Add getAvailableStaffByJob to staff package

Co-authored-by: Simon Bruder <simon.bruder@mailbox.tu-dresden.de>

src/main/asciidoc/models/design/staff.puml

@@ -10,6 +10,11 @@ package Spring {
 	class Model
 }
 
+package catering.order {
+	class OrderManagement
+	class CustomOrder
+}
+
 package catering.staff {
 
   class Employee {
@@ -48,13 +53,16 @@ package catering.staff {
 	StaffController ..> Errors
 
 	class StaffManagement {
-		+ StaffManagement(staffRepository: StaffRepository)
+		+ StaffManagement(staffRepository: StaffRepository, orderManagement:OrderManagement<CustomOrder>)
     + findById(id: Long): Optional<Employee>
     + save(employee: Employee): Employee
     + findAll(): Streamable<Employee>
     + delete(id: Long): void
+	+ getAvailableStaffByJob(job: JobType, start:LocalDateTime, finish:LocalDateTime): Set<Employee>
 	}
 		StaffManagement --> StaffRepository : -staffRepository
+		StaffManagement --> OrderManagement : -orderManagement
+		StaffManagement ..> Set
 
 	interface StaffRepository {
     + findAll(): Streamable<Employee>

src/main/java/catering/staff/StaffController.java

@@ -2,6 +2,8 @@ package catering.staff;
 
 import org.springframework.security.access.prepost.PreAuthorize;
 import org.springframework.stereotype.Controller;
+import org.springframework.ui.Model;
+import org.springframework.validation.Errors;
 import org.springframework.web.bind.annotation.GetMapping;
 import org.springframework.web.bind.annotation.ModelAttribute;
 import org.springframework.web.bind.annotation.PathVariable;
@@ -10,9 +12,6 @@ import org.springframework.web.bind.annotation.RequestParam;
 
 import jakarta.validation.Valid;
 
-import org.springframework.ui.Model;
-import org.springframework.validation.Errors;
-
 @Controller
 public class StaffController {
 

src/main/java/catering/staff/StaffManagement.java

@@ -1,10 +1,19 @@
 package catering.staff;
 
+import java.time.LocalDateTime;
 import java.util.Optional;
+import java.util.Set;
+import java.util.function.Predicate;
+import java.util.stream.Collectors;
+
+import org.salespointframework.order.OrderManagement;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.util.Streamable;
+import org.springframework.stereotype.Component;
 import org.springframework.transaction.annotation.Transactional;
 import org.springframework.web.bind.annotation.SessionAttributes;
-import org.springframework.stereotype.Component;
+
-import org.springframework.data.util.Streamable;
+import catering.order.CustomOrder;
 
 @Component
 @Transactional
@@ -12,9 +21,11 @@ import org.springframework.data.util.Streamable;
 public class StaffManagement {
 
 	private final StaffRepository staffRepository;
+	private final OrderManagement<CustomOrder> orderManagement;
 
-	public StaffManagement(StaffRepository staffRepository) {
+	public StaffManagement(StaffRepository staffRepository, OrderManagement<CustomOrder> orderManagement) {
 		this.staffRepository = staffRepository;
+		this.orderManagement = orderManagement;
 	}
 
 	public Optional<Employee> findById(Long id) {
@@ -33,4 +44,64 @@ public class StaffManagement {
 		staffRepository.deleteById(id);
 	}
 
+	/**
+	 * Returns a {@link Set} of all {@link Employee}s of given {@link JobType}
+	 * available in the full time range between the given start and end
+	 * {@link LocalDateTime}s.
+	 *
+	 * The range is inclusive, e.g., {@link Employee}s part of an order that lasts
+	 * until the given start
+	 * are not considered available.
+	 *
+	 * @param job    the {@link JobType} of {@link Employee}s to search for
+	 * @param start  a {@link LocalDateTime} describing the start of the range the
+	 *               employee is needed for
+	 * @param finish a {@link LocalDateTime} describing the end of the range the
+	 *               employee is needed for
+	 * @return a {@link Set} of {@link Employee}s matching the requirements
+	 */
+	public Set<Employee> getAvailableStaffByJob(JobType job, LocalDateTime start, LocalDateTime finish) {
+		/*
+		 * This function first computes all unavailable employees
+		 * to then later take the set difference of all employees and the previous
+		 * result
+		 * to get a set of all employees available in the given range.
+		 */
+		Set<Employee> unavailable = orderManagement.findAll(Pageable.unpaged()).stream()
+				/*
+				* The most complex part is getting all orders overlapping the given range.
+				* It can be computed with the following:
+				* Let (S, F) be the tuple describing the start and finish of any given order O,
+				* let (S', F') be the tuple describing the start and finish of the given date range.
+				* Then the following holds:
+				*
+				* @formatter:off
+				*   O overlaps with (S', F')
+				* ⇔ F ≥ S' ∧ S ≤ F'
+				* ⇔ ¬¬(F ≥ S' ∧ S ≤ F')  (¬¬X ⇔ X ∀ X ∈ {0,1})
+				* ⇔ ¬(¬(F ≥ S') ∨ ¬(S ≤ F'))  (De Morgan’s laws: ¬(X ∧ Y) ⇔ ¬X ∨ ¬Y ∀ X,Y ∈ {0,1})
+				* ⇔ ¬(F < S' ∨ S > F')  (¬(a ≥ b) ⇔ a < b and ¬(a ≤ b) ⇔ a > b ∀ a,b totally ordered)
+				* ⇔ ¬(F < S') ∧ ¬(S > F')  (De Morgan’s laws: ¬(X ∨ Y) ⇔ ¬X ∧ ¬Y ∀ X,Y ∈ {0,1})
+				* @formatter:on
+				*
+				* The last expression can be easily implemented with two filters,
+				* as chaining filters is equivalent to the logical conjunction,
+				* using LocalDateTime::isBefore and LocalDateTime::isAfter,
+				* which are < and > on the total ordering of all LocalDateTimes.
+				*
+				* Sadly, we can’t really avoid lambdas here
+				* as function composition and partial application are not first-class citizens in Java.
+				*/
+				.filter(order -> !order.getFinish().isBefore(start))
+				.filter(order -> !order.getStart().isAfter(finish))
+				.map(CustomOrder::getStaff)
+				.flatMap(Set::stream)
+				.filter(employee -> employee.getJob().equals(job))
+				.collect(Collectors.toSet());
+		return findAll().stream()
+				.filter(e -> e.getJob().equals(job))
+				.filter(Predicate.not(unavailable::contains))
+				.collect(Collectors.toSet());
+	}
+
 }

