import { createTopBar } from '../components/topbar.js';
import {
  authService,
  authorizeSession,
  consumeAuthReturnPage,
  isAddingProfileLogin,
  clearAuthMessages,
  clearBrowserClientData,
  refreshSessions,
  setAuthBusy,
  setAuthError,
  setAuthInfo,
  state,
  terminateCurrentSession,
} from '../state.js';
import { showToast } from '../services/channels-ux.js';
import {
  decryptPairingPayloadFromEnvelope,
  deriveEspPairingPasswordHash,
  createRequesterPairingMaterial,
  formatPairingShortCode,
} from '../services/device-pairing-service.js';
import { clearClientAuthData, saveEncryptedUserSecrets } from '../services/key-vault.js';
import { clearStoredMessages } from '../services/message-store.js';
import { toUserMessage } from '../services/ui-error-texts.js';

export const pageMeta = { id: 'login-other-device-view', title: 'Вход с другого устройства', showAppChrome: false };

function formatRemaining(ms) {
  const safe = Math.max(0, Math.ceil(Number(ms || 0) / 1000));
  return `${Math.floor(safe / 60)}:${String(safe % 60).padStart(2, '0')}`;
}

export function render({ navigate }) {
  const screen = document.createElement('section');
  screen.className = 'stack pairing-login';
  let pollTimer = 0;
  let countdownTimer = 0;
  let activePairingId = '';
  let requesterMaterial = null;
  let activeExpiresAtMs = 0;
  let isDisposed = false;

  clearAuthMessages();

  const who = document.createElement('p');
  who.className = 'pairing-who';

  // Код и то, что с ним делать.
  const codeBlock = document.createElement('div');
  codeBlock.className = 'pairing-code-block';
  codeBlock.innerHTML = `
    <div class="pairing-code-card">
      <p class="pairing-code-card__label">Код для входа</p>
      <div class="pairing-code" id="pairing-short-code"></div>
      <div class="pairing-timer" aria-live="off">
        <div class="pairing-timer__bar"><span id="pairing-timer-fill"></span></div>
        <span class="pairing-timer__text" id="pairing-timer-text"></span>
      </div>
      <p class="pairing-online" id="pairing-online"></p>
    </div>
    <ol class="pairing-steps">
      <li>Откройте Сияние, где вы уже вошли</li>
      <li>Настройки → Устройства</li>
      <li>«Подключить по коду» – введите код</li>
    </ol>
    <p class="pairing-waiting"><span class="pairing-spinner" aria-hidden="true"></span>Ждём подтверждения…</p>
  `;

  // Сообщение о ходе дела или об ошибке — вместо кода.
  const notice = document.createElement('div');
  notice.className = 'pairing-notice';
  notice.setAttribute('role', 'status');
  const noticeSpinner = document.createElement('span');
  noticeSpinner.className = 'pairing-spinner';
  noticeSpinner.setAttribute('aria-hidden', 'true');
  const noticeText = document.createElement('p');
  notice.append(noticeSpinner, noticeText);

  const passwordWrap = document.createElement('label');
  passwordWrap.className = 'stack pairing-password';
  passwordWrap.innerHTML = `
    <span class="field-label">Пароль подключения</span>
    <input class="input" type="password" autocomplete="current-password" placeholder="Задан на другом устройстве" />
  `;

  const startBtn = document.createElement('button');
  startBtn.className = 'primary-btn';
  startBtn.type = 'button';
  startBtn.textContent = 'Получить код';

  const loginInput = { value: String(state.loginDraft.login || '').trim() };
  const usePasswordInput = { checked: false };
  const passwordInput = passwordWrap.querySelector('input');
  who.textContent = loginInput.value ? `Вход для @${loginInput.value}` : '';
  const shortCodeEl = codeBlock.querySelector('#pairing-short-code');
  const timerFillEl = codeBlock.querySelector('#pairing-timer-fill');
  const timerTextEl = codeBlock.querySelector('#pairing-timer-text');
  const onlineEl = codeBlock.querySelector('#pairing-online');
  let activeStartedAtMs = 0;

  // Этапы: creating → code → approving; отдельно password (нужен пароль) и retry (истекло, отклонено, ошибка).
  const showStage = (stage, message = '', { error = false, action = '' } = {}) => {
    codeBlock.hidden = stage !== 'code';
    passwordWrap.hidden = stage !== 'password';
    notice.hidden = stage === 'code' || (stage === 'password' && !message);
    noticeSpinner.hidden = !(stage === 'creating' || stage === 'approving');
    noticeText.textContent = message;
    notice.classList.toggle('is-error', error);
    startBtn.hidden = !(stage === 'password' || stage === 'retry');
    if (action) startBtn.textContent = action;
  };

  const stopPolling = () => {
    if (pollTimer) {
      window.clearTimeout(pollTimer);
      pollTimer = 0;
    }
  };

  const stopCountdown = () => {
    if (countdownTimer) {
      window.clearInterval(countdownTimer);
      countdownTimer = 0;
    }
  };

