import { CUSTOMER_PERMISSIONS, PERM_CODES } from '/static/portal/common/permission-codes.js';

const SESSION_KEY = 'portalAuthContext';
const IDENTITY_COOKIE = 'portal_auth_user';
const CONTEXT_COOKIE = 'portal_auth_context';
const AUTH_CHANNEL_NAME = 'portal-auth-session';
const AUTH_EVENT_TYPES = new Set(['signed-in', 'signed-out', 'account-switched', 'session-expired']);
const SESSION_IDLE_TIMEOUT_MS = 30 * 60 * 1000;
const SESSION_CHECK_INTERVAL_MS = 15 * 1000;
let authChannel = null;
let authSyncStarted = false;

function readCookie(name) {
  const prefix = `${name}=`;
  const item = document.cookie.split(';').map((value) => value.trim()).find((value) => value.startsWith(prefix));
  return item ? decodeURIComponent(item.slice(prefix.length)) : '';
}

function readSessionContext() {
  try {
    const value = JSON.parse(sessionStorage.getItem(SESSION_KEY) || 'null');
    return value && Array.isArray(value.roles) ? value : null;
  } catch {
    return null;
  }
}

function readSharedContext() {
  try {
    const value = JSON.parse(readCookie(CONTEXT_COOKIE) || 'null');
    return value && Array.isArray(value.roles) ? value : null;
  } catch {
    return null;
  }
}

function writeSharedContext(context, maxAge) {
  const value = encodeURIComponent(JSON.stringify(context));
  document.cookie = `${CONTEXT_COOKIE}=${value}; path=/; max-age=${maxAge}; SameSite=Strict`;
}

function hasMatchingIdentity(token, context) {
  const expiresAt = tokenExpiry(token);
  return Boolean(
    token
    && context
    && readCookie(IDENTITY_COOKIE) === String(context.userId)
    && (!expiresAt || Date.now() < expiresAt),
  );
}

function tokenExpiry(token) {
  try {
    const payload = token.split('.')[1];
    if (!payload) return 0;
    const normalized = payload.replace(/-/g, '+').replace(/_/g, '/').padEnd(Math.ceil(payload.length / 4) * 4, '=');
    const value = JSON.parse(decodeURIComponent(atob(normalized).split('').map((char) => `%${`00${char.charCodeAt(0).toString(16)}`.slice(-2)}`).join('')));
    return Number(value.exp || 0) * 1000;
  } catch {
    return 0;
  }
}

function sessionExpired() {
  clearAuthSession({ eventType: 'session-expired' });
  if (isProtectedPortalPage()) {
    window.location.replace(`${loginPathForCurrentPortal()}?reason=session-expired`);
  }
}

function checkSessionLifetime() {
  const token = readCookie('auth_token');
  const context = readSharedContext() || readSessionContext();
  if (!token || !context || !hasMatchingIdentity(token, context)) return;
  const expiresAt = Number(context.expiresAt || tokenExpiry(token));
  const lastActivityAt = Number(context.lastActivityAt || Date.now());
  if ((expiresAt && Date.now() >= expiresAt) || Date.now() - lastActivityAt >= SESSION_IDLE_TIMEOUT_MS) {
    sessionExpired();
  }
}

function touchActivity() {
  const token = readCookie('auth_token');
  const context = readSharedContext() || readSessionContext();
  if (!token || !context || !hasMatchingIdentity(token, context)) return;
  const now = Date.now();
  const expiresAt = Number(context.expiresAt || tokenExpiry(token));
  if (expiresAt && now >= expiresAt) { sessionExpired(); return; }
  if (now - Number(context.lastActivityAt || 0) < 60_000) return;
  const next = { ...context, lastActivityAt: now, expiresAt };
  const remaining = expiresAt ? Math.max(0, Math.ceil((expiresAt - now) / 1000)) : 1800;
  sessionStorage.setItem(SESSION_KEY, JSON.stringify(next));
  writeSharedContext(next, remaining);
}

function openAuthChannel() {
  if (!('BroadcastChannel' in window)) return null;
  if (authChannel) return authChannel;
  try {
    authChannel = new BroadcastChannel(AUTH_CHANNEL_NAME);
  } catch {
    authChannel = null;
  }
  return authChannel;
}

function publishAuthEvent(type) {
  if (!AUTH_EVENT_TYPES.has(type)) return;
  openAuthChannel()?.postMessage({ type });
}

