import 'dart:async';

import 'package:flutter/material.dart';
import 'package:http/http.dart' as http;
import 'package:provider/provider.dart';

import '../../../core/constants/env_config.dart';
import '../../../core/theme/theme_provider.dart';
import '../../../core/utils/validators.dart';
import '../../../data/datasources/event_remote_data_source.dart';
import '../../../data/datasources/user_remote_data_source.dart';
import '../../../data/models/user_model.dart';
import '../../../data/providers/user_provider.dart';
import '../../../data/services/preferences_helper.dart';
import '../../../data/services/secure_storage.dart';
import '../../../domain/entities/user.dart';
import '../../widgets/custom_button.dart';
import '../home/home_screen.dart';
import '../signup/SignUpScreen.dart';

/// Écran de connexion avec design moderne et compact.
///
/// Cet écran permet aux utilisateurs de s'authentifier avec leur email
/// et mot de passe. Il inclut la validation des champs, la gestion d'erreurs,
/// et une interface utilisateur optimisée.
///
/// **Fonctionnalités:**
/// - Validation des champs en temps réel
/// - Affichage/masquage du mot de passe
/// - Gestion d'erreurs robuste
/// - Support du thème clair/sombre
/// - Navigation vers l'inscription
class LoginScreen extends StatefulWidget {
  const LoginScreen({super.key});

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

class _LoginScreenState extends State<LoginScreen>
    with SingleTickerProviderStateMixin {
  // ============================================================================
  // FORMULAIRE
  // ============================================================================

  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();

  // ============================================================================
  // ÉTATS
  // ============================================================================

  bool _isPasswordVisible = false;
  bool _isSubmitting = false;
  String? _errorMessage;

  // ============================================================================
  // SERVICES
  // ============================================================================

  late final UserRemoteDataSource _userRemoteDataSource;
  late final SecureStorage _secureStorage;
  late final PreferencesHelper _preferencesHelper;

  // ============================================================================
  // ANIMATIONS
  // ============================================================================

  late AnimationController _animationController;
  late Animation<double> _fadeAnimation;

  @override
  void initState() {
    super.initState();
    _initializeServices();
    _initializeAnimations();
  }

  void _initializeServices() {
    _userRemoteDataSource = UserRemoteDataSource(http.Client());
    _secureStorage = SecureStorage();
    _preferencesHelper = PreferencesHelper();
  }

  void _initializeAnimations() {
    _animationController = AnimationController(
      vsync: this,
      duration: const Duration(milliseconds: 800),
    );
    _fadeAnimation = CurvedAnimation(
      parent: _animationController,
      curve: Curves.easeIn,
    );
    _animationController.forward();
  }

  @override
  void dispose() {
    _emailController.dispose();
    _passwordController.dispose();
    _animationController.dispose();
    super.dispose();
  }

  // ============================================================================
  // ACTIONS
  // ============================================================================

  /// Bascule la visibilité du mot de passe.
  void _togglePasswordVisibility() {
    setState(() {
      _isPasswordVisible = !_isPasswordVisible;
    });
  }

  /// Soumet le formulaire de connexion.
  Future<void> _handleSubmit() async {
    if (!_formKey.currentState!.validate()) {
      return;
    }

    setState(() {
      _isSubmitting = true;
      _errorMessage = null;
    });

    try {
      final email = _emailController.text.trim();
      final password = _passwordController.text;

      final user = await _userRemoteDataSource.authenticateUser(email, password);

      if (user.userId.isEmpty) {
        throw Exception('ID utilisateur manquant dans la réponse');
      }

      await _saveUserData(user);
      await _navigateToHome(user);
    } catch (e) {
      _handleError(e);
    } finally {
      if (mounted) {
        setState(() {
          _isSubmitting = false;
        });
      }
    }
  }

  /// Sauvegarde les données utilisateur.
  Future<void> _saveUserData(UserModel user) async {
    await _secureStorage.saveUserId(user.userId);
    await _preferencesHelper.saveUserName(user.userLastName);
    await _preferencesHelper.saveUserLastName(user.userFirstName);

    final userProvider = Provider.of<UserProvider>(context, listen: false);
    userProvider.setUser(
      User(
        userId: user.userId,
        userLastName: user.userLastName,
        userFirstName: user.userFirstName,
        email: user.email,
        motDePasse: 'motDePasseHashé',
        profileImageUrl: user.profileImageUrl,
        eventsCount: user.eventsCount ?? 0,
        friendsCount: user.friendsCount ?? 0,
        postsCount: user.postsCount ?? 0,
        visitedPlacesCount: user.visitedPlacesCount ?? 0,
      ),
    );
  }

  /// Navigue vers l'écran d'accueil.
  Future<void> _navigateToHome(UserModel user) async {
    if (!mounted) return;

    Navigator.pushReplacement(
      context,
      MaterialPageRoute(
        builder: (context) => HomeScreen(
          userId: user.userId,
          userFirstName: user.userFirstName,
          userLastName: user.userLastName,
          userProfileImage: user.profileImageUrl,
          eventRemoteDataSource: EventRemoteDataSource(http.Client()),
        ),
      ),
    );
  }

