module RabbitFeed
  module ConsoleConsumer
    extend self

    APPLICATION_NAME = 'rabbit_feed_console'.freeze

    def init
      @event_count = 0
      set_application
      route_all_events
      puts welcome_message
      ask_to_purge_queue unless queue_empty?
      puts 'Ready. Press CTRL+C to exit.'
    end

    def formatted(event)
      Formatter.new(event).to_s
    end

    def event_count_message
      "#{@event_count} events received."
    end

    def increment_event_count
      @event_count += 1
    end

    private

    def welcome_message
      "RabbitFeed console starting at #{Time.now.utc}...\n"\
      "Environment: #{RabbitFeed.environment}\n"\
      "Queue: #{RabbitFeed.configuration.queue}"
    end

    def queue_empty?
      ConsumerConnection.instance.queue_depth.zero?
    end

    def ask_to_purge_queue
      puts "There are currently #{ConsumerConnection.instance.queue_depth} message(s) in the console's queue.\n"\
           'Would you like to purge the queue before proceeding? (y/N)>'
      response = STDIN.gets.chomp
      purge_queue if response == 'y'
    end

    def purge_queue
      ConsumerConnection.instance.purge_queue
      puts 'Queue purged.'
    end

    def route_all_events
      scope = self
      EventRouting do
        accept_from(:any) do
          event(:any) do |event|
            scope.increment_event_count
            puts scope.formatted(event)
            puts scope.event_count_message
          end
        end
      end
    end

    def set_application
      RabbitFeed.application = APPLICATION_NAME
    end

    class Formatter
      BORDER_WIDTH = 100
      BORDER_CHAR  = '-'.freeze
      DIVIDER_CHAR = '*'.freeze
      NEWLINE      = "\n".freeze

      attr_reader :event

      def initialize(event)
        @event = event
      end

      def to_s
        [header, metadata, divider, payload, footer].join(NEWLINE)
      end

      private

      def header
        event_detail = "#{event.name}: #{event.created_at_utc}"
        border_filler = BORDER_CHAR * ((BORDER_WIDTH - event_detail.length) / 2)
        border_filler + event_detail + border_filler
      end

      def footer
        BORDER_CHAR * BORDER_WIDTH
      end

      def metadata
        pretty_print_hash 'Event metadata', event.metadata
      end

      def divider
        DIVIDER_CHAR * BORDER_WIDTH
      end

      def payload
        pretty_print_hash 'Event payload', event.payload
      end

      def pretty_print_hash(description, hash)
        '#' + description + NEWLINE +
          hash.keys.sort.map do |key|
            "#{key}: #{hash[key]}"
          end.join(NEWLINE)
      end
    end
  end
end