module Bullet
  LOAD_TARGET_RGX = /load_target/
  module ActiveRecord
    def self.enable
      require 'active_record'
      ::ActiveRecord::Base.class_eval do
        class << self
          alias_method :origin_find_every, :find_every
          # if select a collection of objects, then these objects have possible to cause N+1 query.
          # if select only one object, then the only one object has impossible to cause N+1 query.
          def find_every(options)
            records = origin_find_every(options)

            if records 
              if records.size > 1
                Bullet::Detector::Association.add_possible_objects(records)
                Bullet::Detector::Counter.add_possible_objects(records)
              elsif records.size == 1
                Bullet::Detector::Association.add_impossible_object(records.first)
                Bullet::Detector::Counter.add_impossible_object(records.first)
              end
            end

            records
          end
        end
      end

      ::ActiveRecord::AssociationPreload::ClassMethods.class_eval do
        alias_method :origin_preload_associations, :preload_associations
        # include query for one to many associations.
        # keep this eager loadings.
        def preload_associations(records, associations, preload_options={})
          records = [records].flatten.compact.uniq
          return if records.empty?
          records.each do |record|
            Bullet::Detector::Association.add_object_associations(record, associations)
          end
          Bullet::Detector::Association.add_eager_loadings(records, associations)
          origin_preload_associations(records, associations, preload_options={})
        end
      end

      ::ActiveRecord::Associations::ClassMethods.class_eval do      
        # add include in named_scope
        alias_method :origin_find_with_associations, :find_with_associations
        def find_with_associations(options)
          records = origin_find_with_associations(options)
          associations = merge_includes(scope(:find, :include), options[:include])
          records.each do |record|
            Bullet::Detector::Association.add_object_associations(record, associations)
            Bullet::Detector::NPlusOneQuery.call_association(record, associations)
          end
          Bullet::Detector::Association.add_eager_loadings(records, associations)
          records
        end
      end

      ::ActiveRecord::Associations::ClassMethods::JoinDependency.class_eval do
        # call join associations
        alias_method :origin_construct_association, :construct_association
        def construct_association(record, join, row)
          associations = join.reflection.name
          Bullet::Detector::Association.add_object_associations(record, associations)
          Bullet::Detector::NPlusOneQuery.call_association(record, associations)
          origin_construct_association(record, join, row)
        end
      end

      ::ActiveRecord::Associations::AssociationCollection.class_eval do
        # call one to many associations
        alias_method :origin_load_target, :load_target
        def load_target
          Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name)
          origin_load_target
        end
      end
      
      ::ActiveRecord::Associations::AssociationProxy.class_eval do
        # call has_one and belong_to association
        alias_method :origin_load_target, :load_target
        def load_target
          # avoid stack level too deep
          result = origin_load_target
          Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name) unless caller.find {|c| c =~ LOAD_TARGET_RGX }
          Bullet::Detector::Association.add_possible_objects(result)
          result
        end
      end
      
      ::ActiveRecord::Associations::HasManyAssociation.class_eval do
        alias_method :origin_has_cached_counter?, :has_cached_counter?
        def has_cached_counter?
          result = origin_has_cached_counter?
          Bullet::Detector::Counter.add_counter_cache(@owner, @reflection.name) unless result
          result
        end
      end

      ::ActiveRecord::Associations::HasManyThroughAssociation.class_eval do
        alias_method :origin_has_cached_counter?, :has_cached_counter?
        def has_cached_counter?
          result = origin_has_cached_counter?
          Bullet::Detector::Counter.add_counter_cache(@owner, @reflection.name) unless result
          result
        end
      end
    end
  end
end