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package streams;

import org.junit.jupiter.api.BeforeEach;

import org.junit.jupiter.api.Test;

import java.util.List;

import java.util.stream.Collectors;

import static org.junit.jupiter.api.Assertions.*;

public class FlatMapExercises {

private List<Customer> customers;

@BeforeEach

public void setUp() {

Customer sheridan = new Customer("Sheridan");

Customer ivanova = new Customer("Ivanova");

Customer garibaldi = new Customer("Garibaldi");

sheridan.addOrder(new Order(1))

.addOrder(new Order(2))

.addOrder(new Order(3));

ivanova.addOrder(new Order(4))

.addOrder(new Order(5));

// garibaldi has no orders

customers = List.of(sheridan, ivanova, garibaldi);

}

@Test

public void getCustomerNames() {

// TODO: Use map to get a List<String> of customer names

// List<String> names = ...

// assertEquals(3, names.size());

// assertTrue(names.contains("Sheridan"));

// assertTrue(names.contains("Ivanova"));

// assertTrue(names.contains("Garibaldi"));

}

@Test

public void getOrdersPerCustomer() {

// TODO: Use map to get a List<List<Order>> showing orders per customer

// Note how this creates a nested structure

// List<List<Order>> ordersPerCustomer = ...

// assertEquals(3, ordersPerCustomer.size());

// assertEquals(3, ordersPerCustomer.get(0).size()); // Sheridan has 3 orders

// assertEquals(2, ordersPerCustomer.get(1).size()); // Ivanova has 2 orders

// assertEquals(0, ordersPerCustomer.get(2).size()); // Garibaldi has 0 orders

}

@Test

public void getAllOrdersFlat() {

// TODO: Use flatMap to get all orders as a flat List<Order>

// List<Order> allOrders = ...

// assertEquals(5, allOrders.size());

// assertTrue(allOrders.stream().anyMatch(o -> o.id() == 1));

// assertTrue(allOrders.stream().anyMatch(o -> o.id() == 5));

}

@Test

public void getAllOrderIds() {

// TODO: Use flatMap to get all order IDs as a List<Integer>

// Hint: You'll need to flatMap to orders, then map to IDs

// List<Integer> orderIds = ...

// assertEquals(5, orderIds.size());

// assertEquals(List.of(1, 2, 3, 4, 5), orderIds);

}

@Test

public void findCustomersWithoutOrders() {

// TODO: Find customers who have no orders

// List<Customer> customersWithoutOrders = ...

// assertEquals(1, customersWithoutOrders.size());

// assertEquals("Garibaldi", customersWithoutOrders.get(0).getName());

}

@Test

public void countTotalOrders() {

// TODO: Count the total number of orders across all customers

// long totalOrders = ...

// assertEquals(5L, totalOrders);

}

@Test

public void getOrdersForCustomersWithOrders() {

// TODO: Use flatMap to get orders only from customers who have orders

// Hint: Use filter before flatMap

// List<Order> ordersFromActiveCustomers = ...

// assertEquals(5, ordersFromActiveCustomers.size());

}

@Test

public void combineCustomerNamesWithOrderIds() {

// TODO: Create strings in format "CustomerName-OrderId" for all orders

// Example: "Sheridan-1", "Sheridan-2", etc.

// List<String> customerOrderStrings = ...

// assertEquals(5, customerOrderStrings.size());

// assertTrue(customerOrderStrings.contains("Sheridan-1"));

// assertTrue(customerOrderStrings.contains("Ivanova-5"));

}

}