thesis_shop/lib/redux/state.dart

import 'package:thesis_shop/models/cart_item.dart';
import 'package:thesis_shop/models/product.dart';
import 'package:thesis_shop/models/remote_resource.dart';

typedef RemoteProducts = RemoteResource<List<Product>>;

typedef ProductTitle = String;
typedef Quantities = Map<ProductTitle, int>;

class AppState {
  final bool isSignedIn;
  final RemoteProducts remoteProducts;
  final Quantities productQuantities;

  const AppState({
    required this.isSignedIn,
    required this.remoteProducts,
    required this.productQuantities,
  });
  AppState.initialState()
      : isSignedIn = false,
        remoteProducts = const RemoteResource.loading(),
        productQuantities = {};

  RemoteProducts get remoteProductsWithDiscount => isSignedIn
      ? remoteProducts.mapIfFinished((products) =>
          products.map((product) => product.copyWithDiscount()).toList())
      : remoteProducts;

  List<CartItem> get cart {
    final products = remoteProductsWithDiscount is FinishedRemoteResource
        ? remoteProductsWithDiscount.asFinished().value
        : <Product>[];
    final productByTitle = {
      for (final product in products) product.title: product
    };
    return productQuantities.entries
        .where((entry) => productByTitle.containsKey(entry.key))
        .map((entry) =>
            CartItem(product: productByTitle[entry.key]!, amount: entry.value))
        .toList();
  }

  double get totalPrice => cart.fold<double>(
        0.0,
        (previousValue, element) =>
            previousValue + element.amount * element.product.price,
      );

  AppState copyWith({
    bool? isSignedIn,
    RemoteResource<List<Product>>? remoteProducts,
    Quantities? productQuantities,
  }) {
    return AppState(
      isSignedIn: isSignedIn ?? this.isSignedIn,
      remoteProducts: remoteProducts ?? this.remoteProducts,
      productQuantities: productQuantities ?? this.productQuantities,
    );
  }
}