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Client/lib/view/pages/timetable/data/lesson_merger.dart
T

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Dart

import '../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
/// Combines back-to-back lessons with identical subject/room/teacher/status
/// into a single visual block. Shared by the calendar tile builder and the
/// home-widget data mapper so both surfaces show the same merged spans.
///
/// Built as a new list rather than mutating inputs — earlier in-place merges
/// extended merged blocks further on every rebuild when the same lesson
/// objects were observed again.
class LessonMerger {
const LessonMerger._();
static const Duration defaultMaxGap = Duration(minutes: 5);
static List<McTimetableEntry> merge(
List<McTimetableEntry> input, {
Duration maxGap = defaultMaxGap,
}) {
if (input.isEmpty) return const [];
final sorted = [...input]
..sort((a, b) => a.startDateTime.compareTo(b.startDateTime));
final merged = <McTimetableEntry>[];
for (final current in sorted) {
if (merged.isNotEmpty && _canMerge(merged.last, current, maxGap)) {
final prev = merged.removeLast();
merged.add(_extendedEnd(prev, current.endTime));
} else {
merged.add(current);
}
}
return merged;
}
static bool _canMerge(
McTimetableEntry a,
McTimetableEntry b,
Duration maxGap,
) {
if (a.subjects.firstOrNull != b.subjects.firstOrNull) return false;
if (a.rooms.firstOrNull != b.rooms.firstOrNull) return false;
if (a.teachers.firstOrNull?.shortName !=
b.teachers.firstOrNull?.shortName) {
return false;
}
if (a.status != b.status) return false;
// Lower bound on the gap — without it, two identical-metadata lessons that
// overlap in time would silently collapse into one.
final gap = b.startDateTime.difference(a.endDateTime);
return !gap.isNegative && gap <= maxGap;
}
static McTimetableEntry _extendedEnd(
McTimetableEntry source,
DateTime newEndTime,
) => McTimetableEntry(
id: source.id,
date: source.date,
startTime: source.startTime,
endTime: newEndTime,
subjects: source.subjects,
teachers: source.teachers,
rooms: source.rooms,
classNames: source.classNames,
lessonType: source.lessonType,
status: source.status,
substitutionText: source.substitutionText,
lessonText: source.lessonText,
infoText: source.infoText,
);
}