PIImageConcern.rb

class PortfolioItem::Image
  dragonfly_accessor :image_original # store original
  dragonfly_accessor :image_medium # 660px
end


class PortfolioItem
  include PortfolioItem::ImagesConcern
end


module PortfolioItem::ImagesConcern
  
  extend ActiveSupport::Concern

  class NoSuchStyleError < StandardError; end

  included do
    has_many :images, dependent: :destroy # , class_name: 'PortfolioItem::Image' # class name may not be necessary
    private :images # only use images through the methods #tile_image, #tile_image=, etc. 
  end

  def tile_image
    images.find_by_slot(:tile).image_original
  end

  def tile_image=(file)
    association_object = images.find_or_initialize_by_slot(:tile)
    association_object.image = file
    association_object.save!
    # TODO verify return value of tile_image with Paperclip. return the same as paperclip would.
    association_object.image
  end

  # 
  # current method name: #teaser
  #
  # How is it currently used? 
  # 
  # teaser.path # no arg means default, :original
  # => replace with #tile_widget_image.path
  #  
  # teaser.path(:preview) 
  # => replace with #tile_widget_image(:medium).path
  #
  # teaser.url(:preview) 
  # => replace with #tile_widget_image(:medium).url
  #
  # teaser.file? (was a file uploaded or is the image a default image) 
  # => replace with #tile_widget_image.present?
  # 
  def tile_widget_image(style = :original)
    association_object = images.find_by_origin(:tile_widget)
    image_attribute    = "image_#{style}".to_sym
    raise NoSuchStyleError.new(style) unless association_object.respond_to?(image_attribute)
    association_object.send(image_attribute)
  end

  #
  # DISCUSS
  # it may be possible to replace all of PortfolioItem::CollectDetailImageCandidates with a method like this:
  #
  # def detail_image_candidates
  #   images
  #     .where(slot: nil)
  #     .where(origin: [:embedly, :tile_widget_upload, :detail_widget_upload, :initial_upload])
  #     .map(:&image_medium) # or return value object instead of the dragonfly object
  # end


end