'use strict';

// ========== Storage abstraction (decisions #1024, #1025) ==========
//
// #1024: probe availability with a real write, NOT typeof/in
// #1025: fallback chain: localStorage → sessionStorage → in-memory

let _storage = null;
let _storageType = 'memory';
const _mem = {};

function _probeStorage(s) {
  try {
    const k = '__baton_probe__';
    s.setItem(k, '1');
    s.removeItem(k);
    return true;
  } catch (_) {
    return false;
  }
}

function _initStorage() {
  if (_probeStorage(localStorage)) {
    _storage = localStorage;
    _storageType = 'local';
  } else if (_probeStorage(sessionStorage)) {
    _storage = sessionStorage;
    _storageType = 'session';
  } else {
    _storage = {
      getItem: (k) => (Object.prototype.hasOwnProperty.call(_mem, k) ? _mem[k] : null),
      setItem: (k, v) => { _mem[k] = String(v); },
      removeItem: (k) => { delete _mem[k]; },
    };
    _storageType = 'memory';
  }
}

// ========== User identity ==========

function _isRegistered() {
  return !!_storage.getItem('baton_auth_token');
}

function _getUserName() {
  return _storage.getItem('baton_login') || '';
}

function _getAuthToken() {
  return _storage.getItem('baton_auth_token') || '';
}

function _saveAuth(token, login) {
  _storage.setItem('baton_auth_token', token);
  _storage.setItem('baton_login', login);
}

function _clearAuth() {
  _storage.removeItem('baton_auth_token');
  _storage.removeItem('baton_login');
}

function _getInitials(name) {
  const trimmed = (name || '').trim();
  if (!trimmed) return '?';
  return trimmed
    .split(/\s+/)
    .map((w) => w[0] || '')
    .join('')
    .toUpperCase()
    .slice(0, 2);
}

// ========== UI helpers ==========

function _showScreen(id) {
  document.querySelectorAll('.screen').forEach((el) => {
    el.hidden = el.id !== id;
  });
}

function _setStatus(msg, cls) {
  const el = document.getElementById('status');
  el.textContent = msg;
  el.className = 'status' + (cls ? ' status--' + cls : '');
  el.hidden = !msg;
}

function _setRegStatus(msg, cls) {
  const el = document.getElementById('reg-status');
  if (!el) return;
  el.textContent = msg;
  el.className = 'reg-status' + (cls ? ' reg-status--' + cls : '');
  el.hidden = !msg;
}

function _setLoginStatus(msg, cls) {
  const el = document.getElementById('login-status');
  if (!el) return;
  el.textContent = msg;
  el.className = 'reg-status' + (cls ? ' reg-status--' + cls : '');
  el.hidden = !msg;
}

function _showView(id) {
  ['view-login', 'view-register'].forEach((vid) => {
    const el = document.getElementById(vid);
    if (el) el.hidden = vid !== id;
  });
}

function _updateNetworkIndicator() {
  const el = document.getElementById('indicator-network');
  if (!el) return;
  el.className = 'network-indicator ' + (navigator.onLine ? 'online' : 'offline');
  el.setAttribute('aria-label', navigator.onLine ? 'Online' : 'Offline');
}

function _updateUserAvatar() {
  const el = document.getElementById('user-avatar');
  if (!el) return;
  el.textContent = _getInitials(_getUserName());
}

// ========== API calls ==========

async function _apiPost(path, body, extraHeaders) {
  const res = await fetch(path, {
    method: 'POST',
    headers: { 'Content-Type': 'application/json', ...extraHeaders },
    body: JSON.stringify(body),
  });
  if (!res.ok) {
    const text = await res.text().catch(() => '');
    const err = new Error('HTTP ' + res.status + (text ? ': ' + text : ''));
    err.status = res.status;
    throw err;
  }
  return res.json();
}

