bookshelf/books_flutter/lib/bloc/navigation_bloc.dart

import 'package:flutter_bloc/flutter_bloc.dart';
import '../models/models.dart';

// Events
sealed class NavigationEvent {}

class NavigateTo extends NavigationEvent {
  final AppScreen screen;
  final Book? selectedBook;
  final Book? prefilledData;
  NavigateTo(this.screen, {this.selectedBook, this.prefilledData});
}

// State
class NavigationState {
  final AppScreen screen;
  final Book? selectedBook;
  final Book? prefilledData;
  const NavigationState({
    this.screen = AppScreen.library,
    this.selectedBook,
    this.prefilledData,
  });

  NavigationState copyWith({
    AppScreen? screen,
    Book? Function()? selectedBook,
    Book? Function()? prefilledData,
  }) {
    return NavigationState(
      screen: screen ?? this.screen,
      selectedBook: selectedBook != null ? selectedBook() : this.selectedBook,
      prefilledData: prefilledData != null
          ? prefilledData()
          : this.prefilledData,
    );
  }
}

// Bloc
class NavigationBloc extends Bloc<NavigationEvent, NavigationState> {
  NavigationBloc() : super(const NavigationState()) {
    on<NavigateTo>((event, emit) {
      emit(
        NavigationState(
          screen: event.screen,
          selectedBook: event.selectedBook ?? state.selectedBook,
          prefilledData: event.prefilledData,
        ),
      );
    });
  }
}