import { renderHeader } from '../components/header.js';
import {
  authService,
  authorizeSession,
  clearAuthMessages,
  clearBrowserClientData,
  refreshSessions,
  setAuthBusy,
  setAuthError,
  setAuthInfo,
  state,
  terminateCurrentSession,
} from '../state.js';
import { clearClientAuthData, saveEncryptedUserSecrets } from '../services/key-vault.js';
import { clearStoredMessages } from '../services/message-store.js';
import {
  describeTransferKeys,
  parseKeyTransferText,
} from '../services/qr-key-transfer-service.js';
import { toUserMessage } from '../services/ui-error-texts.js';

export const pageMeta = { id: 'login-camera-view', title: 'Войти по QR-коду', showAppChrome: false };

function canUseBarcodeDetector() {
  return typeof window.BarcodeDetector === 'function';
}

async function createQrDetector() {
  if (!canUseBarcodeDetector()) return null;
  try {
    const formats = await window.BarcodeDetector.getSupportedFormats?.();
    if (Array.isArray(formats) && !formats.includes('qr_code')) return null;
  } catch {
    // Некоторые браузеры не реализуют getSupportedFormats, но сам detector работает.
  }
  return new window.BarcodeDetector({ formats: ['qr_code'] });
}

function setStatus(statusEl, message, kind = 'info') {
  statusEl.classList.toggle('is-unavailable', kind === 'error');
  statusEl.classList.toggle('is-available', kind !== 'error');
  statusEl.textContent = message;
  statusEl.style.display = message ? '' : 'none';
}

function escapeHtml(value) {
  return String(value || '')
    .replace(/&/g, '&')
    .replace(/</g, '&lt;')
    .replace(/>/g, '&gt;')
    .replace(/"/g, '&quot;')
    .replace(/'/g, '&#39;');
}

function renderParsedTransfer(resultEl, transfer) {
  const keys = describeTransferKeys(transfer.keys);
  resultEl.innerHTML = `
    <p class="meta-muted">Отсканированный логин: <strong>${escapeHtml(transfer.login)}</strong></p>
    <p class="meta-muted">Получены ключи: <strong>${escapeHtml(keys.join(', '))}</strong></p>
    <p class="meta-muted">Войти под этим логином и очистить локальную историю старого логина?</p>
  `;
}

export function render({ navigate }) {
  const screen = document.createElement('section');
  screen.className = 'stack';

  clearAuthMessages();

  const frame = document.createElement('div');
  frame.className = 'camera-shell';
  frame.innerHTML = `
    <video class="camera-video" autoplay playsinline muted></video>
    <div class="camera-frame"></div>
    <div class="camera-hint">Наведите QR-код переноса ключей в рамку</div>
    <div class="camera-error" id="login-camera-error" style="display:none;"></div>
  `;

  const manualCard = document.createElement('details');
  manualCard.className = 'card stack';
  manualCard.innerHTML = `
    <summary>Ввести QR-текст вручную</summary>
    <textarea class="input" id="login-qr-manual" rows="4" placeholder="shine-key-transfer-v1:..."></textarea>
    <button class="ghost-btn" type="button" id="login-qr-manual-parse">Проверить QR-текст</button>
  `;

  const resultCard = document.createElement('div');
  resultCard.className = 'card stack';
  resultCard.style.display = 'none';
  resultCard.innerHTML = `
    <div id="login-qr-result"></div>
    <div class="row">
      <button class="ghost-btn" type="button" id="login-qr-cancel">Нет</button>
      <button class="primary-btn" type="button" id="login-qr-confirm">Да</button>
    </div>
  `;

  const status = document.createElement('p');
  status.className = 'status-line is-unavailable';
  status.style.display = 'none';

  const backButton = document.createElement('button');
  backButton.className = 'ghost-btn';
  backButton.type = 'button';
  backButton.textContent = 'Назад';

  const video = frame.querySelector('video');
  const cameraError = frame.querySelector('#login-camera-error');
  const manualInput = manualCard.querySelector('#login-qr-manual');
  const parseManualButton = manualCard.querySelector('#login-qr-manual-parse');
  const resultEl = resultCard.querySelector('#login-qr-result');
  const cancelButton = resultCard.querySelector('#login-qr-cancel');
  const confirmButton = resultCard.querySelector('#login-qr-confirm');

