feat(backend): Verwerking van leerobjecten in ZIP-formaat.

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

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+import unzipper from 'unzipper';
+import mime from 'mime-types';
+import {LearningObjectMetadata} from "@dwengo-1/common/dist/interfaces/learning-content";
+import {LearningObject} from "../../entities/content/learning-object.entity";
+import {getAttachmentRepository, getLearningObjectRepository} from "../../data/repositories";
+
+/**
+ * Process an uploaded zip file and construct a LearningObject from its contents.
+ * @param filePath Path of the zip file to process.
+ */
+export async function processLearningObjectZip(filePath: string): Promise<LearningObject> {
+    const learningObjectRepo = getLearningObjectRepository();
+    const attachmentRepo = getAttachmentRepository();
+
+    const zip = await unzipper.Open.file(filePath);
+
+    let metadata: LearningObjectMetadata | null = null;
+    const attachments: {name: string, content: Buffer}[] = [];
+    let content: Buffer | null = null;
+
+    for (const file of zip.files) {
+        if (file.type === "Directory") {
+            throw Error("The learning object zip file should not contain directories.");
+        } else if (file.path === "metadata.json") {
+            metadata = await processMetadataJson(file);
+        } else if (file.path.startsWith("index.")) {
+            content = await processFile(file);
+        } else {
+            attachments.push({
+                name: file.path,
+                content: await processFile(file)
+            });
+        }
+    }
+
+    if (!metadata) {
+        throw Error("Missing metadata.json file");
+    }
+    if (!content) {
+        throw Error("Missing index file");
+    }
+
+    const learningObject = learningObjectRepo.create(metadata);
+    const attachmentEntities = attachments.map(it => attachmentRepo.create({
+        name: it.name,
+        content: it.content,
+        mimeType: mime.lookup(it.name) || "text/plain",
+        learningObject
+    }))
+    learningObject.attachments.push(...attachmentEntities);
+
+    return learningObject;
+}
+
+async function processMetadataJson(file: unzipper.File): LearningObjectMetadata {
+    const buf = await file.buffer();
+    const content = buf.toString();
+    return JSON.parse(content);
+}
+
+async function processFile(file: unzipper.File): Promise<Buffer> {
+    return await file.buffer();
+}