type name = string

type userinfo = {
  username : string;
  realname : string;
  hostname : string;
}

let pp_userinfo ppf { username; realname; hostname } =
  ignore realname;
  Format.fprintf ppf "!%s@%s" username hostname

let name_type s =
  let rec valid i =
    if i >= String.length s then true
    else
      match s.[i] with
      | ' ' | '@' | '+' | ',' -> false
      | _ -> valid (i + 1)
  in
  if s = "" then `invalid
  else
    match s.[0] with
    | ':' -> `invalid
    | '#' -> if valid 1 then `chan else `invalid
    | _ -> if valid 0 then `nick else `invalid