Allow wgpw to prompt for a password through stdin

If the user does not pass the password as a parameter, they are prompted
for it through stdin.
The password is not echoed back, just like any other command-line log-in
prompt (ie. sudo).

How_to_generate_an_bcrypt_hash.md

@@ -15,6 +15,12 @@ To generate a bcrypt password hash using docker, run the following command :
 docker run ghcr.io/wg-easy/wg-easy wgpw YOUR_PASSWORD
 PASSWORD_HASH='$2b$12$coPqCsPtcFO.Ab99xylBNOW4.Iu7OOA2/ZIboHN6/oyxca3MWo7fW' // literally YOUR_PASSWORD
 ```
+If a password is not provided, the tool will prompt you for one :
+```sh
+docker run ghcr.io/wg-easy/wg-easy wgpw
+Enter your password:      // hidden prompt, type in your password
+PASSWORD_HASH='$2b$12$coPqCsPtcFO.Ab99xylBNOW4.Iu7OOA2/ZIboHN6/oyxca3MWo7fW'
+```
 
 **Important** : make sure to enclose your password in **single quotes** when you run `docker run` command :
 

src/wgpw.mjs

@@ -2,6 +2,8 @@
 
 // Import needed libraries
 import bcrypt from 'bcryptjs';
+import { Writable } from 'stream'
+import readline from 'readline'
 
 // Function to generate hash
 const generateHash = async (password) => {
@@ -31,12 +33,38 @@ const comparePassword = async (password, hash) => {
   }
 };
 
+const readStdinPassword = () => {
+
+  return new Promise((resolve) => {
+    process.stdout.write("Enter your password: ");
+
+    const rl = readline.createInterface({
+      input: process.stdin,
+      output: new Writable({
+        write(_chunk, _encoding, callback) {
+          callback()
+        }
+      }),
+      terminal: true,
+    });
+
+    rl.question('', answer => {
+      rl.close();
+      // Print a new line after password prompt
+      process.stdout.write('\n');
+      resolve(answer);
+    })
+
+  })
+
+}
+
 (async () => {
   try {
     // Retrieve command line arguments
     const args = process.argv.slice(2); // Ignore the first two arguments
     if (args.length > 2) {
-      throw new Error('Usage : wgpw YOUR_PASSWORD [HASH]');
+      throw new Error('Usage : wgpw [YOUR_PASSWORD] [HASH]');
     }
 
     const [password, hash] = args;
@@ -44,6 +72,9 @@ const comparePassword = async (password, hash) => {
       await comparePassword(password, hash);
     } else if (password) {
       await generateHash(password);
+    } else {
+      const password = await readStdinPassword();
+      await generateHash(password)
     }
   } catch (error) {
     // eslint-disable-next-line no-console