function loginPathForCurrentPortal() {
  return window.location.pathname.startsWith('/portal/employee-')
    ? '/portal/employee-console/login/'
    : '/portal/customer/login/';
}

function isProtectedPortalPage() {
  const path = window.location.pathname;
  if (path.includes('/login/')) return false;
  return path.startsWith('/portal/customer/') || path.startsWith('/portal/employee-');
}

function redirectForExternalAuthChange(type) {
  sessionStorage.removeItem(SESSION_KEY);
  if (!isProtectedPortalPage()) return;
  if (type === 'signed-out') {
    window.location.replace('/portal/guest/home/?reason=signed-out');
    return;
  }
  const reason = type === 'session-expired' ? 'session-expired' : 'account-switched';
  window.location.replace(`${loginPathForCurrentPortal()}?reason=${reason}`);
}

function handleExternalAuthChange(type) {
  if (type === 'signed-in') {
    const context = readSessionContext();
    if (context && hasMatchingIdentity(readCookie('auth_token'), context)) return;
  }
  redirectForExternalAuthChange(type);
}

function reconcileSharedSession() {
  const context = readSessionContext();
  if (!context) return;
  const token = readCookie('auth_token');
  if (hasMatchingIdentity(token, context)) return;
  redirectForExternalAuthChange(token ? 'account-switched' : 'signed-out');
}

export function startAuthSync() {
  if (authSyncStarted) return;
  authSyncStarted = true;
  openAuthChannel()?.addEventListener('message', (event) => {
    const type = event.data?.type;
    if (AUTH_EVENT_TYPES.has(type)) handleExternalAuthChange(type);
  });
  window.addEventListener('focus', reconcileSharedSession);
  window.addEventListener('pageshow', reconcileSharedSession);
  ['pointerdown', 'keydown', 'touchstart'].forEach((eventName) => {
    window.addEventListener(eventName, touchActivity, { passive: true });
  });
  window.setInterval(checkSessionLifetime, SESSION_CHECK_INTERVAL_MS);
  checkSessionLifetime();
}

export function getAccessToken() {
  const token = readCookie('auth_token');
  // Cross-tab fix: legacy precedence remains documented as readSessionContext() || readSharedContext();
  const context = readSharedContext() || readSessionContext();
  if (context && !hasMatchingIdentity(token, context)) {
    sessionStorage.removeItem(SESSION_KEY);
    return '';
  }
  return token;
}

export function setAuthSession(loginData, username) {
  const maxAge = Number(loginData.expires_in || 3600);
  document.cookie = `auth_token=${encodeURIComponent(loginData.access_token)}; path=/; max-age=${maxAge}; SameSite=Strict`;
  const context = {
    username,
    userId: String(loginData.user_id || ''),
    roles: Array.isArray(loginData.roles) ? loginData.roles : [],
    dataScope: loginData.data_scope || 'self',
    permissions: Array.isArray(loginData.permissions) ? loginData.permissions : [],
    expiresAt: Date.now() + maxAge * 1000,
    lastActivityAt: Date.now(),
  };
  document.cookie = `${IDENTITY_COOKIE}=${encodeURIComponent(context.userId)}; path=/; max-age=${maxAge}; SameSite=Strict`;
  writeSharedContext(context, maxAge);
  sessionStorage.setItem(SESSION_KEY, JSON.stringify(context));
  publishAuthEvent('signed-in');
  return context;
}

export function clearAuthSession({ eventType = 'signed-out', notify = true } = {}) {
  document.cookie = 'auth_token=; path=/; max-age=0; SameSite=Strict';
  document.cookie = `${IDENTITY_COOKIE}=; path=/; max-age=0; SameSite=Strict`;
  document.cookie = `${CONTEXT_COOKIE}=; path=/; max-age=0; SameSite=Strict`;
  sessionStorage.removeItem(SESSION_KEY);
  if (notify) publishAuthEvent(eventType);
}

export function switchAccount(mode = 'customer') {
  clearAuthSession({ eventType: 'account-switched' });
  const loginPath = mode === 'customer'
    ? '/portal/customer/login/'
    : '/portal/employee-console/login/';
  window.location.assign(`${loginPath}?reason=account-switched`);
}

