module PrintingPress
  module Model

    def self.included(base)
      base.send :extend, ClassMethods
    end
		
    module ClassMethods
      def publishable(options = {})
        send :include, InstanceMethods

				class_attribute :published_table_name
				self.published_table_name = options[:table_name] || "published_#{table_name}"
				
				class_attribute :dependencies
				self.dependencies = options[:dependent_on] || []

				class_attribute :printing_press_enabled_for_model				
      end

      def printing_press_off
        self.printing_press_enabled_for_model = false
				self.reset_column_information
      end

      def printing_press_on
        self.printing_press_enabled_for_model = true
				self.reset_column_information
      end

			def table_name
				if self.printing_press_enabled_for_model
					self.published_table_name
				else
					self.reset_table_name
				end
			end

			def drafts
				self.find_by_sql("SELECT o.* FROM #{self.reset_table_name} o, #{self.published_table_name} p WHERE (o.id = p.id AND o.updated_at != p.updated_at)") +
				self.find_by_sql("SELECT * FROM #{self.reset_table_name} WHERE id NOT IN (SELECT id FROM #{self.published_table_name}) GROUP BY id")
			end
    end

    module InstanceMethods		
			def published_version
				@published_version ||= self.class.find_by_sql("SELECT * FROM #{self.class.published_table_name} WHERE id = #{self.id}").first
			end
			
			def publish
				return if published?
				
				remove_published_version if not published_version.nil?
				connection.insert("INSERT INTO #{self.class.published_table_name} SELECT * FROM #{self.class.reset_table_name} WHERE id = #{self.id}")
				
				# We need to handle belongs_to dependencies as well
				self.class.dependencies.each do |dependency|
					self.try(dependency).try(:publish)
				end
			end
			
			def published?
				not published_version.nil? and published_version.updated_at == self.updated_at
			end
			
			def destroy
				remove_published_version
				super
			end
			
			def published_at
				published_version.nil? ? nil : published_version.updated_at
			end
			
			private
			
			def remove_published_version
				connection.delete("DELETE FROM #{self.class.published_table_name} WHERE id = #{self.id}")
			end
    end

  end
end