[jtx rewrite] Add Handlers for Recurrence Fields

[ArnyminerZ]

Added RecurrenceFieldsHandler and tests.

[Copilot]

Pull request overview

Adds recurrence-field mapping from jtx Board rows to ical4j components as part of the ongoing jtx rewrite, plus unit tests to validate the new handler behavior.

Changes:

• Introduces RecurrenceFieldsHandler to map RRULE, RDATE, EXDATE, and exception RECURRENCE-ID.
• Registers the new handler in JtxObjectHandler.
• Adds RecurrenceFieldsHandlerTest covering multiple timezone/all-day/floating scenarios.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
lib/src/main/kotlin/at/bitfire/synctools/mapping/jtx/JtxObjectHandler.kt	Registers the new recurrence handler; currently gates exception mapping based only on RRULE.
lib/src/main/kotlin/at/bitfire/synctools/mapping/jtx/handler/RecurrenceFieldsHandler.kt	Implements mapping from jtx recurrence columns to iCal properties (main + exceptions).
lib/src/test/kotlin/at/bitfire/synctools/mapping/jtx/handler/RecurrenceFieldsHandlerTest.kt	Adds unit tests for RRULE/RDATE/EXDATE/RECURID across timezone modes.

Comments suppressed due to low confidence (1)

lib/src/main/kotlin/at/bitfire/synctools/mapping/jtx/handler/RecurrenceFieldsHandler.kt:115

• issue (blocking): Invalid DTSTART_TIMEZONE values should fall back to UTC instead of dropping RDATE/EXDATE.

JtxContract.JtxICalObject.DTSTART_TIMEZONE documents that invalid timezone IDs must be ignored and interpreted as UTC. Currently, ZoneId.of(dtstartTimezone) can throw and causes the whole RDATE/EXDATE mapping to be skipped (caught in processMain). Handle invalid/unknown timezone IDs inside timestampsToDateList() and fall back to UTC so recurrence sets are still preserved.

 else ->
DateList(timestamps.map {
ZonedDateTime.ofInstant(Instant.ofEpochMilli(it), ZoneId.of(dtstartTimezone))
})

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

Comments suppressed due to low confidence (1)

lib/src/main/kotlin/at/bitfire/synctools/mapping/jtx/handler/RecurrenceFieldsHandler.kt:75

• issue (blocking): EXDATE mapping has the same missing-parameter problem as RDATE.

When timestampsToDateList() returns ZonedDateTime or LocalDate, the resulting ExDate(DateList(...)) should carry TZID or VALUE=DATE respectively; otherwise the iCalendar semantics can change (timezone dropped, dates interpreted as DATE-TIME).

 values.getAsString(JtxContract.JtxICalObject.EXDATE)?.takeIf { it.isNotBlank() }?.let { exdateString ->
try {
val timestamps = JtxContract.getLongListFromString(exdateString)
if (timestamps.isNotEmpty()) {
to += ExDate(timestampsToDateList(timestamps, dtstartTimezone))
}

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated no new comments.