mastodon/app/services/concerns/author_extractor.rb

# frozen_string_literal: true

module AuthorExtractor
  def author_from_xml(xml)
    return nil if xml.nil?

    # Try <email> for acct
    acct = xml.at_xpath('./xmlns:author/xmlns:email', xmlns: TagManager::XMLNS)&.content

    # Try <name> + <uri>
    if acct.blank?
      username = xml.at_xpath('./xmlns:author/xmlns:name', xmlns: TagManager::XMLNS)&.content
      uri      = xml.at_xpath('./xmlns:author/xmlns:uri', xmlns: TagManager::XMLNS)&.content

      return nil if username.blank? || uri.blank?

      domain = Addressable::URI.parse(uri).normalize.host
      acct   = "#{username}@#{domain}"
    end

    FollowRemoteAccountService.new.call(acct)
  end
end