chore(backend): Opzetten processing begonnen.

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/text/text_processor.js

@@ -0,0 +1,36 @@
+import DOMPurify from 'isomorphic-dompurify'
+import Processor from "../processor.ts"
+import path from "path"
+
+class TextProcessor extends Processor {
+    constructor() {
+        super();
+    }
+
+    /**
+     *
+     * @param {string} plain text
+     * @param {object} args Optional arguments
+     * @returns
+     */
+    render(text, args = {}) {
+        // Sanitize plain text to prevent xss.
+        return DOMPurify.sanitize(text);
+    }
+
+    processFiles(files, metadata){
+        let inputString = "";
+        let file  = files.find((f) => {
+            let ext = path.extname(f.originalname);
+            if (ext == ".txt") {
+                inputString = f.buffer.toString('utf8');
+                return true;
+            }else{
+                return false;
+            }
+        });
+        return [this.render(inputString), files]
+    }
+}
+
+export default TextProcessor;