Merge branch 'feat/service-layer' into feat/service-layer-adriaan

# Conflicts:
#	backend/src/controllers/classes.ts
#	backend/src/controllers/students.ts
#	backend/src/data/users/teacher-repository.ts
#	backend/src/interfaces/assignment.ts
#	backend/src/interfaces/teacher.ts
#	backend/src/routes/classes.ts
#	backend/src/services/assignments.ts
#	backend/src/services/class.ts
#	backend/src/services/students.ts
#	backend/src/util/translation-helper.ts

backend/src/interfaces/assignment.ts

@@ -0,0 +1,36 @@
+import { Assignment } from "../entities/assignments/assignment.entity.js";
+import { GroupDTO, mapToGroupDTO } from "./groups.js";
+
+export interface AssignmentDTO {
+    id: number,
+    class: string, // id of class 'within'
+    title: string,
+    description: string,
+    learningPath: string,
+    language: string,
+    groups?: GroupDTO[] | string[], // TODO
+}
+
+export function mapToAssignmentDTOId(assignment: Assignment): AssignmentDTO {
+    return {
+        id: assignment.id,
+        class: assignment.within.classId,
+        title: assignment.title,
+        description: assignment.description,
+        learningPath: assignment.learningPathHruid,
+        language: assignment.learningPathLanguage,
+        // groups: assignment.groups.map(group => group.groupNumber),
+    }
+}
+
+export function mapToAssignmentDTO(assignment: Assignment): AssignmentDTO {
+    return {
+        id: assignment.id,
+        class: assignment.within.classId,
+        title: assignment.title,
+        description: assignment.description,
+        learningPath: assignment.learningPathHruid,
+        language: assignment.learningPathLanguage,
+        // groups: assignment.groups.map(mapToGroupDTO),
+    };
+}