defmodule TestTimex do
  defmodule Timex do
    def now(timezone \\ "UTC") do
      case timezone do
        "UTC" -> DateTime.utc_now()
        tz when is_binary(tz) and tz != "" -> 
          DateTime.utc_now()
        _ -> 
          {:error, :invalid_timezone}
      end
    end
    
    def year(datetime) when is_struct(datetime, DateTime), do: datetime.year
    def hour(datetime) when is_struct(datetime, DateTime), do: datetime.hour
    
    def day(datetime, :ordinal) when is_struct(datetime, DateTime) do
      date = DateTime.to_date(datetime)
      start_of_year = Date.new!(date.year, 1, 1)
      Date.diff(date, start_of_year) + 1
    end
    
    def format!(datetime, format, :strftime) when is_struct(datetime, DateTime) do
      case format do
        "%m%d%H%M%S" ->
          "#{String.pad_leading("#{datetime.month}", 2, "0")}" <>
          "#{String.pad_leading("#{datetime.day}", 2, "0")}" <>
          "#{String.pad_leading("#{datetime.hour}", 2, "0")}" <>
          "#{String.pad_leading("#{datetime.minute}", 2, "0")}" <>
          "#{String.pad_leading("#{datetime.second}", 2, "0")}"
        _ ->
          DateTime.to_iso8601(datetime)
      end
    end
  end
end

now = TestTimex.Timex.now()
IO.puts("Current datetime: #{inspect(now)}")
IO.puts("Year: #{TestTimex.Timex.year(now)}")
IO.puts("Hour: #{TestTimex.Timex.hour(now)}")
IO.puts("Day of year: #{TestTimex.Timex.day(now, :ordinal)}")
IO.puts("Formatted: #{TestTimex.Timex.format!(now, "%m%d%H%M%S", :strftime)}")
IO.puts("All Timex functions work correctly!")