74 lines
2.2 KiB
Dart
74 lines
2.2 KiB
Dart
import 'package:flutter/material.dart';
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import 'package:async/async.dart';
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import '../model/flood_station.dart';
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import 'api.dart';
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class FloodStationProvider extends ChangeNotifier {
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// since the getter and setter for the following two fields would be empty, they are publicly accessible
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FloodStation? selectedStation;
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bool filtered = false;
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List<FloodStation> _allStations = [];
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List<FloodStation> _filteredStations = [];
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CancelableOperation? _filteredStationsFuture;
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List<FloodStation> get allStations => _allStations;
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List<FloodStation> get filteredStations => _filteredStations;
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CancelableOperation? get filteredStationsFuture => _filteredStationsFuture;
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/// loads all stations in batches of 500 and notifies listeners with every loop except if [silent] = true
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/// this has lower performance than loading them all at once an shouldn't be used
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Future loadAllStationsInBatches({silent = false}) {
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int offset = 0;
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return Future.doWhile(() async {
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final stations = await Api.fetchStationsByRange(500, offset);
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if (stations.isNotEmpty) {
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_allStations.addAll(stations);
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if (!silent) {
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notifyListeners();
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}
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offset += 500;
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return true;
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} else {
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return false;
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}
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});
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}
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/// loads all flood stations and notifies listeners when done
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Future loadAllStations({silent = false}) {
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return Api.fetchAllStations().then(
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(value) {
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_allStations = value;
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if (!silent) {
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notifyListeners();
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}
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},
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);
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}
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/// loads all stations whose label contains [filter]
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Future loadFilteredStations(String filter, {silent = false}) {
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if (_filteredStationsFuture != null) {
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_filteredStationsFuture!.cancel();
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}
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final future = Api.fetchFilteredStations(filter);
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_filteredStationsFuture = CancelableOperation.fromFuture(future).then(
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(value) {
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_filteredStations = value;
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if (!silent) {
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notifyListeners();
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}
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},
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);
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return future;
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}
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/// cancels loading of filtered results.
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void cancelFilterLoading() {
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if (_filteredStationsFuture != null) {
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_filteredStationsFuture!.cancel();
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}
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}
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}
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