import { useEffect, useState } from 'react';

import { useAuthStore } from '@/stores/auth';
import { useUIStore } from '@/stores/ui';
import { ErrorBoundary } from '@/components/ErrorBoundary';
import { PWAInstallBanner } from '@/components/pwa/PWAInstallBanner';
import { ToastProvider } from '@/components/feedback/ToastProvider';
import { AppRouter } from '@/router';
import { csrfService } from '@/services/csrf';
import { useGlobalKeyboardShortcuts } from '@/hooks/useGlobalKeyboardShortcuts';
import { KeyboardShortcutsHelp } from '@/components/keyboard/KeyboardShortcutsHelp';
import { useStateHydration } from '@/utils/stateHydration';
import { useQueryInvalidation } from '@/hooks/useQueryInvalidation';

export function App() {
  const { refreshUser } = useAuthStore();
  const { theme, setTheme, language, setLanguage } = useUIStore();
  const [showKeyboardHelp, setShowKeyboardHelp] = useState(false);

  // FE-COMP-022: Enable global keyboard shortcuts
  useGlobalKeyboardShortcuts({
    enabled: true,
    onHelpOpen: () => setShowKeyboardHelp(true),
  });

  // FE-STATE-003: Hydrate state from server on app load
  const { isHydrating } = useStateHydration({
    hydrateAuth: true,
    hydrateLibrary: false, // Can be enabled if needed
    hydrateChat: false, // Can be enabled if needed
    requireAuth: false, // Hydrate auth even if not authenticated (to check status)
  });

  // FE-STATE-004: Listen for query invalidation events
  useQueryInvalidation();

  // Initialiser l'application
  useEffect(() => {
    // Note: refreshUser is now called by useStateHydration, but we keep it here
    // as a fallback in case hydration is disabled
    if (!isHydrating) {
      refreshUser();
    }
    
    // Récupérer le token CSRF si l'utilisateur est déjà authentifié
    // (refreshUser() est asynchrone, donc on vérifie après un court délai)
    const checkAndFetchCSRF = async () => {
      // Attendre un peu pour que refreshUser() se termine
      await new Promise(resolve => setTimeout(resolve, 100));
      const { isAuthenticated } = useAuthStore.getState();
      if (isAuthenticated) {
        csrfService.refreshToken().catch((error) => {
          console.warn('Failed to fetch CSRF token on app init:', error);
        });
      }
    };
    checkAndFetchCSRF();

    // Appliquer le thème au chargement (le store persist le fait déjà, mais on s'assure qu'il est appliqué)
    setTheme(theme);

    // Synchroniser la langue avec i18n au chargement
    if (typeof window !== 'undefined' && window.i18n) {
      const currentLang = window.i18n.language || language;
      if (currentLang !== language) {
        window.i18n.changeLanguage(language);
      } else if (language !== currentLang) {
        setLanguage(currentLang as 'en' | 'fr');
      }
    }
  }, [refreshUser, setTheme, theme, language, setLanguage]);

  // Écouter les changements de préférence système pour le mode 'system'
  useEffect(() => {
    if (theme !== 'system') return;

    const mediaQuery = window.matchMedia('(prefers-color-scheme: dark)');
    const handleChange = (e: MediaQueryListEvent) => {
      const root = document.documentElement;
      if (e.matches) {
        root.classList.add('dark');
      } else {
        root.classList.remove('dark');
      }
    };

    // Écouter les changements
    if (mediaQuery.addEventListener) {
      mediaQuery.addEventListener('change', handleChange);
    } else {
      // Fallback pour les navigateurs plus anciens
      mediaQuery.addListener(handleChange);
    }

    return () => {
      if (mediaQuery.removeEventListener) {
        mediaQuery.removeEventListener('change', handleChange);
      } else {
        mediaQuery.removeListener(handleChange);
      }
    };
  }, [theme]);

  return (
    <ErrorBoundary>
      <ToastProvider>
        <AppRouter />
        {/* PWA Install Banner */}
        <PWAInstallBanner />
        {/* Keyboard Shortcuts Help */}
        <KeyboardShortcutsHelp
          open={showKeyboardHelp}
          onClose={() => setShowKeyboardHelp(false)}
        />
      </ToastProvider>
    </ErrorBoundary>
  );
}