module RailsConnector

  # This module contains helpers that can be used to reference images and other assets stored in the CMS.
  #
  # @api public
  module CmsAssetHelper

    # Calculates an HTML image tag for an image stored in the CMS.
    #
    # @note There are two different signatures of this method: the first one generates an HTML image tag with no
    #   inplace editing possible, the second one generated an HTML image tag for inplace editing.
    #
    # @overload cms_image_tag target, tag_options={}
    #   @note If you do not specify an HTML +alt+ attribute, the helper method will use +target+'s +display_title+.
    #   Calculates HTML image tag (no inplace editing possible).
    #
    #   @param [Obj, Link] target Target containing image stored in CMS.
    #   @param [Hash] tag_options Additional HTML attributes for the tag.
    #
    #   @example
    #     cms_image_tag @target
    #     cms_image_tag @target, alt: 'Interesting picture', class: 'my_image'
    #
    # @overload cms_image_tag obj, linklist, tag_options={}, editing_options={}
    #   @note If you do not specify an HTML +alt+ attribute, the helper method will use +display_title+ of the target object.
    #   Calculates HTML image tag for inplace editing.
    #
    #   @param [Obj] obj Obj with an attribute of type {LinkList}.
    #   @param [String, Symbol] linklist Name of {LinkList} attribute, which contains the image.
    #   @param [Hash] tag_options Additional HTML attributes for the tag.
    #
    #   @param [Hash] editing_options Additional options for inplace editing.
    #   @option editing_options [String] :placeholder ('/assets/rails_connector/image_placeholder.png') URL or path to image to be displayed if target is missing.
    #
    #   @example
    #     cms_image_tag @obj, :my_linklist
    #     cms_image_tag @obj, :my_linklist, alt: 'Interesting picture', class: 'my_image'
    #     cms_image_tag @obj, :my_linklist, {}, placeholder: image_path('my_placeholder.png')
    #     cms_image_tag @obj, :my_linklist, {class: 'my_image'}, placeholder: 'http://placehold.it/350x150'
    #
    # @return [String] HTML image tag
    # @api public
    def cms_image_tag(*args)
      if args.second.nil? || args.second.is_a?(Hash)
        # Backwards compatibility.
        target = args.first

        tag_options = args.second || {}
        tag_options.symbolize_keys!
        tag_options[:src] = cms_path(target)
        tag_options[:alt] ||= display_title(target)

        tag('img', tag_options)
      else
        obj             = args.first
        field_name      = args.second
        tag_options     = args.third || {}
        editing_options = args.fourth || {}

        cms_tag('img', obj, field_name, cms_image_tag_options(obj, field_name,
            tag_options.symbolize_keys, editing_options.symbolize_keys))
      end

    end

    private

    def cms_image_tag_options(obj, field_name, tag_options, editing_options)
      tag_options.reverse_merge(src: cms_image_tag_src(obj, field_name, editing_options),
          alt: cms_image_tag_alt(obj, field_name))
    end

    def cms_image_tag_src(obj, field_name, editing_options)
      cms_image_tag_path(obj, field_name) || editing_options[:placeholder] ||
          image_path('rails_connector/image_placeholder.png')
    end

    def cms_image_tag_alt(obj, field_name)
      display_title(obj[field_name])
    end

    def cms_image_tag_path(obj, field_name)
      field_type = obj.type_of_attribute(field_name)
      field_value = obj[field_name]

      case field_type
      when 'reference' then field_value && cms_path(field_value)
      when 'linklist'
        path = cms_path(field_value)
        path == DefaultCmsRoutingHelper::LINK_TO_EMPTY_LINKLIST ? nil : path
      end
    end

    def display_title(target)
      if target.respond_to?(:display_title)
        return target.display_title
      elsif target.respond_to?(:first) && target.first.respond_to?(:display_title)
        return target.first.display_title
      end
    end

  end
end