feat(backend): Added endpoint to fetch HTML version of learning object (from Dwengo backend)

Also refactored a bit to make this easier.

backend/src/controllers/learning-objects.ts

@@ -0,0 +1,62 @@
+import { Request, Response } from 'express';
+import { FALLBACK_LANG } from '../config.js';
+import {FilteredLearningObject, LearningObjectIdentifier, LearningPathIdentifier} from '../interfaces/learning-content';
+import learningObjectService from "../services/learning-content/learning-object-service";
+import {EnvVars, getEnvVar} from "../util/envvars";
+import {Language} from "../entities/content/language";
+import {BadRequestException} from "../exceptions";
+
+function getLearningObjectIdentifierFromRequest(req: Request): LearningObjectIdentifier {
+    if (!req.params.hruid) {
+        throw new BadRequestException("HRUID is required.");
+    }
+    return {
+        hruid: req.params.hruid as string,
+        language: (req.query.language || getEnvVar(EnvVars.FallbackLanguage)) as Language,
+        version: req.query.version as string
+    };
+}
+
+function getLearningPathIdentifierFromRequest(req: Request): LearningPathIdentifier {
+    if (!req.query.hruid) {
+        throw new BadRequestException("HRUID is required.");
+    }
+    return {
+        hruid: req.params.hruid as string,
+        language: (req.query.language as Language) || FALLBACK_LANG
+    }
+}
+
+export async function getAllLearningObjects(
+    req: Request,
+    res: Response
+): Promise<void> {
+    const learningPathId = getLearningPathIdentifierFromRequest(req);
+    const full = req.query.full;
+
+    let learningObjects: FilteredLearningObject[] | string[];
+    if (full) {
+        learningObjects = await learningObjectService.getLearningObjectsFromPath(learningPathId);
+    } else {
+        learningObjects = await learningObjectService.getLearningObjectIdsFromPath(learningPathId);
+    }
+
+    res.json(learningObjects);
+}
+
+export async function getLearningObject(
+    req: Request,
+    res: Response
+): Promise<void> {
+    const learningObjectId = getLearningObjectIdentifierFromRequest(req);
+
+    const learningObject = await learningObjectService.getLearningObjectById(learningObjectId);
+    res.json(learningObject);
+}
+
+export async function getLearningObjectHTML(req: Request, res: Response): Promise<void> {
+    const learningObjectId = getLearningObjectIdentifierFromRequest(req);
+
+    const learningObject = await learningObjectService.getLearningObjectHTML(learningObjectId);
+    res.send(learningObject);
+}