activitypub-academy/app/lib/activitypub/activity/create.rb

# frozen_string_literal: true

class ActivityPub::Activity::Create < ActivityPub::Activity
  def perform
    return reject_payload! if unsupported_object_type? || invalid_origin?(@object['id']) || Tombstone.exists?(uri: @object['id']) || !related_to_local_activity?

    RedisLock.acquire(lock_options) do |lock|
      if lock.acquired?
        return if delete_arrived_first?(object_uri) || poll_vote?

        @status = find_existing_status

        if @status.nil?
          process_status
        elsif @options[:delivered_to_account_id].present?
          postprocess_audience_and_deliver
        end
      else
        raise Mastodon::RaceConditionError
      end
    end

    @status
  end

  private

  def process_status
    @tags     = []
    @mentions = []
    @params   = {}

    process_status_params
    process_tags
    process_audience

    ApplicationRecord.transaction do
      @status = Status.create!(@params)
      attach_tags(@status)
    end

    resolve_thread(@status)
    fetch_replies(@status)
    distribute(@status)
    forward_for_reply if @status.public_visibility? || @status.unlisted_visibility?
  end

  def find_existing_status
    status   = status_from_uri(object_uri)
    status ||= Status.find_by(uri: @object['atomUri']) if @object['atomUri'].present?
    status
  end

  def process_status_params
    @params = begin
      {
        uri: @object['id'],
        url: object_url || @object['id'],
        account: @account,
        text: text_from_content || '',
        language: detected_language,
        spoiler_text: converted_object_type? ? '' : (text_from_summary || ''),
        created_at: @object['published'],
        override_timestamps: @options[:override_timestamps],
        reply: @object['inReplyTo'].present?,
        sensitive: @object['sensitive'] || false,
        visibility: visibility_from_audience,
        thread: replied_to_status,
        conversation: conversation_from_uri(@object['conversation']),
        media_attachment_ids: process_attachments.take(4).map(&:id),
        owned_poll: process_poll,
      }
    end
  end

  def process_audience
    (as_array(@object['to']) + as_array(@object['cc'])).uniq.each do |audience|
      next if audience == ActivityPub::TagManager::COLLECTIONS[:public]

      # Unlike with tags, there is no point in resolving accounts we don't already
      # know here, because silent mentions would only be used for local access
      # control anyway
      account = account_from_uri(audience)

      next if account.nil? || @mentions.any? { |mention| mention.account_id == account.id }

      @mentions << Mention.new(account: account, silent: true)

      # If there is at least one silent mention, then the status can be considered
      # as a limited-audience status, and not strictly a direct message, but only
      # if we considered a direct message in the first place
      next unless @params[:visibility] == :direct

      @params[:visibility] = :limited
    end

    # If the payload was delivered to a specific inbox, the inbox owner must have
    # access to it, unless they already have access to it anyway
    return if @options[:delivered_to_account_id].nil? || @mentions.any? { |mention| mention.account_id == @options[:delivered_to_account_id] }

    @mentions << Mention.new(account_id: @options[:delivered_to_account_id], silent: true)

    return unless @params[:visibility] == :direct

    @params[:visibility] = :limited
  end

  def postprocess_audience_and_deliver
    return if @status.mentions.find_by(account_id: @options[:delivered_to_account_id])

    delivered_to_account = Account.find(@options[:delivered_to_account_id])

    @status.mentions.create(account: delivered_to_account, silent: true)
    @status.update(visibility: :limited) if @status.direct_visibility?

    return unless delivered_to_account.following?(@account)

    FeedInsertWorker.perform_async(@status.id, delivered_to_account.id, :home)
  end

  def attach_tags(status)
    @tags.each do |tag|
      status.tags << tag
      TrendingTags.record_use!(tag, status.account, status.created_at) if status.public_visibility?
    end

    @mentions.each do |mention|
      mention.status = status
      mention.save
    end
  end

  def process_tags
    return if @object['tag'].nil?