  const updateCountdown = () => {
    const leftMs = activeExpiresAtMs - Date.now();
    if (leftMs <= 0) {
      stopPolling();
      stopCountdown();
      activePairingId = '';
      activeExpiresAtMs = 0;
      startBtn.disabled = false;
      showStage('retry', 'Время ожидания истекло', { error: true, action: 'Получить новый код' });
      return;
    }
    const totalMs = Math.max(1, activeExpiresAtMs - activeStartedAtMs);
    timerFillEl.style.width = `${Math.min(100, (leftMs / totalMs) * 100).toFixed(1)}%`;
    timerTextEl.textContent = formatRemaining(leftMs);
  };

  const startCountdown = (expiresAtMs) => {
    activeExpiresAtMs = Number(expiresAtMs || 0);
    activeStartedAtMs = Date.now();
    stopCountdown();
    updateCountdown();
    countdownTimer = window.setInterval(updateCountdown, 1000);
  };

  const clearActivePairing = () => {
    stopPolling();
    stopCountdown();
    activePairingId = '';
    activeExpiresAtMs = 0;
  };

  const finalizeAuthorizedLogin = async (keys, login) => {
    const session = await authService.createSessionFromImportedSecrets(login, keys);
    const addingProfile = isAddingProfileLogin();
    if (!addingProfile) {
      await terminateCurrentSession({ closeServerSession: true, notifySessionReset: false });
      clearBrowserClientData();
      await clearClientAuthData().catch(() => {});
    }
    await clearStoredMessages(session.login).catch(() => {});
    await saveEncryptedUserSecrets(session.login, session.storagePwd, keys);
    await authService.persistSessionMaterial(session.login, session.sessionMaterial);
    const resumed = await authService.resumeSession(session.login, session.sessionId);
    authorizeSession({
      login: resumed.login || session.login,
      sessionId: resumed.sessionId || session.sessionId,
      storagePwd: resumed.storagePwd || session.storagePwd,
    });
    state.loginDraft.login = resumed.login || session.login;
    state.loginDraft.password = '';
    await refreshSessions();
    setAuthInfo(`Вход через другое устройство выполнен для @${resumed.login || session.login}.`);
    showToast(`Устройство подключено для @${resumed.login || session.login}`);
    navigate(consumeAuthReturnPage('profile-view'));
  };

  const finalizeAuthorizedSessionAttach = async (payloadSession, login, requesterKeys) => {
    const sessionId = String(payloadSession?.sessionId || '').trim();
    const storagePwd = String(payloadSession?.storagePwd || '').trim();
    if (!sessionId || !storagePwd) {
      throw new Error('В session-only payload нет sessionId или storagePwd');
    }
    const sessionMaterial = {
      sessionId,
      sessionKey: requesterKeys.sessionKey,
      sessionPrivPkcs8: requesterKeys.sessionPrivPkcs8,
      sessionType: Number(payloadSession?.sessionType || 50) || 50,
    };

    const addingProfile = isAddingProfileLogin();
    if (!addingProfile) {
      await terminateCurrentSession({ closeServerSession: true, notifySessionReset: false });
      clearBrowserClientData();
      await clearClientAuthData().catch(() => {});
    }
    await clearStoredMessages(login).catch(() => {});
    await authService.persistSessionMaterial(login, sessionMaterial);
    const resumed = await authService.resumeSession(login, sessionId);
    authorizeSession({
      login: resumed.login || login,
      sessionId: resumed.sessionId || sessionId,
      storagePwd: resumed.storagePwd || storagePwd,
    });
    state.loginDraft.login = resumed.login || login;
    state.loginDraft.password = '';
    await refreshSessions();
    setAuthInfo(`Session-only вход выполнен для @${resumed.login || login}.`);
    showToast(`Wallet-session подключена для @${resumed.login || login}`);
    navigate(consumeAuthReturnPage('profile-view'));
  };

  const schedulePoll = () => {
    stopPolling();
    if (!activePairingId || isDisposed) return;
    pollTimer = window.setTimeout(async () => {
      try {
        const payload = await authService.getTrustedDeviceLoginStatus(activePairingId);
        const stateValue = String(payload?.state || '');
        if (stateValue === 'created') {
          schedulePoll();
          return;
        }
        if (stateValue === 'approved') {
          stopCountdown();
          showStage('approving', 'Вход подтверждён. Подключаем устройство…');
          const decoded = await decryptPairingPayloadFromEnvelope(payload?.encryptedPayload, requesterMaterial);
          const decodedType = String(decoded?.type || '');
          if (decodedType === 'shine-esp-session-attach') {
            await finalizeAuthorizedSessionAttach(decoded.session, decoded.login || loginInput.value, requesterMaterial);
            return;
          }
          if (decodedType !== 'shine-esp-pairing-transfer') {
            throw new Error('Получен неподдерживаемый pairing payload');
          }
          await finalizeAuthorizedLogin(decoded.keys, decoded.login || loginInput.value);
          return;
        }
        if (stateValue === 'rejected') {
          clearActivePairing();
          startBtn.disabled = false;
          showStage('retry', 'Вход отклонён на другом устройстве', { error: true, action: 'Получить новый код' });
          return;
        }
        if (stateValue === 'canceled') {
          clearActivePairing();
          startBtn.disabled = false;
          showStage('retry', 'Заявка отменена', { error: true, action: 'Получить новый код' });
          return;
        }
        if (stateValue === 'expired') {
          clearActivePairing();
          startBtn.disabled = false;
          showStage('retry', 'Время ожидания истекло', { error: true, action: 'Получить новый код' });
          return;
        }
        schedulePoll();
      } catch (error) {
        clearActivePairing();
        startBtn.disabled = false;
        const message = toUserMessage(error, 'Не удалось проверить, подтверждён ли вход.');
        setAuthError(message);
        showStage('retry', message, { error: true, action: 'Получить новый код' });
      }
    }, 2200);
  };

