require 'messaging/routing/message_matcher'
require 'messaging/routing/subscriber'
require 'messaging/routing/background_job_subscriber'
require 'messaging/routing/enqueue_message_handler'

module Messaging
  module Routing
    # Public: Sets up subscribers for the events that matches the given pattern
    #
    # pattern  - Which messages to subscribe to. Can be a string, a regexp,
    #            a Message class, a module or anything that responds to call.
    #
    # call:    -  Any object that responds to call.
    #             Will be called immediately for matching messages.
    #
    # enqueue: -  A constant that responds to call.
    #             Will be enqueued with Sidekiq for matching messages.
    #             Needs to be a constant that Sidekiq can serialize to a string
    #             and back again to a constant as you can't store procs in Redis.
    #
    # block    -  An optional block that will be called with each matching message.
    #
    #
    # Examples
    #
    # Messaging.routes.draw do
    #   on 'Events::BidPlaced', call: NotifyOtherBidders
    #
    #   on Events::BidPlaced, enqueue: NotifyOtherBidders
    #
    #   on Events, do |event|
    #     puts event.inspect
    #   end
    #
    #   on /.*Updated$/, enqueue: AuditChanges
    #
    #   on ->(m) { m.topic == 'my-topic' }, call: DoSometing, enqueue: DoSomethingElseWithSidekiq
    # end
    #
    def on(pattern = /.*/, topic: nil, call: nil, enqueue: nil, &block)
      subscribers << Subscriber.new(pattern, topic, call) if call
      subscribers << Subscriber.new(pattern, topic, block) if block_given?
      subscribers << BackgroundJobSubscriber.new(pattern, topic, enqueue) if enqueue
    end

    # Internal: Handles the message with the matching subscribers
    def handle(message)
      subscribers.map { |subscriber| subscriber.call(message) }
      message
    end

    # Internal: Used by Rails reloading in development.
    def clear_subscribers!
      @subscribers = Set.new
    end

    private

    def subscribers
      @subscribers ||= Set.new
    end

    def topics
      subscribers.flat_map(&:topics).map(&:to_s).uniq
    end
  end
end