// 11. Zwróć firmę która dokonała zakupów na największą kwotę
    public static void exercise11X(List<Company> companies){
        companies
                .stream()
                .collect(Collectors.groupingBy(Company::getName, Collectors.mapping(c -> c.getPurchaseList().stream().mapToDouble(p -> p.getQuantity() * p.getProduct().getPrice()).sum() , Collectors.toList())));


         companies
                .stream()
                .collect(Collectors.toMap(Company::getName, c -> c.getPurchaseList().stream().mapToDouble(p -> p.getQuantity() * p.getProduct().getPrice()).sum(), (c1,c2) -> c1+c2))
                .entrySet()
                .stream()
                .max(Comparator.comparingDouble(Entry::getValue));

    }

    public static Optional<Company> exercise11(List<Company> companies){

         return companies
                 .stream()
                 .max(Comparator.comparingDouble(c -> c.getPurchaseList().stream().mapToDouble(p -> p.getQuantity() * p.getProduct().getPrice()).sum()));

    }


    // 14. Wypisz firmy które 15 stycznia 2018 kupiły "Network Switch"
    public static void exercise14(List<Company> companies){
        companies
                .stream()
                .filter(c -> c.getPurchaseList().stream().map(p -> p.getPurchaseDate()).anyMatch(d -> d.isEqual(LocalDate.of(2018, 1, 15))))
                .filter(c -> c.getPurchaseList().stream().map(p -> p.getProduct().getName()).anyMatch(n -> n.equalsIgnoreCase("network switch")))
                .forEach(c -> System.out.println(c.getName() +  " " + c.getCityHeadquarters()));
    }