class ActiveRecord::Associations::BelongsToAssociation

def build(attributes = {})
  replace(@reflection.build_association(attributes))
end

def create(attributes = {})
  replace(@reflection.create_association(attributes))
end

def find_target
  find_method = if @reflection.options[:primary_key]
                  "find_by_#{@reflection.options[:primary_key]}"
                else
                  "find"
                end
  the_target = @reflection.klass.send(find_method,
    @owner[@reflection.primary_key_name],
    :select     => @reflection.options[:select],
    :conditions => conditions,
    :include    => @reflection.options[:include],
    :readonly   => @reflection.options[:readonly]
  ) if @owner[@reflection.primary_key_name]
  set_inverse_instance(the_target, @owner)
  the_target
end

def foreign_key_present
  !@owner[@reflection.primary_key_name].nil?
end

def previous_record_id
  @previous_record_id ||= if @reflection.options[:primary_key]
                            previous_record = @owner.send(@reflection.name)
                            previous_record.nil? ? nil : previous_record.id
                          else
                            @owner[@reflection.primary_key_name]
                          end
end

def record_id(record)
  record.send(@reflection.options[:primary_key] || :id)
end

def replace(record)
  counter_cache_name = @reflection.counter_cache_column
  if record.nil?
    if counter_cache_name && !@owner.new_record?
      @reflection.klass.decrement_counter(counter_cache_name, previous_record_id) if @owner[@reflection.primary_key_name]
    end
    @target = @owner[@reflection.primary_key_name] = nil
  else
    raise_on_type_mismatch(record)
    if counter_cache_name && !@owner.new_record?
      @reflection.klass.increment_counter(counter_cache_name, record.id)
      @reflection.klass.decrement_counter(counter_cache_name, @owner[@reflection.primary_key_name]) if @owner[@reflection.primary_key_name]
    end
    @target = (AssociationProxy === record ? record.target : record)
    @owner[@reflection.primary_key_name] = record_id(record) unless record.new_record?
    @updated = true
  end
  set_inverse_instance(record, @owner)
  loaded
  record
end

def updated?
  @updated
end

def we_can_set_the_inverse_on_this?(record)
  @reflection.has_inverse? && @reflection.inverse_of.macro == :has_one
end