import 'dart:async';

import 'package:flutter/foundation.dart';

import '../../data/models/location_reading.dart';
import '../../data/repositories/settings_repository.dart';
import '../../data/services/telemetry_bridge.dart';
import '../../data/services/weather_service.dart';

/// Location-based temperature fallback used only when OBD has no ambient value.
class WeatherController extends ChangeNotifier {
  WeatherController(
    this._platform,
    this._settings, {
    WeatherService? weatherService,
  }) : _weatherService = weatherService ?? WeatherService();

  final TelemetryPlatform _platform;
  final SettingsRepository _settings;
  final WeatherService _weatherService;

  bool _enabled = false;
  bool _loading = false;
  bool _active = false;
  bool _disposed = false;
  double? _temperatureCelsius;
  String? _locationName;
  String? _error;
  Timer? _refreshTimer;

  bool get enabled => _enabled;

  bool get loading => _loading;

  double? get temperatureCelsius => _temperatureCelsius;

  String? get locationName => _locationName;

  String? get error => _error;

  bool get hasTemperature =>
      _enabled && _temperatureCelsius != null && _locationName != null;

  void initialize() {
    _enabled = _settings.weatherLocationTemperature;
  }

  Future<void> start() async {
    if (!_enabled || _active) return;
    _active = true;
    await refresh();
    _refreshTimer?.cancel();
    _refreshTimer = Timer.periodic(
      const Duration(minutes: 15),
      (_) => unawaited(refresh()),
    );
  }

  void stop() {
    _active = false;
    _refreshTimer?.cancel();
    _refreshTimer = null;
  }

  /// Enables the fallback and asks for location access at that moment.
  Future<bool> setEnabled(bool value) async {
    if (value == _enabled) return true;
    if (value) {
      final granted = await _platform.ensureLocationPermission();
      if (!granted) {
        _error = 'Location permission is required for weather.';
        _notify();
        return false;
      }
    }
    _enabled = value;
    await _settings.setWeatherLocationTemperature(value);
    if (value) {
      _active = true;
      await refresh();
      _refreshTimer?.cancel();
      _refreshTimer = Timer.periodic(
        const Duration(minutes: 15),
        (_) => unawaited(refresh()),
      );
    } else {
      stop();
      _temperatureCelsius = null;
      _locationName = null;
      _error = null;
    }
    _notify();
    return true;
  }

  Future<void> refresh() async {
    if (!_enabled || _loading) return;
    _loading = true;
    _notify();
    try {
      final LocationReading location;
      try {
        location = await _platform.getLocation();
      } on TelemetryException catch (problem) {
        _error = problem.message;
        _temperatureCelsius = null;
        _locationName = null;
        return;
      }
      final temperature = await _weatherService.temperatureCelsius(
        latitude: location.latitude,
        longitude: location.longitude,
      );
      if (temperature == null) {
        _error = 'Weather is unavailable.';
        _temperatureCelsius = null;
        _locationName = null;
        return;
      }
      _temperatureCelsius = temperature;
      _locationName = location.displayPlace;
      _error = null;
    } finally {
      _loading = false;
      _notify();
    }
  }

  void _notify() {
    if (!_disposed) notifyListeners();
  }

  @override
  void dispose() {
    _disposed = true;
    _refreshTimer?.cancel();
    super.dispose();
  }
}