                        uid = "test2"
+                        recurrenceId = RecurrenceId(DateTime("20190118T073000", DateUtils.tzRegistry.getTimeZone("Europe/London")))
+                        summary = "Normal exception"
+                    },
+                    Event().apply {
+                        uid = "test3"
+                        recurrenceId = RecurrenceId(Date("20190223"))
+                        summary = "Full-day exception"
+                    }
+            )
+        }
+        val baos = ByteArrayOutputStream()
+        event.write(baos)
+        val iCal = baos.toString()
+        assertTrue(iCal.contains("UID:test1\r\n"))
+        assertTrue(iCal.contains("DTSTART;TZID=Europe/Berlin:20190117T083000\r\n"))
+
+        // first RECURRENCE-ID has been rewritten
+        // - to main event's UID
+        // - to time zone Europe/Berlin (with one hour time difference)
+        assertTrue(iCal.contains("UID:test1\r\n" +
+                "RECURRENCE-ID;TZID=Europe/Berlin:20190118T083000\r\n" +
+                "SUMMARY:Normal exception\r\n" +
+                "END:VEVENT"))
+
+        // no RECURRENCE-ID;VALUE=DATE:20190223
+        assertFalse(iCal.contains(":20190223"))
+    }
+
     @Test
     fun testRecurringWithException() {
         val event = parseCalendar("recurring-with-exception1.ics").first()