class ActiveRecord::Associations::BelongsToAssociation

def decrement_counters
  update_counters(-1)
end

def decrement_counters_before_last_save
  if reflection.polymorphic?
    model_type_was = owner.attribute_before_last_save(reflection.foreign_type)
    model_was = owner.class.polymorphic_class_for(model_type_was) if model_type_was
  else
    model_was = klass
  end
  foreign_key_was = owner.attribute_before_last_save(reflection.foreign_key)
  if foreign_key_was && model_was < ActiveRecord::Base
    update_counters_via_scope(model_was, foreign_key_was, -1)
  end
end

def default(&block)
  writer(owner.instance_exec(&block)) if reader.nil?
end

def find_target?
  !loaded? && foreign_key_present? && klass
end

def foreign_key_present?
  Array(reflection.foreign_key).all? { |fk| owner._read_attribute(fk) }
end

def handle_dependency
  return unless load_target
  case options[:dependent]
  when :destroy
    raise ActiveRecord::Rollback unless target.destroy
  when :destroy_async
    if reflection.foreign_key.is_a?(Array)
      primary_key_column = reflection.active_record_primary_key
      id = reflection.foreign_key.map { |col| owner.public_send(col) }
    else
      primary_key_column = reflection.active_record_primary_key
      id = owner.public_send(reflection.foreign_key)
    end
    association_class = if reflection.polymorphic?
      owner.public_send(reflection.foreign_type)
    else
      reflection.klass
    end
    enqueue_destroy_association(
      owner_model_name: owner.class.to_s,
      owner_id: owner.id,
      association_class: association_class.to_s,
      association_ids: [id],
      association_primary_key_column: primary_key_column,
      ensuring_owner_was_method: options.fetch(:ensuring_owner_was, nil)
    )
  else
    target.public_send(options[:dependent])
  end
end

def increment_counters
  update_counters(1)
end

def inversed_from(record)
  replace_keys(record)
  super
end

def invertible_for?(record)
  inverse = inverse_reflection_for(record)
  inverse && (inverse.has_one? || inverse.klass.has_many_inversing)
end

def primary_key(klass)
  reflection.association_primary_key(klass)
end

def replace(record)
  if record
    raise_on_type_mismatch!(record)
    set_inverse_instance(record)
    @updated = true
  elsif target
    remove_inverse_instance(target)
  end
  replace_keys(record, force: true)
  self.target = record
end

def replace_keys(record, force: false)
  reflection_fk = reflection.foreign_key
  if reflection_fk.is_a?(Array)
    target_key_values = record ? Array(primary_key(record.class)).map { |key| record._read_attribute(key) } : []
    if force || reflection_fk.map { |fk| owner._read_attribute(fk) } != target_key_values
      reflection_fk.each_with_index do |key, index|
        owner[key] = target_key_values[index]
      end
    end
  else
    target_key_value = record ? record._read_attribute(primary_key(record.class)) : nil
    if force || owner._read_attribute(reflection_fk) != target_key_value
      owner[reflection_fk] = target_key_value
    end
  end
end

def require_counter_update?
  reflection.counter_cache_column && owner.persisted?
end

def reset
  super
  @updated = false
end

def saved_change_to_target?
  owner.saved_change_to_attribute?(reflection.foreign_key)
end

def stale_state
  owner._read_attribute(reflection.foreign_key) { |n| owner.send(:missing_attribute, n, caller) }
end

def target_changed?
  owner.attribute_changed?(reflection.foreign_key) || (!foreign_key_present? && target&.new_record?)
end

def target_previously_changed?
  owner.attribute_previously_changed?(reflection.foreign_key)
end

def update_counters(by)
  if require_counter_update? && foreign_key_present?
    if target && !stale_target?
      target.increment!(reflection.counter_cache_column, by, touch: reflection.options[:touch])
    else
      update_counters_via_scope(klass, owner._read_attribute(reflection.foreign_key), by)
    end
  end
end

def update_counters_via_scope(klass, foreign_key, by)
  scope = klass.unscoped.where!(primary_key(klass) => foreign_key)
  scope.update_counters(reflection.counter_cache_column => by, touch: reflection.options[:touch])
end

def updated?
  @updated
end