Tangle and reload webapp via Guard and Google Chrome Dev tools websocket

tangle-and-reload.rb

require 'org-converge'
require 'uri'
require 'net/http'
require 'eventmachine'
require 'faye/websocket'
require 'json'

ORG_FILE = 'org/app.org'
WEBAPP_URL = 'localhost:8000'
CHROME_DEVTOOLS_URL = 'http://localhost:9222/json'

watch(ORG_FILE) do |m|
  OrgConverge::Command.new({
                             '<org_file>' => ORG_FILE,
                             '--tangle'   => true
                           }).execute!

  begin
    json   = Net::HTTP.get(URI(CHROME_DEVTOOLS_URL))
    chrome = JSON.parse(json)
  rescue => e
    puts "Could not retrieve debug session info from Google Chrome Dev tools: #{e}"
  end
  application_tab     = chrome.find {|tab|  tab['url'] =~ /#{WEBAPP_URL}/}

  if application_tab.nil?
    puts "Tab for the web app is not open at #{webapp_url}!"
    return
  end
  websocket_debug_url = application_tab['webSocketDebuggerUrl']
  # https://github.com/cyrus-and/chrome-remote-interface#chromesendmethod-params-callback
  reload_tab_command = {
    'id'     => rand(1000),
    'method' => 'Page.reload'
  }.to_json

  EM.run do
    ws = Faye::WebSocket::Client.new(websocket_debug_url)
    ws.onopen = lambda do |event|
      puts "Reloading application via debug websocket running at #{ws.url}..."
      ws.send(reload_tab_command)
    end

    ws.onmessage = lambda do |event|
      event_info = JSON.parse(event.data)
      if event_info['error']
        puts "Could not reload application: #{event_info['error']}"
      else
        puts "Done reloading application!"
      end

      EM.stop
    end
  end
end

interactor :off