import 'package:flutter/material.dart';
import 'package:flutter/services.dart';

/// Reusable authentication form with email and password fields
class AuthForm extends StatefulWidget {
  final GlobalKey<FormState> formKey;
  final String email;
  final ValueChanged<String>? onEmailChanged;
  final String? emailError;
  final String password;
  final ValueChanged<String>? onPasswordChanged;
  final String? passwordError;
  final VoidCallback? onSubmit;
  final String submitButtonText;
  final bool isLoading;
  final bool showPasswordToggle;
  final String? confirmPassword;
  final ValueChanged<String>? onConfirmPasswordChanged;
  final String? confirmPasswordError;
  final bool autofocusEmail;
  final String? emailLabel;
  final String? passwordLabel;
  final String? confirmPasswordLabel;

  const AuthForm({
    super.key,
    required this.formKey,
    this.email = '',
    this.onEmailChanged,
    this.emailError,
    this.password = '',
    this.onPasswordChanged,
    this.passwordError,
    this.onSubmit,
    this.submitButtonText = 'Submit',
    this.isLoading = false,
    this.showPasswordToggle = true,
    this.confirmPassword,
    this.onConfirmPasswordChanged,
    this.confirmPasswordError,
    this.autofocusEmail = true,
    this.emailLabel = 'Email',
    this.passwordLabel = 'Password',
    this.confirmPasswordLabel = 'Confirm Password',
  });

  @override
  State<AuthForm> createState() => _AuthFormState();
}

class _AuthFormState extends State<AuthForm> {
  bool _obscurePassword = true;
  bool _obscureConfirmPassword = true;

  @override
  Widget build(BuildContext context) {
    return Form(
      key: widget.formKey,
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.stretch,
        children: [
          _buildEmailField(),
          const SizedBox(height: 16),
          _buildPasswordField(),
          if (widget.confirmPassword != null) ...[
            const SizedBox(height: 16),
            _buildConfirmPasswordField(),
          ],
          const SizedBox(height: 24),
          _buildSubmitButton(),
        ],
      ),
    );
  }

  Widget _buildEmailField() {
    return TextFormField(
      initialValue: widget.email,
      onChanged: widget.onEmailChanged,
      autofocus: widget.autofocusEmail,
      keyboardType: TextInputType.emailAddress,
      textInputAction: TextInputAction.next,
      decoration: InputDecoration(
        labelText: widget.emailLabel,
        hintText: 'Enter your email address',
        prefixIcon: const Icon(Icons.email_outlined),
        errorText: widget.emailError,
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.emailError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.outline,
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.emailError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.primary,
            width: 2,
          ),
        ),
      ),
      validator: (value) {
        if (value == null || value.trim().isEmpty) {
          return 'Email is required';
        }
        
        // Basic email validation regex
        final emailRegex = RegExp(
          r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$',
        );
        
        if (!emailRegex.hasMatch(value.trim())) {
          return 'Please enter a valid email address';
        }
        
        return null;
      },
      inputFormatters: [
        FilteringTextInputFormatter.deny(RegExp(r'\s')), // Prevent spaces
      ],
    );
  }

  Widget _buildPasswordField() {
    return TextFormField(
      initialValue: widget.password,
      onChanged: widget.onPasswordChanged,
      obscureText: _obscurePassword,
      textInputAction: widget.confirmPassword != null
          ? TextInputAction.next
          : TextInputAction.done,
      onFieldSubmitted: (_) {
        if (widget.confirmPassword != null) {
          // Move focus to confirm password field
          FocusScope.of(context).nextFocus();
        } else {
          // Submit form
          widget.onSubmit?.call();
        }
      },
      decoration: InputDecoration(
        labelText: widget.passwordLabel,
        hintText: 'Enter your password',
        prefixIcon: const Icon(Icons.lock_outline),
        suffixIcon: widget.showPasswordToggle
            ? IconButton(
                icon: Icon(
                  _obscurePassword ? Icons.visibility_off : Icons.visibility,
                ),
                onPressed: () {
                  setState(() {
                    _obscurePassword = !_obscurePassword;
                  });
                },
                tooltip: _obscurePassword ? 'Show password' : 'Hide password',
              )
            : null,
        errorText: widget.passwordError,
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.passwordError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.outline,
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.passwordError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.primary,
            width: 2,
          ),
        ),
      ),
      validator: (value) {
        if (value == null || value.isEmpty) {
          return 'Password is required';
        }
        
        if (value.length < 6) {
          return 'Password must be at least 6 characters';
        }
        
        // Check for at least one letter and one number
        final hasLetter = RegExp(r'[a-zA-Z]').hasMatch(value);
        final hasNumber = RegExp(r'\d').hasMatch(value);
        
        if (!hasLetter || !hasNumber) {
          return 'Password must contain both letters and numbers';
        }
        
        return null;
      },
    );
  }

  Widget _buildConfirmPasswordField() {
    return TextFormField(
      initialValue: widget.confirmPassword,
      onChanged: widget.onConfirmPasswordChanged,
      obscureText: _obscureConfirmPassword,
      textInputAction: TextInputAction.done,
      onFieldSubmitted: (_) => widget.onSubmit?.call(),
      decoration: InputDecoration(
        labelText: widget.confirmPasswordLabel,
        hintText: 'Confirm your password',
        prefixIcon: const Icon(Icons.lock_outline),
        suffixIcon: widget.showPasswordToggle
            ? IconButton(
                icon: Icon(
                  _obscureConfirmPassword ? Icons.visibility_off : Icons.visibility,
                ),
                onPressed: () {
                  setState(() {
                    _obscureConfirmPassword = !_obscureConfirmPassword;
                  });
                },
                tooltip: _obscureConfirmPassword ? 'Show password' : 'Hide password',
              )
            : null,
        errorText: widget.confirmPasswordError,
        border: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
        ),
        enabledBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.confirmPasswordError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.outline,
          ),
        ),
        focusedBorder: OutlineInputBorder(
          borderRadius: BorderRadius.circular(8),
          borderSide: BorderSide(
            color: widget.confirmPasswordError != null
                ? Theme.of(context).colorScheme.error
                : Theme.of(context).colorScheme.primary,
            width: 2,
          ),
        ),
      ),
      validator: (value) {
        if (value == null || value.isEmpty) {
          return 'Please confirm your password';
        }
        
        if (value != widget.password) {
          return 'Passwords do not match';
        }
        
        return null;
      },
    );
  }

  Widget _buildSubmitButton() {
    return ElevatedButton(
      onPressed: widget.isLoading ? null : widget.onSubmit,
      style: ElevatedButton.styleFrom(
        backgroundColor: Theme.of(context).colorScheme.primary,
        foregroundColor: Theme.of(context).colorScheme.onPrimary,
        disabledBackgroundColor: Theme.of(context).colorScheme.primary.withOpacity(0.12),
        disabledForegroundColor: Theme.of(context).colorScheme.onPrimary.withOpacity(0.38),
        elevation: 2,
        shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.circular(8),
        ),
        minimumSize: const Size(double.infinity, 48),
      ),
      child: widget.isLoading
          ? SizedBox(
              height: 20,
              width: 20,
              child: CircularProgressIndicator(
                strokeWidth: 2,
                valueColor: AlwaysStoppedAnimation<Color>(
                  Theme.of(context).colorScheme.onPrimary,
                ),
              ),
            )
          : Text(
              widget.submitButtonText,
              style: Theme.of(context).textTheme.labelLarge?.copyWith(
                fontWeight: FontWeight.w600,
              ),
            ),
    );
  }
}