Added Bundle class implementation along with tests

src/Bundle.ts

@@ -0,0 +1,99 @@
+import { Stream } from "stream";
+import { ZipFile } from "yazl";
+
+export const filesSymbol = Symbol("bundleFiles");
+const bundleStateSymbol = Symbol("state");
+const archiveSymbol = Symbol("zip");
+
+enum BundleState {
+	CLOSED = 0,
+	OPEN = 1,
+}
+
+namespace Mime {
+	export type type = string;
+	export type subtype = string;
+}
+
+/**
+ * Defines a container ready to be distributed.
+ * If no mimeType is passed to the constructor,
+ * it will throw an error.
+ */
+
+export default class Bundle {
+	private [bundleStateSymbol]: BundleState = BundleState.OPEN;
+	private [filesSymbol]: { [key: string]: Buffer } = {};
+	private [archiveSymbol] = new ZipFile();
+
+	constructor(public mimeType: `${Mime.type}/${Mime.subtype}`) {
+		if (!mimeType) {
+			throw new Error("Cannot build Bundle. MimeType is missing");
+		}
+	}
+
+	/**
+	 * Freezes / Closes the bundle so no more files
+	 * can be added any further.
+	 */
+
+	private freeze() {
+		if (this[bundleStateSymbol] === BundleState.CLOSED) {
+			return;
+		}
+
+		this[bundleStateSymbol] = BundleState.CLOSED;
+		this[archiveSymbol].end();
+	}
+
+	/**
+	 * Allows files to be added to the bundle.
+	 * If the bundle is closed, it will throw an error.
+	 *
+	 * @param fileName
+	 * @param buffer
+	 */
+
+	public addBuffer(fileName: string, buffer: Buffer) {
+		if (this[bundleStateSymbol] === BundleState.CLOSED) {
+			throw new Error("Cannot add file. Bundle is closed.");
+		}
+
+		this[filesSymbol][fileName] = buffer;
+		this[archiveSymbol].addBuffer(buffer, fileName);
+	}
+
+	/**
+	 * Closes the bundle and returns it as a Buffer.
+	 * Once closed, the bundle does not allow files
+	 * to be added any further.
+	 *
+	 * @returns Promise<Buffer>
+	 */
+
+	public getAsBuffer(): Promise<Buffer> {
+		const stream = this.getAsStream();
+		const chunks = [];
+
+		return new Promise((resolve) => {
+			stream.on("data", (data: Buffer) => {
+				chunks.push(data);
+			});
+
+			stream.on("end", () => resolve(Buffer.from(chunks)));
+		});
+	}
+
+	/**
+	 * Closes the bundle and returns it as a stream.
+	 * Once closed, the bundle does not allow files
+	 * to be added any further.
+	 *
+	 * @returns
+	 */
+
+	public getAsStream(): Stream {
+		this.freeze();
+		return this[archiveSymbol].outputStream;
+	}
+}