    as_array(@object['tag']).each do |tag|
      if equals_or_includes?(tag['type'], 'Hashtag')
        process_hashtag tag
      elsif equals_or_includes?(tag['type'], 'Mention')
        process_mention tag
      elsif equals_or_includes?(tag['type'], 'Emoji')
        process_emoji tag
      end
    end
  end

  def process_hashtag(tag)
    return if tag['name'].blank?

    hashtag = tag['name'].gsub(/\A#/, '').mb_chars.downcase
    hashtag = Tag.where(name: hashtag).first_or_create!(name: hashtag)

    return if @tags.include?(hashtag)

    @tags << hashtag
  rescue ActiveRecord::RecordInvalid
    nil
  end

  def process_mention(tag)
    return if tag['href'].blank?

    account = account_from_uri(tag['href'])
    account = ::FetchRemoteAccountService.new.call(tag['href']) if account.nil?

    return if account.nil?

    @mentions << Mention.new(account: account, silent: false)
  end

  def process_emoji(tag)
    return if skip_download?
    return if tag['name'].blank? || tag['icon'].blank? || tag['icon']['url'].blank?

    shortcode = tag['name'].delete(':')
    image_url = tag['icon']['url']
    uri       = tag['id']
    updated   = tag['updated']
    emoji     = CustomEmoji.find_by(shortcode: shortcode, domain: @account.domain)

    return unless emoji.nil? || image_url != emoji.image_remote_url || (updated && updated >= emoji.updated_at)

    emoji ||= CustomEmoji.new(domain: @account.domain, shortcode: shortcode, uri: uri)
    emoji.image_remote_url = image_url
    emoji.save
  end

  def process_attachments
    return [] if @object['attachment'].nil?

    media_attachments = []

    as_array(@object['attachment']).each do |attachment|
      next if attachment['url'].blank?

      href             = Addressable::URI.parse(attachment['url']).normalize.to_s
      media_attachment = MediaAttachment.create(account: @account, remote_url: href, description: attachment['name'].presence, focus: attachment['focalPoint'])
      media_attachments << media_attachment

      next if unsupported_media_type?(attachment['mediaType']) || skip_download?

      media_attachment.file_remote_url = href
      media_attachment.save
    end

    media_attachments
  rescue Addressable::URI::InvalidURIError => e
    Rails.logger.debug e

    media_attachments
  end

  def process_poll
    return unless @object['type'] == 'Question' && (@object['anyOf'].is_a?(Array) || @object['oneOf'].is_a?(Array))

    expires_at = begin
      if @object['closed'].is_a?(String)
        @object['closed']
      elsif !@object['closed'].nil? && !@object['closed'].is_a?(FalseClass)
        Time.now.utc
      else
        @object['endTime']
      end
    end

    if @object['anyOf'].is_a?(Array)
      multiple = true
      items    = @object['anyOf']
    else
      multiple = false
      items    = @object['oneOf']
    end

    @account.polls.new(
      multiple: multiple,
      expires_at: expires_at,
      options: items.map { |item| item['name'].presence || item['content'] },
      cached_tallies: items.map { |item| item.dig('replies', 'totalItems') || 0 }
    )
  end

  def poll_vote?
    return false if replied_to_status.nil? || replied_to_status.poll.nil? || !replied_to_status.local? || !replied_to_status.poll.options.include?(@object['name'])
    replied_to_status.poll.votes.create!(account: @account, choice: replied_to_status.poll.options.index(@object['name']), uri: @object['id'])
  end

  def resolve_thread(status)
    return unless status.reply? && status.thread.nil? && Request.valid_url?(in_reply_to_uri)
    ThreadResolveWorker.perform_async(status.id, in_reply_to_uri)
  end

  def fetch_replies(status)
    collection = @object['replies']
    return if collection.nil?
    replies = ActivityPub::FetchRepliesService.new.call(status, collection, false)
    return unless replies.nil?
    uri = value_or_id(collection)
    ActivityPub::FetchRepliesWorker.perform_async(status.id, uri) unless uri.nil?
  end

