/**
 * Toolkit - String Validation
 * 
 * String validation utilities.
 */

/**
 * Check if string is empty or only whitespace
 */
export function isEmpty(str: string | null | undefined): boolean {
  return !str || str.trim().length === 0;
}

/**
 * Check if string has minimum length
 */
export function hasMinLength(str: string, minLength: number): boolean {
  return str.trim().length >= minLength;
}

/**
 * Check if string has maximum length
 */
export function hasMaxLength(str: string, maxLength: number): boolean {
  return str.trim().length <= maxLength;
}

/**
 * Check if string contains only alphanumeric characters
 */
export function isAlphanumeric(str: string): boolean {
  return /^[a-z0-9]+$/i.test(str);
}

/**
 * Check if string contains only letters
 */
export function isAlpha(str: string): boolean {
  return /^[a-z]+$/i.test(str);
}

/**
 * Check if string contains only digits
 */
export function isNumeric(str: string): boolean {
  return /^\d+$/.test(str);
}