implemented recurrence exception (EXDATE) support for custom events, refactored timetable break and holiday generation logic, and refined RRule editor UI/theming and tile layouts

lib/view/pages/timetable/data/calendar_logic.dart

@@ -106,10 +106,21 @@ partitionAppointmentsForWeek(
       final parsed = RecurrenceRule.fromString(rule);
       final anchorUtc = a.startTime.toUtc();
       final duration = a.endTime.difference(a.startTime);
+      // Day-keyed set of exception dates so occurrences scheduled for one
+      // of them get skipped. Syncfusion's own recurrenceExceptionDates
+      // handling never runs because we expand the rule manually here.
+      final exceptionDayKeys = (a.recurrenceExceptionDates ?? const <DateTime>[])
+          .map((d) => '${d.year}-${d.month}-${d.day}')
+          .toSet();
       for (final occUtc in parsed.getInstances(start: anchorUtc)) {
         if (!occUtc.isBefore(weekEndUtc)) break;
         if (occUtc.isBefore(weekStartUtc)) continue;
         final occLocal = occUtc.toLocal();
+        if (exceptionDayKeys.contains(
+          '${occLocal.year}-${occLocal.month}-${occLocal.day}',
+        )) {
+          continue;
+        }
         final idx = DateTime(
           occLocal.year,
           occLocal.month,

lib/view/pages/timetable/data/rrule_with_exceptions.dart

@@ -0,0 +1,57 @@
+/// Parses recurrence-rule strings produced by the `rrule_generator` widget
+/// into a clean RRULE plus a separate list of exception dates.
+///
+/// `rrule_generator` appends excluded dates as `;EXDATE=20260514T000000,...`
+/// to the rule string, which is **not** valid iCalendar — `EXDATE` is its
+/// own property, not an RRULE parameter. Anything reading the raw string
+/// with a strict parser (Syncfusion, package:rrule) silently drops the
+/// EXDATE bit, so exclusions never apply. Split the two here.
+class ParsedRRule {
+  final String rule;
+  final List<DateTime> exceptions;
+  const ParsedRRule({required this.rule, required this.exceptions});
+
+  static const empty = ParsedRRule(rule: '', exceptions: []);
+}
+
+ParsedRRule parseRRuleWithExceptions(String input) {
+  if (input.isEmpty) return ParsedRRule.empty;
+  final match = RegExp(r';EXDATE=([^;]+)$').firstMatch(input);
+  final exceptions = match == null
+      ? const <DateTime>[]
+      : match
+            .group(1)!
+            .split(',')
+            .map(_parseExdate)
+            .whereType<DateTime>()
+            .toList();
+  // Keep the rule string as-is (still has its `RRULE:` content-line prefix
+  // when present). Both Syncfusion's `Appointment.recurrenceRule` and
+  // `package:rrule`'s `RecurrenceRule.fromString` parse it correctly with
+  // the prefix; stripping it was a regression that confused Syncfusion's
+  // weekly BYDAY decoder on multi-day rules.
+  final rule = match == null ? input : input.substring(0, match.start);
+  return ParsedRRule(rule: rule, exceptions: exceptions);
+}
+
+/// Parses one `yyyyMMddTHHmmss` chunk into a local-time [DateTime].
+DateTime? _parseExdate(String s) {
+  if (s.length < 15 || s[8] != 'T') return null;
+  final year = int.tryParse(s.substring(0, 4));
+  final month = int.tryParse(s.substring(4, 6));
+  final day = int.tryParse(s.substring(6, 8));
+  final hour = int.tryParse(s.substring(9, 11));
+  final minute = int.tryParse(s.substring(11, 13));
+  final second = int.tryParse(s.substring(13, 15));
+  if ([
+    year,
+    month,
+    day,
+    hour,
+    minute,
+    second,
+  ].any((e) => e == null)) {
+    return null;
+  }
+  return DateTime(year!, month!, day!, hour!, minute!, second!);
+}

lib/view/pages/timetable/data/timetable_appointment_factory.dart

@@ -10,6 +10,7 @@ import '../custom_events/custom_event_colors.dart';
 import 'arbitrary_appointment.dart';
 import 'lesson_color.dart';
 import 'lesson_status.dart';
+import 'rrule_with_exceptions.dart';
 import 'timetable_name_mode.dart';
 import 'webuntis_time.dart';
 
@@ -81,6 +82,23 @@ class TimetableAppointmentFactory {
 
   Appointment _customEventToAppointment(CustomTimetableEvent event) {
     final allDay = isCustomEventAllDay(event);
+    // rrule_generator stores excluded dates as a non-standard ";EXDATE=..."
+    // suffix on the rule string. Strip it and feed the dates separately —
+    // Syncfusion matches recurrence exceptions through this property, not
+    // through anything inside `recurrenceRule`.
+    final parsed = parseRRuleWithExceptions(event.rrule);
+    final exceptionDates = parsed.exceptions
+        .map(
+          (d) => DateTime(
+            d.year,
+            d.month,
+            d.day,
+            event.startDate.hour,
+            event.startDate.minute,
+            event.startDate.second,
+          ),
+        )
+        .toList();
     return Appointment(
       id: CustomAppointment(event),
       startTime: event.startDate,
@@ -101,7 +119,8 @@ class TimetableAppointmentFactory {
           ? null
           : event.description.trim(),
       subject: _collapseWhitespace(event.title) ?? event.title,
-      recurrenceRule: event.rrule,
+      recurrenceRule: parsed.rule,
+      recurrenceExceptionDates: exceptionDates.isEmpty ? null : exceptionDates,
       color: TimetableColors.getColorFromString(
         event.color ?? TimetableColors.defaultColor.name,
       ),