class Paperclip::AttachmentAdapter

def self.register
  Paperclip.io_adapters.register self do |target|
    Paperclip::Attachment === target || Paperclip::Style === target
  end
end

def cache_current_values
  self.original_filename = @target.original_filename
  @content_type = @target.content_type
  @tempfile = copy_to_tempfile(@target)
  @size = @tempfile.size || @target.size
end

def copy_to_tempfile(source)
  if source.staged?
    link_or_copy_file(source.staged_path(@style), destination.path)
  else
    begin
      source.copy_to_local_file(@style, destination.path)
    rescue Errno::EACCES
      # clean up lingering tempfile if we cannot access source file
      destination.close(true)
      raise
    end
  end
  destination
end

def initialize(target, options = {})
  super
  @target, @style = case target
  when Paperclip::Attachment
    [target, :original]
  when Paperclip::Style
    [target.attachment, target.name]
  end
  cache_current_values
end