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, GlobalEntryState> {
  final GlobalEntryState initialState;
  final FoodStorage storage;

  FoodEntryBloc({required this.initialState, required this.storage})
      : super(initialState) {
    on<PageBeingInitialized>(handlePageBeingInitialized);
    on<FoodEntryEvent>(handleFoodEntryEvent);
    on<FoodChangedEvent>(handleFoodChangedEvent);
    on<FoodDeletionEvent>(handleDeleteFoodEvent);
    on<BarcodeScanned>(handleBarcodeScannedEvent);
    on<FoodEntryTapped>(handleFoodEntryTapped);
  }
  void handlePageBeingInitialized(
      PageBeingInitialized event, Emitter<GlobalEntryState> emit) async {
    var newList = await storage.getEntriesForDate(event.forDate);
    state.foodEntries.addAll({event.forDate: newList});

    emit(GlobalEntryState(foodEntries: state.foodEntries));
  }

  void handleFoodEntryEvent(
      FoodEntryEvent event, Emitter<GlobalEntryState> emit) async {
    var entriesForDate = state.foodEntries[event.forDate];
    entriesForDate ??= [];

    entriesForDate.add(event.entry);

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

    // this is just checking if writing to the database worked
    // can be optimized out by just emitting newState
    var newList = await storage.getEntriesForDate(event.forDate);

    var newFoodEntries = state.foodEntries;
    newFoodEntries.addAll({event.forDate: newList});

    emit(GlobalEntryState(foodEntries: newFoodEntries));
  }

  void handleFoodChangedEvent(
      FoodChangedEvent event, Emitter<GlobalEntryState> emit) async {
    var entriesForDate = state.foodEntries[event.forDate];
    if (entriesForDate == null) return;

    var index = entriesForDate.indexWhere((entry) {
      return entry.id == event.newEntry.id;
    });

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

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

    // this is just checking if writing to the database worked
    // can be optimized out by just emitting newState
    var newList = await storage.getEntriesForDate(event.forDate);

    var newFoodEntries = state.foodEntries;
    newFoodEntries.addAll({event.forDate: newList});

    emit(GlobalEntryState(foodEntries: newFoodEntries));
  }

  void handleDeleteFoodEvent(
      FoodDeletionEvent event, Emitter<GlobalEntryState> emit) async {
    var entriesForDate = state.foodEntries[event.forDate];
    if (entriesForDate == null) return;

    entriesForDate.removeWhere((entry) => entry.id == event.entryID);

    await storage.writeEntriesForDate(event.forDate, entriesForDate);

    // this is just checking if writing to the database worked
    // can be optimized out by just emitting newState
    var newList = await storage.getEntriesForDate(event.forDate);

    var newFoodEntries = state.foodEntries;
    newFoodEntries.addAll({event.forDate: newList});

    emit(GlobalEntryState(foodEntries: newFoodEntries));
  }

  void handleBarcodeScannedEvent(
      BarcodeScanned event, Emitter<GlobalEntryState> emit) async {
    var entriesForDate = state.foodEntries[event.forDate];
    if (entriesForDate == null) return;

    var client = FoodFactLookupClient();
    var scanResult = await event.scanResultFuture;

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

    var newEntryWaiting = FoodEntryState(
      kcalPer100: 0,
      name: "",
      mass: 0,
      waitingForNetwork: true,
      isSelected: false,
    );
    entriesForDate.add(newEntryWaiting);
    var newFoodEntries = state.foodEntries;
    newFoodEntries.addAll({event.forDate: entriesForDate});
    emit(GlobalEntryState(foodEntries: newFoodEntries));

    await responseFuture.then((response) async {
      var index = entriesForDate
          .indexWhere((entryState) => entryState.id == newEntryWaiting.id);

      // element not found (was deleted previously)
      if (index == -1) {
        return;
      }

      if (response.status == FoodFactResponseStatus.barcodeNotFound) {
        entriesForDate.removeWhere((entry) => entry.id == newEntryWaiting.id);
        var newFoodEntries = state.foodEntries;
        newFoodEntries.addAll({event.forDate: entriesForDate});

        emit(GlobalEntryState(
            foodEntries: newFoodEntries,
            errorString: "Barcode konnte nicht gefunden werden."));
        return;
      }
      if (response.status ==
          FoodFactResponseStatus.foodFactServerNotReachable) {
        entriesForDate.removeWhere((entry) => entry.id == newEntryWaiting.id);
        var newFoodEntries = state.foodEntries;
        newFoodEntries.addAll({event.forDate: entriesForDate});

        emit(GlobalEntryState(
            foodEntries: newFoodEntries,
            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,
        isSelected: false,
      );

      entriesForDate.removeAt(index);
      entriesForDate.insert(index, newEntryFinishedWaiting);

      await storage.writeEntriesForDate(event.forDate, entriesForDate);
      storage.addFoodEntryToLookupDatabase(newEntryFinishedWaiting);

      var entriesFromStorage = await storage.getEntriesForDate(event.forDate);
      var newFoodEntries = state.foodEntries;
      newFoodEntries.addAll({event.forDate: entriesFromStorage});

      emit(GlobalEntryState(foodEntries: newFoodEntries));
    });
  }

  void handleFoodEntryTapped(
      FoodEntryTapped event, Emitter<GlobalEntryState> emit) async {
    var entriesForDate = state.foodEntries[event.forDate];
    if (entriesForDate == null) return;

    var oldStateOfTappedEntry = event.entry.isSelected;

    for (var entry in entriesForDate) {
      entry.isSelected = false;
    }

    var selectedEntry = entriesForDate.firstWhere((entry) {
      return entry.id == event.entry.id;
    });

    selectedEntry.isSelected = !oldStateOfTappedEntry;

    emit(GlobalEntryState(foodEntries: state.foodEntries));
  }
}

class FoodEvent {
  final DateTime forDate;

  FoodEvent({required this.forDate});
}

class PageBeingInitialized extends FoodEvent {
  PageBeingInitialized({required super.forDate});
}

class FoodEntryEvent extends FoodEvent {
  final FoodEntryState entry;

  FoodEntryEvent({required this.entry, required super.forDate});
}

class FoodChangedEvent extends FoodEvent {
  final FoodEntryState newEntry;

  FoodChangedEvent({required this.newEntry, required super.forDate});
}

class FoodDeletionEvent extends FoodEvent {
  final String entryID;

  FoodDeletionEvent({required this.entryID, required super.forDate});
}

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

  BarcodeScanned({required this.scanResultFuture, required super.forDate});
}

class FoodEntryTapped extends FoodEvent {
  final FoodEntryState entry;

  FoodEntryTapped({required this.entry, required super.forDate});
}

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

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

  factory GlobalEntryState.init() {
    return GlobalEntryState(foodEntries: {});
  }

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

  bool addEntry(FoodEntryState entry, DateTime date) {
    var list = foodEntries[date];

    if (list == null) {
      return false;
    }

    list.add(entry);

    return true;
  }
}

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

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

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

  @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';
  }
}