/// Utility class for input validation
class Validators {
  Validators._();

  /// Validate email
  static String? validateEmail(String? value) {
    if (value == null || value.isEmpty) {
      return 'Email is required';
    }
    final emailRegex = RegExp(r'^[\w-\.]+@([\w-]+\.)+[\w-]{2,4}$');
    if (!emailRegex.hasMatch(value)) {
      return 'Enter a valid email';
    }
    return null;
  }

  /// Validate required field
  static String? validateRequired(String? value, {String? fieldName}) {
    if (value == null || value.isEmpty) {
      return '${fieldName ?? 'This field'} is required';
    }
    return null;
  }

  /// Validate price
  static String? validatePrice(String? value) {
    if (value == null || value.isEmpty) {
      return 'Price is required';
    }
    final price = double.tryParse(value);
    if (price == null) {
      return 'Enter a valid price';
    }
    if (price <= 0) {
      return 'Price must be greater than 0';
    }
    return null;
  }

  /// Validate quantity
  static String? validateQuantity(String? value) {
    if (value == null || value.isEmpty) {
      return 'Quantity is required';
    }
    final quantity = int.tryParse(value);
    if (quantity == null) {
      return 'Enter a valid quantity';
    }
    if (quantity < 0) {
      return 'Quantity cannot be negative';
    }
    return null;
  }

  /// Validate phone number
  static String? validatePhone(String? value) {
    if (value == null || value.isEmpty) {
      return 'Phone number is required';
    }
    final phoneRegex = RegExp(r'^\+?[\d\s-]{10,}$');
    if (!phoneRegex.hasMatch(value)) {
      return 'Enter a valid phone number';
    }
    return null;
  }
}