import 'package:flutter/foundation.dart';
import 'package:flutter/services.dart';
import 'package:aslan/chatvibe_ui/components/at_tts.dart';
import 'package:url_launcher/url_launcher.dart';
import 'package:webview_flutter/webview_flutter.dart';

class ATWebViewNavigationHandler {
  static const MethodChannel _externalIntentChannel = MethodChannel(
    'com.chat.auu.webview/external_intent',
  );

  static const Set<String> _webSchemes = {
    'about',
    'blob',
    'data',
    'file',
    'http',
    'https',
    'javascript',
  };

  static Future<NavigationDecision> handleNavigationRequest(
    NavigationRequest request,
  ) async {
    final uri = Uri.tryParse(request.url);
    if (uri == null) return NavigationDecision.prevent;

    final scheme = uri.scheme.toLowerCase();
    if (scheme.isEmpty || _webSchemes.contains(scheme)) {
      return NavigationDecision.navigate;
    }

    final launched = await launchExternal(uri);
    if (!launched) {
      showOpenAppFailedTip(uri);
    }

    return NavigationDecision.prevent;
  }

  static Future<bool> handleWebResourceError(WebResourceError error) async {
    final errorUrl = error.url;
    if (errorUrl == null || errorUrl.isEmpty) return false;

    final uri = Uri.tryParse(errorUrl);
    if (uri == null) return false;

    final scheme = uri.scheme.toLowerCase();
    if (scheme.isEmpty || _webSchemes.contains(scheme)) {
      return false;
    }

    final launched = await launchExternal(uri);
    if (!launched) {
      showOpenAppFailedTip(uri);
    }

    return launched;
  }

  static Future<bool> launchExternal(Uri uri) async {
    for (final targetUri in [uri, ..._fallbackUris(uri)]) {
      if (await _tryLaunch(targetUri)) {
        return true;
      }
    }

    return false;
  }

  static Future<bool> _tryLaunch(Uri uri) async {
    if (await _tryLaunchNative(uri)) {
      return true;
    }

    if (defaultTargetPlatform == TargetPlatform.android && _isPaymentUri(uri)) {
      return false;
    }

    try {
      return await launchUrl(uri, mode: LaunchMode.externalApplication);
    } catch (e) {
      debugPrint('Open external app failed: $uri, error: $e');
      return false;
    }
  }

  static Future<bool> _tryLaunchNative(Uri uri) async {
    if (defaultTargetPlatform != TargetPlatform.android) {
      return false;
    }

    try {
      final result = await _externalIntentChannel.invokeMethod<bool>(
        'openExternalUrl',
        uri.toString(),
      );
      return result ?? false;
    } on MissingPluginException {
      return false;
    } catch (e) {
      debugPrint('Open native external app failed: $uri, error: $e');
      return false;
    }
  }

  static List<Uri> _fallbackUris(Uri uri) {
    final fallbackUris = <Uri>[];
    final browserFallbackUrl = _intentFallbackUrl(uri);
    if (browserFallbackUrl != null) {
      fallbackUris.add(browserFallbackUrl);
    }

    final upiFallbackUrl = _upiFallbackUrl(uri);
    if (upiFallbackUrl != null) {
      fallbackUris.add(upiFallbackUrl);
    }

    fallbackUris.addAll(_paymentAppSchemeFallbackUrls(upiFallbackUrl ?? uri));
    fallbackUris.addAll(_upiIntentFallbackUrls(upiFallbackUrl ?? uri));
    return fallbackUris;
  }

  static Uri? _intentFallbackUrl(Uri uri) {
    if (uri.scheme.toLowerCase() != 'intent') return null;

    final fallback = RegExp(
      r'S\.browser_fallback_url=([^;]+)',
    ).firstMatch(uri.toString())?.group(1);
    if (fallback == null || fallback.isEmpty) return null;

    return Uri.tryParse(Uri.decodeComponent(fallback));
  }

  static Uri? _upiFallbackUrl(Uri uri) {
    final scheme = uri.scheme.toLowerCase();
    if (scheme != 'phonepe' &&
        scheme != 'paytmmp' &&
        scheme != 'bhim' &&
        scheme != 'bhimupi') {
      return null;
    }

    final path = uri.path.isNotEmpty ? uri.path : uri.host;
    if (!path.split('/').contains('pay')) return null;

    return uri.replace(scheme: 'upi', host: 'pay', path: '');
  }

  static Iterable<Uri> _paymentAppSchemeFallbackUrls(Uri uri) sync* {
    if (uri.scheme.toLowerCase() != 'upi') return;

    final path = uri.path.isNotEmpty ? uri.path : uri.host;
    if (path != 'pay') return;

    const schemes = ['phonepe', 'paytmmp', 'bhim'];
    for (final scheme in schemes) {
      yield uri.replace(scheme: scheme, host: 'pay', path: '');
    }
  }

  static Iterable<Uri> _upiIntentFallbackUrls(Uri uri) sync* {
    if (!_isPaymentUri(uri)) return;

    final upiUri =
        uri.scheme.toLowerCase() == 'upi' ? uri : _upiFallbackUrl(uri);
    if (upiUri == null) return;

    final path = upiUri.path.isNotEmpty ? upiUri.path : upiUri.host;
    if (path != 'pay') return;

    const packageNames = [
      'com.phonepe.app',
      'net.one97.paytm',
      'com.google.android.apps.nbu.paisa.user',
      'in.org.npci.upiapp',
    ];
    final query = upiUri.hasQuery ? '?${upiUri.query}' : '';
    for (final packageName in packageNames) {
      yield Uri.parse(
        'intent://pay$query#Intent;scheme=upi;package=$packageName;end',
      );
    }
  }

  static bool _isPaymentUri(Uri uri) {
    final scheme = uri.scheme.toLowerCase();
    return scheme == 'phonepe' ||
        scheme == 'paytmmp' ||
        scheme == 'bhim' ||
        scheme == 'bhimupi' ||
        scheme == 'upi' ||
        scheme == 'intent';
  }

  static void showOpenAppFailedTip(Uri uri) {
    ATTts.show(
      _isPaymentUri(uri)
          ? 'Please install or set up the payment app first.'
          : 'App is not installed.',
    );
  }
}