  let stream = null;
  let detector = null;
  let scanTimer = 0;
  let scannedTransfer = null;
  let stopped = false;

  const stopCamera = () => {
    stopped = true;
    if (scanTimer) {
      window.clearTimeout(scanTimer);
      scanTimer = 0;
    }
    if (stream) {
      stream.getTracks().forEach((track) => track.stop());
      stream = null;
    }
  };

  const showTransfer = (transfer) => {
    scannedTransfer = transfer;
    stopCamera();
    renderParsedTransfer(resultEl, transfer);
    resultCard.style.display = '';
    setStatus(status, '', 'info');
  };

  const parseTransferText = (text) => {
    try {
      const transfer = parseKeyTransferText(text);
      if (!transfer.keys.deviceKey) {
        throw new Error('В QR-коде нет device key для входа');
      }
      showTransfer(transfer);
    } catch (error) {
      setStatus(status, error?.message || 'Не удалось прочитать QR-код.', 'error');
    }
  };

  const scanLoop = async () => {
    if (stopped || !detector || !video || video.readyState < 2) {
      if (!stopped) scanTimer = window.setTimeout(scanLoop, 250);
      return;
    }
    try {
      const codes = await detector.detect(video);
      const text = String(codes?.[0]?.rawValue || '').trim();
      if (text) {
        parseTransferText(text);
        return;
      }
    } catch {
      // Ошибки отдельных кадров игнорируем, камера продолжит сканирование.
    }
    if (!stopped) scanTimer = window.setTimeout(scanLoop, 300);
  };

  const startCamera = async () => {
    try {
      detector = await createQrDetector();
      if (!detector) {
        throw new Error('Этот браузер не поддерживает сканирование QR через камеру. Используйте ручной ввод QR-текста.');
      }
      if (!navigator.mediaDevices?.getUserMedia) {
        throw new Error('Камера не поддерживается в этом браузере.');
      }
      stream = await navigator.mediaDevices.getUserMedia({ video: { facingMode: 'environment' }, audio: false });
      video.srcObject = stream;
      await video.play?.();
      scanLoop();
    } catch (error) {
      cameraError.textContent = error?.message || 'Не удалось открыть камеру. Проверьте разрешения браузера.';
      cameraError.style.display = '';
      setStatus(status, cameraError.textContent, 'error');
    }
  };

  parseManualButton.addEventListener('click', () => parseTransferText(manualInput.value));
  cancelButton.addEventListener('click', () => {
    scannedTransfer = null;
    resultCard.style.display = 'none';
    stopped = false;
    void startCamera();
  });
  confirmButton.addEventListener('click', async () => {
    if (!scannedTransfer) return;
    confirmButton.disabled = true;
    cancelButton.disabled = true;
    setAuthBusy(true);
    setAuthError('');
    setStatus(status, 'Входим по QR-коду...', 'info');
    try {
      await authService.reconnect(state.entrySettings.shineServer);
      const session = await authService.createSessionFromImportedSecrets(scannedTransfer.login, scannedTransfer.keys);
      await clearStoredMessages().catch(() => {});
      clearBrowserClientData();
      await clearClientAuthData().catch(() => {});
      await terminateCurrentSession();
      await saveEncryptedUserSecrets(session.login, session.storagePwd, scannedTransfer.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 по QR-коду выполнен для @${resumed.login || session.login}.`);
      navigate('profile-view');
    } catch (error) {
      const message = toUserMessage(error, 'Не удалось войти по QR-коду.');
      setAuthError(message);
      setStatus(status, message, 'error');
    } finally {
      setAuthBusy(false);
      confirmButton.disabled = false;
      cancelButton.disabled = false;
    }
  });

  backButton.addEventListener('click', () => {
    stopCamera();
    navigate('login-view');
  });

  screen.append(
    renderHeader({
      title: 'Войти по QR-коду',
      leftAction: {
        label: '←',
        onClick: () => {
          stopCamera();
          navigate('login-view');
        },
      },
    }),
    frame,
    manualCard,
    resultCard,
    status,
    backButton,
  );

  void startCamera();
  screen.cleanup = stopCamera;
  return screen;
}