import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:shared_preferences/shared_preferences.dart';

import '../../../core/models/sensor_defs.dart';

/// What the dashboard shows, per the requirement document: a selectable
/// main sensor (gauge) + sub sensor, 10 selectable values (landscape: 5 left
/// + 5 right; portrait: 2×5) and 4 selectable flags. Persisted.
class DashboardConfig {
  static const valueCount = 10;
  static const flagCount = 4;

  final String main;
  final String sub;
  final List<String> values;
  final List<String> flags;

  const DashboardConfig({
    required this.main,
    required this.sub,
    required this.values,
    required this.flags,
  });

  static const defaults = DashboardConfig(
    main: 'rpm',
    sub: 'vss',
    values: [
      'vss', 'ect', 'iat', 'map', 'o2', // left
      'tps', 'bat', 'ign', 'inj', 'eth', // right
    ],
    flags: ['mil', 'fanout', 'vtec', 'knock'],
  );

  DashboardConfig copyWith({
    String? main,
    String? sub,
    List<String>? values,
    List<String>? flags,
  }) =>
      DashboardConfig(
        main: main ?? this.main,
        sub: sub ?? this.sub,
        values: values ?? this.values,
        flags: flags ?? this.flags,
      );
}

const _kMain = 'dash.main';
const _kSub = 'dash.sub';
const _kValues = 'dash.values';
const _kFlags = 'dash.flags';

class DashboardConfigNotifier extends StateNotifier<DashboardConfig> {
  DashboardConfigNotifier() : super(DashboardConfig.defaults) {
    _load();
  }

  static bool _isSensor(String id) => sensorDefs.any((d) => d.id == id);
  static bool _isFlag(String id) => flagDefs.any((f) => f.id == id);

  Future<void> _load() async {
    try {
      final p = await SharedPreferences.getInstance();
      const d = DashboardConfig.defaults;
      List<String> list(String key, int n, bool Function(String) valid,
          List<String> fallback) {
        final saved = p.getStringList(key);
        if (saved == null || saved.length != n || !saved.every(valid)) {
          return fallback;
        }
        return saved;
      }

      final main = p.getString(_kMain);
      final sub = p.getString(_kSub);
      final next = DashboardConfig(
        main: main != null && _isSensor(main) ? main : d.main,
        sub: sub != null && _isSensor(sub) ? sub : d.sub,
        values: list(_kValues, DashboardConfig.valueCount, _isSensor, d.values),
        flags: list(_kFlags, DashboardConfig.flagCount, _isFlag, d.flags),
      );
      if (mounted) state = next;
    } catch (_) {
      // Keep defaults if preferences can't be read.
    }
  }

  void _persist() {
    final s = state;
    SharedPreferences.getInstance().then((p) {
      p.setString(_kMain, s.main);
      p.setString(_kSub, s.sub);
      p.setStringList(_kValues, s.values);
      p.setStringList(_kFlags, s.flags);
    }).catchError((Object _) {});
  }

  void setMain(String id) {
    state = state.copyWith(main: id);
    _persist();
  }

  void setSub(String id) {
    state = state.copyWith(sub: id);
    _persist();
  }

  void setValue(int index, String id) {
    state = state.copyWith(values: [...state.values]..[index] = id);
    _persist();
  }

  void setFlag(int index, String id) {
    state = state.copyWith(flags: [...state.flags]..[index] = id);
    _persist();
  }
}

final dashboardConfigProvider =
    StateNotifierProvider<DashboardConfigNotifier, DashboardConfig>(
  (ref) => DashboardConfigNotifier(),
);