import 'dart:async';
import 'dart:convert';

import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:flutter_dotenv/flutter_dotenv.dart';
import 'package:go_router/go_router.dart';
import 'package:google_sign_in/google_sign_in.dart';
import 'package:google_sign_in_web/web_only.dart' as web;
import 'package:qpay/models/responsive_policy.dart';
import 'package:qpay/screens/onboarding/login/login_controller.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:skeletonizer/skeletonizer.dart';

class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

  @override
  State<LoginScreen> createState() => _LoginScreenState();
}

class _LoginScreenState extends State<LoginScreen> {
  late SharedPreferences prefs;
  late GoogleSignIn googleSignIn;

  final _formKey = GlobalKey<FormState>();
  bool _loading = false;

  List<String> scopes = <String>[
    'https://www.googleapis.com/auth/contacts.readonly',
  ];

  late LoginController _loginController;
  StreamSubscription<GoogleSignInAuthenticationEvent>? _authSubscription;

  @override
  void initState() {
    super.initState();
    _loginController = LoginController(context);

    googleSignIn = GoogleSignIn.instance;
    if (kIsWeb) {
      googleSignIn.initialize();
      _authSubscription = googleSignIn.authenticationEvents
          .handleError(_handleAuthenticationError)
          .listen(_handleAuthenticationEvent);
    } else {
      unawaited(
        googleSignIn.initialize(serverClientId: dotenv.env['CLIENTID']),
      );
    }
  }

  Future<void> signInWithGoogle() async {
    if (GoogleSignIn.instance.supportsAuthenticate()) {
      _authSubscription?.cancel();
      unawaited(
        GoogleSignIn.instance.authenticate().then((value) async {
          _authSubscription = googleSignIn.authenticationEvents
              .handleError(_handleAuthenticationError)
              .listen(_handleAuthenticationEvent);
        }),
      );
    }
  }

  void saveUser(GoogleSignInAccount user) async {
    final Map<String, dynamic> data = <String, dynamic>{
      'displayName': user.displayName,
      'email': user.email,
      'id': user.id,
      'photoUrl': user.photoUrl,
    };

    prefs = await SharedPreferences.getInstance();
    if (prefs.getString("googleUser") == null) {
      prefs.setString("googleUser", jsonEncode(data));
    }
  }

  Future<void> _handleAuthenticationEvent(
    GoogleSignInAuthenticationEvent event,
  ) async {
    if (!mounted) return;

    // #docregion CheckAuthorization
    final GoogleSignInAccount? user = // ...
        // #enddocregion CheckAuthorization
        switch (event) {
          GoogleSignInAuthenticationEventSignIn() => event.user,
          GoogleSignInAuthenticationEventSignOut() => null,
        };

    if (user == null || !mounted) return;

    // Check for existing authorization.
    // #docregion CheckAuthorization
    final GoogleSignInClientAuthorization? authorization = await user
        ?.authorizationClient
        .authorizationForScopes(scopes);
    // #enddocregion CheckAuthorization

    print(user);
    saveUser(user);

    if (!mounted) return;

    final response = await _loginController.login(user.email, user.id);
    if (response.isSuccess) {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text("Login successful!"),
          behavior: SnackBarBehavior.floating,
          backgroundColor: Colors.green,
        ),
      );
    } else {
      ScaffoldMessenger.of(context).showSnackBar(
        SnackBar(
          content: Text(response.error ?? "Login failed"),
          behavior: SnackBarBehavior.floating,
          backgroundColor: Colors.deepOrange,
        ),
      );
    }
    if (!mounted) return;
    context.go('/');
  }

  Future<void> _handleAuthenticationError(Object e) async {
    print(e.toString());
  }

  @override
  void dispose() {
    _authSubscription?.cancel();
    _loginController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SingleChildScrollView(
        child: Padding(
          padding: const EdgeInsets.all(25),
          child: Form(
            key: _formKey,
            child: Center(
              child: LayoutBuilder(
                builder: (context, constraints) {
                  final maxWidth = constraints.maxWidth > ResponsivePolicy.md
                      ? ResponsivePolicy.md.toDouble()
                      : constraints.maxWidth;
                  return SizedBox(
                    width: maxWidth,
                    child: Column(
                      mainAxisAlignment: MainAxisAlignment.center,
                      crossAxisAlignment: CrossAxisAlignment.center,
                      children: [
                        SizedBox(height: 75),
                        Text(
                          'Login',
                          style: TextStyle(
                            fontSize: 30,
                            fontWeight: FontWeight.bold,
                            color: Theme.of(context).colorScheme.primary,
                          ),
                        ),
                        SizedBox(height: 5),
                        Text(
                          'Welcome back to Velocity',
                          style: TextStyle(fontSize: 18),
                          textAlign: TextAlign.center,
                        ),
                        SizedBox(height: 30),
                        Image.asset('assets/password.png', width: 300),
                        Text(
                          'Tap on your preferred social media platform to get started',
                          style: TextStyle(fontSize: 18),
                          textAlign: TextAlign.center,
                        ),
                        // Username Field
                        SizedBox(height: 20),
                        // Forgot Password Link
                        // Divider with "or" text
                        Row(
                          children: [
                            Expanded(
                              child: Divider(color: Colors.grey.shade300),
                            ),
                            Padding(
                              padding: EdgeInsets.symmetric(horizontal: 16),
                              child: Text(
                                'choose from the options below to continue',
                                style: TextStyle(
                                  color: Colors.grey.shade600,
                                  fontSize: 14,
                                ),
                                textAlign: TextAlign.center,
                              ),
                            ),
                            Expanded(
                              child: Divider(color: Colors.grey.shade300),
                            ),
                          ],
                        ),
                        SizedBox(height: 30),
                        // Social Login Buttons
                        if (GoogleSignIn.instance.supportsAuthenticate())
                          _buildGoogleButton()
                        else ...<Widget>[if (kIsWeb) web.renderButton()],
                        SizedBox(height: 40),
                        TextButton(
                          onPressed: () {
                            context.go('/');
                          },
                          child: Text(
                            'Continue as guest?',
                            style: TextStyle(fontSize: 14),
                          ),
                        ),
                      ],
                    ),
                  );
                },
              ),
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildGoogleButton() {
    return Skeletonizer(
      enabled: _loading,
      child: Row(
        children: [
          Expanded(
            child: OutlinedButton.icon(
              onPressed: () {
                signInWithGoogle();
              },
              icon: Image.asset('assets/google.png', width: 20, height: 20),
              label: Text('Google', style: TextStyle(fontSize: 16)),
              style: OutlinedButton.styleFrom(
                padding: EdgeInsets.symmetric(vertical: 16),
                side: BorderSide(color: Colors.grey.shade300),
                shape: RoundedRectangleBorder(
                  borderRadius: BorderRadius.circular(12),
                ),
              ),
            ),
          ),
          SizedBox(width: 16),
        ],
      ),
    );
  }
}