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';

/// Sign up screen with user registration
class SignupPage extends ConsumerStatefulWidget {
  const SignupPage({super.key});

  @override
  ConsumerState<SignupPage> createState() => _SignupPageState();
}

class _SignupPageState extends ConsumerState<SignupPage> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  final _passwordController = TextEditingController();
  final _confirmPasswordController = TextEditingController();
  
  bool _isLoading = false;
  String? _errorMessage;
  bool _agreedToTerms = false;

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

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Sign Up'),
        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(
                    'Create Account',
                    style: Theme.of(context).textTheme.headlineMedium?.copyWith(
                      fontWeight: FontWeight.bold,
                      color: Theme.of(context).colorScheme.onSurface,
                    ),
                    textAlign: TextAlign.center,
                  ),
                  const SizedBox(height: 8),
                  
                  Text(
                    'Start tracking your household inventory today',
                    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,
                    confirmPassword: _confirmPasswordController.text,
                    onConfirmPasswordChanged: (value) {
                      setState(() {
                        _errorMessage = null;
                        _confirmPasswordController.text = value;
                      });
                    },
                    confirmPasswordError: null,
                    onSubmit: _handleSignup,
                    submitButtonText: 'Create Account',
                    isLoading: _isLoading,
                    autofocusEmail: true,
                    formWideError: _errorMessage,
                    onErrorDismissed: () {
                      setState(() {
                        _errorMessage = null;
                      });
                    },
                  ),
                   
                   // Terms and conditions checkbox
                  _buildTermsCheckbox(),
                  const SizedBox(height: 24),
                  
                  // Sign in link
                  Row(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: [
                      Text(
                        'Already have an account? ',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.onSurfaceVariant,
                        ),
                      ),
                      TextButton(
                        onPressed: _handleSignIn,
                        child: Text(
                          'Sign In',
                          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                            color: Theme.of(context).colorScheme.primary,
                            fontWeight: FontWeight.w600,
                          ),
                        ),
                      ),
                    ],
                  ),
                  const SizedBox(height: 12),
                  
                  // Forgot password link
                  Align(
                    alignment: Alignment.center,
                    child: TextButton(
                      onPressed: _handleForgotPassword,
                      child: Text(
                        'Forgot Password?',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.primary,
                          fontWeight: FontWeight.w500,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }

  Widget _buildTermsCheckbox() {
    return Row(
      children: [
        Checkbox(
          value: _agreedToTerms,
          onChanged: (value) {
            setState(() {
              _agreedToTerms = value ?? false;
            });
          },
          materialTapTargetSize: MaterialTapTargetSize.shrinkWrap,
        ),
        Expanded(
          child: GestureDetector(
            onTap: () {
              setState(() {
                _agreedToTerms = !_agreedToTerms;
              });
            },
            child: Text.rich(
              TextSpan(
                text: 'I agree to the ',
                style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                  color: Theme.of(context).colorScheme.onSurface,
                ),
                children: [
                  WidgetSpan(
                    child: GestureDetector(
                      onTap: _handleTermsOfService,
                      child: Text(
                        'Terms of Service',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.primary,
                          decoration: TextDecoration.underline,
                        ),
                      ),
                    ),
                  ),
                  const TextSpan(text: ' and '),
                  WidgetSpan(
                    child: GestureDetector(
                      onTap: _handlePrivacyPolicy,
                      child: Text(
                        'Privacy Policy',
                        style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                          color: Theme.of(context).colorScheme.primary,
                          decoration: TextDecoration.underline,
                        ),
                      ),
                    ),
                  ),
                ],
              ),
            ),
          ),
        ),
      ],
    );
  }

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

    // Get form values
    final email = _emailController.text.trim();
    final password = _passwordController.text;
    final confirmPassword = _confirmPasswordController.text;

    // Validate terms agreement
    if (!_agreedToTerms) {
      setState(() {
        _errorMessage = 'Please agree to Terms of Service and Privacy Policy';
      });
      return;
    }

    // Check password match before form validation
    if (password != confirmPassword) {
      setState(() {
        _errorMessage = 'Passwords do not match. Please ensure both passwords are identical.';
      });
      return;
    }

