defmodule PhaseDB.Server.Protocol do
  alias PhaseDB.{Result, Session, Request}

  def init_message do
    Result.new(
      fields: ~w|server_version engine_version|,
      rows: [
        [PhaseDB.Server.version, PhaseDB.version]
      ]
    )
  end

  def handle(json, session_pid) when is_binary(json) do
    handle Request.from_json(json), session_pid
  end

  def handle %Request{id: id, query: query}, session_pid do
    response =
      session_pid
      |> Session.query(query)
    %{response | id: id}
    |> Poison.encode!
  end

  def error(message), do: Result.error(message)
end