gistfile1.rb

Facebook::Profile to introduce current_user

current_user.likes? Application.object_key

module Facebook

  class Cache < Struct.new(:graph)

    # Invalide cache after 10 minutes
    #
    # For automatic invalidation, see
    # https://developers.facebook.com/docs/reference/api/realtime/
    TTL = 10.minutes

    def self.new(graph, key)
      key.to_s == 'me' ? graph : super(graph)
    end

    attr_accessor :ttl

    def initialize(graph)
      super graph
      @ttl = TTL
    end

    # Koala::Facebook::API
    def get_connections(key, k)
      fetch(key, 'connections', k) { graph.get_connections key, k }
    end
    def get_picture(key)
      fetch(key, 'picture_url') { graph.get_picture key }
    end
    def get_object(key)
      fetch(key, 'object') { graph.get_object key }
    end

    protected

      def fetch(*a)
        Rails.cache.fetch(['fb', *a] * ':', expires_in: @ttl) { yield }
      end

  end

  class Object
    # includes some ActiveModel modules

    # Returns instance with graph object for token set
    def self.connect(token, object_key)
      new Koala::Facebook::API.new(token), object_key
    end

    # Allow to inject graph object for stubbing
    def initialize(graph, key)
      @graph, @key = Cache.new(graph, key), key
      @cache = Hash.new { |h, k| h[k] = @graph.get_connections key, k }
    end

    # getter for common properties
    def id
      object.fetch 'id'
    end
    def name
      object.fetch 'name'
    end

    protected

      def connections(type)
        Enumerator.new { |y| @cache[type].each { |c| y << c } }
      end
      def object
        @object ||= @graph.get_object @key
      end

  end

  class Profile < Facebook::Object
    # includes some ActiveModel modules

    # be aware that 'me' cannot be cached
    def self.me(token)
      connect token, 'me'
    end

    def picture_url
      @picture_url ||= @graph.get_picture id.to_s
    end

    # common query methods
    def likes? cid
      connections('likes').any? { |c| c.fetch('id') == cid }
    end


    require 'active_support/concern'

    module Extension
      extend ActiveSupport::Concern

      included do
        cattr_accessor :fb_token, :fb_key
        delegate :likes?, :picture_url, to: profile
      end

      def profile
        Facebook::Profile.connect \
          read_attribute(fb_token), read_attribute(fb_key)
      end

    end

    module ClassMethods
      def has_profile(options = {})
        include Facebook::Profile::Extension
        self.fb_token = options.fetch :token_column, :facebook_token
        self.fb_key = optione.fetch :key_column, :facebook_id
      end
    end

  end

end