src/test/java/catering/staff/StaffManagementIntegrationTests.java

@@ -0,0 +1,91 @@
+package catering.staff;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.LocalDateTime;
+import java.util.Set;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.salespointframework.order.OrderManagement;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import catering.order.CustomCart;
+import catering.order.CustomOrder;
+import catering.order.OrderType;
+import catering.users.User;
+import catering.users.UserManagement;
+
+@SpringBootTest
+class StaffManagmentIntegratonTest {
+
+	@Autowired
+	private StaffManagement staffManagement;
+
+	@Autowired
+	private OrderManagement<CustomOrder> orderManagement;
+
+	@Autowired
+	private UserManagement userManagement;
+
+	private User defaultUser;
+
+	Employee e1;
+	Employee e2;
+	Employee e3;
+	Employee e4;
+	Employee e5;
+	Employee e6;
+
+	CustomOrder c1;
+	CustomOrder c2;
+	CustomOrder c3;
+	CustomOrder c4;
+	CustomOrder c5;
+	CustomOrder c6;
+	CustomOrder c7;
+
+	CustomOrder createCustomOrder(LocalDateTime start, LocalDateTime end, Set<Employee> staff) {
+		CustomOrder order = orderManagement.save(new CustomOrder(defaultUser.getUserAccount().getId(),
+				new CustomCart(OrderType.EVENT_CATERING, start, end)));
+		staff.forEach(order::addEmployee);
+		return orderManagement.save(order);
+	}
+
+	@BeforeEach
+	void addEmployees() {
+		defaultUser = userManagement.createCustomer("sarah", "Baum Weg", "123", "Sarah Klaus");
+
+		e1 = staffManagement.save(new Employee("Alan Turing", JobType.COOK));
+		e2 = staffManagement.save(new Employee("Ada Lovelace", JobType.COOK));
+		e3 = staffManagement.save(new Employee("Donald Knuth", JobType.COOK));
+		e4 = staffManagement.save(new Employee("Grace Hopper", JobType.SERVICE));
+		e5 = staffManagement.save(new Employee("John von Neumann", JobType.SERVICE));
+		e6 = staffManagement.save(new Employee("Noam Chomsky", JobType.SERVICE));
+
+		c1 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 6, 0), LocalDateTime.of(2023, 10, 27, 20, 0), Set.of(e1));
+		c2 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 8, 0), LocalDateTime.of(2023, 10, 27, 16, 0), Set.of(e2));
+		c3 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 18, 0), LocalDateTime.of(2023, 10, 27, 22, 0),
+				Set.of(e3));
+		c4 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 16, 0), LocalDateTime.of(2023, 10, 27, 18, 0),
+				Set.of(e4));
+		c5 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 8, 0), LocalDateTime.of(2023, 10, 27, 12, 0), Set.of(e5));
+		c6 = createCustomOrder(LocalDateTime.of(2023, 10, 21, 12, 0), LocalDateTime.of(2023, 10, 21, 22, 0),
+				Set.of(e6));
+		c7 = createCustomOrder(LocalDateTime.of(2023, 10, 27, 19, 0), LocalDateTime.of(2023, 10, 28, 12, 0), Set.of(e2, e3));
+	}
+
+	@Test
+	void getAvailableEmployees() throws Exception {
+		Set<Employee> availableService = staffManagement.getAvailableStaffByJob(JobType.SERVICE,
+				LocalDateTime.of(2023, 10, 27, 16, 0), LocalDateTime.of(2023, 10, 27, 18, 0));
+		Set<Employee> availableCook = staffManagement.getAvailableStaffByJob(JobType.COOK,
+				LocalDateTime.of(2023, 10, 27, 16, 0), LocalDateTime.of(2023, 10, 27, 18, 0));
+
+		assertThat(availableCook.size()).isEqualTo(0);
+		assertThat(availableService.size()).isEqualTo(2);
+		assertThat(availableService).contains(e5, e6);
+	}
+
+}