// ========== Geolocation (optional, non-blocking) ==========

function _getGeo() {
  return new Promise((resolve) => {
    if (!navigator.geolocation) { resolve(null); return; }
    navigator.geolocation.getCurrentPosition(
      ({ coords }) =>
        resolve({
          lat: coords.latitude,
          lon: coords.longitude,
          accuracy: coords.accuracy,
        }),
      () => resolve(null),
      { timeout: 5000, maximumAge: 30000 }
    );
  });
}

// ========== Handlers ==========

async function _handleLogin() {
  const loginInput = document.getElementById('login-input');
  const passInput = document.getElementById('login-password');
  const btn = document.getElementById('btn-login');
  const login = loginInput.value.trim();
  const password = passInput.value;
  if (!login || !password) return;

  btn.disabled = true;
  _setLoginStatus('', '');

  try {
    const data = await _apiPost('/api/auth/login', {
      login_or_email: login,
      password: password,
    });
    _saveAuth(data.token, data.login);
    passInput.value = '';
    _updateUserAvatar();
    _showMain();
  } catch (err) {
    let msg = 'Ошибка входа. Попробуйте ещё раз.';
    if (err && err.message) {
      const colonIdx = err.message.indexOf(': ');
      if (colonIdx !== -1) {
        try {
          const parsed = JSON.parse(err.message.slice(colonIdx + 2));
          if (parsed.detail) msg = parsed.detail;
        } catch (_) {}
      }
    }
    _setLoginStatus(msg, 'error');
    btn.disabled = false;
  }
}

function _setSosState(state) {
  const btn = document.getElementById('btn-sos');
  if (!btn) return;
  btn.dataset.state = state;
  btn.disabled = state === 'sending';
}

async function _handleTestSignal() {
  if (!navigator.onLine) {
    _setStatus('Нет соединения.', 'error');
    return;
  }
  const token = _getAuthToken();
  if (!token) return;

  _setStatus('', '');
  try {
    const geo = await _getGeo();
    const body = { timestamp: Date.now(), is_test: true };
    if (geo) body.geo = geo;
    await _apiPost('/api/signal', body, { Authorization: 'Bearer ' + token });
    _setStatus('Тест отправлен', 'success');
    setTimeout(() => _setStatus('', ''), 1500);
  } catch (err) {
    if (err && err.status === 401) {
      _clearAuth();
      _setStatus('Сессия истекла. Войдите заново.', 'error');
      setTimeout(() => _showOnboarding(), 1500);
    } else {
      _setStatus('Ошибка отправки.', 'error');
    }
  }
}

async function _handleSignal() {
  if (!navigator.onLine) {
    _setStatus('Нет соединения. Проверьте сеть и попробуйте снова.', 'error');
    return;
  }

  const token = _getAuthToken();
  if (!token) {
    _clearAuth();
    _showOnboarding();
    return;
  }

  _setSosState('sending');
  _setStatus('', '');

  try {
    const geo = await _getGeo();
    const body = { timestamp: Date.now() };
    if (geo) body.geo = geo;

    await _apiPost('/api/signal', body, { Authorization: 'Bearer ' + token });

    _setSosState('success');
    _setStatus('Сигнал отправлен!', 'success');
    setTimeout(() => {
      _setSosState('default');
      _setStatus('', '');
    }, 2000);
  } catch (err) {
    _setSosState('default');
    if (err && err.status === 401) {
      _clearAuth();
      _setStatus('Сессия истекла. Войдите заново.', 'error');
      setTimeout(() => _showOnboarding(), 1500);
    } else {
      _setStatus('Ошибка отправки. Попробуйте ещё раз.', 'error');
    }
  }
}

