refactor: avoid Action Cable "hard" monkey-patching

This PR changes the (historical) way of making Action Cable compatible with AnyCable:

- Extend (via #prepend) instead of reopening classes
- Preserve the original functionality (by using #anycabled? checks where necessary)

Closes #165

CHANGELOG.md

@@ -2,6 +2,8 @@
 
 ## master
 
+- Refactored Action Cable patching to preserve original functionality and avoid monkey-patching collisions. ([@palkan][])
+
 ## 1.2.1 (2021-01-31)
 
 - Add a temporary fix to be compatible with `sentry-rails`. ([@palkan][])

Gemfile

@@ -2,7 +2,7 @@ source 'https://rubygems.org'
 
 gemspec
 
-gem "pry-byebug", platform: :mri
+gem "debug", platform: :mri
 
 local_gemfile = "#{File.dirname(__FILE__)}/Gemfile.local"
 
@@ -11,7 +11,8 @@ eval_gemfile "gemfiles/rubocop.gemfile"
 if File.exist?(local_gemfile)
   eval(File.read(local_gemfile)) # rubocop:disable Lint/Eval
 else
-  gem 'sqlite3', '~> 1.3'
-  gem 'actioncable', '~> 6.0'
-  gem 'activerecord'
+  gem 'actioncable', '~> 7.0'
 end
+
+gem 'sqlite3', '~> 1.3'
+gem 'activerecord'

lib/anycable/rails/action_cable_ext/channel.rb

@@ -0,0 +1,47 @@
+# frozen_string_literal: true
+
+require "action_cable/channel"
+
+ActionCable::Channel::Base.prepend(Module.new do
+  def subscribe_to_channel(force: false)
+    return if anycabled? && !force
+    super()
+  end
+
+  def handle_subscribe
+    subscribe_to_channel(force: true)
+  end
+
+  def start_periodic_timers
+    super unless anycabled?
+  end
+
+  def stop_periodic_timers
+    super unless anycabled?
+  end
+
+  def stream_from(broadcasting, _callback = nil, _options = {})
+    return super unless anycabled?
+
+    connection.anycable_socket.subscribe identifier, broadcasting
+  end
+
+  def stop_stream_from(broadcasting)
+    return super unless anycabled?
+
+    connection.anycable_socket.unsubscribe identifier, broadcasting
+  end
+
+  def stop_all_streams
+    return super unless anycabled?
+
+    connection.anycable_socket.unsubscribe_from_all identifier
+  end
+
+  private
+
+  def anycabled?
+    # Use instance variable check here for testing compatibility
+    connection.instance_variable_defined?(:@anycable_socket)
+  end
+end)

lib/anycable/rails/action_cable_ext/connection.rb

@@ -0,0 +1,30 @@
+# frozen_string_literal: true
+
+require "action_cable/connection"
+require "anycable/rails/connections/serializable_identification"
+
+ActionCable::Connection::Base.include(AnyCable::Rails::Connections::SerializableIdentification)
+ActionCable::Connection::Base.prepend(Module.new do
+  attr_reader :anycable_socket
+  attr_accessor :anycable_request_builder
+
+  # In AnyCable, we lazily populate env by passing it through the middleware chain,
+  # so we access it via #request
+  def env
+    return super unless anycabled?
+
+    request.env
+  end
+
+  def anycabled?
+    @anycable_socket
+  end
+
+  private
+
+  def request
+    return super unless anycabled?
+
+    @request ||= anycable_request_builder.build_rack_request(@env)
+  end
+end)

lib/anycable/rails/actioncable/remote_connections.rb → lib/anycable/rails/action_cable_ext/remote_connections.rb

@@ -2,7 +2,7 @@
 
 require "action_cable/remote_connections"
 
-ActionCable::RemoteConnections::RemoteConnection.include(ActionCable::Connection::SerializableIdentification)
+ActionCable::RemoteConnections::RemoteConnection.include(AnyCable::Rails::Connections::SerializableIdentification)
 
 ActionCable::RemoteConnections::RemoteConnection.prepend(Module.new do
   def disconnect(reconnect: true)