import {
    StatusBar,
    useColorScheme,
    View,
    StyleSheet,
    Text,
    TouchableOpacity,
    Alert,
    NativeModules,
    Image,
    ScrollView,
} from 'react-native';
import { SafeAreaProvider } from 'react-native-safe-area-context';
import { useState, useEffect } from 'react';

import Login from './src/components/Login';
import Register from './src/components/Register';
import { authAPI } from './src/services/authAPI';
import { networkService } from './src/services/networkService';
import { ScannerScreen } from './src/screens/ScannerScreen';
import Map from './src/screens/Map';

type Screen = 'login' | 'register' | 'home' | 'scanner' | 'map';

const { MyNativeModule } = NativeModules;

function App() {
    const isDarkMode = useColorScheme() === 'dark';

    const [currentScreen, setCurrentScreen] = useState<Screen>('login');
    const [isInitialized, setIsInitialized] = useState(false);
    const [isOnline, setIsOnline] = useState(true);
    const [currentUser, setCurrentUser] = useState<any>(null);
    const [qrCode, setQrCode] = useState<string | null>(null);
    const [isGeneratingQR, setIsGeneratingQR] = useState(false);
    const [scannedCodes, setScannedCodes] = useState<any[]>([]);

    /* -------------------- INIT -------------------- */
    useEffect(() => {
        initializeApp();

        console.log('MyNativeModule:', MyNativeModule);
        MyNativeModule?.greet?.('John').then((msg: any) => {
            console.log(msg);
        });

        const unsubscribe = networkService.addListener(networkState => {
            setIsOnline(networkState.isConnected);
        });

        return unsubscribe;
    }, []);

    const initializeApp = async () => {
        try {
            await authAPI.initialize();

            const isLoggedIn = await authAPI.isLoggedIn();
            if (isLoggedIn) {
                const user = await authAPI.getCurrentUser();
                setCurrentUser(user);
                setCurrentScreen('home');
            }
        } catch (error) {
            console.error('Initialization error:', error);
        } finally {
            setIsInitialized(true);
        }
    };

    /* -------------------- NAVIGATION -------------------- */
    const navigateToLogin = () => {
        setCurrentUser(null);
        setQrCode(null);
        setCurrentScreen('login');
    };

    const navigateToRegister = () => {
        setCurrentScreen('register');
    };

    const navigateToHome = async () => {
        const user = await authAPI.getCurrentUser();
        setCurrentUser(user);
        setQrCode(null);
        setCurrentScreen('home');
    };

    const openScanner = () => {
        setCurrentScreen('scanner');
    };

    const openMap = () => {
        setCurrentScreen('map');
    };

    /* -------------------- ACTIONS -------------------- */
    const handleLogout = async () => {
        try {
            await authAPI.logout();
            setQrCode(null);
            navigateToLogin();
            Alert.alert('Success', 'Logged out successfully');
        } catch {
            Alert.alert('Error', 'Failed to logout');
        }
    };

    const showAppStatus = async () => {
        try {
            const status = await authAPI.getAppStatus();
            Alert.alert(
                'App Status',
                `Network: ${status.network.isOnline ? 'Online' : 'Offline'}
Users: ${status.storage.totalUsers}
Current User: ${status.authentication.currentUser || 'None'}
Logged In: ${status.authentication.isLoggedIn ? 'Yes' : 'No'}`
            );
        } catch {
            Alert.alert('Error', 'Failed to get app status');
        }
    };

    const generateQRCode = async () => {
        if (!currentUser?.email) {
            Alert.alert('Error', 'No user email available');
            return;
        }

        setIsGeneratingQR(true);
        try {
            const qrData = `User: ${currentUser.fullName}\nEmail: ${currentUser.email}`;
            const base64Image = await MyNativeModule.generateQRCode(qrData, 300, 300);
            setQrCode(base64Image);
        } catch (error) {
            console.error(error);
            Alert.alert('Error', 'Failed to generate QR code');
        } finally {
            setIsGeneratingQR(false);
        }
    };

    const handleScanResult = (result: any) => {
        setScannedCodes(prev => [
            {
                code: result.code,
                format: result.format,
                timestamp: new Date().toLocaleTimeString(),
            },
            ...prev,
        ]);

