GitJournal/lib/experiments/main_background.dart

import 'dart:async';
import 'package:flutter/material.dart';

import 'package:background_fetch/background_fetch.dart';

// [Android-only] This "Headless Task" is run when the Android app
// is terminated with enableHeadless: true
void backgroundFetchHeadlessTask(HeadlessTask task) async {
  String taskId = task.taskId;
  bool isTimeout = task.timeout;
  if (isTimeout) {
    // This task has exceeded its allowed running-time.
    // You must stop what you're doing and immediately .finish(taskId)
    print("[BackgroundFetch] Headless task timed-out: $taskId");
    BackgroundFetch.finish(taskId);
    return;
  }
  print('[BackgroundFetch] Headless event received.');
  // Do your work here...
  BackgroundFetch.finish(taskId);
}

void main() {
  // Enable integration testing with the Flutter Driver extension.
  // See https://flutter.io/testing/ for more info.
  runApp(MyApp());

  // Register to receive BackgroundFetch events after app is terminated.
  // Requires {stopOnTerminate: false, enableHeadless: true}
  BackgroundFetch.registerHeadlessTask(backgroundFetchHeadlessTask);
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  bool _enabled = true;
  int _status = 0;
  final List<DateTime> _events = [];

  @override
  void initState() {
    super.initState();
    initPlatformState();
  }

  // Platform messages are asynchronous, so we initialize in an async method.
  Future<void> initPlatformState() async {
    // Configure BackgroundFetch.
    int status = await BackgroundFetch.configure(
        BackgroundFetchConfig(
            minimumFetchInterval: 15,
            stopOnTerminate: false,
            enableHeadless: true,
            requiresBatteryNotLow: false,
            requiresCharging: false,
            requiresStorageNotLow: false,
            requiresDeviceIdle: false,
            requiredNetworkType: NetworkType.NONE), (String taskId) async {
      // <-- Event handler
      // This is the fetch-event callback.
      print("[BackgroundFetch] Event received $taskId");
      setState(() {
        _events.insert(0, DateTime.now());
      });
      // IMPORTANT:  You must signal completion of your task or the OS can punish your app
      // for taking too long in the background.
      BackgroundFetch.finish(taskId);
    }, (String taskId) async {
      // <-- Task timeout handler.
      // This task has exceeded its allowed running-time.  You must stop what you're doing and immediately .finish(taskId)
      print("[BackgroundFetch] TASK TIMEOUT taskId: $taskId");
      BackgroundFetch.finish(taskId);
    });
    print('[BackgroundFetch] configure success: $status');
    setState(() {
      _status = status;
    });

    // If the widget was removed from the tree while the asynchronous platform
    // message was in flight, we want to discard the reply rather than calling
    // setState to update our non-existent appearance.
    if (!mounted) return;
  }

  void _onClickEnable(enabled) {
    setState(() {
      _enabled = enabled;
    });
    if (enabled) {
      BackgroundFetch.start().then((int status) {
        print('[BackgroundFetch] start success: $status');
      }).catchError((e) {
        print('[BackgroundFetch] start FAILURE: $e');
      });
    } else {
      BackgroundFetch.stop().then((int status) {
        print('[BackgroundFetch] stop success: $status');
      });
    }
  }

  void _onClickStatus() async {
    int status = await BackgroundFetch.status;
    print('[BackgroundFetch] status: $status');
    setState(() {
      _status = status;
    });
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
            title: const Text('BackgroundFetch Example',
                style: TextStyle(color: Colors.black)),
            backgroundColor: Colors.amberAccent,
            actions: <Widget>[
              Switch(value: _enabled, onChanged: _onClickEnable),
            ]),
        body: Container(
          color: Colors.black,
          child: ListView.builder(
              itemCount: _events.length,
              itemBuilder: (BuildContext context, int index) {
                DateTime timestamp = _events[index];
                return InputDecorator(
                    decoration: const InputDecoration(
                        contentPadding:
                            EdgeInsets.only(left: 10.0, top: 10.0, bottom: 0.0),
                        labelStyle: TextStyle(
                            color: Colors.amberAccent, fontSize: 20.0),
                        labelText: "[background fetch event]"),
                    child: Text(timestamp.toString(),
                        style: const TextStyle(
                            color: Colors.white, fontSize: 16.0)));
              }),
        ),
        bottomNavigationBar: BottomAppBar(
            child: Row(children: <Widget>[
          ElevatedButton(
              onPressed: _onClickStatus, child: const Text('Status')),
          Container(
              child: Text("$_status"),
              margin: const EdgeInsets.only(left: 20.0))
        ])),
      ),
    );
  }
}

// Stuff to be saved -
// (gitRepo, remoteName, lastSyncedWhen, lastError)