Define proper name for a version.

It may be undesirable to retain original filenames (eg, it may contain personally identifiable information, vulgarity, vulnerabilities with Unicode characters, etc).

You may specify the destination filename for uploaded versions through your definition module.

A common pattern is to combine directories scoped to a particular model's primary key, along with static filenames. (eg: user_avatars/1/thumb.png).

# To retain the original filename, but prefix the version and user id:
def filename(version, {file, scope}) do
  file_name = Path.basename(file.file_name, Path.extname(file.file_name))
  "#{scope.id}_#{version}_#{file_name}"
end

# To make the destination file the same as the version:
def filename(version, _), do: version