import React, { useEffect, useState } from 'react';
import { View } from 'react-native';
import { Stack, useRouter, useSegments } from 'expo-router';
import { PaperProvider, MD3DarkTheme, ActivityIndicator, Snackbar, Button, Text } from 'react-native-paper';
import { SafeAreaProvider } from 'react-native-safe-area-context';
import { GestureHandlerRootView } from 'react-native-gesture-handler';
import * as LocalAuthentication from 'expo-local-authentication';
import { useAppStore } from '../src/store/appStore';
import { registerToastCallback } from '../src/utils/errorHandler';

/**
 * Thème Material Design 3 sombre personnalisé pour n8n Pilot.
 * L'orange (#FF6D3E) est la couleur d'accent principale — cohérente avec l'identité n8n.
 */
const APP_THEME = {
  ...MD3DarkTheme,
  colors: {
    ...MD3DarkTheme.colors,
    primary: '#FF6D3E',
    primaryContainer: '#5C1C00',
    secondary: '#FF9E7D',
    background: '#121212',
    surface: '#1E1E1E',
    surfaceVariant: '#2C2C2C',
  },
};

/**
 * Layout racine de l'application.
 * Responsabilités :
 * 1. Fournit les providers globaux (GestureHandler, SafeArea, Paper)
 * 2. Charge la configuration au démarrage depuis le secure store
 * 3. Redirige vers /setup si aucune configuration n'existe
 * 4. Enregistre le callback de toast pour l'errorHandler global
 * 5. Affiche le toast d'erreur global en overlay
 */
export default function RootLayout() {
  const router = useRouter();
  const segments = useSegments();
  const { config, preferences, isAuthenticated, loadConfig, setAuthenticated } = useAppStore();
  const [isReady, setIsReady] = useState(false);
  const [toastMessage, setToastMessage] = useState('');
  const [toastVisible, setToastVisible] = useState(false);

  /**
   * Enregistre le callback de toast dans l'errorHandler au premier montage.
   * Permet à toute la couche API de remonter des erreurs vers l'UI sans couplage direct.
   */
  useEffect(() => {
    registerToastCallback((message) => {
      setToastMessage(message);
      setToastVisible(true);
    });
  }, []);

  const runBiometricAuth = async (): Promise<boolean> => {
    const result = await LocalAuthentication.authenticateAsync({
      promptMessage: 'Authentifiez-vous pour accéder à n8n Pilot',
      cancelLabel: 'Annuler',
    });
    return result.success;
  };

  useEffect(() => {
    const init = async () => {
      await loadConfig();
      const { preferences: prefs } = useAppStore.getState();
      if (prefs.biometricEnabled) {
        const success = await runBiometricAuth();
        setAuthenticated(success);
      } else {
        setAuthenticated(true);
      }
      setIsReady(true);
    };
    init();
  }, []);

  const handleUnlock = async (): Promise<void> => {
    const success = await runBiometricAuth();
    if (success) setAuthenticated(true);
  };

  useEffect(() => {
    if (!isReady) return;
    if (preferences.biometricEnabled && !isAuthenticated) return;
    const inSetup = segments[0] === 'setup';
    if (!config.isConfigured && !inSetup) {
      router.replace('/setup');
    } else if (config.isConfigured && inSetup) {
      router.replace('/(tabs)');
    }
  }, [isReady, config.isConfigured, isAuthenticated, preferences.biometricEnabled, segments]);

  if (!isReady) {
    return (
      <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center', backgroundColor: '#121212' }}>
        <ActivityIndicator color="#FF6D3E" size="large" />
      </View>
    );
  }

  if (preferences.biometricEnabled && !isAuthenticated) {
    return (
      <GestureHandlerRootView style={{ flex: 1 }}>
        <SafeAreaProvider>
          <PaperProvider theme={APP_THEME}>
            <View style={{ flex: 1, alignItems: 'center', justifyContent: 'center', backgroundColor: '#121212', paddingHorizontal: 32 }}>
              <Text variant="headlineMedium" style={{ color: '#FF6D3E', marginBottom: 12 }}>
                n8n Pilot
              </Text>
              <Text variant="bodyMedium" style={{ color: '#FFFFFF', marginBottom: 32, textAlign: 'center' }}>
                Authentification biométrique requise
              </Text>
              <Button mode="contained" onPress={handleUnlock} icon="fingerprint">
                Déverrouiller
              </Button>
            </View>
          </PaperProvider>
        </SafeAreaProvider>
      </GestureHandlerRootView>
    );
  }

  return (
    <GestureHandlerRootView style={{ flex: 1 }}>
      <SafeAreaProvider>
        <PaperProvider theme={APP_THEME}>
          <Stack screenOptions={{ headerShown: false }}>
            <Stack.Screen name="(tabs)" />
            <Stack.Screen
              name="setup"
              options={{
                headerShown: true,
                headerTitle: 'Configuration',
                headerStyle: { backgroundColor: '#1E1E1E' },
                headerTintColor: '#FF6D3E',
              }}
            />
            <Stack.Screen
              name="execution/[id]"
              options={{
                headerShown: true,
                headerTitle: "Logs d'exécution",
                headerStyle: { backgroundColor: '#1E1E1E' },
                headerTintColor: '#FF6D3E',
                presentation: 'card',
              }}
            />
          </Stack>

          {/* Toast global pour toutes les erreurs remontées par l'errorHandler */}
          <Snackbar
            visible={toastVisible}
            onDismiss={() => setToastVisible(false)}
            duration={4000}
            style={{ backgroundColor: '#4A0000' }}
          >
            {toastMessage}
          </Snackbar>
        </PaperProvider>
      </SafeAreaProvider>
    </GestureHandlerRootView>
  );
}