module LaserLemon
  module CacheFlow
    def self.included(base)
      base.class_eval do
        class_inheritable_accessor :cache_serialization
        self.cache_serialization = false

        extend ClassMethods
        include InstanceMethods

        alias_method_chain :to_xml, :cache_flow
        alias_method_chain :to_json, :cache_flow
      end
    end

    module ClassMethods
      def cache_flow(value = true)
        if block_given?
          old_value = cache_serialization
          begin
            self.cache_serialization = value
            yield
          ensure
            self.cache_serialization = old_value
          end
        else
          self.cache_serialization = value
        end
      end
    end

    module InstanceMethods
      def to_xml_with_cache_flow(options = {})
        with_cache_flow(:xml, options) do
          to_xml_without_cache_flow(options)
        end
      end

      def to_json_with_cache_flow(options = {})
        with_cache_flow(:json, options) do
          to_json_without_cache_flow(options)
        end
      end

      private

        def with_cache_flow(extension, options, &block)
          if options.has_key?(:cache) ? options.delete(:cache) : self.class.cache_serialization
            options.merge!(:cache => false)
            key, value = send("#{extension}_cache_key", options), yield
            Rails.cache.fetch(key){ value.respond_to?(:dup) ? value.dup : value }
          else
            yield
          end
        end

        def xml_cache_key(options)
          level = options.has_key?(:builder) ? options[:builder].instance_eval{ @level } : nil
          serialized_cache_key(:xml, options.except(:builder).merge(:level => level))
        end

        def json_cache_key(options)
          serialized_cache_key(:json, options)
        end

        def serialized_cache_key(extension, options)
          query = options.except(:cache).reject{|k,v| v.nil? }.to_query
          ["#{cache_key}.#{extension}", query].delete_if(&:blank?).join('?')
        end
    end
  end
end

ActiveRecord::Base.send(:include, LaserLemon::CacheFlow)