# frozen_string_literal: true

# This Karafka component is a Pro component under a commercial license.
# This Karafka component is NOT licensed under LGPL.
#
# All of the commercial components are present in the lib/karafka/pro directory of this
# repository and their usage requires commercial license agreement.
#
# Karafka has also commercial-friendly license, commercial support and commercial components.
#
# By sending a pull request to the pro components, you are agreeing to transfer the copyright of
# your code to Maciej Mensfeld.

module Karafka
  module Pro
    module Processing
      module Strategies
        # Namespace for all the strategies starting with DLQ
        module Dlq
          # Only dead letter queue enabled
          module Default
            include Strategies::Default

            # Features for this strategy
            FEATURES = %i[
              dead_letter_queue
            ].freeze

            # When we encounter non-recoverable message, we skip it and go on with our lives
            def handle_after_consume
              coordinator.on_finished do |last_group_message|
                return if revoked?

                if coordinator.success?
                  coordinator.pause_tracker.reset

                  return if coordinator.manual_pause?

                  mark_as_consumed(last_group_message)
                elsif coordinator.pause_tracker.attempt <= topic.dead_letter_queue.max_retries
                  retry_after_pause
                # If we've reached number of retries that we could, we need to skip the first
                # message that was not marked as consumed, pause and continue, while also moving
                # this message to the dead topic
                else
                  # We reset the pause to indicate we will now consider it as "ok".
                  coordinator.pause_tracker.reset
                  skippable_message, = find_skippable_message
                  dispatch_to_dlq(skippable_message) if dispatch_to_dlq?
                  mark_as_consumed(skippable_message)
                  pause(coordinator.seek_offset, nil, false)
                end
              end
            end

            # Finds the message may want to skip (all, starting from first)
            # @private
            # @return [Array<Karafka::Messages::Message, Boolean>] message we may want to skip and
            #   information if this message was from marked offset or figured out via mom flow
            def find_skippable_message
              skippable_message = messages.find do |msg|
                coordinator.marked? && msg.offset == coordinator.seek_offset
              end

              # If we don't have the message matching the last comitted offset, it means that
              # user operates with manual offsets and we're beyond the batch in which things
              # broke for the first time. Then we skip the first (as no markings) and we
              # move on one by one.
              skippable_message ? [skippable_message, true] : [messages.first, false]
            end

            # Moves the broken message into a separate queue defined via the settings
            #
            # @param skippable_message [Array<Karafka::Messages::Message>] message we want to
            #   dispatch to DLQ
            def dispatch_to_dlq(skippable_message)
              producer.produce_async(
                build_dlq_message(
                  skippable_message
                )
              )

              # Notify about dispatch on the events bus
              Karafka.monitor.instrument(
                'dead_letter_queue.dispatched',
                caller: self,
                message: skippable_message
              )
            end

            # @param skippable_message [Array<Karafka::Messages::Message>]
            # @return [Hash] dispatch DLQ message
            def build_dlq_message(skippable_message)
              original_partition = skippable_message.partition.to_s

              dlq_message = {
                topic: topic.dead_letter_queue.topic,
                key: original_partition,
                payload: skippable_message.raw_payload,
                headers: skippable_message.headers.merge(
                  'original_topic' => topic.name,
                  'original_partition' => original_partition,
                  'original_offset' => skippable_message.offset.to_s,
                  'original_consumer_group' => topic.consumer_group.id
                )
              }

              # Optional method user can define in consumer to enhance the dlq message hash with
              # some extra details if needed or to replace payload, etc
              if respond_to?(:enhance_dlq_message, true)
                enhance_dlq_message(
                  dlq_message,
                  skippable_message
                )
              end

              dlq_message
            end

            # @return [Boolean] should we dispatch the message to DLQ or not. When the dispatch
            #   topic is set to false, we will skip the dispatch, effectively ignoring the broken
            #   message without taking any action.
            def dispatch_to_dlq?
              topic.dead_letter_queue.topic
            end
          end
        end
      end
    end
  end
end