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

/// Password reset request page where users can initiate password recovery
class ResetPasswordPage extends ConsumerStatefulWidget {
  const ResetPasswordPage({super.key});

  @override
  ConsumerState<ResetPasswordPage> createState() => _ResetPasswordPageState();
}

class _ResetPasswordPageState extends ConsumerState<ResetPasswordPage> {
  final _formKey = GlobalKey<FormState>();
  final _emailController = TextEditingController();
  
  bool _isLoading = false;
  String? _errorMessage;
  String? _successMessage;
  bool _emailSent = false;
  bool _canResendAfter = false;
  DateTime? _lastAttemptTime;

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

  /// Handles email input changes and clears errors
  void _handleEmailChanged(String value) {
    setState(() {
      _errorMessage = null;
      _successMessage = null;
    });
  }

  Future<void> _handlePasswordReset(String email) async {
    if (!_formKey.currentState!.validate()) return;

    // Check for empty email
    final trimmedEmail = email.trim();
    if (trimmedEmail.isEmpty) {
      setState(() {
        _errorMessage = 'Please enter your email address';
      });
      return;
    }

    setState(() {
      _isLoading = true;
      _errorMessage = null;
      _successMessage = null;
    });

    try {
      final authProvider = ref.read(authProvider.notifier);
      await authProvider.resetPassword(trimmedEmail);
      
      if (mounted) {
        setState(() {
          _isLoading = false;
          _emailSent = true;
          _successMessage = 'Password reset email sent! Check your inbox for further instructions.';
        });
        
        // Announce success for accessibility
        _announceMessageForAccessibility(_successMessage!);
      }
    } catch (e) {
      if (mounted) {
        setState(() {
          _isLoading = false;
          _errorMessage = _mapErrorToUserFriendlyMessage(e);
        });
        
        // Announce error for accessibility
        _announceErrorForAccessibility(_errorMessage!);
      }
    }
  }

  String _mapErrorToUserFriendlyMessage(Object error) {
    if (error is UserNotFoundException) {
      return 'No account found with this email address. Please check the email or sign up for a new account.';
    } else if (error is TooManyRequestsException) {
      return 'Too many reset attempts. Please wait 15 minutes before trying again, or contact support.';
    } else if (error is NetworkException) {
      return 'Network connection failed. Please check your internet connection and try again.';
    } else if (error is AuthDisabledException) {
      return 'Password reset is currently disabled. Please try again later or contact support.';
    } else if (error is InvalidTokenException) {
      return 'Reset request failed. Please start the password reset process again.';
    } else if (error is AuthException) {
      return error.message;
    } else {
      return 'An unexpected error occurred. Please try again or contact support if the problem persists.';
    }
  }

  /// Announces success message for screen readers
  void _announceMessageForAccessibility(String message) {
    SemanticsService.announce(message, TextDirection.ltr);
  }

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

  void _navigateToLogin() {
    Navigator.of(context).pushReplacementNamed('/login');
  }

  @override
  Widget build(BuildContext context) {
    final theme = Theme.of(context);
    final colorScheme = theme.colorScheme;

    return Scaffold(
      appBar: AppBar(
        title: const Text('Reset Password'),
        backgroundColor: Colors.transparent,
        elevation: 0,
        leading: IconButton(
          icon: const Icon(Icons.arrow_back),
          onPressed: _navigateToLogin,
          tooltip: 'Back to Login',
        ),
      ),
      body: SafeArea(
        child: SingleChildScrollView(
          padding: const EdgeInsets.all(24.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            children: [
              const SizedBox(height: 32),
              _buildHeader(),
              const SizedBox(height: 32),
              if (!_emailSent) ...[
                _buildInstructions(),
                const SizedBox(height: 32),
                PasswordResetForm(
                  formKey: _formKey,
                  emailController: _emailController,
                  isLoading: _isLoading,
                  errorMessage: _errorMessage,
                  onEmailChanged: _handleEmailChanged,
                  onSubmit: _handlePasswordReset,
                ),
              ] else ...[
                _buildSuccessMessage(),
                const SizedBox(height: 32),
                _buildBackToLoginButton(),
              ],
            ],
          ),
        ),
      ),
    );
  }

