import 'dart:async';

import 'package:flutter/material.dart';

const pollInterval = Duration(seconds: 5);

/// Calls [onPoll] every five seconds while the app is resumed.
class ForegroundPoll extends StatefulWidget {
  const ForegroundPoll({super.key, required this.onPoll, required this.child});

  final Future<void> Function() onPoll;
  final Widget child;

  @override
  State<ForegroundPoll> createState() => _ForegroundPollState();
}

class _ForegroundPollState extends State<ForegroundPoll>
    with WidgetsBindingObserver {
  Timer? _timer;

  @override
  void initState() {
    super.initState();
    WidgetsBinding.instance.addObserver(this);
    _start();
  }

  @override
  void dispose() {
    _stop();
    WidgetsBinding.instance.removeObserver(this);
    super.dispose();
  }

  @override
  void didChangeAppLifecycleState(AppLifecycleState state) {
    switch (state) {
      case AppLifecycleState.resumed:
        _start();
        unawaited(widget.onPoll());
      case AppLifecycleState.paused:
      case AppLifecycleState.hidden:
      case AppLifecycleState.detached:
        _stop();
      case AppLifecycleState.inactive:
        break;
    }
  }

  void _start() {
    _timer ??= Timer.periodic(pollInterval, (_) {
      unawaited(widget.onPoll());
    });
  }

  void _stop() {
    _timer?.cancel();
    _timer = null;
  }

  @override
  Widget build(BuildContext context) => widget.child;
}