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/controllers/classes.ts

@@ -1,5 +1,6 @@
 import { Request, Response } from 'express';
-import { getAllClasses, getClass, getClassStudents, getClassTeacherInvitations } from '../services/class.js';
+import { getAllClasses, getClass, getClassStudents, getClassStudentsIds, getClassTeacherInvitations } from '../services/class.js';
+import { ClassDTO } from '../interfaces/classes.js';
 
 export async function getAllClassesHandler(
     req: Request,
@@ -47,7 +48,9 @@ export async function getClassStudentsHandler(
     const classId = req.params.id;
     const full = req.query.full === "true";
 
-    const students = await getClassStudents(classId, full);
+    let students = full
+        ? await getClassStudents(classId)
+        : await getClassStudentsIds(classId);
 
     res.json({
         students: students,

backend/src/controllers/learning-objects.ts

@@ -3,9 +3,9 @@ import {
     getLearningObjectById,
     getLearningObjectIdsFromPath,
     getLearningObjectsFromPath,
-} from '../services/learningObjects.js';
+} from '../services/learning-objects.js';
 import { FALLBACK_LANG } from '../config.js';
-import { FilteredLearningObject } from '../interfaces/learningPath';
+import { FilteredLearningObject } from '../interfaces/learning-path';
 
 export async function getAllLearningObjects(
     req: Request,

backend/src/controllers/learning-paths.ts

@@ -4,7 +4,7 @@ import { FALLBACK_LANG } from '../config.js';
 import {
     fetchLearningPaths,
     searchLearningPaths,
-} from '../services/learningPaths.js';
+} from '../services/learning-paths.js';
 /**
  * Fetch learning paths based on query parameters.
  */

backend/src/controllers/teachers.ts

@@ -0,0 +1,155 @@
+import { Request, Response } from 'express';
+import {
+    createTeacher,
+    deleteTeacher,
+    getTeacherByUsername,
+    getClassesByTeacher,
+    getClassIdsByTeacher,
+    getAllTeachers,
+    getAllTeachersIds, getStudentsByTeacher, getStudentIdsByTeacher, getQuestionsByTeacher, getQuestionIdsByTeacher
+} from '../services/teachers.js';
+import {TeacherDTO} from "../interfaces/teacher";
+import {ClassDTO} from "../interfaces/class";
+import {StudentDTO} from "../interfaces/student";
+import {QuestionDTO, QuestionId} from "../interfaces/question";
+
+export async function getTeacherHandler(req: Request, res: Response): Promise<void> {
+    try {
+        const full = req.query.full === 'true';
+        const username = req.query.username as string;
+
+        if (username){
+            const teacher = await getTeacherByUsername(username);
+            if (!teacher){
+                res.status(404).json({ error: `Teacher with username '${username}' not found.` });
+                return;
+            }
+            res.json(teacher);
+            return;
+        }
+
+        let teachers: TeacherDTO[] | string[];
+
+        if (full) teachers = await getAllTeachers();
+        else teachers = await getAllTeachersIds();
+
+        res.json(teachers);
+    } catch (error) {
+        console.error("❌ Error fetching teachers:", error);
+        res.status(500).json({ error: "Internal server error" });
+    }
+}
+
+export async function createTeacherHandler(
+    req: Request,
+    res: Response
+): Promise<void> {
+    try {
+        const teacherData = req.body as TeacherDTO;
+
+        if (!teacherData.username || !teacherData.firstName || !teacherData.lastName) {
+            res.status(400).json({ error: 'Missing required fields: username, firstName, lastName' });
+            return;
+        }
+
+        const newTeacher = await createTeacher(teacherData);
+        res.status(201).json(newTeacher);
+    } catch (error) {
+        console.error('Error creating teacher:', error);
+        res.status(500).json({ error: 'Internal server error' });
+    }
+}
+
+export async function deleteTeacherHandler(
+    req: Request,
+    res: Response
+): Promise<void> {
+    try {
+        const username = req.params.username as string;
+
+        if (!username) {
+            res.status(400).json({ error: 'Missing required field: username' });
+            return;
+        }
+
+        const deletedTeacher = await deleteTeacher(username);
+
+        if (!deletedTeacher) {
+            res.status(400).json({ error: `Did not find teacher with username ${username}` });
+            return;
+        }
+
+        res.status(201).json(deletedTeacher);
+    } catch (error) {
+        console.error('Error deleting teacher:', error);
+        res.status(500).json({ error: 'Internal server error' });
+    }
+}
+
+export async function getTeacherClassHandler(req: Request, res: Response): Promise<void> {
+    try {
+        const username = req.params.username as string;
+        const full = req.query.full === 'true';
+
+        if (!username) {
+            res.status(400).json({ error: 'Missing required field: username' });
+            return;
+        }
+
+        let classes: ClassDTO[] | string[];
+
+        if (full) classes = await getClassesByTeacher(username);
+        else classes = await getClassIdsByTeacher(username);
+
+        res.status(201).json(classes);
+    } catch (error) {
+        console.error('Error fetching classes by teacher:', error);
+        res.status(500).json({ error: 'Internal server error' });
+    }
+}
+
+export async function getTeacherStudentHandler(req: Request, res: Response): Promise<void> {
+    try {
+        const username = req.params.username as string;
+        const full = req.query.full === 'true';
+
+        if (!username) {
+            res.status(400).json({ error: 'Missing required field: username' });
+            return;
+        }
+
+        let students: StudentDTO[] | string[];
+
+        if (full) students = await getStudentsByTeacher(username);
+        else students = await getStudentIdsByTeacher(username);
+
+        res.status(201).json(students);
+    } catch (error) {
+        console.error('Error fetching students by teacher:', error);
+        res.status(500).json({ error: 'Internal server error' });
+    }
+}
+
+export async function getTeacherQuestionHandler(req: Request, res: Response): Promise<void> {
+    try {
+        const username = req.params.username as string;
+        const full = req.query.full === 'true';
+
+        if (!username) {
+            res.status(400).json({ error: 'Missing required field: username' });
+            return;
+        }
+
+        let questions: QuestionDTO[] | QuestionId[];
+
+        if (full) questions = await getQuestionsByTeacher(username);
+        else questions = await getQuestionIdsByTeacher(username);
+
+        res.status(201).json(questions);
+    } catch (error) {
+        console.error('Error fetching questions by teacher:', error);
+        res.status(500).json({ error: 'Internal server error' });
+    }
+}
+
+

backend/src/controllers/themes.ts

@@ -1,6 +1,6 @@
 import { Request, Response } from 'express';
 import { themes } from '../data/themes.js';
-import { loadTranslations } from "../util/translationHelper.js";
+import { loadTranslations } from "../util/translation-helper.js";
 import { FALLBACK_LANG } from '../config.js';
 
 interface Translations {