import 'package:flutter/material.dart';
import 'package:real_estate_mobile/core/constants/app_colors.dart';
import 'package:real_estate_mobile/core/services/twitter_auth_service.dart';
import 'package:webview_flutter/webview_flutter.dart';

/// Opens a webview for Twitter OAuth 2.0 PKCE login.
/// Returns the user data map on success, or null on cancel/failure.
class TwitterLoginScreen extends StatefulWidget {
  const TwitterLoginScreen({super.key});

  @override
  State<TwitterLoginScreen> createState() => _TwitterLoginScreenState();
}

class _TwitterLoginScreenState extends State<TwitterLoginScreen> {
  late final TwitterAuthService _authService;
  late final WebViewController _webViewController;
  bool _isExchanging = false;

  @override
  void initState() {
    super.initState();
    _authService = TwitterAuthService();
    _webViewController = WebViewController()
      ..setJavaScriptMode(JavaScriptMode.unrestricted)
      ..setUserAgent(
        'Mozilla/5.0 (iPhone; CPU iPhone OS 17_0 like Mac OS X) '
        'AppleWebKit/605.1.15 (KHTML, like Gecko) Version/17.0 '
        'Mobile/15E148 Safari/604.1',
      )
      ..setNavigationDelegate(NavigationDelegate(
        onPageStarted: (url) {
          final code = _authService.extractCodeFromUrl(url);
          if (code != null) {
            _handleCode(code);
          }
        },
        onNavigationRequest: (request) {
          final code = _authService.extractCodeFromUrl(request.url);
          if (code != null) {
            _handleCode(code);
            return NavigationDecision.prevent;
          }
          // User cancelled — Twitter redirects to main page or login
          final url = request.url;
          if (url == 'https://twitter.com/' ||
              url == 'https://x.com/' ||
              url.startsWith('https://twitter.com/home') ||
              url.startsWith('https://x.com/home') ||
              url.startsWith('https://twitter.com/i/flow/login') ||
              url.startsWith('https://x.com/i/flow/login')) {
            Navigator.pop(context, null);
            return NavigationDecision.prevent;
          }
          return NavigationDecision.navigate;
        },
      ))
      ..loadRequest(Uri.parse(_authService.authorizationUrl));
  }

  Future<void> _handleCode(String code) async {
    if (_isExchanging) return;
    setState(() => _isExchanging = true);

    try {
      final userData = await _authService.exchangeCodeForUser(code);
      if (mounted) Navigator.pop(context, userData);
    } catch (e) {
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(content: Text('X login failed. Please try again.')),
        );
        Navigator.pop(context, null);
      }
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: SafeArea(
        child: Column(
          children: [
            // Minimal top bar with back button
            SizedBox(
              height: 44,
              child: Row(
                children: [
                  IconButton(
                    icon: const Icon(Icons.arrow_back_ios_new_rounded,
                        size: 18, color: AppColors.primaryDark),
                    onPressed: () => Navigator.pop(context, null),
                  ),
                  const Expanded(
                    child: Text(
                      'Sign in with X',
                      textAlign: TextAlign.center,
                      style: TextStyle(
                        fontFamily: 'Fractul',
                        fontSize: 15,
                        fontWeight: FontWeight.w600,
                        color: AppColors.primaryDark,
                      ),
                    ),
                  ),
                  const SizedBox(width: 48),
                ],
              ),
            ),
            // Webview
            Expanded(
              child: Stack(
                children: [
                  WebViewWidget(controller: _webViewController),
                  if (_isExchanging)
                    Container(
                      color: Colors.white.withValues(alpha: 0.8),
                      child: const Center(
                        child: Column(
                          mainAxisSize: MainAxisSize.min,
                          children: [
                            CircularProgressIndicator(
                                color: AppColors.accentOrange),
                            SizedBox(height: 16),
                            Text('Signing in...',
                                style: TextStyle(
                                  fontFamily: 'Fractul',
                                  fontSize: 14,
                                  color: AppColors.primaryDark,
                                )),
                          ],
                        ),
                      ),
                    ),
                ],
              ),
            ),
          ],
        ),
      ),
    );
  }
}