module Bullet::ActiveRecord

def self.enable
  require 'active_record'
  ::ActiveRecord::Base.class_eval do
    class << self
      alias_method :origin_find_by_sql, :find_by_sql
      def find_by_sql(sql, binds = [])
        result = origin_find_by_sql(sql, binds)
        if Bullet.start?
          if result.is_a? Array
            if result.size > 1
              Bullet::Detector::NPlusOneQuery.add_possible_objects(result)
              Bullet::Detector::CounterCache.add_possible_objects(result)
            elsif result.size == 1
              Bullet::Detector::NPlusOneQuery.add_impossible_object(result.first)
              Bullet::Detector::CounterCache.add_impossible_object(result.first)
            end
          elsif result.is_a? ::ActiveRecord::Base
            Bullet::Detector::NPlusOneQuery.add_impossible_object(result)
            Bullet::Detector::CounterCache.add_impossible_object(result)
          end
        end
        result
      end
    end
  end
  ::ActiveRecord::Relation.class_eval do
    alias_method :origin_to_a, :to_a
    # 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 to_a
      records = origin_to_a
      if Bullet.start?
        if records.size > 1
          Bullet::Detector::NPlusOneQuery.add_possible_objects(records)
          Bullet::Detector::CounterCache.add_possible_objects(records)
        elsif records.size == 1
          Bullet::Detector::NPlusOneQuery.add_impossible_object(records.first)
          Bullet::Detector::CounterCache.add_impossible_object(records.first)
        end
      end
      records
    end
  end
  ::ActiveRecord::Persistence.class_eval do
    def _create_record_with_bullet(*args)
      _create_record_without_bullet(*args).tap do
        Bullet::Detector::NPlusOneQuery.update_inversed_object(self)
        Bullet::Detector::NPlusOneQuery.add_impossible_object(self)
      end
    end
    alias_method_chain :_create_record, :bullet
  end
  ::ActiveRecord::Associations::Preloader.class_eval do
    # include query for one to many associations.
    # keep this eager loadings.
    alias_method :origin_initialize, :initialize
    def initialize(records, associations, preload_scope = nil)
      origin_initialize(records, associations, preload_scope)
      if Bullet.start?
        records = [records].flatten.compact.uniq
        return if records.empty?
        records.each { |record| Bullet::Detector::Association.add_object_associations(record, associations) }
        Bullet::Detector::UnusedEagerLoading.add_eager_loadings(records, associations)
      end
    end
  end
  ::ActiveRecord::FinderMethods.class_eval do
    # add includes in scope
    alias_method :origin_find_with_associations, :find_with_associations
    def find_with_associations
      records = origin_find_with_associations
      if Bullet.start?
        associations = (eager_load_values + includes_values).uniq
        records.each { |record| Bullet::Detector::Association.add_object_associations(record, associations) }
        Bullet::Detector::UnusedEagerLoading.add_eager_loadings(records, associations)
      end
      records
    end
  end
  ::ActiveRecord::Associations::JoinDependency.class_eval do
    alias_method :origin_instantiate, :instantiate
    alias_method :origin_construct_association, :construct_association
    def instantiate(rows)
      @bullet_eager_loadings = {}
      records = origin_instantiate(rows)
      if Bullet.start?
        @bullet_eager_loadings.each do |_klazz, eager_loadings_hash|
          objects = eager_loadings_hash.keys
          Bullet::Detector::UnusedEagerLoading.add_eager_loadings(objects, eager_loadings_hash[objects.first].to_a)
        end
      end
      records
    end
    # call join associations
    def construct_association(record, join, row)
      result = origin_construct_association(record, join, row)
      if Bullet.start?
        associations = [join.reflection.name]
        if join.reflection.nested?
          associations << join.reflection.through_reflection.name
        end
        associations.each do |association|
          Bullet::Detector::Association.add_object_associations(record, association)
          Bullet::Detector::NPlusOneQuery.call_association(record, association)
          @bullet_eager_loadings[record.class] ||= {}
          @bullet_eager_loadings[record.class][record] ||= Set.new
          @bullet_eager_loadings[record.class][record] << association
        end
      end
      result
    end
  end
  ::ActiveRecord::Associations::CollectionAssociation.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) if Bullet.start?
      origin_load_target
    end
    alias_method :origin_include?, :include?
    def include?(object)
      Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name) if Bullet.start?
      origin_include?(object)
    end
  end
  ::ActiveRecord::Associations::HasManyAssociation.class_eval do
    alias_method :origin_empty?, :empty?
    def empty?
      if Bullet.start? && !loaded? && !has_cached_counter?(@reflection)
        Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name)
      end
      origin_empty?
    end
  end
  ::ActiveRecord::Associations::HasAndBelongsToManyAssociation.class_eval do
    alias_method :origin_empty?, :empty?
    def empty?
      Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name) if Bullet.start? && !loaded?
      origin_empty?
    end
  end
  ::ActiveRecord::Associations::SingularAssociation.class_eval do
    # call has_one and belongs_to associations
    alias_method :origin_reader, :reader
    def reader(force_reload = false)
      result = origin_reader(force_reload)
      if Bullet.start?
        unless @inversed
          Bullet::Detector::NPlusOneQuery.call_association(@owner, @reflection.name)
          Bullet::Detector::NPlusOneQuery.add_possible_objects(result)
        end
      end
      result
    end
  end
  ::ActiveRecord::Associations::HasManyAssociation.class_eval do
    alias_method :origin_has_cached_counter?, :has_cached_counter?
    def has_cached_counter?(reflection = reflection())
      result = origin_has_cached_counter?(reflection)
      Bullet::Detector::CounterCache.add_counter_cache(owner, reflection.name) if Bullet.start? && !result
      result
    end
  end
  ::ActiveRecord::Associations::CollectionProxy.class_eval do
    def count(column_name = nil, options = {})
      if Bullet.start?
        Bullet::Detector::CounterCache.add_counter_cache(proxy_association.owner, proxy_association.reflection.name)
        Bullet::Detector::NPlusOneQuery.call_association(proxy_association.owner, proxy_association.reflection.name)
      end
      super(column_name, options)
    end
  end
end