/// Form validators for authentication
class AuthValidators {
  AuthValidators._();

  /// Validates email format
  static String? validateEmail(String? value) {
    if (value == null || value.isEmpty) {
      return 'Email is required';
    }

    final emailRegex = RegExp(
      r'^[a-zA-Z0-9._%+-]+@[a-zA-Z0-9.-]+\.[a-zA-Z]{2,}$',
    );

    if (!emailRegex.hasMatch(value)) {
      return 'Please enter a valid email address';
    }

    return null;
  }

  /// Validates password strength
  /// Requirements: min 8 characters, at least one uppercase, one lowercase, one number
  static String? validatePassword(String? value) {
    if (value == null || value.isEmpty) {
      return 'Password is required';
    }

    if (value.length < 8) {
      return 'Password must be at least 8 characters';
    }

    if (!RegExp(r'[A-Z]').hasMatch(value)) {
      return 'Password must contain at least one uppercase letter';
    }

    if (!RegExp(r'[a-z]').hasMatch(value)) {
      return 'Password must contain at least one lowercase letter';
    }

    if (!RegExp(r'[0-9]').hasMatch(value)) {
      return 'Password must contain at least one number';
    }

    return null;
  }

  /// Validates name field
  static String? validateName(String? value) {
    if (value == null || value.isEmpty) {
      return 'Name is required';
    }

    if (value.length < 2) {
      return 'Name must be at least 2 characters';
    }

    if (value.length > 50) {
      return 'Name must not exceed 50 characters';
    }

    return null;
  }

  /// Validates password confirmation
  static String? validateConfirmPassword(String? value, String password) {
    if (value == null || value.isEmpty) {
      return 'Please confirm your password';
    }

    if (value != password) {
      return 'Passwords do not match';
    }

    return null;
  }

  /// Simple password validator for login (no strength requirements)
  static String? validateLoginPassword(String? value) {
    if (value == null || value.isEmpty) {
      return 'Password is required';
    }

    return null;
  }
}