Async requests with ActiveJob

lib/telegram/bot/async.rb

@@ -0,0 +1,138 @@
+module Telegram
+  module Bot
+    # Telegram & Botan clients can perform requests in async way with
+    # any job adapter (ActiveJob by default). Using Rails you don't need any
+    # additional configuration. However you may want to enable async requests
+    # by default with `async: true` in `secrets.yml`. Botan client doesn't inherit
+    # async setting from client and must be configured separately.
+    #
+    #   telegram:
+    #     bots:
+    #       chat_async:
+    #         token: secret
+    #         async: true # enable async mode for client
+    #         botan: botan_token # in this way botan will not be async
+    #         botan: # in this way - it's in async mode
+    #           token: botan_token
+    #           async: true
+    #
+    # Without Rails To start using async requests
+    # initialize client with `id` kwarg and make sure the client is
+    # accessible via `Teletgram.bots[id]` in job worker. Or just use
+    # `Telegram.bots_config=` for configuration.
+    #
+    # Being in async mode `#request` enqueues job instead to perform
+    # http request instead of performing it directly.
+    # Async behavior is controlled with `#async=` writer
+    # and can be enabled/disabled for the block with `#async`:
+    #
+    #   client = Telegram::Bot::Client.new(**config, async: true)
+    #   client.send_message(message)
+    #   client.async(false) { client.send_message(other_one) }
+    #
+    # It can be set with custom job class or classname. By default it defines
+    # job classes for every client class, inherited from ApplicationRecord, which
+    # can be accessed via `.default_async_job`. You can integrate it with any
+    # other job provider by defining a class with `.perform_later(bot_id, *args)`
+    # method. See Async::Job for implemetation.
+    module Async
+      module Job
+        class << self
+          def included(base)
+            base.singleton_class.send :attr_accessor, :client_class
+          end
+        end
+
+        def perform(client_id, *args)
+          client = self.class.client_class.wrap(client_id.to_sym)
+          client.async(false) { client.request(*args) }
+        end
+      end
+
+      module ClassMethods
+        def default_async_job
+          @default_async_job ||= begin
+            begin
+              ApplicationJob
+            rescue NameError
+              raise 'Define ApplicationJob class or setup #async= with custom job class'
+            end
+            klass = Class.new(ApplicationJob) { include Job }
+            klass.client_class = self
+            const_set(:AsyncJob, klass)
+          end
+        end
+
+        # This is used in specs.
+        def default_async_job=(val)
+          @default_async_job = val
+          remove_const(:AsyncJob) if const_defined?(:AsyncJob, false)
+        end
+
+        # Prepares argments for async job. ActiveJob doesn't support
+        # Symbol in argumens. Also we can encode json bodies only once here,
+        # so it would not be unnecessarily serialized-deserialized.
+        #
+        # This is stub method, which returns input. Every client class
+        # must prepare args itself.
+        def prepare_async_args(*args)
+          args
+        end
+      end
+
+      class << self
+        def prepended(base)
+          base.extend(ClassMethods)
+        end
+
+        # Transforms symbols to strings in hash values.
+        def prepare_hash(hash)
+          return hash unless hash.is_a?(Hash)
+          hash = hash.dup
+          hash.each { |key, val| hash[key] = val.to_s if val.is_a?(Symbol) }
+        end
+      end
+
+      attr_reader :id
+
+      def initialize(*, id: nil, async: nil, **options)
+        @id = id
+        self.async = async
+        super
+      end
+
+      # Sets `@async` to `self.class.default_async_job` if `true` is given
+      # or uses given value.
+      # Pass custom job class to perform async calls with.
+      def async=(val)
+        @async =
+          case val
+          when true then self.class.default_async_job
+          when String then const_get(val)
+          else val
+          end
+      end
+
+      # Returns value of `@async` if no block is given. Otherwise sets this value
+      # for a block.
+      def async(val = true)
+        return @async unless block_given?
+        begin
+          old_val = @async
+          self.async = val
+          yield
+        ensure
+          @async = old_val
+        end
+      end
+
+      # Uses job if #async is set.
+      def request(*args)
+        job_class = async
+        return super unless job_class
+        raise 'Can not enqueue job without client id' unless id
+        job_class.perform_later(id.to_s, *self.class.prepare_async_args(*args))
+      end
+    end
+  end
+end