Set the Islands

Mark the islands as set

Once players are done moving their islands around, they need to mark their islands as a set in place. The Channel only needs to pass an atom that represents the player down to Game.set_islands/2 and pattern match on the result to send the right response.

A player successfully setting his islands is something we want both players to know about, so we use broadcast!/3 to respond when Game.set_islands/2 succeeds. If it fails, we want to let only that player know, so we use a :reply tuple.

To make it easier for any front-end code to display all the islands once they are set successfully, we will also have to send a :reply tuple with the full map of the islands. We send this only to the caller since we would not want the opponent to see this.

def handle_in("set_islands", player, socket) do
  player = String.to_existing_atom(player)
  case Game.set_islands(via(socket.topic), player) do
    {:ok, board} ->
      broadcast! socket, "player_set_islands", %{player: player}
      {:reply, {:ok, %{board: board}}, socket}
    _ -> {:reply, :error, socket}
  end
end

Note: Run the app below and open the SPA link in two separate browser tabs. Run the following commands as instructed.