defmodule Ace.HTTP2.Frame.RstStream do
  @moduledoc false
  @enforce_keys [:stream_id, :error]
  defstruct @enforce_keys

  def new(stream_id, error) do
    %__MODULE__{stream_id: stream_id, error: error}
  end

  def decode({3, _flags, stream_id, <<error_code::32>>}) when stream_id > 0 do
    error = Ace.HTTP2.Frame.GoAway.error(error_code)
    {:ok, new(stream_id, error)}
  end
  def decode({3, _flags, 0, <<_::32>>}) do
    {:error, {:protocol_error, "RstStream frame not valid on stream 0"}}
  end
  def decode({3, _flags, _stream_id, _payload}) do
    {:error, {:protocol_error, "RstStream frame invalid payload length"}}
  end

  def serialize(frame) do
    # DEBT move to general errors
    payload = <<Ace.HTTP2.Frame.GoAway.error_code(frame.error)::32>>
    <<4::24, 3::8, 0::8, 0::1, frame.stream_id::31, payload::binary>>
  end
end