backend

backend/lib/backend_web/channels/game_channel.ex

@@ -0,0 +1,60 @@
+defmodule BackendWeb.GameChannel do
+  @moduledoc """
+  Channel for handling game events and player movements.
+  """
+  use BackendWeb, :channel
+  require Logger
+
+  @impl true
+  def join("game:lobby", _payload, socket) do
+    Logger.info("WebSocket connected to #{node()}, waiting for name")
+    Phoenix.PubSub.subscribe(Backend.PubSub, "game_state")
+
+    current_state = Backend.GameState.get_state()
+    {:ok, %{players: current_state}, socket}
+  end
+
+  @impl true
+  def handle_info({:game_state_updated, state}, socket) do
+    push(socket, "game_state", %{players: state})
+    {:noreply, socket}
+  end
+
+  @impl true
+  def handle_in("join_game", %{"name" => name}, socket) do
+    Logger.info("Player '#{name}' joining game on #{node()}")
+
+    socket = assign(socket, :player_name, name)
+    Backend.GameState.add_player(name)
+
+    {:reply, :ok, socket}
+  end
+
+  @impl true
+  def handle_in("move", %{"directions" => directions}, socket) do
+    case socket.assigns[:player_name] do
+      nil ->
+        Logger.warning("Move attempted without joining game")
+        {:noreply, socket}
+
+      player_name ->
+        Logger.debug("Player '#{player_name}' moved #{inspect(directions)} on #{node()}")
+        Backend.GameState.move_player(player_name, directions)
+        {:noreply, socket}
+    end
+  end
+
+  @impl true
+  def terminate(_reason, socket) do
+    case socket.assigns[:player_name] do
+      nil ->
+        Logger.info("WebSocket disconnected from #{node()}")
+
+      player_name ->
+        Logger.info("Player '#{player_name}' disconnected from #{node()}")
+        Backend.GameState.remove_player(player_name)
+    end
+
+    :ok
+  end
+end

backend/lib/backend_web/channels/user_socket.ex

@@ -0,0 +1,36 @@
+defmodule BackendWeb.UserSocket do
+  use Phoenix.Socket
+
+  # A Socket handler
+  #
+  # It's possible to control the websocket connection and
+  # assign values that can be accessed by your channel topics.
+
+  ## Channels
+  channel("game:*", BackendWeb.GameChannel)
+
+  # Socket params are passed from the client and can
+  # be used to verify and authenticate a user. After
+  # verification, you can put default assigns into
+  # the socket that will be set for all channels, ie
+  #
+  #     {:ok, assign(socket, :user_id, verified_user_id)}
+  #
+  # To deny connection, return `:error` or `{:error, term}`.
+  @impl true
+  def connect(_params, socket, _connect_info) do
+    {:ok, socket}
+  end
+
+  # Socket id's are topics that allow you to identify all sockets for a given user:
+  #
+  #     def id(socket), do: "user_socket:#{socket.assigns.user_id}"
+  #
+  # Would allow you to broadcast a "disconnect" event and terminate
+  # all active sockets and channels for a given user:
+  #
+  #
+  # Returning `nil` makes this socket anonymous.
+  @impl true
+  def id(_socket), do: nil
+end