calorimeter/lib/perdate/perdate_widget.dart

import 'package:calorimeter/food_entry/food_entry_bloc.dart';
import 'package:calorimeter/perdate/entry_list.dart';
import 'package:calorimeter/storage/storage.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:provider/provider.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> {
  late FoodStorage storage;
  late Future<List<FoodEntryState>> entriesFuture;
  List<FoodEntryState> entries = [];

  @override
  void initState() {
    storage = FoodStorage.getInstance();
    entriesFuture = storage.getEntriesForDate(widget.date);
    entriesFuture.then((val) {
      entries = val;
    });
    super.initState();
  }

  @override
  void dispose() {
    super.dispose();
  }

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

    return FutureBuilder(
        future: entriesFuture,
        builder: (context, snapshot) {
          return snapshot.connectionState != ConnectionState.done
              ? const Center(child: CircularProgressIndicator())
              : BlocProvider(
                  create: (context) => FoodEntryBloc(
                    initialState: PageState(foodEntries: entries),
                    storage: storage,
                    forDate: widget.date,
                  ),
                  child: BlocConsumer<FoodEntryBloc, PageState>(
                    listener: (context, pageState) {
                      if (pageState.errorString != null) {
                        showNewSnackbarWith(context, pageState.errorString!);
                      }
                    },
                    builder: (context, pageState) {
                      return FoodEntryList(entries: pageState.foodEntries);
                    },
                  ),
                );
        });
  }

  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);
}