# frozen_string_literal: true

module Karafka
  module Consumers
    # Additional callbacks that can be used to trigger some actions on certain moments like
    # manual offset management, committing or anything else outside of a standard messages flow
    # They are not included by default, as we don't want to provide functionalities that are
    # not required by users by default
    # Please refer to the wiki callbacks page for more details on how to use them
    module Callbacks
      # Types of events on which we run callbacks
      TYPES = %i[
        after_fetch
        after_poll
        before_poll
        before_stop
      ].freeze

      # Class methods needed to make callbacks run
      module ClassMethods
        TYPES.each do |type|
          # A Creates a callback wrapper
          # @param method_name [Symbol, String] method name or nil if we plan to provide a block
          # @yield A block with a code that should be executed before scheduling
          define_method type do |method_name = nil, &block|
            set_callback type, :before, method_name || block
          end
        end
      end

      # @param consumer_class [Class] consumer class that we extend with callbacks
      def self.included(consumer_class)
        consumer_class.class_eval do
          extend ClassMethods
          include ActiveSupport::Callbacks

          # The call method is wrapped with a set of callbacks
          # We won't run process if any of the callbacks throw abort
          # @see http://api.rubyonrails.org/classes/ActiveSupport/Callbacks/ClassMethods.html#method-i-get_callbacks
          TYPES.each { |type| define_callbacks type }
        end
      end

      # Executes the default consumer flow, runs callbacks and if not halted will call process
      # method of a proper backend. It is here because it interacts with the default Karafka
      # call flow and needs to be overwritten to support callbacks
      def call
        run_callbacks :after_fetch do
          process
        end
      end
    end
  end
end