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/extern/extern-processor.ts

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+/**
+ * Based on https://github.com/dwengovzw/Learning-Object-Repository/blob/main/app/processors/extern/extern_processor.js
+ */
+
+import Processor from "../processor.js";
+import DOMPurify from 'isomorphic-dompurify';
+import {ProcessingError} from "../processing-error";
+import {isValidHttpUrl} from "../../../../util/links";
+import {DwengoContentType} from "../content-type";
+
+class ExternProcessor extends Processor<string> {
+    constructor() {
+        super(DwengoContentType.EXTERN);
+    }
+
+    override renderFn(externURL: string) {
+        if (!isValidHttpUrl(externURL)) {
+            throw new ProcessingError("The url is not valid: " + externURL);
+        }
+
+        // If a seperate youtube-processor would be added, this code would need to move to that processor
+        // Converts youtube urls to youtube-embed urls
+        let match = /(.*youtube.com\/)watch\?v=(.*)/.exec(externURL)
+        if (match) {
+            externURL = match[1] + "embed/" + match[2];
+        }
+
+        return DOMPurify.sanitize(`
+            <div class="iframe-container">
+                <iframe src="${externURL}" allowfullscreen></iframe>
+            </div>`,
+            { ADD_TAGS: ["iframe"], ADD_ATTR: ['allow', 'allowfullscreen', 'frameborder', 'scrolling']}
+        );
+
+    }
+}
+
+export default ExternProcessor;