Use argparse for parsing command-line options

package.json

@@ -16,10 +16,12 @@
     "format:js": "prettier --write src/"
   },
   "dependencies": {
+    "argparse": "^2.0.1",
     "ramda": "^0.27.1",
     "xml": "^1.0.1"
   },
   "devDependencies": {
+    "@types/argparse": "^2.0.0",
     "@types/jest": "^26.0.14",
     "@types/node": "^14.10.3",
     "@types/ramda": "types/npm-ramda#dist",

src/index.ts

@@ -2,16 +2,11 @@ import * as fs from "fs";
 import { generateZwo } from "./generateZwo";
 import { parse } from "./parser";
 import { stats } from "./stats";
+import { parseCliOptions } from "./parseCliOptions";
 
-const opts = { stats: false, filename: "" };
-if (process.argv[2] === "--stats") {
-  opts.stats = true;
-  opts.filename = process.argv[3];
-} else {
-  opts.filename = process.argv[2];
-}
+const opts = parseCliOptions();
 
-const workout = parse(fs.readFileSync(opts.filename, "utf8"));
+const workout = parse(fs.readFileSync(opts.file, "utf8"));
 
 if (opts.stats) {
   console.log(stats(workout));

src/parseCliOptions.ts

@@ -0,0 +1,29 @@
+import { ArgumentParser } from "argparse";
+
+export type CliOptions = {
+  file: string;
+  stats: boolean;
+};
+
+export const parseCliOptions = (): CliOptions => {
+  const argParser = new ArgumentParser({
+    description: "Zwift workout generator",
+    add_help: true,
+  });
+
+  argParser.add_argument("--stats", {
+    help: "output aggregate statistics instead of ZWO file",
+    action: "store_true",
+    default: false,
+  });
+
+  argParser.add_argument("file", { nargs: 1 });
+
+  // As we only allow one file as input,
+  // convert filenames array to just a single string.
+  const { file, ...rest } = argParser.parse_args();
+  return {
+    file: file[0],
+    ...rest,
+  };
+};

yarn.lock

@@ -519,6 +519,11 @@
   dependencies:
     "@sinonjs/commons" "^1.7.0"
 
+"@types/argparse@^2.0.0":
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/@types/argparse/-/argparse-2.0.0.tgz#df1bb55f4c3bbbb3c744a6b35f78a401d3283a89"
+  integrity sha512-FFW98gJUgUWGq7ZMd0gJmNRoOPqAaq9oiNqfc/RM6+C5BZKHHuHTwvlU5hrOULIXEfZz3rhw9jakwYe6cqNv3Q==
+
 "@types/babel__core@^7.0.0", "@types/babel__core@^7.1.7":
   version "7.1.9"
   resolved "https://registry.yarnpkg.com/@types/babel__core/-/babel__core-7.1.9.tgz#77e59d438522a6fb898fa43dc3455c6e72f3963d"
@@ -838,6 +843,11 @@ argparse@^1.0.7:
   dependencies:
     sprintf-js "~1.0.2"
 
+argparse@^2.0.1:
+  version "2.0.1"
+  resolved "https://registry.yarnpkg.com/argparse/-/argparse-2.0.1.tgz#246f50f3ca78a3240f6c997e8a9bd1eac49e4b38"
+  integrity sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==
+
 arr-diff@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/arr-diff/-/arr-diff-4.0.0.tgz#d6461074febfec71e7e15235761a329a5dc7c520"