  startBtn.addEventListener('click', async () => {
    const login = String(loginInput.value || '').trim();
    const usePassword = !!usePasswordInput.checked;
    const password = String(passwordInput.value || '');
    if (!login) {
      navigate('login-view');
      return;
    }
    if (usePassword && !password) {
      showStage('password', 'Введите пароль подключения', { error: true, action: 'Получить код' });
      passwordInput.focus();
      return;
    }

    startBtn.disabled = true;
    setAuthBusy(true);
    setAuthError('');
    setAuthInfo('');
    clearActivePairing();
    showStage('creating', 'Создаём код для входа…');

    try {
      await authService.reconnect(state.entrySettings.shineServer);
      const resolved = await authService.resolveLoginForAuth(login);
      if (String(resolved?.resolution || '').toUpperCase() !== 'LOCAL') {
        state.loginDraft.login = String(resolved?.login || login).trim();
        navigate('login-view');
        return;
      }

      requesterMaterial = await createRequesterPairingMaterial();
      const passwordHash = usePassword
        ? await deriveEspPairingPasswordHash(login, password)
        : '';
      const payload = await authService.startTrustedDeviceLogin({
        login,
        passwordHash,
        requesterSessionKey: requesterMaterial.sessionKey,
        payloadType: 3,
      });

      activePairingId = String(payload?.pairingId || '');
      if (!activePairingId) {
        throw new Error('Сервер не вернул pairingId.');
      }

      shortCodeEl.textContent = formatPairingShortCode(payload?.shortCode || '');
      shortCodeEl.setAttribute('aria-label', `Код для входа: ${String(payload?.shortCode || '').split('').join(' ')}`);
      const online = !!payload?.trustedSessionOnline;
      onlineEl.textContent = online ? 'Устройство в сети' : 'Устройство не в сети – заявка подождёт';
      onlineEl.classList.toggle('is-online', online);
      showStage('code');
      startCountdown(payload?.expiresAtMs);
      state.loginDraft.login = login;
      schedulePoll();
    } catch (error) {
      startBtn.disabled = false;
      if (String(error?.code || '').toUpperCase() === 'PAIRING_PASSWORD_INVALID' && !usePassword) {
        usePasswordInput.checked = true;
        showStage('password', 'Для входа по коду на другом устройстве задан пароль подключения.', { action: 'Получить код' });
        window.setTimeout(() => passwordInput.focus(), 0);
      } else if (String(error?.code || '').toUpperCase() === 'PAIRING_PASSWORD_INVALID') {
        showStage('password', 'Неверный пароль подключения', { error: true, action: 'Получить код' });
        window.setTimeout(() => passwordInput.focus(), 0);
      } else {
        const message = toUserMessage(error, 'Не удалось начать вход через другое устройство.');
        setAuthError(message);
        showStage('retry', message, { error: true, action: 'Повторить' });
      }
    } finally {
      setAuthBusy(false);
    }
  });

  const cancelActivePairingAndBack = async () => {
    const pairingId = activePairingId;
    const requesterSessionKey = requesterMaterial?.sessionKey;
    isDisposed = true;
    stopPolling();
    stopCountdown();
    if (pairingId && requesterSessionKey) {
      try {
        await authService.cancelTrustedDeviceLogin(pairingId, requesterSessionKey);
      } catch {
        // Навигацию назад не блокируем из-за ошибки отмены уже созданной заявки.
      }
    }
    navigate('login-view');
  };

  screen.cleanup = () => {
    isDisposed = true;
    stopPolling();
    stopCountdown();
    if (activePairingId && requesterMaterial?.sessionKey) {
      void authService.cancelTrustedDeviceLogin(activePairingId, requesterMaterial.sessionKey).catch(() => {});
    }
  };

  passwordInput.addEventListener('keydown', (event) => {
    if (event.key === 'Enter') startBtn.click();
  });

  screen.append(
    createTopBar({
      title: 'Вход с другого устройства',
      back: { label: '←', onClick: () => { void cancelActivePairingAndBack(); } },
    }),
    who,
    codeBlock,
    notice,
    passwordWrap,
    startBtn,
  );

  if (!String(loginInput.value || '').trim()) {
    window.setTimeout(() => navigate('login-view'), 0);
  } else {
    // После проверки логина на предыдущем экране код создаётся сразу.
    window.setTimeout(() => startBtn.click(), 0);
  }
  return screen;
}