module Roar
  module Rails
    class Responder < ActionController::Responder
      def display(model, *args)
        if represent_format?
          handle_lonely_collection!(model) and return super # :represent_items_with

          model = prepare_model_for(format, model, options)
        end

        super(create_response(model), *args) # AC::Responder: this calls controller.render which calls render_to_body which calls renderer[:json] which calls model.to_json.
      end

    private

      def default_represented_formats
        ::Rails.application.config.representer.represented_formats
      end

      # First check for user option overrides, then check for defaults, then trigger
      # previous behavior and always represent for the requested format.
      def represent_format?
        formats = Array((options[:represented_formats] || default_represented_formats || [format]))
        formats.include?(format)
      end

      def resourceful?
        # FIXME: find out if we have a representer? what about old behaviour?
        #resource.respond_to?("to_#{format}")
        true
      end

      def create_response(model)
        render_method = "to_#{format}"
        media_format  = Mime[format]
        Response.new(model.send(render_method, options), media_format).body
      end

      def handle_lonely_collection!(collection)
        return false unless representer = options.delete(:represent_items_with)

        setup_items_with(collection, representer) # convenience API, not recommended since it's missing hypermedia.
        true
      end

      def setup_items_with(collection, representer)
        collection.map! do |mdl|  # DISCUSS: i don't like changing the method argument here.
          representer.prepare(mdl).to_hash(options) # FIXME: huh? and what about XML?
        end
      end


      module PrepareModel
        def prepare_model_for(format, model, options) # overwritten in VersionStrategy/3.0.
          controller.prepare_model_for(format, model, options)
        end
      end
      include PrepareModel
      include VersionStrategy


      class Response
        attr_reader :content_type, :body # DISCUSS: how to add more header fields? #headers?

        def initialize(body, content_type)
          @body         = body
          @content_type = content_type
        end
      end
    end
  end
end