/**
 * User-related utility functions
 */

interface UserLike {
  displayName?: string | null;
  email: string;
}

/**
 * Generate initials from a user's display name or email.
 * - For display names with 2+ words: first and last initials (e.g., "John Doe" -> "JD")
 * - For single word names: first 2 characters (e.g., "John" -> "JO")
 * - Falls back to first 2 characters of email if no display name
 * - Returns "??" if user is null/undefined
 *
 * @example
 * getUserInitials({ displayName: "John Doe", email: "john@example.com" }) // "JD"
 * getUserInitials({ displayName: "John", email: "john@example.com" })     // "JO"
 * getUserInitials({ email: "john@example.com" })                          // "JO"
 * getUserInitials(null)                                                   // "??"
 */
export function getUserInitials(user: UserLike | null | undefined): string {
  if (!user) {
    return "??";
  }

  if (user.displayName) {
    const parts = user.displayName.split(" ");
    const firstPart = parts[0];
    const lastPart = parts[parts.length - 1];
    if (parts.length >= 2 && firstPart && lastPart) {
      return (firstPart.charAt(0) + lastPart.charAt(0)).toUpperCase();
    }
    return user.displayName.slice(0, 2).toUpperCase();
  }

  return user.email.slice(0, 2).toUpperCase();
}

/**
 * Format a role string for display (capitalizes first letter).
 *
 * @example
 * formatRole("admin")  // "Admin"
 * formatRole("member") // "Member"
 * formatRole("owner")  // "Owner"
 */
export function formatRole(role: string): string {
  return role.charAt(0).toUpperCase() + role.slice(1);
}