module Delayed
  module Workless
    module Scaler

      autoload :Heroku,      "workless/scalers/heroku"
      autoload :HerokuCedar, "workless/scalers/heroku_cedar"
      autoload :Local,       "workless/scalers/local"
      autoload :Null,        "workless/scalers/null"

      def self.included(base)
        base.send :extend, ClassMethods
        if base.to_s =~ /ActiveRecord/
          base.class_eval do
            after_commit "self.class.scaler.down", :on => :update, :if => Proc.new {|r| !r.failed_at.nil? }
            after_commit "self.class.scaler.down", :on => :destroy, :if => Proc.new {|r| r.destroyed? or !r.failed_at.nil? }
            after_commit "self.class.scaler.up", :on => :create
          end          
        elsif base.to_s =~ /Sequel/
          base.send(:define_method, 'after_destroy') do
            super
            self.class.scaler.down
          end
          base.send(:define_method, 'after_create') do
            super
            self.class.scaler.up
          end
          base.send(:define_method, 'after_update') do
            super
            self.class.scaler.down
          end
        else
          base.class_eval do
            after_destroy "self.class.scaler.down"
            after_create "self.class.scaler.up"
            after_update "self.class.scaler.down", :unless => Proc.new {|r| r.failed_at.nil? }
          end
        end
      end

      module ClassMethods
        def scaler
          @scaler ||= if ENV.include?("HEROKU_API_KEY")
            Scaler::HerokuCedar
          else
            Scaler::Local
          end
        end

        def scaler=(scaler)
          @scaler = "Delayed::Workless::Scaler::#{scaler.to_s.camelize}".constantize
        end
      end

    end

  end
end