require 'active_support/concern'

# expects underlying model to have filename, class, and id attributes
module HalApi::Representer::Embeds
  extend ActiveSupport::Concern

  included do
    Representable::Mapper.send(:include, Resources) if !Representable::Mapper.include?(Resources)
  end

  module Resources

    def skip_property?(binding, options)
      super(binding, options) || suppress_embed?(binding, options)
    end

    # embed if zoomed
    def suppress_embed?(binding, options)
      name     = (binding[:as] || binding.name).to_s
      embedded = !!binding[:embedded]

      # not embedded, return false - nothing to suppress
      return false if !embedded

      # check if it should be zoomed, suppress if not
      !embed_zoomed?(name, binding[:zoom], options[:zoom])
    end

    def embed_zoomed?(name, zoom_def=nil, zoom_param=nil)
      # if the embed in the representer definition has `zoom: :always` defined
      # always embed it, even if it is in another embed
      # (this is really meant for collections where embedded items must be included)
      return true if zoom_def == :always

      # passing nil explicitly overwrites defaults in signature,
      # so we default to nil and fix in the method body
      zoom_def = true if zoom_def.nil?

      # if there is no zoom specified in the request params (options)
      # then embed based on the zoom option in the representer definition

      # if there is a zoom specified in the request params (options)
      # then do not zoom when this name is not in the request
      zoom_param.nil? ? zoom_def : zoom_param.include?(name)
    end
  end

  # Possible values for zoom option in the embed representer definition
  # * false - will be zoomed only if in the root doc and in the zoom param
  # * true - zoomed in root doc if no zoom_param, or if included in zoom_param
  # * always - zoomed no matter what is in zoom param, and even if in embed
  module ClassMethods

    def embed(name, options={})
      options[:embedded] = true
      options[:writeable] = false
      options[:if] ||= ->(_a) { id } unless options[:zoom] == :always

      if options[:paged]
        opts = {
          no_curies: true,
          item_class: options.delete(:item_class),
          url: options.delete(:url),
          item_decorator: options.delete(:item_decorator),
          per: options.delete(:per) || Kaminari.config.default_per_page
        }
        options[:getter] ||= ->(*) do
          # set # per page based on default, option value integer, or special :all
          per = opts.delete(:per)
          per = self.send(name).count if per == :all
          PagedCollection.new(self.send(name).page(1).per(per), nil, opts.merge({parent: self}))
        end
        options[:decorator] = Api::PagedCollectionRepresenter
      end

      property(name, options)
    end

    def embeds(name, options={})
      options[:embedded] = true
      options[:writeable] = false
      options[:if] ||= ->(_a) { id } unless options[:zoom] == :always

      collection(name, options)
    end
  end
end