// /utils/credentials.js
'use strict';

const crypto = require('crypto');

const LETTERS = 'abcdefghijkmnpqrstuvwxyz';
const DIGITS = '23456789';

const randomFrom = (alphabet, length) => {
  let out = '';
  const bytes = crypto.randomBytes(length);
  for (let i = 0; i < length; i += 1) {
    out += alphabet[bytes[i] % alphabet.length];
  }
  return out;
};

/** Simple password: exactly 2 English letters + 4 digits (e.g. kx4821) */
const generateSimplePassword = () => `${randomFrom(LETTERS, 2)}${randomFrom(DIGITS, 4)}`;

/** Random username: u + 6 digits (e.g. u482910) */
const generateUsername = () => `u${randomFrom(DIGITS, 6)}`;

module.exports = {
  generateSimplePassword,
  generateUsername,
};