/**
 * Validates email format (basic RFC 5322 pattern)
 * @param email - Email address to validate
 * @returns true if valid email format
 */
export function isValidEmail(email: string): boolean {
  const emailRegex = /^[^\s@]+@[^\s@]+\.[^\s@]+$/
  return emailRegex.test(email)
}

/**
 * Validates URL format
 * @param url - URL to validate
 * @returns true if valid URL format
 */
export function isValidUrl(url: string): boolean {
  try {
    new URL(url)
    return true
  } catch {
    return false
  }
}

/**
 * Checks if string is empty or only whitespace
 * @param text - Text to check
 * @returns true if empty or whitespace-only
 */
export function isEmpty(text: string): boolean {
  return text.trim().length === 0
}

/**
 * Checks if string contains only alphanumeric characters
 * @param text - Text to check
 * @returns true if alphanumeric only
 */
export function isAlphanumeric(text: string): boolean {
  return /^[a-zA-Z0-9]+$/.test(text)
}

/**
 * Validates username format (alphanumeric, underscores, hyphens, 3-30 chars)
 * @param username - Username to validate
 * @returns true if valid username format
 */
export function isValidUsername(username: string): boolean {
  return /^[a-zA-Z0-9_-]{3,30}$/.test(username)
}