  /// Gère les erreurs de connexion.
  void _handleError(Object error) {
    String message = 'Erreur lors de la connexion';

    if (error.toString().contains('Unauthorized') ||
        error.toString().contains('incorrect')) {
      message = 'Email ou mot de passe incorrect';
    } else if (error.toString().contains('network') ||
        error.toString().contains('timeout')) {
      message = 'Problème de connexion. Vérifiez votre réseau';
    } else {
      message = error.toString().replaceAll('Exception: ', '');
    }

    setState(() {
      _errorMessage = message;
    });

    if (EnvConfig.enableDetailedLogs) {
      debugPrint('[LoginScreen] Erreur: $error');
    }
  }

  /// Navigue vers l'écran d'inscription.
  void _navigateToSignUp() {
    Navigator.push(
      context,
      MaterialPageRoute(
        builder: (context) => const SignUpScreen(),
      ),
    );
  }

  /// Gère la réinitialisation du mot de passe.
  Future<void> _handleForgotPassword() async {
    final emailController = TextEditingController();
    final formKey = GlobalKey<FormState>();

    final result = await showDialog<bool>(
      context: context,
      builder: (context) => AlertDialog(
        title: const Text('Réinitialisation du mot de passe'),
        content: Form(
          key: formKey,
          child: TextFormField(
            controller: emailController,
            keyboardType: TextInputType.emailAddress,
            decoration: const InputDecoration(
              labelText: 'Email',
              hintText: 'Entrez votre email',
            ),
            validator: Validators.validateEmail,
          ),
        ),
        actions: [
          TextButton(
            onPressed: () => Navigator.pop(context, false),
            child: const Text('Annuler'),
          ),
          TextButton(
            onPressed: () {
              if (formKey.currentState!.validate()) {
                Navigator.pop(context, true);
              }
            },
            child: const Text('Envoyer'),
          ),
        ],
      ),
    );

    if (result == true && emailController.text.isNotEmpty) {
      try {
        await _userRemoteDataSource.requestPasswordReset(
          emailController.text.trim(),
        );
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text(
                'Un email de réinitialisation a été envoyé à votre adresse',
              ),
              behavior: SnackBarBehavior.floating,
            ),
          );
        }
      } catch (e) {
        if (mounted) {
          ScaffoldMessenger.of(context).showSnackBar(
            SnackBar(
              content: Text('Erreur: ${e.toString()}'),
              behavior: SnackBarBehavior.floating,
            ),
          );
        }
      }
    }
  }

  // ============================================================================
  // BUILD
  // ============================================================================

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final isKeyboardVisible = MediaQuery.of(context).viewInsets.bottom > 0;

    return Scaffold(
      body: Stack(
        children: [
          _buildBackground(theme),
          _buildContent(theme, isKeyboardVisible),
          _buildThemeToggle(theme),
          if (_isSubmitting) _buildLoadingOverlay(theme),
        ],
      ),
    );
  }

  /// Construit l'arrière-plan avec dégradé.
  Widget _buildBackground(ThemeData theme) {
    return AnimatedContainer(
      duration: const Duration(seconds: 3),
      decoration: BoxDecoration(
        gradient: LinearGradient(
          colors: [
            theme.colorScheme.primary,
            theme.colorScheme.secondary,
          ],
          begin: Alignment.topLeft,
          end: Alignment.bottomRight,
        ),
      ),
    );
  }

  /// Construit le contenu principal.
  Widget _buildContent(ThemeData theme, bool isKeyboardVisible) {
    return FadeTransition(
      opacity: _fadeAnimation,
      child: Center(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(24),
          child: Form(
            key: _formKey,
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: [
                if (!isKeyboardVisible) _buildLogo(theme),
                if (!isKeyboardVisible) const SizedBox(height: 32),
                _buildTitle(theme),
                const SizedBox(height: 40),
                _buildEmailField(theme),
                const SizedBox(height: 16),
                _buildPasswordField(theme),
                const SizedBox(height: 24),
                _buildSubmitButton(theme),
                const SizedBox(height: 16),
                _buildSignUpLink(theme),
                _buildForgotPasswordLink(theme),
                if (_errorMessage != null) _buildErrorMessage(theme),
              ],
            ),
          ),
        ),
      ),
    );
  }

  /// Construit le logo.
  Widget _buildLogo(ThemeData theme) {
    return Image.asset(
      'lib/assets/images/logo.png',
      height: 120,
      errorBuilder: (context, error, stackTrace) {
        return Icon(
          Icons.event,
          size: 80,
          color: theme.colorScheme.onPrimary,
        );
      },
    );
  }

  /// Construit le titre.
  Widget _buildTitle(ThemeData theme) {
    return Text(
      'Bienvenue sur AfterWork',
      style: theme.textTheme.headlineSmall?.copyWith(
        color: theme.colorScheme.onPrimary,
        fontWeight: FontWeight.bold,
      ),
      textAlign: TextAlign.center,
    );
  }

