module Feedjira
  module Parser
    # Parser for dealing with Atom feeds.
    class Atom
      include SAXMachine
      include FeedUtilities

      element :title
      element :subtitle, as: :description
      element :link, as: :url, value: :href, with: { type: "text/html" }
      element :link, as: :feed_url, value: :href, with: { rel: "self" }
      elements :link, as: :links, value: :href
      elements :link, as: :hubs, value: :href, with: { rel: "hub" }
      elements :entry, as: :entries, class: AtomEntry

      def self.able_to_parse?(xml)
        %r{\<feed[^\>]+xmlns\s?=\s?[\"\'](http://www\.w3\.org/2005/Atom|http://purl\.org/atom/ns\#)[\"\'][^\>]*\>} =~ xml # rubocop:disable Metrics/LineLength
      end

      def url
        @url || (links - [feed_url]).last || links.last
      end

      def feed_url
        @feed_url ||= links.first
      end

      def self.preprocess(xml)
        Preprocessor.new(xml).to_xml
      end
    end
  end
end