Resolve "[Queue-2.0] Enqueueing errors when no student group is found"

This MR creates a Student Group for students that do not have one yet and try to enqueue automatically. This is to prevent errors in the first few weeks. A cleaner solution can definitely still be made, but should be for future work.

Closes #387 (closed)

src/main/java/nl/tudelft/queue/service/RequestService.java

@@ -25,8 +25,11 @@ import java.util.stream.Collectors;
 import javax.transaction.Transactional;
 
 import nl.tudelft.labracore.api.StudentGroupControllerApi;
-import nl.tudelft.labracore.api.dto.PersonSummaryDTO;
+import nl.tudelft.labracore.api.dto.*;
 import nl.tudelft.labracore.lib.security.user.Person;
+import nl.tudelft.queue.cache.AssignmentCacheManager;
+import nl.tudelft.queue.cache.PersonCacheManager;
+import nl.tudelft.queue.cache.SessionCacheManager;
 import nl.tudelft.queue.dto.create.RequestCreateDTO;
 import nl.tudelft.queue.dto.util.RequestTableFilterDTO;
 import nl.tudelft.queue.model.ClosableTimeSlot;
@@ -40,6 +43,8 @@ import nl.tudelft.queue.repository.RequestRepository;
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Service;
 
+import reactor.core.publisher.Mono;
+
 @Service
 public class RequestService {
 	@Autowired
@@ -60,6 +65,15 @@ public class RequestService {
 	@Autowired
 	private StudentGroupControllerApi sgApi;
 
+	@Autowired
+	private AssignmentCacheManager aCache;
+
+	@Autowired
+	private PersonCacheManager pCache;
+
+	@Autowired
+	private SessionCacheManager sCache;
+
 	/**
 	 * Creates a request in the request daabase based on the person that posted the request and the
 	 * information the user posted in the form of a {@link RequestCreateDTO}.
@@ -73,8 +87,10 @@ public class RequestService {
 	public void createRequest(RequestCreateDTO dto, Long personId, boolean sendEvent) {
 		Request request = dto.apply();
 		request.setRequester(personId);
-		request.setStudentGroup(sgApi.getGroupForPersonAndAssignment(
-				personId, dto.getAssignment()).block().getId());
+		request.setStudentGroup(sgApi
+				.getGroupForPersonAndAssignment(personId, dto.getAssignment())
+				.onErrorResume(e -> createIndividualStudentGroup(dto, personId))
+				.block().getId());
 
 		if (request.getLab().getCommunicationMethod().isOnline()) {
 			request.setJitsiRoom(js.createJitsiRoomName(request));
@@ -295,4 +311,30 @@ public class RequestService {
 
 		return requests.stream().skip(new Random().nextInt(requests.size())).findFirst();
 	}
+
+	/**
+	 * Creates an individual student group for one student without a current group so that they may place a
+	 * request with that student group.
+	 *
+	 * TODO: Create a two-in-one function in StudentGroupController to check whether one exists and create a
+	 * student group if one does not exist yet.
+	 *
+	 * @param  dto      The DTO containing user request information.
+	 * @param  personId The id of the person that posted the request.
+	 * @return          A mono containing the created student group.
+	 */
+	private Mono<StudentGroupDetailsDTO> createIndividualStudentGroup(RequestCreateDTO dto, Long personId) {
+		var person = pCache.getOrThrow(personId);
+		var assignment = aCache.getOrThrow(dto.getAssignment());
+		var session = sCache.getOrThrow(dto.getLab().getSession());
+
+		return sgApi.addGroup(new StudentGroupCreateDTO()
+				.name(person.getDisplayName())
+				.capacity(1)
+				.addMembersItem(new RoleIdDTO().id(new Id()
+						.personId(person.getId())
+						.editionId(session.getEdition().getId())))
+				.module(new ModuleIdDTO().id(assignment.getModule().getId())))
+				.flatMap(id -> sgApi.getStudentGroupsById(List.of(id)).collectList().map(l -> l.get(0)));
+	}
 }