'use strict';

/**
 * Shared validation for user account fields.
 * Email is MANDATORY on every account: it is how approval notifications and
 * system messages reach people, so an account without one cannot function.
 */

const EMAIL_RE = /^[^@\s]+@[^@\s]+\.[^@\s]+$/;
const USERNAME_RE = /^[A-Za-z0-9._-]{3,32}$/;

/**
 * Normalise an email for storage: trim surrounding whitespace.
 * Returns '' for null/undefined so callers can treat "missing" and "blank"
 * the same way.
 */
function normaliseEmail(value) {
  return value === undefined || value === null ? '' : String(value).trim();
}

/**
 * Validate a mandatory email address.
 * @returns {string|null} an error message, or null when valid.
 */
function validateEmail(value) {
  const email = normaliseEmail(value);
  if (!email) return 'An email address is required.';
  if (email.length > 254) return 'That email address is too long.';
  if (!EMAIL_RE.test(email)) return 'Please enter a valid email address.';
  return null;
}

function validateUsername(value) {
  const username = value === undefined || value === null ? '' : String(value).trim();
  if (!username) return 'A username is required.';
  if (!USERNAME_RE.test(username)) {
    return 'Username must be 3-32 characters: letters, numbers, dot, underscore or hyphen.';
  }
  return null;
}

function validatePassword(value) {
  const password = value === undefined || value === null ? '' : String(value);
  if (!password) return 'A password is required.';
  if (password.length < 10) return 'Password must be at least 10 characters long.';
  if (!/[A-Za-z]/.test(password) || !/[0-9]/.test(password)) {
    return 'Password must contain at least one letter and one number.';
  }
  return null;
}

module.exports = {
  EMAIL_RE, USERNAME_RE, normaliseEmail, validateEmail, validateUsername, validatePassword,
};