  /// Construit le champ email.
  Widget _buildEmailField(ThemeData theme) {
    return TextFormField(
      controller: _emailController,
      keyboardType: TextInputType.emailAddress,
      textInputAction: TextInputAction.next,
      decoration: InputDecoration(
        labelText: 'Email',
        prefixIcon: Icon(Icons.email, color: theme.colorScheme.onPrimary),
        filled: true,
        fillColor: theme.colorScheme.onPrimary.withOpacity(0.1),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(
            color: theme.colorScheme.onPrimary.withOpacity(0.3),
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(
            color: theme.colorScheme.onPrimary,
            width: 2,
          ),
        ),
        labelStyle: TextStyle(color: theme.colorScheme.onPrimary),
      ),
      style: TextStyle(color: theme.colorScheme.onPrimary),
      validator: Validators.validateEmail,
    );
  }

  /// Construit le champ mot de passe.
  Widget _buildPasswordField(ThemeData theme) {
    return TextFormField(
      controller: _passwordController,
      obscureText: !_isPasswordVisible,
      textInputAction: TextInputAction.done,
      onFieldSubmitted: (_) => _handleSubmit(),
      decoration: InputDecoration(
        labelText: 'Mot de passe',
        prefixIcon: Icon(Icons.lock, color: theme.colorScheme.onPrimary),
        suffixIcon: IconButton(
          icon: Icon(
            _isPasswordVisible ? Icons.visibility : Icons.visibility_off,
            color: theme.colorScheme.onPrimary.withOpacity(0.7),
          ),
          onPressed: _togglePasswordVisibility,
        ),
        filled: true,
        fillColor: theme.colorScheme.onPrimary.withOpacity(0.1),
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide.none,
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(
            color: theme.colorScheme.onPrimary.withOpacity(0.3),
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(12),
          borderSide: BorderSide(
            color: theme.colorScheme.onPrimary,
            width: 2,
          ),
        ),
        labelStyle: TextStyle(color: theme.colorScheme.onPrimary),
      ),
      style: TextStyle(color: theme.colorScheme.onPrimary),
      validator: Validators.validatePassword,
    );
  }

  /// Construit le bouton de soumission (compact).
  Widget _buildSubmitButton(ThemeData theme) {
    return SizedBox(
      width: double.infinity,
      child: CustomButton(
        text: 'Connexion',
        icon: Icons.login,
        onPressed: () => _handleSubmit(),
        isLoading: _isSubmitting,
        isEnabled: !_isSubmitting,
        variant: ButtonVariant.primary,
        size: ButtonSize.medium,
      ),
    );
  }

  /// Construit le lien vers l'inscription.
  Widget _buildSignUpLink(ThemeData theme) {
    return TextButton(
      onPressed: _navigateToSignUp,
      child: Text(
        'Pas encore de compte ? Inscrivez-vous',
        style: theme.textTheme.bodyMedium?.copyWith(
          color: theme.colorScheme.onPrimary.withOpacity(0.9),
          decoration: TextDecoration.underline,
        ),
      ),
    );
  }

  /// Construit le lien mot de passe oublié.
  Widget _buildForgotPasswordLink(ThemeData theme) {
    return TextButton(
      onPressed: _handleForgotPassword,
      child: Text(
        'Mot de passe oublié ?',
        style: theme.textTheme.bodySmall?.copyWith(
          color: theme.colorScheme.onPrimary.withOpacity(0.7),
        ),
      ),
    );
  }

  /// Construit le message d'erreur.
  Widget _buildErrorMessage(ThemeData theme) {
    return Padding(
      padding: const EdgeInsets.only(top: 16),
      child: Container(
        padding: const EdgeInsets.all(12),
        decoration: BoxDecoration(
          color: theme.colorScheme.error.withOpacity(0.1),
          borderRadius: BorderRadius.circular(8),
          border: Border.all(
            color: theme.colorScheme.error.withOpacity(0.3),
          ),
        ),
        child: Row(
          children: [
            Icon(
              Icons.error_outline,
              color: theme.colorScheme.error,
              size: 20,
            ),
            const SizedBox(width: 8),
            Expanded(
              child: Text(
                _errorMessage!,
                style: theme.textTheme.bodySmall?.copyWith(
                  color: theme.colorScheme.error,
                ),
              ),
            ),
          ],
        ),
      ),
    );
  }

  /// Construit le bouton de basculement de thème.
  Widget _buildThemeToggle(ThemeData theme) {
    return Positioned(
      top: MediaQuery.of(context).padding.top + 8,
      right: 16,
      child: IconButton(
        icon: Icon(
          Provider.of<ThemeProvider>(context).isDarkMode
              ? Icons.light_mode
              : Icons.dark_mode,
          color: theme.colorScheme.onPrimary,
        ),
        onPressed: () {
          Provider.of<ThemeProvider>(context, listen: false).toggleTheme();
        },
        tooltip: 'Changer le thème',
      ),
    );
  }

  /// Construit l'overlay de chargement.
  Widget _buildLoadingOverlay(ThemeData theme) {
    return Container(
      color: Colors.black.withOpacity(0.3),
      child: Center(
        child: CircularProgressIndicator(
          valueColor: AlwaysStoppedAnimation<Color>(
            theme.colorScheme.onPrimary,
          ),
        ),
      ),
    );
  }
}