Minor refactoring of RecurrenceFieldsHandler (#158)

- Add test case for all-day recurring events
- Simplify `alignUntil` method in `RecurrenceFieldsHandler`
- Update `AndroidTimeUtils` for better handling of RDATE/EXDATE lists

Author: rfc2822

lib/src/main/kotlin/at/bitfire/synctools/mapping/calendar/handler/RecurrenceFieldsHandler.kt

@@ -152,9 +152,7 @@ class RecurrenceFieldsHandler(
      * @see at.bitfire.synctools.mapping.calendar.builder.EndTimeBuilder.alignWithDtStart
      */
     fun alignUntil(recur: Recur, startDate: Date): Recur {
-        val until: Date? = recur.until
-        if (until == null)
-            return recur
+        val until: Date = recur.until ?: return recur
 
         if (until is DateTime) {
             // UNTIL is DATE-TIME

lib/src/main/kotlin/at/bitfire/synctools/util/AndroidTimeUtils.kt

@@ -21,7 +21,6 @@ import net.fortuna.ical4j.model.TimeZoneRegistryFactory
 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 net.fortuna.ical4j.util.TimeZones
 import java.text.SimpleDateFormat
@@ -256,7 +255,7 @@ object AndroidTimeUtils {
 
         val limiter = dbStr.indexOf(RECURRENCE_LIST_TZID_SEPARATOR)
         if (limiter != -1) {    // TZID given
-            val tzId = dbStr.substring(0, limiter)
+            val tzId = dbStr.take(limiter)
             timeZone = tzRegistry.getTimeZone(tzId)
             if (TimeZones.isUtc(timeZone))
                 timeZone = null
@@ -296,7 +295,7 @@ object AndroidTimeUtils {
     /**
      * Concatenates, if necessary, multiple RDATE/EXDATE lists and converts them to
      * a formatted string which OpenTasks can process.
-     * OpenTasks expect a list of RFC 5545 DATE ("yyyymmdd") or DATE-TIME ("yyyymmdd[Z]") values,
+     * OpenTasks expect a list of RFC 5545 DATE (`yyyymmdd`) or DATE-TIME (`yyyymmdd[Z]`) values,
      * where the time zone is stored in a separate field.
      *
      * @param dates         one more more lists of RDATE or EXDATE
@@ -308,21 +307,20 @@ object AndroidTimeUtils {
         val allDay = tz == null
         val strDates = LinkedList<String>()
         for (dateListProp in dates) {
-            if (dateListProp is RDate)
-                if (dateListProp.periods.isNotEmpty())
-                    logger.warning("RDATE PERIOD not supported, ignoring")
-                else if (dateListProp is ExDate)
-                    if (dateListProp.periods.isNotEmpty())
-                        logger.warning("EXDATE PERIOD not supported, ignoring")
+            if (dateListProp is RDate && dateListProp.periods.isNotEmpty())
+                logger.warning("RDATE PERIOD not supported, ignoring")
 
             for (date in dateListProp.dates) {
                 val dateToUse =
-                        if (date is DateTime && allDay)             // VALUE=DATE-TIME, but allDay=1
+                    when (date) {
+                        is DateTime if allDay ->    // VALUE=DATE-TIME, but allDay=1
                             Date(date)
-                        else if (date !is DateTime && !allDay)      // VALUE=DATE, but allDay=0
+
+                        !is DateTime if !allDay ->  // VALUE=DATE, but allDay=0
                             DateTime(date.toString(), tz)
-                        else
-                            date
+
+                        else -> date
+                    }
                 if (dateToUse is DateTime && !dateToUse.isUtc)
                     dateToUse.timeZone = tz!!
                 strDates += dateToUse.toString()

lib/src/test/kotlin/at/bitfire/synctools/mapping/calendar/handler/RecurrenceFieldHandlerTest.kt

@@ -13,12 +13,14 @@ import androidx.core.content.contentValuesOf
 import io.mockk.mockk
 import junit.framework.TestCase.assertEquals
 import net.fortuna.ical4j.model.Date
+import net.fortuna.ical4j.model.DateList
 import net.fortuna.ical4j.model.DateTime
 import net.fortuna.ical4j.model.ParameterList
 import net.fortuna.ical4j.model.Property
 import net.fortuna.ical4j.model.Recur
 import net.fortuna.ical4j.model.TimeZoneRegistryFactory
 import net.fortuna.ical4j.model.component.VEvent
+import net.fortuna.ical4j.model.parameter.Value
 import net.fortuna.ical4j.model.property.ExDate
 import net.fortuna.ical4j.model.property.ExRule
 import net.fortuna.ical4j.model.property.RDate
@@ -75,10 +77,10 @@ class RecurrenceFieldHandlerTest {
     fun `Recurring main event`() {
         val result = VEvent()
         val entity = Entity(contentValuesOf(
-            Events.DTSTART to System.currentTimeMillis(),
-            Events.RRULE to "FREQ=DAILY;COUNT=10",
-            Events.RDATE to "20251010T010203Z",
-            Events.EXRULE to "FREQ=WEEKLY;COUNT=1",
+            Events.DTSTART to 1759403653000,    // Thu Oct 02 2025 11:14:13 GMT+0000
+            Events.RRULE to "FREQ=DAILY;COUNT=10",      // Oct 02 ... Oct 12
+            Events.RDATE to "20251002T111413Z,20251015T010203Z",    // RDATE at event start as required by Android plus Oct 15
+            Events.EXRULE to "FREQ=WEEKLY;COUNT=1",     // meaningless EXRULE/EXDATE
             Events.EXDATE to "20260201T010203Z"
         ))
         handler.process(entity, entity, result)
@@ -87,7 +89,7 @@ class RecurrenceFieldHandlerTest {
             result.getProperties<RRule>(Property.RRULE)
         )
         assertEquals(
-            listOf(RDate(ParameterList(), "20251010T010203Z")),
+            listOf(RDate(ParameterList(), "20251015T010203Z")),
             result.getProperties<RDate>(Property.RDATE)
         )
         assertEquals(
@@ -100,6 +102,35 @@ class RecurrenceFieldHandlerTest {
         )
     }
 
+    @Test
+    fun `Recurring main event (all-day)`() {
+        val result = VEvent()
+        val entity = Entity(contentValuesOf(
+            Events.ALL_DAY to 1,
+            Events.DTSTART to 1759363200000,    // Thu Oct 02 2025 00:00:00 GMT+0000
+            Events.RRULE to "FREQ=DAILY;COUNT=10",      // Oct 02 ... Oct 12
+            Events.RDATE to "20251002,20251015",        // RDATE at event start as required by Android plus Oct 15
+            Events.EXRULE to "FREQ=WEEKLY;COUNT=1",     // meaningless EXRULE/EXDATE
+            Events.EXDATE to "20260201T010203Z"
+        ))
+        handler.process(entity, entity, result)
+        assertEquals(
+            listOf(RRule("FREQ=DAILY;COUNT=10")),
+            result.getProperties<RRule>(Property.RRULE)
+        )
+        assertEquals(
+            listOf(RDate(DateList(Value.DATE).apply { add(Date("20251015")) })),
+            result.getProperties<RDate>(Property.RDATE)
+        )
+        assertEquals(
+            "FREQ=WEEKLY;COUNT=1",
+            result.getProperties<ExRule>(Property.EXRULE).joinToString { it.value }
+        )
+        assertEquals(
+            "20260201",
+            result.getProperties<ExDate>(Property.EXDATE).joinToString { it.value }
+        )
+    }
 
     @Test
     fun `RRULE with UNTIL before DTSTART`() {