feat(get): create intergity verification function

src/get/verify.js

@@ -1,13 +1,49 @@
+import crypto from 'node:crypto';
+import fs from 'node:fs';
 import path from 'node:path';
 
-import request from './request';
+import request from './request.js';
+
+console.log(await verify('0.89.0', 'sdk', 'linux', 'x64', './node_modules/nw'))
 
 /**
  * Verify the integrity of the NW.js binary after downloading and before decompressing.
- * @version {string}
+ * @param {string} version
+ * @param {string} flavor
+ * @param {string} platform
+ * @param {string} arch
+ * @param {string} cacheDir
+ * @returns {Promise<void>}
  */
-export default async function verify(version, cacheDir) {
+export default async function verify(version, flavor, platform, arch, cacheDir) {
+
+    const nwDir = [
+        `nwjs`,
+        flavor === 'sdk' ? '-sdk' : '',
+        `-v${version}-${platform}-${arch}`,
+      ].join('');
+
+      const nwFile = [
+        nwDir,
+        platform === 'linux' ? "tar.gz" : "zip"
+      ].join('.');
+
+    /* Download text file which contains SHA256 checksum. */
     const sha256url = `https://dl.nwjs.io/v${version}/SHASUMS256.txt`;
-    const sha256out = path.resolve(cacheDir);
+    const sha256out = path.resolve(cacheDir, `nwjs-v${version}-${platform}-${arch}-SHASUM256.txt`);
     await request(sha256url, sha256out);
+
+    /* Generate SHA256 checksum of downloaded file. */
+    const fileBuffer = await fs.promises.readFile(path.resolve(cacheDir, nwFile));
+    const computedChecksum = crypto.createHash('sha256').update(fileBuffer).digest('hex');
+    const downloadChecksums = await fs.promises.readFile(sha256out, {encoding: 'utf-8'});
+    for (const line of downloadChecksums.split('\n')) {
+        const [hex, file] = line.split('  ');
+        if (file === nwFile) {
+            if (hex === computedChecksum) {
+                return true;
+            }
+        }
+    }
+    return false;
 }