Guess the Coordinates

For this final piece, we need to pass a player and a coordinate into Game.guess_coordinate/3. We should show the result of a successful guess to both players, so we broadcast those. If a guess fails, we return a :reply tuple.

This is exactly what we’ve done for the past few handle_in/3 clauses, but this one has a twist. The response we get back from Game.guess_coordinate/3 will be a tuple, but we need to use a map for our brodcast’s payload. This means we’ll need to do a little pattern matching to destructure the tuple and build it back up again as a map:

def handle_in("guess_coordinate", params, socket) do
  %{"player" => player, "row" => row, "col" => col} = params
  player = String.to_existing_atom(player)
  case Game.guess_coordinate(via(socket.topic), player, row, col) do
    {:hit, island, win} ->
      result = %{hit: true, island: island, win: win}
      broadcast! socket, "player_guessed_coordinate",
                 %{player: player, row: row, col: col, result: result}
      {:noreply, socket}
    {:miss, island, win} ->
      result = %{hit: false, island: island, win: win}
      broadcast! socket, "player_guessed_coordinate",
                 %{player: player, row: row, col: col, result: result}
      {:noreply, socket}
    :error ->
      {:reply, {:error, %{player: player, reason: "Not your turn."}}, socket}
    {:error, reason} ->
      {:reply, {:error, %{player: player, reason: reason}}, socket}
  end
end

IEx session