inherited_selector_example.dart

// ignore_for_file: avoid_print

import 'package:flutter/material.dart';
import 'package:unidirectional/inherited_selector.dart';

class AdditionModel {
  final int first;
  final int second;

  const AdditionModel(this.first, this.second);

  @override
  int get hashCode => Object.hashAll([first, second]);

  @override
  bool operator ==(Object other) =>
      identical(this, other) ||
      (other is AdditionModel &&
          other.first == first &&
          other.second == second);

  AdditionModel copyWith({
    int? first,
    int? second,
  }) =>
      AdditionModel(
        first ?? this.first,
        second ?? this.second,
      );
}

class AdditionScope extends StatefulWidget {
  final Widget child;

  const AdditionScope({required this.child, super.key});

  static _AdditionScopeState? _stateOf(BuildContext context) =>
      context.findAncestorStateOfType<_AdditionScopeState>();

  static void incrementFirst(BuildContext context) {
    _stateOf(context)?.incrementFirst();
  }

  static void incrementSecond(BuildContext context) {
    _stateOf(context)?.incrementSecond();
  }

  static int firstOf(BuildContext context) => InheritedSelector.select(
        context,
        (AdditionModel data) => data.first,
        listen: true,
      );

  static int secondOf(BuildContext context) => InheritedSelector.select(
        context,
        (AdditionModel data) => data.second,
        listen: true,
      );

  static int sumOf(BuildContext context) => InheritedSelector.select(
        context,
        (AdditionModel data) => data.first + data.second,
        listen: true,
      );

  @override
  State<AdditionScope> createState() => _AdditionScopeState();
}

class _AdditionScopeState extends State<AdditionScope> {
  AdditionModel model = const AdditionModel(0, 0);

  void setModel(AdditionModel newModel) {
    setState(() {
      model = newModel;
    });
  }

  void incrementFirst() {
    setModel(
      model.copyWith(first: model.first + 1),
    );
  }

  void incrementSecond() {
    setModel(
      model.copyWith(second: model.second + 1),
    );
  }

  @override
  Widget build(BuildContext context) => InheritedSelector(
        data: model,
        child: widget.child,
      );
}

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

  @override
  Widget build(BuildContext context) {
    print(runtimeType);

    return AdditionScope(
      child: Scaffold(
        body: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Row(
              children: const [
                InheritedSelectorFirst(),
                Text('+'),
                InheritedSelectorSecond(),
                Text('='),
                InheritedSelectorSum(),
              ],
            ),
            const InheritedSelectorButtons(),
          ],
        ),
      ),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    print(runtimeType);

    return Row(
      children: [
        ElevatedButton(
          onPressed: () => AdditionScope.incrementFirst(context),
          child: const Text('Increment First'),
        ),
        ElevatedButton(
          onPressed: () => AdditionScope.incrementSecond(context),
          child: const Text('Increment Second'),
        ),
      ],
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    print(runtimeType);
    final first = AdditionScope.firstOf(context);

    return Text(
      first.toString(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    print(runtimeType);
    final second = AdditionScope.secondOf(context);

    return Text(
      second.toString(),
    );
  }
}

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

  @override
  Widget build(BuildContext context) {
    print(runtimeType);
    final sum = AdditionScope.sumOf(context);

    return Text(
      sum.toString(),
    );
  }
}