chore(backend): Aanpassingen Dwengo Learning-Object-Repository

Processing uit Dwengo Learning-Object-Repository geconverteerd naar TypeScript en aangepast aan onze app.

Functionaliteit van Dwengo Learning-Object-Repository in ons project gekopiëerd en deels aanBestanden die enkel types of interfaces exporteren hernoemd naar *.d.tsgepast aan TypeScript en ons project.

backend/src/services/learning-objects/processing/processing-service.ts

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+/**
+ * Based on https://github.com/dwengovzw/Learning-Object-Repository/blob/main/app/processors/processing_proxy.js
+ */
+
+import BlockImageProcessor from "./image/block-image-processor.js";
+import InlineImageProcessor from "./image/inline-image-processor.js";
+import { MarkdownProcessor } from "./markdown/markdown-processor.js";
+import TextProcessor from "./text/text-processor.js";
+import AudioProcessor from "./audio/audio-processor.js";
+import PdfProcessor from "./pdf/pdf-processor.js";
+import ExternProcessor from "./extern/extern-processor.js";
+import GiftProcessor from "./gift/gift-processor.js";
+import {LearningObject} from "../../../entities/content/learning-object.entity";
+import Processor from "./processor";
+import {DwengoContentType} from "./content-type";
+import {LearningObjectIdentifier} from "../../../interfaces/learning-content";
+import {Language} from "../../../entities/content/language";
+
+const EMBEDDED_LEARNING_OBJECT_PLACEHOLDER = /<learning-object hruid="([^"]+)" language="([^"]+)" version="([^"]+)"\/>/g;
+
+class ProcessingService {
+    private processors!: Map<DwengoContentType, Processor<any>>;
+
+    constructor() {
+        const processors = [
+            new InlineImageProcessor(),
+            new BlockImageProcessor(),
+            new MarkdownProcessor(),
+            new TextProcessor(),
+            new AudioProcessor(),
+            new PdfProcessor(),
+            new ExternProcessor(),
+            new GiftProcessor()
+        ];
+
+        processors.forEach(processor => {
+            this.processors.set(processor.contentType, processor);
+        });
+    }
+
+    /**
+     * Render the given learning object.
+     * @param learningObject The learning object to render
+     * @param fetchEmbeddedLearningObjects A function which takes a learning object identifier as an argument and
+     *                                     returns the corresponding learning object. This is used to fetch learning
+     *                                     objects embedded into this one.
+     *                                     If this argument is omitted, embedded learning objects will be represented
+     *                                     by placeholders.
+     * @returns Rendered HTML for this LearningObject as a string.
+     */
+    render(learningObject: LearningObject, fetchEmbeddedLearningObjects?: (loId: LearningObjectIdentifier) => LearningObject): string {
+        let html = this.processors.get(learningObject.contentType)!.renderLearningObject(learningObject);
+        if (fetchEmbeddedLearningObjects) {
+            // Replace all embedded learning objects.
+            return html.replace(
+                EMBEDDED_LEARNING_OBJECT_PLACEHOLDER,
+                (_, hruid: string, language: string, version: string): string => {
+                    // Fetch the embedded learning object...
+                    const learningObject = fetchEmbeddedLearningObjects({hruid, language: language as Language, version})
+
+                    // ... and render it.
+                    return this.render(learningObject);
+                }
+            );
+        }
+        return html;
+    }
+}
+
+export default ProcessingService;