main.dart

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

import 'package:package_replaced/package_replaced.dart';
import 'package:path_provider/path_provider.dart' as path_provider;

void main() {
  runApp(MyApp());
  PackageReplaced.setHandlerFunction(handlePackageReplaced);
}

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

void handlePackageReplaced() async {
  await _incrementReplaceCount();
}

class _MyAppState extends State<MyApp> {
  int _replaceCount = 0;
  String _miscMessage = "";

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

  void _showReplaceCount() async {
    final replaceCount = await _getReplaceCount();

    setState(() {
      _replaceCount = replaceCount;
    });
  }

  void _artificalIncrement() async {
    await _incrementReplaceCount();
    _showReplaceCount();
  }

  void _artificalReset() async {
    await _setReplaceCount(0);
    _showReplaceCount();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
          appBar: AppBar(
            title: const Text('package_replaced plugin example app'),
          ),
          body: Center(
            child: Column(
              children: <Widget>[
                Text('Package replaced $_replaceCount time(s)'),
                Text(_miscMessage)
              ],
            ),
          ),
          floatingActionButton: Column(
            children: <Widget>[
              FloatingActionButton(
                child: Text("+"),
                onPressed: _artificalIncrement,
              ),
              FloatingActionButton(
                child: Text("0"),
                onPressed: _artificalReset,
              ),
            ],
            mainAxisAlignment: MainAxisAlignment.end,
          )),
    );
  }
}

Future<File> getCountFile() async {
  final myStorageDirectory =
      await path_provider.getApplicationDocumentsDirectory();

  var countFilePath = myStorageDirectory.path;

  if (!countFilePath.endsWith("/")) {
    countFilePath += "/";
  }

  countFilePath += "org.thebus.package_replaced_example.replaceCount";

  return File(countFilePath);
}

Future<int> _getReplaceCount() async {
  var retCount = 0;

  final countFile = await getCountFile();

  if (await countFile.exists()) {
    retCount = int.tryParse((await countFile.readAsString()));

    if (retCount == null) {
      retCount = 0;
    }
  }

  return retCount;
}

Future<void> _setReplaceCount(int newCountValue) async {
  final countFile = await getCountFile();

  if (!(await countFile.parent.exists())) {
    await countFile.parent.create(recursive: true);
  }

  await countFile.writeAsString(newCountValue.toString());
}

Future<void> _incrementReplaceCount() async {
  final currentReplaceCount = await _getReplaceCount();
  await _setReplaceCount(currentReplaceCount + 1);
}