chat_controller.rb

require 'chat'
require 'async/websocket/adapters/rails'

class ChatController < ApplicationController
  def index
  end

  def connect
    channel = params.fetch(:channel, 'chat.general')

    self.response = Async::WebSocket::Adapters::Rails.open(request) do |connection|
      client = Chat::Redis.instance

      subscription_task = Async do
        # Subscribe to the channel and broadcast incoming messages:
        client.subscribe(channel) do |context|
          while true
            type, name, message = context.listen

            # The message is text, but contains JSON.
            connection.send_text(message)
            connection.flush
          end
        end
      end

      # Perpetually read incoming messages and publish them to Redis:
      while message = connection.read
        client.publish(channel, message.buffer)
      end
    ensure
      subscription_task&.stop
    end
  end
end