export const AUTH_STORAGE_KEY = 'authUser';

const FAKE_ACCOUNTS = [
  { username: 'admin', password: 'admin123', displayName: 'Admin' },
  {
    username: 'editor',
    password: 'editor123',
    displayName: 'Editor',
  },
  {
    username: 'viewer',
    password: 'viewer123',
    displayName: 'Viewer',
  },
];

function normalizeIdentifier(identifier = '') {
  return String(identifier || '')
    .trim()
    .toLowerCase();
}

export function getFakeAccounts() {
  return [...FAKE_ACCOUNTS];
}

export function findAccount(username, password) {
  const normalizedUser = normalizeIdentifier(username);
  return FAKE_ACCOUNTS.find(
    (account) =>
      normalizeIdentifier(account.username) === normalizedUser &&
      account.password === String(password || '')
  );
}

export function getAuthUser() {
  try {
    const raw = localStorage.getItem(AUTH_STORAGE_KEY);
    if (!raw) return null;
    const parsed = JSON.parse(raw);
    if (!parsed?.username) return null;
    return parsed;
  } catch (error) {
    console.error('Failed to read auth user', error);
    return null;
  }
}

export function saveAuthUser(account) {
  if (!account) return null;
  const payload = {
    username: account.username,
    displayName: account.displayName || account.username,
    loggedInAt: Date.now(),
  };
  localStorage.setItem(AUTH_STORAGE_KEY, JSON.stringify(payload));
  return payload;
}

export function clearAuthUser() {
  localStorage.removeItem(AUTH_STORAGE_KEY);
}

export function ensureAuthenticated(redirectOnMissing = true) {
  const user = getAuthUser();
  if (!user && redirectOnMissing && typeof window !== 'undefined') {
    window.location.href = 'login.html';
  }
  return user;
}

export function startAuthWatcher(intervalMs = 5000) {
  if (typeof window === 'undefined') return () => {};
  const timerId = window.setInterval(() => {
    if (!getAuthUser()) {
      window.location.href = 'login.html';
    }
  }, intervalMs);
  return () => window.clearInterval(timerId);
}