        Alert.alert(
            'Scanned Successfully',
            `Code: ${result.code}\nFormat: ${result.format}`,
            [{ text: 'OK', onPress: () => setCurrentScreen('home') }]
        );
    };

    /* -------------------- RENDER -------------------- */
    const renderScreen = () => {
        switch (currentScreen) {
            case 'login':
                return (
                    <Login
                        onNavigateToRegister={navigateToRegister}
                        onLoginSuccess={navigateToHome}
                    />
                );

            case 'register':
                return (
                    <Register
                        onNavigateToLogin={navigateToLogin}
                        onRegisterSuccess={navigateToHome}
                    />
                );

            case 'scanner':
                return (
                    <ScannerScreen
                        presignedUrl="https://your-backend-presigned-url.com"
                        onScan={handleScanResult}
                    />
                );

            case 'home':
                return (
                    <ScrollView style={styles.homeContainer} contentContainerStyle={styles.scrollContent} >
                        <Text style={styles.welcomeText}>
                            Welcome, {currentUser?.fullName || 'User'
                            }
                        </Text>

                        {
                            qrCode && (
                                <Image source={{ uri: qrCode }} style={styles.qrImage} />
                            )
                        }

                        <TouchableOpacity style={styles.scannerButton} onPress={openScanner} >
                            <Text style={styles.buttonText}> Scan QR / Barcode </Text>
                        </TouchableOpacity>

                        < TouchableOpacity
                            style={styles.qrButton}
                            onPress={generateQRCode}
                            disabled={isGeneratingQR}
                        >
                            <Text style={styles.buttonText}>
                                {isGeneratingQR ? 'Generating...' : 'Generate QR Code'}
                            </Text>
                        </TouchableOpacity>

                        < TouchableOpacity style={styles.statusButton} onPress={showAppStatus} >
                            <Text style={styles.buttonText}> App Status </Text>
                        </TouchableOpacity>

                        < TouchableOpacity style={styles.mapButton} onPress={openMap} >
                            <Text style={styles.buttonText}> Open Map </Text>
                        </TouchableOpacity>

                        < TouchableOpacity style={styles.logoutButton} onPress={handleLogout} >
                            <Text style={styles.buttonText}> Logout </Text>
                        </TouchableOpacity>
                    </ScrollView>
                );

            case 'map':
                return (
                    <View style={{ flex: 1 }}>
                        <Map onClose={() => setCurrentScreen('home')} />
                    </View>
                );

            default:
                return null;
        }
    };

    /* -------------------- LOADING -------------------- */
    if (!isInitialized) {
        return (
            <SafeAreaProvider>
                <View style={styles.loadingContainer} >
                    <Text style={styles.loadingText}> Initializing...</Text>
                </View>
            </SafeAreaProvider>
        );
    }

    return (
        <SafeAreaProvider>
            <StatusBar barStyle={isDarkMode ? 'light-content' : 'dark-content'} />
            {renderScreen()}
        </SafeAreaProvider>
    );
}

const styles = StyleSheet.create({
    loadingContainer: { flex: 1, justifyContent: 'center', alignItems: 'center' },
    loadingText: { fontSize: 18, fontWeight: '600' },
    homeContainer: { flex: 1 },
    scrollContent: { alignItems: 'center', padding: 20 },
    welcomeText: { fontSize: 24, fontWeight: '700', marginBottom: 20 },
    qrImage: { width: 300, height: 300, marginBottom: 20 },
    scannerButton: { backgroundColor: '#9333ea', padding: 14, borderRadius: 20, marginBottom: 10 },
    qrButton: { backgroundColor: '#10b981', padding: 14, borderRadius: 20, marginBottom: 10 },
    statusButton: { backgroundColor: '#3bb6d8', padding: 14, borderRadius: 20, marginBottom: 10 },
    mapButton: { backgroundColor: '#2563eb', padding: 14, borderRadius: 20, marginBottom: 10 },
    logoutButton: { backgroundColor: '#ff6b6b', padding: 14, borderRadius: 20 },
    buttonText: { color: '#fff', fontWeight: '600' },
});

export default App;