caching is added

packages/weather/lib/src/weather_factory.dart

@@ -1,5 +1,8 @@
 part of weather_library;
 
+const _weatherKey = "cached-weather-data";
+const _forecastKey = "cached-forecast-data";
+
 /// Plugin for fetching weather data in JSON.
 class WeatherFactory {
  String _apiKey;
@@ -10,8 +13,11 @@ class WeatherFactory {
 
  late http.Client _httpClient;
 
+ final Completer<SharedPreferences> _sharedPreferenceCompleter = Completer();
+
  WeatherFactory(this._apiKey, {this.language = Language.ENGLISH}) {
  _httpClient = http.Client();
+ SharedPreferences.getInstance().then((value) => _sharedPreferenceCompleter.complete(value));
  }
 
  /// Fetch current weather based on geographical coordinates
@@ -48,6 +54,33 @@ class WeatherFactory {
  return forecasts;
  }
 
+ Future<Weather> getCachedWeather() async {
+ final _prefs = await _sharedPreferenceCompleter.future;
+ final _restoredData = _prefs.getString(_weatherKey);
+
+ if(_restoredData != null) {
+ Map<String, dynamic>? jsonBody = json.decode(_restoredData);
+ return Weather(jsonBody!);
+ } else {
+ throw OpenWeatherAPIException("No cached data for weather");
+ }
+ }
+
+ Future<List<Weather>?> getCachedForecast() async {
+ final _prefs = await _sharedPreferenceCompleter.future;
+ final _restoredData = _prefs.getString(_forecastKey);
+
+ if(_restoredData != null){
+ Map<String, dynamic>? jsonBody = json.decode(_restoredData);
+ List<Weather> forecasts = _parseForecast(jsonBody!);
+ return forecasts;
+
+ } else {
+ throw OpenWeatherAPIException("No cached data for forecast");
+ }
+ }
+
+
  Future<Map<String, dynamic>?> _sendRequest(String tag, {double? lat, double? lon, String? cityName}) async {
  /// Build HTTP get url by passing the required parameters
  String url = _buildUrl(tag, cityName, lat, lon);
@@ -58,6 +91,10 @@ class WeatherFactory {
  /// Perform error checking on response:
  /// Status code 200 means everything went well
  if (response.statusCode == STATUS_OK) {
+
+ final _prefs = await _sharedPreferenceCompleter.future;
+ _prefs.setString(tag == FIVE_DAY_FORECAST ? _forecastKey : _weatherKey, response.body);
+
  Map<String, dynamic>? jsonBody = json.decode(response.body);
  return jsonBody;
  }

packages/weather/lib/weather.dart

@@ -10,6 +10,7 @@ library weather_library;
 import 'dart:async';
 import 'dart:convert';
 import 'package:http/http.dart' as http;
+import 'package:shared_preferences/shared_preferences.dart';
 
 part 'package:weather/src/weather_domain.dart';
 part 'package:weather/src/weather_factory.dart';

packages/weather/pubspec.yaml

@@ -10,6 +10,7 @@ dependencies:
  flutter:
  sdk: flutter
  http: ^0.13.1
+ shared_preferences: ^2.0.8
 
 dev_dependencies:
  test: ^1.6.1