export function getAuthContext() {
  const token = readCookie('auth_token');
  // The shared cookie is authoritative across portal pages and tabs; sessionStorage
  // is only a fast per-tab cache and can lag after navigation or account switching.
  const context = readSharedContext() || readSessionContext();
  if (!hasMatchingIdentity(token, context)) {
    sessionStorage.removeItem(SESSION_KEY);
    return null;
  }
  sessionStorage.setItem(SESSION_KEY, JSON.stringify(context));
  return context;
}

export function hasRole(...allowedRoles) {
  const context = getAuthContext();
  return Boolean(context && context.roles.some((role) => allowedRoles.includes(role)));
}

export function getPermissions() {
  const context = getAuthContext();
  if (!context) return [];
  if (Array.isArray(context.permissions) && context.permissions.length) return [...context.permissions];
  if (context.roles.includes('admin') || context.roles.includes('super_admin')) {
    return [...CUSTOMER_PERMISSIONS, PERM_CODES.AUDIT_READ];
  }
  return context.roles.includes('customer') ? [...CUSTOMER_PERMISSIONS] : [];
}

export function updateAuthPermissions(permissions, dataScope) {
  const context = getAuthContext();
  if (!context) return null;
  const next = {
    ...context,
    permissions: Array.isArray(permissions) ? [...permissions] : [],
    dataScope: dataScope || context.dataScope,
  };
  const expiresAt = Number(next.expiresAt || tokenExpiry(readCookie('auth_token')));
  const remaining = expiresAt ? Math.max(0, Math.ceil((expiresAt - Date.now()) / 1000)) : 1800;
  next.expiresAt = expiresAt;
  next.lastActivityAt = Date.now();
  sessionStorage.setItem(SESSION_KEY, JSON.stringify(next));
  writeSharedContext(next, remaining);
  return next;
}

export function staffHomeForRoles(roles = []) {
  if (roles.includes('admin') || roles.includes('super_admin')) return '/portal/employee-console/workspace/';
  if (roles.includes('risk_operator')) return '/portal/employee-risk/dashboard/';
  if (roles.includes('advisor')) return '/portal/employee-advisor/dashboard/';
  if (roles.includes('operator')) return '/portal/employee-operations/dashboard/';
  return '/portal/employee-console/workspace/';
}

export function requireCustomer() {
  if (!getAccessToken() || !hasRole('customer', 'admin', 'super_admin')) {
    const next = encodeURIComponent(`${window.location.pathname}${window.location.search}`);
    window.location.replace(`/portal/customer/login/?next=${next}`);
    return false;
  }
  return true;
}

export function requireCustomerOnly() {
  if (!getAccessToken()) {
    const next = encodeURIComponent(`${window.location.pathname}${window.location.search}`);
    window.location.replace(`/portal/customer/login/?next=${next}`);
    return false;
  }
  if (!hasRole('customer')) {
    window.location.replace(staffHomeForRoles(getAuthContext()?.roles || []));
    return false;
  }
  return true;
}

export function requireStaff() {
  const staffRoles = ['risk_operator', 'operator', 'advisor', 'admin', 'super_admin'];
  if (!getAccessToken() || !hasRole(...staffRoles)) {
    window.location.replace('/portal/employee-console/login/');
    return false;
  }
  return true;
}

export function requireAdmin() {
  if (!getAccessToken() || !hasRole('admin', 'super_admin')) {
    window.location.replace(hasRole('risk_operator') ? '/portal/employee-risk/dashboard/' : '/portal/employee-console/login/');
    return false;
  }
  return true;
}

export function requireRiskStaff() {
  if (!getAccessToken() || !hasRole('risk_operator', 'admin', 'super_admin')) {
    window.location.replace('/portal/employee-console/login/');
    return false;
  }
  return true;
}

export function requireAdvisor() {
  if (!getAccessToken()) {
    window.location.replace('/portal/employee-console/login/');
    return false;
  }
  if (!hasRole('advisor', 'admin', 'super_admin')) {
    window.location.replace(staffHomeForRoles(getAuthContext()?.roles || []));
    return false;
  }
  return true;
}

export function requireOperator() {
  if (!getAccessToken()) {
    window.location.replace('/portal/employee-console/login/');
    return false;
  }
  if (!hasRole('operator', 'admin', 'super_admin')) {
    window.location.replace(staffHomeForRoles(getAuthContext()?.roles || []));
    return false;
  }
  return true;
}