defmodule Reactivity.Registry do
  use GenServer
  
  require Logger
  
  alias Reactivity.Signal.Source
  
  alias Reactivity.Signal.Derived

  #############
  # GenServer #
  #############

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

  def init(args) do
    table = :ets.new(:sources, [:named_table, :set])
    Logger.debug "Table: #{inspect table}"
    {:ok, table}
  end

  #############
  # Callbacks #
  #############

  def handle_cast(m, state) do
    Logger.debug "Cast: #{inspect m}"
    {:noreply, state}
  end

  
  def handle_call({:insert, source, name}, _from, table) do
    :ets.insert(table, {name, source})
    {:reply, :ok, table}
  end
  
  def handle_call({:remove, name}, _from, table) do
    :ets.delete(table, name)
    {:reply, :ok, table}
  end
  
  def handle_call({:get, name}, _from, table) do
    case :ets.lookup(table, name) do
      [{^name, val}] -> {:reply, {:ok, val}, table}
      []             -> {:reply, {:error, "not found"}, table}
    end
  end  
  
  def handle_call(m, from, state) do
    Logger.debug "Call: #{inspect m} from #{inspect from}"
    {:reply, :ok, state}
  end

  def handle_info(m, state) do
    Logger.debug "Info: #{inspect m}"
    {:noreply, state}
  end

  ###########
  # Private #
  ###########

  #############
  # Interface #
  #############

  def add_source(source, name) do
    GenServer.call(__MODULE__, {:insert, source, name})
  end

  def remove_source(name) do
    GenServer.call(__MODULE__, {:remove, name})
  end

  def get_source(name) do
    GenServer.call(__MODULE__, {:get, name})
  end

end