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

    // Check for empty fields
    if (email.isEmpty || password.isEmpty || confirmPassword.isEmpty) {
      setState(() {
        _errorMessage = 'Please fill in all required fields';
      });
      return;
    }

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

    try {
      final authProvider = ref.read(authProvider.notifier);
      await authProvider.signUp(email, password);
      
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          SnackBar(
            content: const Text('Account created successfully! Please sign in.'),
            duration: const Duration(seconds: 3),
            backgroundColor: Colors.green,
            action: SnackBarAction(
              label: 'Sign In',
              onPressed: () => context.go('/login'),
            ),
          ),
        );
        
        // Navigate to login page after a short delay
        Future.delayed(const Duration(seconds: 1), () {
          if (mounted) {
            context.go('/login');
          }
        });
      }
    } 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 EmailAlreadyInUseException) {
      return 'This email address is already registered. Please use a different email or try signing in.';
    } else if (error is WeakPasswordException) {
      return 'Password is too weak. Please use a stronger password with at least 8 characters, including uppercase, lowercase, and numbers.';
    } else if (error is InvalidCredentialsException) {
      return 'Invalid email format. Please enter a valid email address.';
    } else if (error is NetworkException) {
      return 'Network connection failed. Please check your internet connection and try again.';
    } else if (error is TooManyRequestsException) {
      return 'Too many registration attempts. Please wait a moment and try again.';
    } else if (error is AuthDisabledException) {
      return 'Account registration is currently disabled. Please try again later.';
    } else if (error is AuthException) {
      return error.message;
    } else {
      return 'Registration failed. Please try again or contact support if the problem persists.';
    }
  }

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

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

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

    try {
      // TODO: Implement actual registration logic
      // For now, simulate API call
      await Future.delayed(const Duration(seconds: 2));
      
      // Simulate successful registration
      if (mounted) {
        ScaffoldMessenger.of(context).showSnackBar(
          const SnackBar(
            content: Text('Account created successfully! Please sign in.'),
            duration: Duration(seconds: 3),
            backgroundColor: Colors.green,
          ),
        );
        
        // Navigate to login page
        context.go('/login');
      }
    } catch (e) {
      // Handle registration errors
      setState(() {
        _isLoading = false;
        
        // TODO: Implement proper error handling
        // For now, show generic errors based on common scenarios
        if (e.toString().contains('email')) {
          _emailError = 'Email is already registered';
        } else {
          _passwordError = 'Registration failed. Please try again.';
        }
      });
    }
  }

  void _handleTermsOfService() {
    // TODO: Navigate to Terms of Service screen or open web view
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Terms of Service'),
          content: const SingleChildScrollView(
            child: Text(
              'Terms of Service placeholder...\n\n'
              'This is a placeholder for the actual Terms of Service document. '
              'In a real application, this would contain detailed information about:\n'
              '- User responsibilities\n'
              '- Data usage policies\n'
              '- Service limitations\n'
              '- Account termination policies\n'
              '- Legal disclaimers\n\n'
              'Please review the actual terms before agreeing.',
            ),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Close'),
            ),
          ],
        );
      },
    );
  }

  void _handlePrivacyPolicy() {
    // TODO: Navigate to Privacy Policy screen or open web view
    showDialog(
      context: context,
      builder: (BuildContext context) {
        return AlertDialog(
          title: const Text('Privacy Policy'),
          content: const SingleChildScrollView(
            child: Text(
              'Privacy Policy placeholder...\n\n'
              'This is a placeholder for the actual Privacy Policy document. '
              'In a real application, this would contain detailed information about:\n'
              '- What data we collect\n'
              '- How we use your data\n'
              '- Data sharing practices\n'
              '- Data security measures\n'
              '- User rights and choices\n\n'
              'Please review the actual policy before agreeing.',
            ),
          ),
          actions: [
            TextButton(
              onPressed: () => Navigator.of(context).pop(),
              child: const Text('Close'),
            ),
          ],
        );
      },
    );
  }

  void _handleSignIn() {
    // Navigate to sign in page
    context.go('/login');
  }

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