player.ex

defmodule Server.Player do
  use GenServer
  require Logger
  alias Server.{Acceleration, Movement, Position, Velocity}

  defstruct user_id: "", movement: %Movement{}, position: %Position{}, velocity: %Velocity{}

  def start_link(user_id) do
    name = via_tuple(user_id)
    GenServer.start_link(__MODULE__, user_id, name: via_tuple(user_id))
  end

  # client

  def handle_call({:move, params}, state) do
    {:reply}
  end

  @impl true
  def handle_cast({:move, params}, state) do
    movement = %Movement{
      forward: params["movement"]["forward"],
      backward: params["movement"]["backward"],
      left: params["movement"]["left"],
      right: params["movement"]["right"],
      jump: params["movement"]["jump"],
      angle: params["movement"]["angle"]
    }

    new_state = %__MODULE__{state | movement: movement}

    {:noreply, new_state}
  end

  @impl true
  def handle_info({:loop, dt}, state) do
    # Logger.info("Looping")
    velocity_vector = Movement.to_vector(state.movement)
    speed_vector = Vector.multiply(velocity_vector, dt / 1000 * 5)
    position_vector = Vector.add(state.position.vector, speed_vector)

    new_state = %{
      state
      | velocity: %Velocity{vector: velocity_vector},
        position: %Position{vector: position_vector}
    }

    ServerWeb.Endpoint.broadcast("player:lobby", "update", %{
      user_id: state.user_id,
      position: vector_to_map(state.position.vector),
      angle: state.movement.angle
    })

    loop()
    {:noreply, new_state}
  end

  @impl true
  def handle_info(:log, state) do
    # IO.inspect(state)
    log()
    {:noreply, state}
  end

  # server

  @impl true
  def init(user_id) do
    Logger.info("Process created... User ID: #{user_id}")
    loop()
    log()
    {:ok, %__MODULE__{user_id: user_id}}
  end

  # helpers

  defp via_tuple(user_id) do
    {:via, Registry, {:player_registry, user_id}}
  end

  defp loop() do
    Process.send_after(self(), {:loop, 100}, 100)
  end

  defp log() do
    Process.send_after(self(), :log, 5000)
  end

  defp vector_to_map({x, y, z}) do
    %{x: x, y: y, z: z}
  end
end