// ========== Screens ==========

function _showOnboarding() {
  _showScreen('screen-onboarding');
  _showView('view-login');

  const loginInput = document.getElementById('login-input');
  const passInput = document.getElementById('login-password');
  const btnLogin = document.getElementById('btn-login');

  function _updateLoginBtn() {
    btnLogin.disabled = !loginInput.value.trim() || !passInput.value;
  }

  loginInput.addEventListener('input', _updateLoginBtn);
  passInput.addEventListener('input', _updateLoginBtn);
  passInput.addEventListener('keydown', (e) => {
    if (e.key === 'Enter' && !btnLogin.disabled) _handleLogin();
  });
  btnLogin.addEventListener('click', _handleLogin);

  const btnToRegister = document.getElementById('btn-switch-to-register');
  if (btnToRegister) {
    btnToRegister.addEventListener('click', () => {
      _setRegStatus('', '');
      _setLoginStatus('', '');
      _showView('view-register');
    });
  }

  const btnToLogin = document.getElementById('btn-switch-to-login');
  if (btnToLogin) {
    btnToLogin.addEventListener('click', () => {
      _setLoginStatus('', '');
      _showView('view-login');
    });
  }

  const btnRegister = document.getElementById('btn-register');
  if (btnRegister) {
    btnRegister.addEventListener('click', _handleSignUp);
  }
}

function _showMain() {
  _showScreen('screen-main');
  _updateUserAvatar();

  const btn = document.getElementById('btn-sos');
  if (btn && !btn.dataset.listenerAttached) {
    btn.addEventListener('click', _handleSignal);
    btn.dataset.listenerAttached = '1';
  }

  // Avatar and network indicator → test signal (only on main screen)
  const avatar = document.getElementById('user-avatar');
  if (avatar && !avatar.dataset.testAttached) {
    avatar.addEventListener('click', _handleTestSignal);
    avatar.dataset.testAttached = '1';
    avatar.style.cursor = 'pointer';
  }
  const indicator = document.getElementById('indicator-network');
  if (indicator && !indicator.dataset.testAttached) {
    indicator.addEventListener('click', _handleTestSignal);
    indicator.dataset.testAttached = '1';
    indicator.style.cursor = 'pointer';
  }
}

// ========== Service Worker ==========

function _registerSW() {
  if (!('serviceWorker' in navigator)) return;
  navigator.serviceWorker.register('/sw.js').catch((err) => {
    console.warn('[baton] SW registration failed:', err);
  });
}

// ========== VAPID / Push subscription ==========

async function _fetchVapidPublicKey() {
  try {
    const res = await fetch('/api/push/public-key');
    if (!res.ok) {
      console.warn('[baton] /api/push/public-key returned', res.status);
      return null;
    }
    const data = await res.json();
    return data.vapid_public_key || null;
  } catch (err) {
    console.warn('[baton] Failed to fetch VAPID public key:', err);
    return null;
  }
}

function _urlBase64ToUint8Array(base64String) {
  const padding = '='.repeat((4 - (base64String.length % 4)) % 4);
  const base64 = (base64String + padding).replace(/-/g, '+').replace(/_/g, '/');
  const raw = atob(base64);
  const output = new Uint8Array(raw.length);
  for (let i = 0; i < raw.length; i++) {
    output[i] = raw.charCodeAt(i);
  }
  return output;
}

async function _initPushSubscription(vapidPublicKey) {
  if (!vapidPublicKey) {
    console.warn('[baton] VAPID public key not available — push subscription skipped');
    return;
  }
  if (!('serviceWorker' in navigator) || !('PushManager' in window)) {
    return;
  }
  try {
    const registration = await navigator.serviceWorker.ready;
    const existing = await registration.pushManager.getSubscription();
    if (existing) return;
    const applicationServerKey = _urlBase64ToUint8Array(vapidPublicKey);
    const subscription = await registration.pushManager.subscribe({
      userVisibleOnly: true,
      applicationServerKey,
    });
    _storage.setItem('baton_push_subscription', JSON.stringify(subscription));
    console.info('[baton] Push subscription created');
  } catch (err) {
    console.warn('[baton] Push subscription failed:', err);
  }
}

