state_mgmt_trigger_alert

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

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(
    MultiProvider(
      providers: [
        Provider(
          create: (_) => AppNotifyOnceProvider()
        )
      ],
      child: MyApp()
    )
  );
}

class AppNotifyOnceProvider {
  
  bool showAlertAtInit = true;
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: Scaffold(
        body: Center(
          child: MyWidget(),
        ),
      ),
    );
  }
}

class MyWidget extends StatefulWidget {
  @override
  MyWidgetState createState() => MyWidgetState();
}

class MyWidgetState extends State<MyWidget> {
  @override
  Widget build(BuildContext context) {
    
    AppNotifyOnceProvider appProvider = Provider.of<AppNotifyOnceProvider>(context, listen: false);
    if(appProvider.showAlertAtInit) {
      Future.delayed(const Duration(seconds: 1), () {
        showDialog(
        context: context,
        builder: (context) {
          return AlertDialog(
            content: AppInitAlert()
          );
        });
      });
    }
    
    return Scaffold(
      appBar: AppBar(),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Text('Hello World', textAlign: TextAlign.center, style: TextStyle(fontSize: 30)),
          TextButton(
            child: Text('Go to Page 2'),
            onPressed: () {
              Navigator.of(context).push(
                MaterialPageRoute(builder: (context) => Page2())
              );
            },
          )
        ]
      )
    );
  }
}


class Page2 extends StatelessWidget {
  @override
  Widget build(BuildContext context) {

    return Scaffold(
      appBar: AppBar(),
      body: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          Text('This is Page 2. Go back to the previous', style: TextStyle(fontSize: 30)),
          TextButton(
            onPressed: () {
              
              Navigator.of(context).push(
                MaterialPageRoute(builder: (context) => MyWidget())
              );
            },
            child: Text("Click here to Push the First Page again, to try and trigger the alert")
          )
        ]
      )
    );
  }
}


class AppInitAlert extends StatelessWidget {
  
  @override
  Widget build(BuildContext context) {
    
    return Container(
      padding: const EdgeInsets.all(30),
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          Text('By clicking the button below, it will make this dialog not appear anymore until you reload the whole app from scratch.'),
          TextButton(
            onPressed: () {
              
              var appProvider = Provider.of<AppNotifyOnceProvider>(context, listen: false);
              appProvider.showAlertAtInit = false;
              Navigator.of(context).pop();
            },
            child: Text("Click here to Dismiss")
          )
        ]
      )
    );
  }
}