import 'package:riverpod_annotation/riverpod_annotation.dart';

import 'package:timetrack/features/reports/data/drift_reports_repository.dart';
import 'package:timetrack/features/reports/data/reports_repository.dart';
import 'package:timetrack/features/reports/domain/report_data.dart';

part 'reports_provider.g.dart';

@riverpod
class ReportsNotifier extends _$ReportsNotifier {
  @override
  Future<ReportData> build() => _loadData();

  ReportPeriod _period = ReportPeriod.week;
  DateTime _anchor = DateTime.now();
  int? _filterProjectId;

  ReportsRepository get _repo => ref.read(reportsRepositoryProvider);

  ReportPeriod get period => _period;

  void selectPeriod(ReportPeriod period) {
    _period = period;
    _anchor = DateTime.now();
    ref.invalidateSelf();
  }

  void goToPrevious() {
    _anchor = _shift(-1);
    ref.invalidateSelf();
  }

  void goToNext() {
    _anchor = _shift(1);
    ref.invalidateSelf();
  }

  void filterByProject(int? projectId) {
    _filterProjectId = projectId;
    ref.invalidateSelf();
  }

  DateTime _shift(int direction) {
    switch (_period) {
      case ReportPeriod.day:
        return _anchor.add(Duration(days: direction));
      case ReportPeriod.week:
        return _anchor.add(Duration(days: 7 * direction));
      case ReportPeriod.month:
        return DateTime(_anchor.year, _anchor.month + direction);
    }
  }

  (DateTime, DateTime) _periodBounds() {
    switch (_period) {
      case ReportPeriod.day:
        final start = DateTime(_anchor.year, _anchor.month, _anchor.day);
        return (start, start.add(const Duration(days: 1)));
      case ReportPeriod.week:
        final monday = _anchor.subtract(Duration(days: _anchor.weekday - 1));
        final start = DateTime(monday.year, monday.month, monday.day);
        return (start, start.add(const Duration(days: 7)));
      case ReportPeriod.month:
        final start = DateTime(_anchor.year, _anchor.month);
        return (start, DateTime(_anchor.year, _anchor.month + 1));
    }
  }

  Future<ReportData> _loadData() async {
    final (from, to) = _periodBounds();
    final total = await _repo.getTotalDuration(from, to, projectId: _filterProjectId);
    final byProject = await _repo.getDurationByProject(from, to);

    final List<double> chartValues;
    switch (_period) {
      case ReportPeriod.day:
        chartValues = List.filled(24, 0.0);
        break;
      case ReportPeriod.week:
        final byDay = await _repo.getDurationByWeekday(from);
        chartValues = List.generate(7, (i) => (byDay[i]?.inMinutes ?? 0).toDouble());
        break;
      case ReportPeriod.month:
        final byDay = await _repo.getDurationByDay(from);
        final daysInMonth = to.difference(from).inDays;
        chartValues = List.generate(
          daysInMonth,
          (i) => (byDay[i + 1]?.inMinutes ?? 0).toDouble(),
        );
        break;
    }

    return ReportData(
      totalDuration: total,
      durationByProject: byProject,
      chartValues: chartValues,
      periodStart: from,
      periodEnd: to,
    );
  }
}