car

Mix.install([
  {:socket, "~> 0.3"},
  {:jason, "~> 1.4"}
])

Section

defmodule ElixirSocketTesting.ClientAgent do
  def start_link do
    Agent.start_link(
      fn ->
        []
      end,
      name: __MODULE__
    )
  end

  def add(client) do
    Agent.update(__MODULE__, fn list ->
      [client | list]
    end)
  end

  def remove(client) do
    Agent.update(__MODULE__, fn list ->
      List.delete(list, client)
    end)
  end

  def all do
    Agent.get(__MODULE__, fn list ->
      list
    end)
  end
end

defmodule Car do
  def agent(a) do
    res = ""

    v =
      a
      |> Jason.decode!()
      |> Map.get("observation")
      |> Map.get("s1")

    v = String.to_float(v)

    if v > 0.4 do
      res = "{\"action\": 0}"
    else
      res = "{\"action\": 1}"
    end
  end
end

defmodule Car.Server do
  alias ElixirSocketTesting.ClientAgent

  def start(port \\ 50002) do
    ClientAgent.start_link()
    server = Socket.Web.listen!(port)
    loop(server)
  end

  def loop(server) do
    client =
      server
      |> Socket.Web.accept!()

    client
    |> Socket.Web.accept!()

    ClientAgent.add(client)

    Task.async(fn ->
      recv(client)
    end)

    loop(server)
  end

  def recv(client) do
    case client |> Socket.Web.recv!() do
      {:text, message} ->
        res = Car.agent(message)
        broadcast({:text, res})
        recv(client)

      {:close, _, _} ->
        ClientAgent.remove(client)

      other ->
        IO.inspect(other)
    end
  end

  def broadcast(packet) do
    ClientAgent.all()
    |> Enum.each(fn client ->
      Socket.Web.send(client, packet)
    end)
  end
end

Car.Server.start()