Handling WebSocket connections with Rack

player_connection.rb

require 'pusher'

class PlayerConnection

  attr_reader :player, :username, :web_socket, :broadcast_id

  def initialize(player:, web_socket:)
    @player = player
    @web_socket = web_socket
  end

  def listen
    [:open, :close, :message].each do |event_name|
      web_socket.on(event_name) do |event|
        safely do
          Rails.logger.tagged('GS') do
            Rails.logger.info "<@#{player.to_s}:#{event_name[0]} -> #{event.data}"
            public_send event_name, event.data
          end
        end
      end
    end
  end

  def message(data)
    Router.raw_route player, Pusher, data
  end

  def open(data)
    @broadcast_id = Game.broadcast.subscribe { |message| web_socket.send(message) }
    @username = player.username

    if Game.online[username]
      Game.online[username] << web_socket
      Pusher.call players_online_json, username
    else
      Game.online[username] = [web_socket]
      Pusher.call players_online_json
    end
  end

  def close(data)
    Game.broadcast.unsubscribe broadcast_id

    Game.online[username].delete(web_socket)

    if Game.online[username].empty?
      Game.online.delete username

      Pusher.call players_online_json
    end
  end

  def players_online_json
    PlayersOnlineView.new(Game.online.keys).render
  end

end

web-sockets-with-rack.rb

require 'safely'

Game.broadcast = EM::Channel.new

module GameServer
  class Backend < Struct.new(:app)

    KEEP_ALIVE_TIME = 15

    def call(env)
      if Faye::WebSocket.websocket?(env)
        web_socket = Faye::WebSocket.new(env, nil, ping: KEEP_ALIVE_TIME)

        player = env['warden'].authenticate(:player)
        PlayerConnection.new(player: player, web_socket: web_socket).listen

        # Return async Rack response
        web_socket.rack_response
      else
        app.call(env)
      end
    end

  end
end