import React, { useState, useRef } from 'react';
import { View, Text, StyleSheet, ActivityIndicator, TouchableOpacity } from 'react-native';
import { WebView } from 'react-native-webview';
import { Ionicons } from '@expo/vector-icons';
import { SafeAreaView } from 'react-native-safe-area-context';
import * as SecureStore from 'expo-secure-store';
import { AppColors, FontSizes, Spacing } from '@/constants/theme';
import { FullScreenError } from '@/components/ui/ErrorMessage';

const DASHBOARD_URL = 'https://react.eluxnetworks.net/dashboard';

export default function DashboardScreen() {
  const webViewRef = useRef<WebView>(null);
  const [isLoading, setIsLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [canGoBack, setCanGoBack] = useState(false);

  const handleRefresh = () => {
    setError(null);
    setIsLoading(true);
    webViewRef.current?.reload();
  };

  const handleBack = () => {
    if (canGoBack) {
      webViewRef.current?.goBack();
    }
  };

  const handleNavigationStateChange = (navState: any) => {
    setCanGoBack(navState.canGoBack);
  };

  const handleError = () => {
    setError('Failed to load dashboard. Please check your internet connection.');
    setIsLoading(false);
  };

  if (error) {
    return (
      <SafeAreaView style={styles.container} edges={['top']}>
        <View style={styles.header}>
          <Text style={styles.headerTitle}> </Text>
        </View>
        <FullScreenError message={error} onRetry={handleRefresh} />
      </SafeAreaView>
    );
  }

  return (
    <SafeAreaView style={styles.container} edges={['top']}>
      {/* Header */}
      <View style={styles.header}>
        {canGoBack && (
          <TouchableOpacity style={styles.backButton} onPress={handleBack}>
            <Ionicons name="arrow-back" size={24} color={AppColors.textPrimary} />
          </TouchableOpacity>
        )}
        <Text style={[styles.headerTitle, canGoBack && styles.headerTitleWithBack]}>
          {/* Empty title - WebView has its own dashboard header */}
        </Text>
        <TouchableOpacity style={styles.refreshButton} onPress={handleRefresh}>
          <Ionicons name="refresh" size={22} color={AppColors.primary} />
        </TouchableOpacity>
      </View>

      {/* WebView */}
      <View style={styles.webViewContainer}>
        <WebView
          ref={webViewRef}
          source={{ uri: DASHBOARD_URL }}
          style={styles.webView}
          onLoadStart={() => setIsLoading(true)}
          onLoadEnd={() => setIsLoading(false)}
          onError={handleError}
          onHttpError={handleError}
          onNavigationStateChange={handleNavigationStateChange}
          javaScriptEnabled={true}
          domStorageEnabled={true}
          startInLoadingState={true}
          scalesPageToFit={true}
          allowsBackForwardNavigationGestures={true}
          renderLoading={() => (
            <View style={styles.loadingContainer}>
              <ActivityIndicator size="large" color={AppColors.primary} />
              <Text style={styles.loadingText}>Loading dashboard...</Text>
            </View>
          )}
        />

        {isLoading && (
          <View style={styles.loadingOverlay}>
            <ActivityIndicator size="large" color={AppColors.primary} />
          </View>
        )}
      </View>
    </SafeAreaView>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: AppColors.background,
  },
  header: {
    flexDirection: 'row',
    alignItems: 'center',
    paddingHorizontal: Spacing.md,
    paddingVertical: Spacing.sm,
    backgroundColor: AppColors.background,
    borderBottomWidth: 1,
    borderBottomColor: AppColors.border,
  },
  backButton: {
    padding: Spacing.xs,
    marginRight: Spacing.sm,
  },
  headerTitle: {
    flex: 1,
    fontSize: FontSizes.xl,
    fontWeight: '700',
    color: AppColors.textPrimary,
  },
  headerTitleWithBack: {
    marginLeft: 0,
  },
  refreshButton: {
    padding: Spacing.xs,
  },
  webViewContainer: {
    flex: 1,
  },
  webView: {
    flex: 1,
  },
  loadingContainer: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    bottom: 0,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: AppColors.background,
  },
  loadingOverlay: {
    position: 'absolute',
    top: 0,
    left: 0,
    right: 0,
    bottom: 0,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: 'rgba(255,255,255,0.8)',
  },
  loadingText: {
    marginTop: Spacing.md,
    fontSize: FontSizes.base,
    color: AppColors.textSecondary,
  },
});
