defmodule Scopes.CSys.Environ do

  alias Scopes.CSys
  alias Scopes.Shape

  defmodule State do
    defstruct [neurons: [], names: %{}, init_seq: []]
  end

  def setup({state, proc}, seq \\ []) do
    scope = {%State{init_seq: seq}, &proc_env/2, [], self()}
    env = CSys.neuron(scope)
    CSys.create(Shape.create([:csys, :zero]), {state, proc, [], env})
    env
  end

  def proc_env(msg, scope) do
    case Shape.head(msg) do
      [:csys, :created | _rest] -> process_creation(msg, scope)
      _ -> nil
    end
    send(CSys.env(scope), msg)
  end

  def process_creation(msg, {state, proc, syns, env}) do
    data = Shape.data(msg)
    new = data.new
    neurons = [new | state.neurons]
    names = data[:name] && Map.put(state.names, data.name, new) || state.names
    {step, seq} = List.pop_at(state.init_seq, 0)
    CSys.update({%State{neurons: neurons, names: names, init_seq: seq}, proc, syns, env})
    if step, do: step.(neurons)
  end
end