defmodule LSG.Token do
  use GenServer

  def start_link() do
    GenServer.start_link(__MODULE__, [], [name: __MODULE__])
  end

  def lookup(id) do
    with \
         [{_, cred, date}] <- :ets.lookup(__MODULE__.ETS, id),
         IO.inspect("cred: #{inspect cred} valid for #{inspect date} now #{inspect DateTime.utc_now()}"),
        d when d > 0 <- DateTime.diff(date, DateTime.utc_now())
    do
      {:ok, cred}
    else
      err -> {:error, err}
    end
  end

  def new(cred) do
    GenServer.call(__MODULE__, {:new, cred})
  end

  def init(_) do
    ets = :ets.new(__MODULE__.ETS, [:ordered_set, :named_table, :protected, {:read_concurrency, true}])
    {:ok, ets}
  end

  def handle_call({:new, cred}, _, ets) do
    id = IRC.UserTrack.Id.large_id()
    expire = DateTime.utc_now()
             |> DateTime.add(15*60, :second)
    obj = {id, cred, expire}
    :ets.insert(ets, obj)
    {:reply, {:ok, id}, ets}
  end

end