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/audio/audio_processor.js

@@ -0,0 +1,82 @@
+/**
+ * Based on
+ */
+import Processor from "../processor.ts";
+import { isValidHttpUrl } from '../../utils/utils.js'
+import { findFile } from '../../utils/file_io.js'
+import InvalidArgumentError from '../../utils/invalid_argument_error.js'
+import DOMPurify from 'isomorphic-dompurify';
+import ProcessingHistory from "../../models/processing_history.js";
+import path from "path"
+import fs from "fs"
+
+class AudioProcessor extends Processor {
+
+    constructor() {
+        super();
+        this.types = ["audio/mpeg"] // TODO add functionality to accept other audio types (ogg, wav)
+    }
+
+    /**
+     *
+     * @param {string} audioUrl
+     * @param {object} args Optional arguments specific to the render function of the AudioProcessor
+     * @returns
+     */
+    render(audioUrl, args = { files: [], metadata: {} }) {
+
+        if ((!args.files || args.files.length <= 0 || !findFile(audioUrl, args.files)) && !isValidHttpUrl(audioUrl)) {
+            if (args.metadata && args.metadata.hruid && args.metadata.version && args.metadata.language){
+                ProcessingHistory.error(args.metadata.hruid, args.metadata.version, args.metadata.language, "The audio file cannot be found. Please check if the url is spelled correctly.")
+            }else{
+                ProcessingHistory.error("generalError", "99999999", "en", "The audio file cannot be found. Please check if the url is spelled correctly.")
+            }
+
+            throw new InvalidArgumentError("The audio file cannot be found. Please check if the url is spelled correctly.");
+        }
+
+        let type;
+        if (!args.metadata || !args.metadata.content_type || !this.types.includes(args.metadata.content_type)) {
+            type = this.types[0];
+        } else {
+            type = args.metadata.content_type;
+        }
+
+        if (isValidHttpUrl(audioUrl)) {
+            return DOMPurify.sanitize(`<audio controls>
+                <source src="${audioUrl}" type=${type}>
+                Your browser does not support the audio element.
+                </audio>`);
+        }
+
+        if (!args.metadata._id) {
+            throw new InvalidArgumentError("The metadata for for the object which uses the file '" + audioUrl + "' is not loaded in the processor.");
+        }
+
+        return DOMPurify.sanitize(`<audio controls>
+                <source src="@@URL_REPLACE@@/${process.env.LEARNING_OBJECT_STORAGE_NAME}/${args.metadata._id}/${audioUrl}" type=${type}>
+                Your browser does not support the audio element.
+                </audio>`);
+
+    }
+
+    processFiles(files, metadata){
+        let args = {}
+        let inputString = "";
+        let file  = files.find((f) => {
+            let ext = path.extname(f.originalname);
+            if (ext == ".mp3") {
+                inputString = f["originalname"]
+                // add files to args to check if file exists
+                args.files = files;
+                args.metadata = metadata
+                return true;
+            }else{
+                return false;
+            }
+        });
+        return [this.render(inputString, args), files]
+    }
+}
+
+export default AudioProcessor;