import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';

void main() {
  runApp(ProviderScope(child: MyApp()));
}

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      debugShowCheckedModeBanner: false,
      home: HomePage(),
    );
  }
}

class HomePage extends StatelessWidget {
  const HomePage({super.key});

  @override
  Widget build(BuildContext context) {
    print("HomePage build");
    return Scaffold(
      body: SafeArea(
        child: Column(
          children: [
            Expanded(child: Top1()),
            Expanded(child: Top2()),
            Expanded(child: Bottom()),
          ],
        ),
      ),
    );
  }
}

class Top1 extends ConsumerWidget {

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    print("Top 1 build");

    int num = ref.watch(numProvider);

    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          const Text("Top 1", style: TextStyle(fontSize: 40, fontWeight: FontWeight.bold)),
          Text("num : ${num}", style: TextStyle(fontSize: 20, fontWeight: FontWeight.bold))
        ],
      ),
    );
  }
}

class Top2 extends ConsumerWidget {
  const Top2({super.key});

  @override
  Widget build(BuildContext context, WidgetRef ref) {
    print("Top 2 build");

    NumVM vm = ref.read(numProvider.notifier);

    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text("Top 2", style: TextStyle(fontSize: 40, fontWeight: FontWeight.bold)),
          ElevatedButton(onPressed: (){
            vm.increase();
          }, child: Icon(Icons.add))
        ],
      ),
    );
  }
}

class Bottom extends StatelessWidget {
  const Bottom({
    super.key,
  });

  @override
  Widget build(BuildContext context) {
    print("Bottom build");
    return Center(
      child: Column(
        mainAxisAlignment: MainAxisAlignment.center,
        children: [
          Text("Bottom", style: TextStyle(fontSize: 40, fontWeight: FontWeight.bold)),
        ],
      ),
    );
  }
}

// 프로바이더 (창고 관리자)
final numProvider = StateNotifierProvider<NumVM, int>((ref) {
  return NumVM(1);
});

// 뷰모델 (창고)
class NumVM extends StateNotifier<int> {
  NumVM(super.state);

  void increase() {
    state++;
  }
}