  Widget _buildHeader() {
    return Column(
      children: [
        Icon(
          Icons.lock_reset_outlined,
          size: 64,
          color: Theme.of(context).colorScheme.primary,
        ),
        const SizedBox(height: 16),
        Text(
          'Forgot Password?',
          style: Theme.of(context).textTheme.headlineMedium?.copyWith(
            fontWeight: FontWeight.bold,
          ),
        ),
      ],
    );
  }

  Widget _buildInstructions() {
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: Theme.of(context).colorScheme.surfaceVariant,
        borderRadius: BorderRadius.circular(12),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Row(
            children: [
              Icon(
                Icons.info_outline,
                size: 20,
                color: Theme.of(context).colorScheme.onSurfaceVariant,
              ),
              const SizedBox(width: 8),
              Expanded(
                child: Text(
                  'Enter your email address below and we\'ll send you a link to reset your password.',
                  style: Theme.of(context).textTheme.bodyMedium?.copyWith(
                    color: Theme.of(context).colorScheme.onSurfaceVariant,
                  ),
                ),
              ),
            ],
          ),
        ],
      ),
    );
  }

  Widget _buildSuccessMessage() {
    return Container(
      padding: const EdgeInsets.all(16),
      decoration: BoxDecoration(
        color: Theme.of(context).colorScheme.primaryContainer,
        borderRadius: BorderRadius.circular(12),
      ),
      child: Column(
        children: [
          Icon(
            Icons.mark_email_read_outlined,
            size: 48,
            color: Theme.of(context).colorScheme.onPrimaryContainer,
          ),
          const SizedBox(height: 16),
          Text(
            'Check Your Email',
            style: Theme.of(context).textTheme.titleLarge?.copyWith(
              fontWeight: FontWeight.bold,
              color: Theme.of(context).colorScheme.onPrimaryContainer,
            ),
          ),
          const SizedBox(height: 8),
          Text(
            _successMessage ?? 'We\'ve sent password reset instructions to your email address.',
            style: Theme.of(context).textTheme.bodyMedium?.copyWith(
              color: Theme.of(context).colorScheme.onPrimaryContainer,
            ),
            textAlign: TextAlign.center,
          ),
          const SizedBox(height: 16),
          Container(
            padding: const EdgeInsets.all(12),
            decoration: BoxDecoration(
              color: Theme.of(context).colorScheme.surface,
              borderRadius: BorderRadius.circular(8),
            ),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'Next Steps:',
                  style: Theme.of(context).textTheme.labelMedium?.copyWith(
                    fontWeight: FontWeight.bold,
                  ),
                ),
                const SizedBox(height: 4),
                Text(
                  '1. Open your email inbox\n'
                  '2. Look for password reset email (check spam folder)\n'
                  '3. Click reset link in the email\n'
                  '4. Create a new password\n'
                  '5. Return to sign in with your new password',
                  style: Theme.of(context).textTheme.bodySmall,
                ),
                const SizedBox(height: 8),
                Text(
                  'Didn\'t receive the email? Check your spam folder or try again in a few minutes.',
                  style: Theme.of(context).textTheme.bodySmall?.copyWith(
                    fontStyle: FontStyle.italic,
                  ),
                ),
              ],
            ),
          ),
          const SizedBox(height: 16),
          _buildResendSection(),
        ],
      ),
    );
  }

  Widget _buildResendSection() {
    return Column(
      children: [
        Text(
          "Didn't receive the email?",
          style: Theme.of(context).textTheme.bodyMedium?.copyWith(
            color: Theme.of(context).colorScheme.onPrimaryContainer,
          ),
        ),
        const SizedBox(height: 8),
        TextButton(
          onPressed: _canResendAfter ? _handleResendEmail : null,
          style: TextButton.styleFrom(
            foregroundColor: _canResendAfter 
                ? Theme.of(context).colorScheme.onPrimaryContainer
                : Theme.of(context).colorScheme.onPrimaryContainer.withOpacity(0.5),
          ),
          child: Text(
            _canResendAfter ? 'Resend Email' : 'Resend Email (available soon)',
          ),
        ),
      ],
    );
  }

  void _handleResendEmail() {
    if (_canResendAfter && _emailController.text.isNotEmpty) {
      _handlePasswordReset(_emailController.text);
    }
  }

  Widget _buildBackToLoginButton() {
    return OutlinedButton(
      onPressed: _navigateToLogin,
      style: OutlinedButton.styleFrom(
        minimumSize: const Size(double.infinity, 48),
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(8),
        ),
      ),
      child: const Text('Back to Login'),
    );
  }
}