activitypub-academy/app/services/process_interaction_service.rb

# frozen_string_literal: true

class ProcessInteractionService < BaseService
  include AuthorExtractor
  include Authorization

  # Record locally the remote interaction with our user
  # @param [String] envelope Salmon envelope
  # @param [Account] target_account Account the Salmon was addressed to
  def call(envelope, target_account)
    body = salmon.unpack(envelope)

    xml = Nokogiri::XML(body)
    xml.encoding = 'utf-8'

    account = author_from_xml(xml.at_xpath('/xmlns:entry', xmlns: OStatus::TagManager::XMLNS))

    return if account.nil? || account.suspended?

    if salmon.verify(envelope, account.keypair)
      RemoteProfileUpdateWorker.perform_async(account.id, body.force_encoding('UTF-8'), true)

      case verb(xml)
      when :follow
        follow!(account, target_account) unless target_account.locked? || target_account.blocking?(account) || target_account.domain_blocking?(account.domain)
      when :request_friend
        follow_request!(account, target_account) unless !target_account.locked? || target_account.blocking?(account) || target_account.domain_blocking?(account.domain)
      when :authorize
        authorize_follow_request!(account, target_account)
      when :reject
        reject_follow_request!(account, target_account)
      when :unfollow
        unfollow!(account, target_account)
      when :favorite
        favourite!(xml, account)
      when :unfavorite
        unfavourite!(xml, account)
      when :post
        add_post!(body, account) if mentions_account?(xml, target_account)
      when :share
        add_post!(body, account) unless status(xml).nil?
      when :delete
        delete_post!(xml, account)
      when :block
        reflect_block!(account, target_account)
      when :unblock
        reflect_unblock!(account, target_account)
      end
    end
  rescue HTTP::Error, OStatus2::BadSalmonError, Mastodon::NotPermittedError
    nil
  end

  private

  def mentions_account?(xml, account)
    xml.xpath('/xmlns:entry/xmlns:link[@rel="mentioned"]', xmlns: OStatus::TagManager::XMLNS).each { |mention_link| return true if [OStatus::TagManager.instance.uri_for(account), OStatus::TagManager.instance.url_for(account)].include?(mention_link.attribute('href').value) }
    false
  end

  def verb(xml)
    raw = xml.at_xpath('//activity:verb', activity: OStatus::TagManager::AS_XMLNS).content
    OStatus::TagManager::VERBS.key(raw)
  rescue
    :post
  end

  def follow!(account, target_account)
    follow = account.follow!(target_account)
    FollowRequest.find_by(account: account, target_account: target_account)&.destroy
    NotifyService.new.call(target_account, follow)
  end

  def follow_request!(account, target_account)
    return if account.requested?(target_account)

    follow_request = FollowRequest.create!(account: account, target_account: target_account)
    NotifyService.new.call(target_account, follow_request)
  end

  def authorize_follow_request!(account, target_account)
    follow_request = FollowRequest.find_by(account: target_account, target_account: account)
    follow_request&.authorize!
    Pubsubhubbub::SubscribeWorker.perform_async(account.id) unless account.subscribed?
  end

  def reject_follow_request!(account, target_account)
    follow_request = FollowRequest.find_by(account: target_account, target_account: account)
    follow_request&.reject!
  end

  def unfollow!(account, target_account)
    account.unfollow!(target_account)
    FollowRequest.find_by(account: account, target_account: target_account)&.destroy
  end

  def reflect_block!(account, target_account)
    UnfollowService.new.call(target_account, account) if target_account.following?(account)
    account.block!(target_account)
  end

  def reflect_unblock!(account, target_account)
    UnblockService.new.call(account, target_account)
  end

  def delete_post!(xml, account)
    status = Status.find(xml.at_xpath('//xmlns:id', xmlns: OStatus::TagManager::XMLNS).content)

    return if status.nil?

    authorize_with account, status, :destroy?

    RemovalWorker.perform_async(status.id)
  end

  def favourite!(xml, from_account)
    current_status = status(xml)

    return if current_status.nil?

    favourite = current_status.favourites.where(account: from_account).first_or_create!(account: from_account)
    NotifyService.new.call(current_status.account, favourite)
  end

  def unfavourite!(xml, from_account)
    current_status = status(xml)

    return if current_status.nil?

    favourite = current_status.favourites.where(account: from_account).first
    favourite&.destroy
  end

  def add_post!(body, account)
    ProcessingWorker.perform_async(account.id, body.force_encoding('UTF-8'))
  end

  def status(xml)
    uri = activity_id(xml)
    return nil unless OStatus::TagManager.instance.local_id?(uri)
    Status.find(OStatus::TagManager.instance.unique_tag_to_local_id(uri, 'Status'))
  end

  def activity_id(xml)
    xml.at_xpath('//activity:object', activity: OStatus::TagManager::AS_XMLNS).at_xpath('./xmlns:id', xmlns: OStatus::TagManager::XMLNS).content
  end

  def salmon
    @salmon ||= OStatus2::Salmon.new
  end
end