gram: nucleus

> ./lib/duck.ex

# iex> pages |> Duck.start_link
# iex> {:ok, r} = :pages |> Duck.conn |> Duckdbex.query("1+1")
# iex> {:ok, r} = :pages |> Duck.conn |> Duckdbex.query("select 1 + 1;")
# iex> r |> Duckdbex.fetch_all
# [[2]]
defmodule Duck do
  use GenServer

  # see: https://www.youtube.com/watch?v=y_b6RTes83c
  defp label(name), do: {:via, :gproc, {:n, :l, {:row, name}}}

  def start_link(name) do
    {:ok, db} = Duckdbex.open
    {:ok, conn} = Duckdbex.connection(db)
    GenServer.start_link(__MODULE__, [conn, db], name: label(name))
  end

  def start_link(name, node) do
    {:ok, db} = Duckdbex.open(node)
    {:ok, conn} = Duckdbex.connection(db)
    GenServer.start_link(__MODULE__, [conn, db], name: label(name))
  end

  def handle_call(:conn, pid, shape = [conn | _]),
    do: {:reply, conn, shape}

  def handle_call(:close, pid, [conn, db]) do
    :ok = Duckdbex.release(conn)
    :ok = Duckdbex.release(db)
    {:exit, 0}
  end

  def conn(name), do: GenServer.call(label(name), :conn)
  def close(name),  do: GenServer.call(label(name), :close)
end