✨ Add arg parser, improv error handling

src/getPatchZip.ts

@@ -0,0 +1,38 @@
+import { getPatchZip, ISsnFileEntry, Product, verifyProductName } from 'ssn';
+import * as yargsParser from 'yargs-parser';
+import failWithError from './failWithError';
+
+const failFunction = failWithError.bind(null, 'node dist/getPatchZip.js --product <product> --from <from> --to <to>');
+
+const args = yargsParser(process.argv.slice(2), { string: ['product', 'from', 'to'] });
+
+//Check that product name is valid
+if (args.product === undefined) {
+  failFunction(`product is a required argument but it was not specified.`);
+}
+if (!verifyProductName(args.product)) {
+  failFunction(`"${args.product.substring(0, 300)}" is not a valid product name.`);
+}
+
+//Check that from is a valid number
+if (args.from === undefined) {
+  failFunction(`from is a required argument but it was not specified.`);
+}
+if (!args.from.match(/^(-1|0|[1-9][0-9]{0,2})$/)) {
+  failFunction(`from value "${args.from.substring(0, 300)}" is not a valid integer; it must be in range [-1, 999].`);
+}
+
+//Check that to is a valid number
+if (args.to === undefined) {
+  failFunction(`to is a required argument but it was not specified.`);
+}
+if (!args.to.match(/^(0|[1-9][0-9]{0,2})$/)) {
+  failFunction(`to value "${args.to.substring(0, 300)}" is not a valid integer; it must be in range [0, 999].`);
+}
+
+//Get the .zip file from this patch and write output to stdout
+getPatchZip(args.product as Product, Number(args.from), Number(args.to)).then((output: ISsnFileEntry[]) => {
+  process.stdout.write(JSON.stringify(output));
+}).catch((error) => {
+  failFunction(error);
+});