import React, { useState, useEffect } from 'react';
import { Routes, Route, Navigate, useLocation, useNavigate } from 'react-router-dom';
import Login from './pages/Login';
import Register from './pages/Register';
import Chat from './pages/Chat';
import { usePlatform } from './platform';
import { useSearch } from './contexts/SearchContext';

const THIRTY_DAYS_MS = 30 * 24 * 60 * 60 * 1000;

function AuthGuard({ children }) {
  const [authState, setAuthState] = useState('loading'); // 'loading' | 'authenticated' | 'unauthenticated'
  const location = useLocation();
  const navigate = useNavigate();
  const { session, settings } = usePlatform();
  const searchCtx = useSearch();

  useEffect(() => {
    let cancelled = false;

    async function restoreSession() {
      // Already have keys in sessionStorage — current session is active
      if (sessionStorage.getItem('privateKey') && sessionStorage.getItem('signingKey')) {
        searchCtx?.initialize();
        if (!cancelled) setAuthState('authenticated');
        return;
      }

      // Try restoring from safeStorage
      if (session) {
        try {
          const savedSession = await session.load();
          if (savedSession && savedSession.savedAt && (Date.now() - savedSession.savedAt) < THIRTY_DAYS_MS) {
            // Restore to localStorage + sessionStorage
            localStorage.setItem('userId', savedSession.userId);
            localStorage.setItem('username', savedSession.username);
            if (savedSession.publicKey) localStorage.setItem('publicKey', savedSession.publicKey);
            sessionStorage.setItem('signingKey', savedSession.signingKey);
            sessionStorage.setItem('privateKey', savedSession.privateKey);
            if (savedSession.searchDbKey) sessionStorage.setItem('searchDbKey', savedSession.searchDbKey);
            searchCtx?.initialize();
            // Restore user preferences from file-based backup into localStorage
            if (settings) {
              try {
                const savedPrefs = await settings.get(`userPrefs_${savedSession.userId}`);
                if (savedPrefs && typeof savedPrefs === 'object') {
                  localStorage.setItem(`userPrefs_${savedSession.userId}`, JSON.stringify(savedPrefs));
                }
              } catch {}
            }
            if (!cancelled) setAuthState('authenticated');
            return;
          }
          // Expired — clear stale session
          if (savedSession && savedSession.savedAt) {
            await session.clear();
          }
        } catch (err) {
          console.error('Session restore failed:', err);
        }
      }

      if (!cancelled) setAuthState('unauthenticated');
    }

    restoreSession();
    return () => { cancelled = true; };
  }, []);

  useEffect(() => {
    if (authState === 'loading') return;

    const isAuthPage = location.pathname === '/' || location.pathname === '/register';
    const hasSession = sessionStorage.getItem('privateKey') && sessionStorage.getItem('signingKey');

    if (hasSession && isAuthPage) {
      navigate('/chat', { replace: true });
    } else if (!hasSession && !isAuthPage) {
      navigate('/', { replace: true });
    }
  }, [authState, location.pathname]);

  if (authState === 'loading') {
    return (
      <div style={{
        display: 'flex',
        alignItems: 'center',
        justifyContent: 'center',
        height: '100vh',
        backgroundColor: 'var(--bg-primary, #313338)',
        color: 'var(--text-normal, #dbdee1)',
        fontSize: '16px',
      }}>
        Loading...
      </div>
    );
  }

  return children;
}

function App() {
  return (
    <AuthGuard>
      <Routes>
        <Route path="/" element={<Login />} />
        <Route path="/register" element={<Register />} />
        <Route path="/chat" element={<Chat />} />
      </Routes>
    </AuthGuard>
  );
}

export default App;
