calorimeter/lib/perdate/perdate_widget.dart

import 'package:calorimeter/food_entry/food_entry_bloc.dart';
import 'package:calorimeter/perdate/entry_list.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';

class PerDateWidget extends StatefulWidget {
  final DateTime date;
  const PerDateWidget({super.key, required this.date});

  @override
  State<PerDateWidget> createState() => _PerDateWidgetState();
}

class _PerDateWidgetState extends State<PerDateWidget>
    with AutomaticKeepAliveClientMixin<PerDateWidget> {
  @override
  void initState() {
    context
        .read<FoodEntryBloc>()
        .add(PageBeingInitialized(forDate: widget.date));
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    super.build(context);

    return BlocConsumer<FoodEntryBloc, GlobalEntryState>(
      listener: (context, pageState) {
        if (pageState.errorString != null) {
          showNewSnackbarWith(context, pageState.errorString!);
        }
      },
      builder: (context, pageState) {
        return FoodEntryList(
            entries: pageState.foodEntries[widget.date] ?? [],
            date: widget.date);
      },
    );
  }

  void showNewSnackbarWith(BuildContext context, String text) {
    var snackbar =
        ErrorSnackbar(colorScheme: Theme.of(context).colorScheme, text: text);

    ScaffoldMessenger.of(context)
      ..removeCurrentSnackBar()
      ..showSnackBar(snackbar);
  }

  @override
  bool get wantKeepAlive => true;
}

class ErrorSnackbar extends SnackBar {
  final String text;
  final ColorScheme colorScheme;
  ErrorSnackbar({
    required this.text,
    required this.colorScheme,
    super.key,
  }) : super(
            content: Text(text, style: TextStyle(color: colorScheme.onError)),
            backgroundColor: colorScheme.error);
}