// ========== Registration (account sign-up) ==========

async function _getPushSubscriptionForReg() {
  if (!('serviceWorker' in navigator) || !('PushManager' in window)) return null;
  try {
    const vapidKey = await _fetchVapidPublicKey();
    if (!vapidKey) return null;
    const registration = await navigator.serviceWorker.ready;
    const existing = await registration.pushManager.getSubscription();
    if (existing) return existing.toJSON();
    const applicationServerKey = _urlBase64ToUint8Array(vapidKey);
    const subscription = await registration.pushManager.subscribe({
      userVisibleOnly: true,
      applicationServerKey,
    });
    return subscription.toJSON();
  } catch (err) {
    console.warn('[baton] Push subscription for registration failed:', err);
    return null;
  }
}

async function _handleSignUp() {
  const emailInput = document.getElementById('reg-email');
  const loginInput = document.getElementById('reg-login');
  const passwordInput = document.getElementById('reg-password');
  const btn = document.getElementById('btn-register');
  if (!emailInput || !loginInput || !passwordInput || !btn) return;

  const email = emailInput.value.trim();
  const login = loginInput.value.trim();
  const password = passwordInput.value;

  if (!email || !login || !password) {
    _setRegStatus('Заполните все поля.', 'error');
    return;
  }
  if (!/^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(email)) {
    _setRegStatus('Введите корректный email.', 'error');
    return;
  }

  btn.disabled = true;
  const originalText = btn.textContent.trim();
  btn.textContent = '...';
  _setRegStatus('', '');

  try {
    const push_subscription = await _getPushSubscriptionForReg().catch(() => null);
    await _apiPost('/api/auth/register', { email, login, password, push_subscription });
    passwordInput.value = '';
    _setRegStatus('Заявка отправлена. Ожидайте подтверждения администратора.', 'success');
  } catch (err) {
    let msg = 'Ошибка. Попробуйте ещё раз.';
    if (err && err.message) {
      const colonIdx = err.message.indexOf(': ');
      if (colonIdx !== -1) {
        try {
          const parsed = JSON.parse(err.message.slice(colonIdx + 2));
          if (parsed.detail) msg = parsed.detail;
        } catch (_) {}
      }
    }
    if (err && err.status === 403 && msg !== 'Ошибка. Попробуйте ещё раз.') {
      _showBlockScreen(msg);
    } else {
      _setRegStatus(msg, 'error');
      btn.disabled = false;
      btn.textContent = originalText;
    }
  }
}

function _showBlockScreen(msg) {
  const screen = document.getElementById('screen-onboarding');
  if (!screen) return;
  screen.innerHTML =
    '<div class="screen-content">' +
    '<p class="block-message">' + msg + '</p>' +
    '<button type="button" class="btn-confirm" id="btn-block-ok">OK</button>' +
    '</div>';
  document.getElementById('btn-block-ok').addEventListener('click', () => {
    location.reload();
  });
}

// ========== Init ==========

function _init() {
  _initStorage();

  // Private mode graceful degradation (decision #1041)
  if (_storageType !== 'local') {
    const banner = document.getElementById('private-mode-banner');
    if (banner) banner.hidden = false;
  }

  // Network indicator — initial state + live updates
  _updateNetworkIndicator();
  window.addEventListener('online', _updateNetworkIndicator);
  window.addEventListener('offline', _updateNetworkIndicator);

  // Route to correct screen based on JWT token presence
  if (_isRegistered()) {
    _showMain();
  } else {
    _showOnboarding();
  }

  // Fire-and-forget: fetch VAPID key from API and subscribe to push (non-blocking)
  _fetchVapidPublicKey().then(_initPushSubscription).catch((err) => {
    console.warn('[baton] Push init error:', err);
  });
}

document.addEventListener('DOMContentLoaded', () => {
  _registerSW();
  _init();
});