Added first untested and incomplete implementation of PKPass.from

src/PKPass.ts

@@ -1,6 +1,7 @@
 import FieldsArray from "../src/fieldsArray";
 import { Certificates } from "../src/schemas";
 import { default as Bundle, filesSymbol } from "./Bundle";
+import { getModelFolderContents } from "./parser";
 
 const fieldKeysPoolSymbol = Symbol("fieldKeysPoolSymbol");
 
@@ -16,6 +17,47 @@ export class PKPass extends Bundle {
 	public headerFields /******/ = new FieldsArray(this[fieldKeysPoolSymbol]);
 	public backFields /********/ = new FieldsArray(this[fieldKeysPoolSymbol]);
 
+	/**
+	 * Either create a pass from another one
+	 * or a disk path.
+	 *
+	 * @param source
+	 * @returns
+	 */
+
+	static async from(source: PKPass | string): Promise<PKPass> {
+		let certificates: Certificates = undefined;
+		let buffers: NamedBuffers = undefined;
+
+		if (source instanceof PKPass) {
+			/** Cloning is happening here */
+			certificates = source.certificates;
+			buffers = {};
+
+			const buffersEntries = Object.entries(source[filesSymbol]);
+
+			/** Cloning all the buffers to prevent unwanted edits */
+			for (let i = 0; i < buffersEntries.length; i++) {
+				const [fileName, contentBuffer] = buffersEntries[i];
+
+				buffers[fileName] = Buffer.from(contentBuffer);
+			}
+		} else {
+			/** Disk model reading is happening here */
+
+			/**
+			 * @TODO Rename bundles in something else.
+			 * @TODO determine how to use localized files
+			 */
+
+			const { bundle, l10nBundle } = await getModelFolderContents(source);
+
+			buffers = bundle;
+		}
+
+		return new PKPass(buffers, certificates);
+	}
+
 	constructor(buffers: NamedBuffers, certificates: Certificates) {
 		super("application/vnd.apple.pkpass");