import 'package:flutter/material.dart';
import 'package:flutter_riverpod/flutter_riverpod.dart';
import 'package:go_router/go_router.dart';
import '../widgets/auth_form.dart';
import '../widgets/auth_button.dart';
import '../../../../providers/auth_provider.dart';
import '../../../../core/errors/auth_exceptions.dart';

/// Login screen with email/password authentication
class LoginPage extends ConsumerStatefulWidget {
  const LoginPage({super.key});

  @override
  ConsumerState<LoginPage> createState() => _LoginPageState();
}

class _LoginPageState extends ConsumerState<LoginPage> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  
  bool _isLoading = false;
  String? _errorMessage;

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Sign In'),
        centerTitle: true,
        elevation: 0,
        backgroundColor: Colors.transparent,
        foregroundColor: Theme.of(context).colorScheme.onSurface,
      ),
      body: SafeArea(
        child: Padding(
          padding: const EdgeInsets.all(24.0),
          child: Center(
            child: SingleChildScrollView(
              child: Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.stretch,
                children: [
                  // Logo or app title could go here
                  Icon(
                    Icons.inventory_2_outlined,
                    size: 80,
                    color: Theme.of(context).colorScheme.primary,
                  ),
                  const SizedBox(height: 32),
                  
                  Text(
                    'Welcome Back',
                    style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                      fontWeight: FontWeight.bold,
                      color: Theme.of(context).colorScheme.onSurface,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 8),
                  
                  Text(
                    'Sign in to track your household inventory',
                    style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                      color: Theme.of(context).colorScheme.onSurfaceVariant,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 32),
                  
                  // Authentication form
                  AuthForm(
                    formKey: _formKey,
                    email: _emailController.text,
                    onEmailChanged: (value) {
                      setState(() {
                        _errorMessage = null;
                        _emailController.text = value;
                      });
                    },
                    emailError: null,
                    password: _passwordController.text,
                    onPasswordChanged: (value) {
                      setState(() {
                        _errorMessage = null;
                        _passwordController.text = value;
                      });
                    },
                    passwordError: null,
                    onSubmit: _handleLogin,
                    submitButtonText: 'Sign In',
                    isLoading: _isLoading,
                    autofocusEmail: true,
),
                   const SizedBox(height: 16),
                   
                   // Error message display
                   if (_errorMessage != null) ...[
                     Container(
                       padding: const EdgeInsets.all(12),
                       decoration: BoxDecoration(
                         color: Theme.of(context).colorScheme.errorContainer,
                         borderRadius: BorderRadius.circular(8),
                         border: Border.all(
                           color: Theme.of(context).colorScheme.error,
                           width: 1,
                         ),
                       ),
                       child: Row(
                         children: [
                           Icon(
                             Icons.error_outline,
                             size: 20,
                             color: Theme.of(context).colorScheme.error,
                           ),
                           const SizedBox(width: 8),
                           Expanded(
                             child: Text(
                               _errorMessage!,
                               style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                                 color: Theme.of(context).colorScheme.onErrorContainer,
                               ),
                             ),
                           ),
                         ],
                       ),
                     ),
                     const SizedBox(height: 16),
                   ],
                   
                   // Forgot password link
                  Align(
                    alignment: Alignment.centerRight,
                    child: TextButton(
                      onPressed: _handleForgotPassword,
                      child: Text(
                        'Forgot Password?',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.primary,
                          fontWeight: FontWeight.w500,
                        ),
                      ),
                    ),
                  ),
                  const SizedBox(height: 24),
                  
                  // Sign up link
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text(
                        'Don\'t have an account? ',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.onSurfaceVariant,
                        ),
                      ),
                      TextButton(
                        onPressed: _handleSignUp,
                        child: Text(
                          'Sign Up',
                          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                            color: Theme.of(context).colorScheme.primary,
                            fontWeight: FontWeight.w600,
                          ),
                        ),
                      ),
                    ],
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  Future<void> _handleLogin() async {
    // Clear previous errors
    setState(() {
      _errorMessage = null;
    });

    // Validate form
    if (!_formKey.currentState!.validate()) {
      return;
    }

    // Check for empty fields
    final email = _emailController.text.trim();
    final password = _passwordController.text;
    
    if (email.isEmpty || password.isEmpty) {
      setState(() {
        _errorMessage = 'Please enter both email and password';
      });
      return;
    }

    // Show loading state
    setState(() {
      _isLoading = true;
    });

    try {
      final authProvider = ref.read(authProvider.notifier);
      await authProvider.signIn(email, password);
      
      if (mounted) {
        // Navigate to home or dashboard
        context.go('/home');
      }
    } catch (e) {
      if (mounted) {
        setState(() {
          _isLoading = false;
          _errorMessage = _mapErrorToUserFriendlyMessage(e);
        });
        
        // Announce error for accessibility
        _announceErrorForAccessibility(_errorMessage!);
      }
    }
  }

  /// Maps authentication exceptions to user-friendly error messages
  String _mapErrorToUserFriendlyMessage(Object error) {
    if (error is InvalidCredentialsException) {
      return 'Invalid password. Please check your password and try again.';
    } else if (error is UserNotFoundException) {
      return 'Account not found. Please check your email address or sign up for a new account.';
    } else if (error is NetworkException) {
      return 'Network connection failed. Please check your internet connection and try again.';
    } else if (error is SessionExpiredException) {
      return 'Your session has expired. Please sign in again.';
    } else if (error is EmailNotVerifiedException) {
      return 'Please verify your email address before signing in. Check your inbox for verification email.';
    } else if (error is AuthDisabledException) {
      return 'Authentication is currently disabled. Please try again later.';
    } else if (error is TooManyRequestsException) {
      return 'Too many login attempts. Please wait a moment and try again.';
    } else if (error is AuthException) {
      return error.message;
    } else {
      return 'An unexpected error occurred. Please try again.';
    }
  }

  /// Announces error message for screen readers
  void _announceErrorForAccessibility(String errorMessage) {
    // Use Semantics to announce the error for screen readers
    SemanticsService.announce(errorMessage, TextDirection.ltr);
  }

  void _handleForgotPassword() {
    // Navigate to password reset page
    context.go('/reset-password');
  }

  void _handleSignUp() {
    // Navigate to sign up page
    context.go('/signup');
  }
}