import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../bluetooth/bt_poller.dart';
import '../models/units.dart';

/// Polling choices offered in Settings. Never faster than 10 Hz: the adapter
/// MCU must have time to read the ECU between requests (device maker's
/// feedback). The poller additionally never sends a new request before the
/// previous one is answered or has timed out.
const List<int> pollingIntervalOptionsMs = [100, 150, 200, 300];

class AppSettings {
  final EcuType ecuType;
  final Duration pollingInterval;

  const AppSettings({
    this.ecuType = EcuType.s300,
    this.pollingInterval = BtPoller.defaultInterval,
  });

  AppSettings copyWith({EcuType? ecuType, Duration? pollingInterval}) =>
      AppSettings(
        ecuType: ecuType ?? this.ecuType,
        pollingInterval: pollingInterval ?? this.pollingInterval,
      );
}

const _ecuTypeKey = 'ecuType';
const _pollingKey = 'pollingIntervalMs';

class SettingsNotifier extends StateNotifier<AppSettings> {
  SettingsNotifier() : super(const AppSettings()) {
    _load();
  }

  Future<void> _load() async {
    try {
      final prefs = await SharedPreferences.getInstance();
      final saved = prefs.getString(_ecuTypeKey);
      final ms = prefs.getInt(_pollingKey);
      var next = state;
      if (saved == EcuType.kpro.name) next = next.copyWith(ecuType: EcuType.kpro);
      if (ms != null && pollingIntervalOptionsMs.contains(ms)) {
        next = next.copyWith(pollingInterval: Duration(milliseconds: ms));
      }
      if (mounted) state = next;
    } catch (_) {
      // Keep defaults if preferences can't be read.
    }
  }

  void setEcuType(EcuType type) {
    state = state.copyWith(ecuType: type);
    SharedPreferences.getInstance()
        .then((prefs) => prefs.setString(_ecuTypeKey, type.name))
        .catchError((Object _) => false);
  }

  void setPollingInterval(Duration d) {
    final ms = pollingIntervalOptionsMs.contains(d.inMilliseconds)
        ? d.inMilliseconds
        : BtPoller.defaultInterval.inMilliseconds;
    state = state.copyWith(pollingInterval: Duration(milliseconds: ms));
    SharedPreferences.getInstance()
        .then((prefs) => prefs.setInt(_pollingKey, ms))
        .catchError((Object _) => false);
  }
}

final settingsProvider = StateNotifierProvider<SettingsNotifier, AppSettings>(
  (ref) => SettingsNotifier(),
);

// ─── Display units ───────────────────────────────────────────────────────────

const _unitKeys = (speed: 'unitSpeed', temp: 'unitTemp', pressure: 'unitPressure');

T? _byName<T extends Enum>(List<T> values, String? name) {
  for (final v in values) {
    if (v.name == name) return v;
  }
  return null;
}

/// Display units (speed / temperature / pressure), persisted.
class UnitPrefsNotifier extends StateNotifier<UnitPrefs> {
  UnitPrefsNotifier() : super(const UnitPrefs()) {
    _load();
  }

  Future<void> _load() async {
    try {
      final prefs = await SharedPreferences.getInstance();
      final next = UnitPrefs(
        speed: _byName(SpeedUnit.values, prefs.getString(_unitKeys.speed)) ??
            state.speed,
        temp: _byName(TempUnit.values, prefs.getString(_unitKeys.temp)) ??
            state.temp,
        pressure: _byName(
                PressureUnit.values, prefs.getString(_unitKeys.pressure)) ??
            state.pressure,
      );
      if (mounted) state = next;
    } catch (_) {
      // Keep defaults if preferences can't be read.
    }
  }

  void _save(String key, Enum v) {
    SharedPreferences.getInstance()
        .then((prefs) => prefs.setString(key, v.name))
        .catchError((Object _) => false);
  }

  void setSpeed(SpeedUnit v) {
    state = state.copyWith(speed: v);
    _save(_unitKeys.speed, v);
  }

  void setTemp(TempUnit v) {
    state = state.copyWith(temp: v);
    _save(_unitKeys.temp, v);
  }

  void setPressure(PressureUnit v) {
    state = state.copyWith(pressure: v);
    _save(_unitKeys.pressure, v);
  }
}

final unitPrefsProvider =
    StateNotifierProvider<UnitPrefsNotifier, UnitPrefs>(
  (ref) => UnitPrefsNotifier(),
);