calorimeter/lib/food_entry/food_entry_bloc.dart

import 'package:barcode_scan2/barcode_scan2.dart';
import 'package:calorimeter/food_scan/food_fact_lookup.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:calorimeter/storage/storage.dart';
import 'package:uuid/uuid.dart';

class FoodEntryBloc extends Bloc<FoodEvent, PageState> {
  final PageState initialState;
  final FoodStorage storage;
  final DateTime forDate;

  FoodEntryBloc(
      {required this.initialState,
      required this.forDate,
      required this.storage})
      : super(initialState) {
    on<FoodEntryEvent>(handleFoodEntryEvent);
    on<FoodChangedEvent>(handleFoodChangedEvent);
    on<FoodDeletionEvent>(handleDeleteFoodEvent);
    on<BarcodeScanned>(handleBarcodeScannedEvent);
  }

  void handleFoodEntryEvent(
      FoodEntryEvent event, Emitter<PageState> emit) async {
    PageState newState = PageState.from(state);
    newState.addEntry(event.entry);

    await storage.writeEntriesForDate(forDate, newState.foodEntries);
    storage.addFoodEntryToLookupDatabase(event.entry);

    emit(newState);
  }

  void handleFoodChangedEvent(
      FoodChangedEvent event, Emitter<PageState> emit) async {
    var entries = state.foodEntries;
    var index = entries.indexWhere((entry) {
      return entry.id == event.newEntry.id;
    });

    entries.removeAt(index);
    entries.insert(index, event.newEntry);

    await storage.writeEntriesForDate(forDate, entries);
    storage.addFoodEntryToLookupDatabase(event.newEntry);

    emit(PageState(foodEntries: entries));
  }

  void handleDeleteFoodEvent(
      FoodDeletionEvent event, Emitter<PageState> emit) async {
    state.foodEntries.removeWhere((entry) => entry.id == event.entryID);

    await storage.writeEntriesForDate(forDate, state.foodEntries);

    emit(PageState.from(state));
  }

  void handleBarcodeScannedEvent(
      BarcodeScanned event, Emitter<PageState> emit) async {
    var client = FoodFactLookupClient();
    var scanResult = await event.scanResultFuture;

    if (scanResult.type == ResultType.Cancelled) {
      return;
    }
    if (scanResult.type == ResultType.Error) {
      emit(PageState(
          foodEntries: state.foodEntries,
          errorString: "Fehler beim Scannen des Barcodes"));
      return;
    }
    var responseFuture = client.retrieveFoodInfo(scanResult.rawContent);

    List<FoodEntryState> newList = List.from(state.foodEntries);
    var newEntryWaiting = FoodEntryState(
        kcalPer100: 0, name: "", mass: 0, waitingForNetwork: true);
    newList.add(newEntryWaiting);
    emit(PageState(foodEntries: newList));

    await responseFuture.then((response) {
      newList.removeWhere((entryState) => entryState.id == newEntryWaiting.id);

      if (response.status == FoodFactResponseStatus.barcodeNotFound) {
        emit(PageState(
            foodEntries: state.foodEntries,
            errorString: "Barcode konnte nicht gefunden werden."));
        return;
      }
      if (response.status ==
          FoodFactResponseStatus.foodFactServerNotReachable) {
        emit(PageState(
            foodEntries: state.foodEntries,
            errorString: "OpenFoodFacts-Server konnte nicht erreicht werden."));
        return;
      }

      var newEntryFinishedWaiting = FoodEntryState(
        name: response.food?.name ?? "",
        mass: response.food?.mass ?? 0,
        kcalPer100: response.food?.kcalPer100g ?? 0,
        waitingForNetwork: false,
      );
      newList.add(newEntryFinishedWaiting);
      emit(PageState(foodEntries: newList));
    });
  }
}

class FoodEvent {}

class FoodEntryEvent extends FoodEvent {
  final FoodEntryState entry;

  FoodEntryEvent({required this.entry});
}

class FoodChangedEvent extends FoodEvent {
  final FoodEntryState newEntry;

  FoodChangedEvent({required this.newEntry});
}

class FoodDeletionEvent extends FoodEvent {
  final String entryID;

  FoodDeletionEvent({required this.entryID});
}

class BarcodeScanned extends FoodEvent {
  final Future<ScanResult> scanResultFuture;

  BarcodeScanned({required this.scanResultFuture});
}

/// This is the state for one date/page
class PageState {
  final List<FoodEntryState> foodEntries;
  final String? errorString;

  PageState({required this.foodEntries, this.errorString});

  factory PageState.init() {
    return PageState(foodEntries: []);
  }

  static from(PageState state) {
    return PageState(foodEntries: state.foodEntries);
  }

  void addEntry(FoodEntryState entry) {
    foodEntries.add(entry);
  }
}

class FoodEntryState {
  final String name;
  final int mass;
  final int kcalPer100;
  final String id;
  final bool waitingForNetwork;

  factory FoodEntryState({
    required name,
    required mass,
    required kcalPer100,
    required waitingForNetwork,
  }) {
    return FoodEntryState.withID(
      id: const Uuid().v1(),
      name: name,
      mass: mass,
      kcalPer100: kcalPer100,
      waitingForNetwork: waitingForNetwork,
    );
  }

  FoodEntryState.withID({
    required this.id,
    required this.name,
    required this.mass,
    required this.kcalPer100,
    required this.waitingForNetwork,
  });

  @override
  String toString() {
    //we use quotation marks around the name because the name might contain
    //commas and we want to store it in a csv file
    return '$id,"$name",$mass,$kcalPer100';
  }
}