require "json"
require "net/http"

module Boty
  class Session
    SLACK_RTM_START_URL = "https://%{domain}.slack.com/api/rtm.start?"+
        "token=%{token}&"+
        "simple_latest=true&no_unreads=true"
    private_constant :SLACK_RTM_START_URL

    attr_reader :bot
    attr_writer :verbose

    def initialize(slack_domain = ENV["SLACK_COMPANY"], verbose: false)
      @rtm_start_url = SLACK_RTM_START_URL.sub "%{domain}", slack_domain
      @rtm_start_url = @rtm_start_url.sub "%{token}", ENV["SLACK_BOT_API_TOKEN"]
      @verbose = verbose
    end

    def start(&block)
      EM.run do
        login
        bot = initialize_bot(&block)

        stablish_connection do |ws|
          ws.on :message do |event|
            on_message event, bot
          end
        end
      end
    end

    private
    def verbose?; @verbose; end

    def debug(message, *stuff)
      return unless verbose?
      $stdout.puts message
      method = $stdout.respond_to?(:pp) ? :pp : :p
      talker = $stdout.method method
      stuff.each do |printable| talker.call printable end
    end

    def login
      debug "logging in against slack right now"
      @slack_info = JSON.parse Net::HTTP.get(URI @rtm_start_url)
      debug "yep! logged in!"
      @session_url = @slack_info["url"]
    end

    def initialize_bot(&block)
      Bot.new(@slack_info["self"], self).tap { |bot|
        block.call bot if block_given?
        debug "bot is configured and ready to go!"
      }
    end

    def on_message(event, bot)
      debug "message arrived", event.data
      bot.event JSON.parse(event.data)
    end

    def on_close
      debug "bye byeb."
    end

    def stablish_connection
      debug "starting to listen on #{@session_url}"
      ws = Faye::WebSocket::Client.new @session_url
      ws.on :close do on_close end
      yield ws if block_given?
    end
  end
end