module Sinbotra::Messenger
  module Handler
    def self.included(base)
      ensure_repos_connected
      base.extend ClassMethods
    end

    def self.ensure_repos_connected
      Sinbotra::Bot::ConversationRepo.connect
      Sinbotra::Bot::UserRepo.connect
    end

    module ClassMethods
      GET_STARTED_ID = "GET_STARTED"

      def handle_message(msg)
        user = Sinbotra::Messenger::User.load(msg)
        bot  = Sinbotra::Messenger::Bot.new(user)
        # Next step in conversation
        # or match the `#hear`
        # or get default fallback
        if user.in_conversation?
          convo = user.current_conversation
          convo.perform_current_step(bot)
        elsif intent = match_intent(bot)
          intent.callback.(bot) unless intent.nil?
        else
          intent = default_intent
          intent.callback.(bot) unless intent.nil?
        end
      end

      def enable_get_started!
        @client = MessengerClient::Client.new(ENV.fetch("FACEBOOK_PAGE_TOKEN"))
        @client.get_started(GET_STARTED_ID)
      end

      def get_started(&blk)
        postback(GET_STARTED_ID, &blk)
      end

      def conversation(id, &blk)
        c = Sinbotra::Bot::Conversation.new(id)
        Sinbotra::Bot::ConversationRepo.create(id, c)
        yield c
      end

      Listener = Struct.new(:matcher, :callback) do
        def default?; false end
      end
      DefaultListener = Struct.new(:callback) do
        def default?; true end
      end
      Postback = Struct.new(:matcher, :callback)

      def postback(matcher, &blk)
        # TODO: THis feels kinda wrong
        @postbacks ||= []
        @postbacks << Postback.new(matcher, blk)
      end

      def hear(matcher=nil, &blk)
        # TODO: THis feels kinda wrong
        @listeners ||= []
        if matcher.nil?
          return @listeners << DefaultListener.new(blk)
        end
        @listeners << Listener.new(matcher, blk)
      end

      def action(name, &blk)
        @actions ||= {}
        @actions[name] = blk
      end

      def get_intent(text)
        puts "NOOP get_intent"
        nil
      end

      def yes?(str)
        str =~ yes_matcher
      end

      def typing(delay=1)
        puts "NOOP show typing for #{delay} seconds"
      end

      def next_dont_understand_phrase
        puts "NOOP next_dont_understand_phrase"
      end

      private

      def yes_matcher
        /^(yes|yeah|ya|ok)/i
      end

      def default_intent
        @listeners.find(&:default?)
      end

      def match_intent(bot)
        msg = bot.current_message
        # look for postback
        postback = msg.postback
        found_pb = @postbacks.find { |pb| postback.match(pb.matcher) }
        return found_pb unless found_pb.nil?
        # if you couldn't find a postback, look for text
        txt = msg.text
        @listeners.find { |l| !l.default? && txt.match(l.matcher) }
      end
    end
  end
end