module Bullet
  module Detector
    class Association < Base
      class <<self
        def add_object_associations(object, associations)
          return unless Bullet.start?
          return if !Bullet.n_plus_one_query_enable? && !Bullet.unused_eager_loading_enable?
          return unless object.primary_key_value

          Bullet.debug('Detector::Association#add_object_associations'.freeze, "object: #{object.bullet_key}, associations: #{associations}")
          object_associations.add(object.bullet_key, associations)
        end

        def add_call_object_associations(object, associations)
          return unless Bullet.start?
          return if !Bullet.n_plus_one_query_enable? && !Bullet.unused_eager_loading_enable?
          return unless object.primary_key_value

          Bullet.debug('Detector::Association#add_call_object_associations'.freeze, "object: #{object.bullet_key}, associations: #{associations}")
          call_object_associations.add(object.bullet_key, associations)
        end

        # possible_objects keep the class to object relationships
        # that the objects may cause N+1 query.
        # e.g. { Post => ["Post:1", "Post:2"] }
        def possible_objects
          Thread.current[:bullet_possible_objects]
        end

        # impossible_objects keep the class to objects relationships
        # that the objects may not cause N+1 query.
        # e.g. { Post => ["Post:1", "Post:2"] }
        # if find collection returns only one object, then the object is impossible object,
        # impossible_objects are used to avoid treating 1+1 query to N+1 query.
        def impossible_objects
          Thread.current[:bullet_impossible_objects]
        end

        private
          # object_associations keep the object relationships
          # that the object has many associations.
          # e.g. { "Post:1" => [:comments] }
          # the object_associations keep all associations that may be or may no be
          # unpreload associations or unused preload associations.
          def object_associations
            Thread.current[:bullet_object_associations]
          end

          # call_object_associations keep the object relationships
          # that object.associations is called.
          # e.g. { "Post:1" => [:comments] }
          # they are used to detect unused preload associations.
          def call_object_associations
            Thread.current[:bullet_call_object_associations]
          end

          # inversed_objects keeps object relationships
          # that association is inversed.
          # e.g. { "Comment:1" => ["post"] }
          def inversed_objects
            Thread.current[:bullet_inversed_objects]
          end

          # eager_loadings keep the object relationships
          # that the associations are preloaded by find :include.
          # e.g. { ["Post:1", "Post:2"] => [:comments, :user] }
          def eager_loadings
            Thread.current[:bullet_eager_loadings]
          end
      end
    end
  end
end