/// Named Overview chart filter snapshots (local favourites).
library;

import '../models/transaction_meta.dart';
import '../widgets/label_filter_dialog.dart';

/// Persisted Overview lens: period, metric, and Labels-chart options.
class OverviewFavourite {
  const OverviewFavourite({
    required this.id,
    required this.name,
    this.display = true,
    this.metric = OverviewMetricMode.flow,
    this.period = OverviewPeriodMode.monthly,
    this.labelIds = const [],
    this.flow = TxFlowFilter.expense,
    this.barStyle = LabelChartBarStyle.parallel,
    this.invertExpensePerspective = false,
    this.updatedAt = 0,
    this.deleted = false,
  });

  final String id;
  final String name;

  /// When true, this favourite appears on the Favourites overview view.
  final bool display;

  final OverviewMetricMode metric;
  final OverviewPeriodMode period;

  /// Empty = all labels (Labels metric only).
  final List<String> labelIds;

  final TxFlowFilter flow;
  final LabelChartBarStyle barStyle;
  final bool invertExpensePerspective;

  /// Epoch ms; used for last-write-wins sync across devices.
  final int updatedAt;

  /// Soft-delete so removals propagate via sync instead of being recreated.
  final bool deleted;

  OverviewFavourite copyWith({
    String? id,
    String? name,
    bool? display,
    OverviewMetricMode? metric,
    OverviewPeriodMode? period,
    List<String>? labelIds,
    TxFlowFilter? flow,
    LabelChartBarStyle? barStyle,
    bool? invertExpensePerspective,
    int? updatedAt,
    bool? deleted,
    bool touchUpdatedAt = false,
  }) {
    return OverviewFavourite(
      id: id ?? this.id,
      name: name ?? this.name,
      display: display ?? this.display,
      metric: metric ?? this.metric,
      period: period ?? this.period,
      labelIds: labelIds ?? this.labelIds,
      flow: flow ?? this.flow,
      barStyle: barStyle ?? this.barStyle,
      invertExpensePerspective:
          invertExpensePerspective ?? this.invertExpensePerspective,
      updatedAt: touchUpdatedAt
          ? DateTime.now().millisecondsSinceEpoch
          : (updatedAt ?? this.updatedAt),
      deleted: deleted ?? this.deleted,
    );
  }

  Map<String, dynamic> toJson() => {
        'id': id,
        'name': name,
        'display': display,
        'metric': metric.name,
        'period': period.name,
        'labelIds': labelIds,
        'flow': flow.name,
        'barStyle': barStyle.name,
        'invertExpensePerspective': invertExpensePerspective,
        'updatedAt': updatedAt,
        'deleted': deleted,
      };

  factory OverviewFavourite.fromJson(Map<String, dynamic> json) {
    final rawUpdated = json['updatedAt'] ?? json['updated_at'];
    final updatedAt = switch (rawUpdated) {
      int n => n,
      num n => n.round(),
      String s => int.tryParse(s) ?? 0,
      _ => 0,
    };
    return OverviewFavourite(
      id: json['id'] as String? ?? 'fav_${DateTime.now().millisecondsSinceEpoch}',
      name: (json['name'] as String?)?.trim().isNotEmpty == true
          ? (json['name'] as String).trim()
          : 'Favourite',
      display: json['display'] as bool? ?? true,
      metric: OverviewMetricMode.values.firstWhere(
        (e) => e.name == json['metric'],
        orElse: () => OverviewMetricMode.flow,
      ),
      period: OverviewPeriodMode.values.firstWhere(
        (e) => e.name == json['period'],
        orElse: () => OverviewPeriodMode.monthly,
      ),
      labelIds: [
        for (final id in (json['labelIds'] as List? ?? const []))
          if (id is String && id.isNotEmpty) id,
      ],
      flow: TxFlowFilter.values.firstWhere(
        (e) => e.name == json['flow'],
        orElse: () => TxFlowFilter.expense,
      ),
      barStyle: LabelChartBarStyle.values.firstWhere(
        (e) => e.name == json['barStyle'],
        orElse: () => LabelChartBarStyle.parallel,
      ),
      invertExpensePerspective:
          json['invertExpensePerspective'] as bool? ?? false,
      updatedAt: updatedAt,
      deleted: json['deleted'] as bool? ?? false,
    );
  }
}

enum OverviewMetricMode { flow, labels }

enum OverviewPeriodMode { monthly, yearly }

/// Union favourites by id with last-write-wins on [OverviewFavourite.updatedAt].
List<OverviewFavourite> mergeOverviewFavourites(
  List<OverviewFavourite> local,
  List<OverviewFavourite> remote,
) {
  final byId = <String, OverviewFavourite>{};
  void put(OverviewFavourite fav) {
    final existing = byId[fav.id];
    if (existing == null || fav.updatedAt >= existing.updatedAt) {
      byId[fav.id] = fav;
    }
  }

  for (final fav in remote) {
    put(fav);
  }
  for (final fav in local) {
    put(fav);
  }
  return byId.values.toList(growable: false);
}