chore(get): factor out node headers download logic (#1022)

### Description of Changes

- Factor out Node headers download logic.

Author: ayushmanchhabra

README.md

@@ -294,7 +294,6 @@ nwbuild({
 - chore(cli): migrate from `yargs` to `commander`
 - chore(get): verify sha checksum for downloads
 - chore(util): factor out file paths as constant variables
-- chore(get): factor out node headers downloader
 - chore(bld): factor out core build step
 - chore(bld): factor out linux config
 - chore(bld): factor out macos config

src/get/node.js

@@ -0,0 +1,50 @@
+import path from "node:path";
+
+import request from "./request.js";
+
+/**
+ * Download NW.js's Node.js headers.
+ *
+ * @param  {string}          downloadUrl  - Download server
+ * @param  {string}          version      - Runtime version
+ * @param  {string}          cacheDir     - Directory to store NW binaries
+ * @return {Promise<string>}              - path of compressed file which contains the Node headers.
+ */
+export default async function nw(downloadUrl, version, cacheDir) {
+
+  /**
+   * Name of directory which contains Node headers.
+   *
+   * @type {string}
+   */
+  const nodeDir = `node-v${version}`;
+
+  /**
+   * Name of compressed file which contains Node headers.
+   *
+   * @type {string}
+   */
+  const nwFile = `${nodeDir}.tar.gz`
+
+  /**
+   * URL to download specific Node headers from.
+   *
+   * @type {string}
+   */
+  const url = [
+    downloadUrl,
+    `v${version}`,
+    `nw-headers-v${version}.tar.gz`
+  ].join('/');
+
+  /**
+   * Absolute path of compressed file which contains Node headers.
+   */
+  const nwFileAbs = path.resolve(
+    cacheDir,
+    nwFile
+  );
+  await request(url, nwFileAbs);
+
+  return nwFileAbs;
+}

src/get/node.test.js

@@ -0,0 +1,25 @@
+import fs from "node:fs";
+
+import { afterEach, describe, expect, it } from "vitest";
+
+import util from "../util.js";
+
+import node from "./node.js";
+
+describe("get/node", function () {
+
+  let nodeFile = '';
+
+  afterEach(function () {
+    fs.promises.rm(nodeFile, { recursive: true, force: true });
+  });
+
+  it("downloades Node headers", async function () {
+    nodeFile = await node(
+      "https://dl.nwjs.io",
+      "0.83.0",
+      "./test/fixture"
+    );
+    expect(util.fileExists(nodeFile)).resolves.toBe(true);
+  }, Infinity);
+});