backend/utils.js

const fs = require("fs");
const path = require("path");
const crypto = require("crypto");

/**
 * Validate if a directory name is valid (alphanumeric and non-empty).
 * @param {string} dirName - Directory name to validate.
 * @returns {boolean} True if valid, false otherwise.
 */
function isValidDirectoryName(dirName) {
  const regex = /^[a-zA-Z0-9_-]+$/;
  return regex.test(dirName);
}

/**
 * Hash a password using SHA-256 for secure storage.
 * @param {string} password - Password to hash.
 * @returns {string} The hashed password.
 */
function hashPassword(password) {
  return crypto.createHash("sha256").update(password).digest("hex");
}

/**
 * Verify a password against a stored hash.
 * @param {string} password - Password to verify.
 * @param {string} hash - Hash to compare against.
 * @returns {boolean} True if the password matches the hash, false otherwise.
 */
function verifyPassword(password, hash) {
  return hashPassword(password) === hash;
}

/**
 * Create a new user directory.
 * @param {string} baseDir - Base directory where user directories are stored.
 * @param {string} dirName - Name of the new directory.
 * @param {string} password - Password to save for the directory.
 */
function createUserDirectory(baseDir, dirName, password) {
  const dirPath = path.join(baseDir, dirName);

  if (fs.existsSync(dirPath)) {
    throw new Error("Directory already exists");
  }

  // Create the directory
  fs.mkdirSync(dirPath, { recursive: true });

  // Save hashed password
  const hashedPassword = hashPassword(password);
  fs.writeFileSync(path.join(dirPath, "password.txt"), hashedPassword, "utf8");

  console.log(`Directory ${dirName} created successfully`);
}

/**
 * Delete a user directory.
 * @param {string} baseDir - Base directory where user directories are stored.
 * @param {string} dirName - Name of the directory to delete.
 * @param {string} password - Password to verify before deletion.
 */
function deleteUserDirectory(baseDir, dirName, password) {
  const dirPath = path.join(baseDir, dirName);

  if (!fs.existsSync(dirPath)) {
    throw new Error("Directory does not exist");
  }

  // Verify password
  const passwordFile = path.join(dirPath, "password.txt");
  if (!fs.existsSync(passwordFile)) {
    throw new Error("Password file is missing");
  }

  const storedHash = fs.readFileSync(passwordFile, "utf8");
  if (!verifyPassword(password, storedHash)) {
    throw new Error("Invalid password");
  }

  // Delete the directory
  fs.rmSync(dirPath, { recursive: true, force: true });
  console.log(`Directory ${dirName} deleted successfully`);
}

/**
 * Log messages to the console with a timestamp.
 * @param {string} message - Message to log.
 */
function logMessage(message) {
  const timestamp = new Date().toISOString();
  console.log(`[${timestamp}] ${message}`);
}

module.exports = {
  isValidDirectoryName,
  hashPassword,
  verifyPassword,
  createUserDirectory,
  deleteUserDirectory,
  logMessage,
};