import '../models/timeline_entry.dart';
import '../models/projected_entry.dart';
import 'time_scale_service.dart';

class TimelineProjectionService {
  const TimelineProjectionService();

  Map<String, List<ProjectedEntry>> project({
    required Iterable<TimelineEntry> entries,
    required DateTime domainStart,
    required DateTime domainEnd,
  }) {
    final byGroup = <String, List<ProjectedEntry>>{};
    for (final e in entries) {
      if (e.overlaps(domainStart, domainEnd)) {
        final startX = TimeScaleService.mapTimeToPosition(
          e.start.isBefore(domainStart) ? domainStart : e.start,
          domainStart,
          domainEnd,
        ).clamp(0.0, 1.0);
        final endX = TimeScaleService.mapTimeToPosition(
          e.end.isAfter(domainEnd) ? domainEnd : e.end,
          domainStart,
          domainEnd,
        ).clamp(0.0, 1.0);

        final pe = ProjectedEntry(entry: e, startX: startX, endX: endX);
        (byGroup[e.groupId] ??= <ProjectedEntry>[]).add(pe);
      }
    }

    // Keep original order stable by lane then startX
    for (final list in byGroup.values) {
      list.sort((a, b) {
        final laneCmp = a.entry.lane.compareTo(b.entry.lane);
        if (laneCmp != 0) return laneCmp;
        return a.startX.compareTo(b.startX);
      });
    }
    return byGroup;
  }
}