.dart

Widget _kDefaultWidget<T>(T value, BuildContext _) => Text('Error.');

typedef BuilderFunction<T> = Widget Function(T value, BuildContext context);
typedef ListenerFunction<T> = void Function(T value, BuildContext context);

class MatchCase<Q> {
  MatchCase(
    this.matcher,
    this.builder,
    this.listener,
  );

  final Matcher matcher;
  final BuilderFunction<Q> builder;
  final ListenerFunction<Q>? listener;
}

/// {@template case_widget}
/// A Very Good Project created by Very Good CLI.
/// {@endtemplate}
class CaseWidget<T> extends StatelessWidget {
  /// {@macro case_widget}
  const CaseWidget({
    required this.value,
    super.key,
    this.onDefault,
  });

  ///sdfsd
  void on(
    Matcher matcher,
    BuilderFunction<T> builder, {
    ListenerFunction<T>? listener,
  }) {
    matchesSet.add(
      MatchCase<T>(
        matcher,
        builder,
        listener,
      ),
    );
  }

  void onType<Q extends T>(BuilderFunction builder) => on(
        isA<Q>(),
        builder,
      );

  void onEquals<T>(T expectedValue, BuilderFunction builder) => on(
        equals(expectedValue),
        builder,
      );

  /// Value of the
  final T value;
  final BuilderFunction<T>? onDefault;

  /// All matches cases
  final Set<MatchCase> matchesSet = const {};

  @override
  @visibleForTesting
  Widget build(BuildContext context) {
    final matches = matchesSet.where(
      (element) => element.matcher.matches(
        value,
        <String, dynamic>{},
      ),
    );
    if (matches.isNotEmpty) {
      final firstMatch = matches.first;
      return firstMatch.builder(value, context);
    }

    return _kDefaultWidget<T>(value, context);
  }
}