  def conversation_from_uri(uri)
    return nil if uri.nil?
    return Conversation.find_by(id: OStatus::TagManager.instance.unique_tag_to_local_id(uri, 'Conversation')) if OStatus::TagManager.instance.local_id?(uri)
    Conversation.find_by(uri: uri) || Conversation.create(uri: uri)
  end

  def visibility_from_audience
    if equals_or_includes?(@object['to'], ActivityPub::TagManager::COLLECTIONS[:public])
      :public
    elsif equals_or_includes?(@object['cc'], ActivityPub::TagManager::COLLECTIONS[:public])
      :unlisted
    elsif equals_or_includes?(@object['to'], @account.followers_url)
      :private
    else
      :direct
    end
  end

  def audience_includes?(account)
    uri = ActivityPub::TagManager.instance.uri_for(account)
    equals_or_includes?(@object['to'], uri) || equals_or_includes?(@object['cc'], uri)
  end

  def replied_to_status
    return @replied_to_status if defined?(@replied_to_status)

    if in_reply_to_uri.blank?
      @replied_to_status = nil
    else
      @replied_to_status   = status_from_uri(in_reply_to_uri)
      @replied_to_status ||= status_from_uri(@object['inReplyToAtomUri']) if @object['inReplyToAtomUri'].present?
      @replied_to_status
    end
  end

  def in_reply_to_uri
    value_or_id(@object['inReplyTo'])
  end

  def text_from_content
    return Formatter.instance.linkify([[text_from_name, text_from_summary.presence].compact.join("\n\n"), object_url || @object['id']].join(' ')) if converted_object_type?

    if @object['content'].present?
      @object['content']
    elsif content_language_map?
      @object['contentMap'].values.first
    end
  end

  def text_from_summary
    if @object['summary'].present?
      @object['summary']
    elsif summary_language_map?
      @object['summaryMap'].values.first
    end
  end

  def text_from_name
    if @object['name'].present?
      @object['name']
    elsif name_language_map?
      @object['nameMap'].values.first
    end
  end

  def detected_language
    if content_language_map?
      @object['contentMap'].keys.first
    elsif name_language_map?
      @object['nameMap'].keys.first
    elsif summary_language_map?
      @object['summaryMap'].keys.first
    elsif supported_object_type?
      LanguageDetector.instance.detect(text_from_content, @account)
    end
  end

  def object_url
    return if @object['url'].blank?

    url_candidate = url_to_href(@object['url'], 'text/html')

    if invalid_origin?(url_candidate)
      nil
    else
      url_candidate
    end
  end

  def summary_language_map?
    @object['summaryMap'].is_a?(Hash) && !@object['summaryMap'].empty?
  end

  def content_language_map?
    @object['contentMap'].is_a?(Hash) && !@object['contentMap'].empty?
  end

  def name_language_map?
    @object['nameMap'].is_a?(Hash) && !@object['nameMap'].empty?
  end

  def unsupported_media_type?(mime_type)
    mime_type.present? && !(MediaAttachment::IMAGE_MIME_TYPES + MediaAttachment::VIDEO_MIME_TYPES).include?(mime_type)
  end

  def skip_download?
    return @skip_download if defined?(@skip_download)
    @skip_download ||= DomainBlock.find_by(domain: @account.domain)&.reject_media?
  end

  def invalid_origin?(url)
    return true if unsupported_uri_scheme?(url)

    needle   = Addressable::URI.parse(url).host
    haystack = Addressable::URI.parse(@account.uri).host

    !haystack.casecmp(needle).zero?
  end

  def reply_to_local?
    !replied_to_status.nil? && replied_to_status.account.local?
  end

  def related_to_local_activity?
    fetch? || followed_by_local_accounts? || requested_through_relay? ||
      responds_to_followed_account? || addresses_local_accounts?
  end

  def responds_to_followed_account?
    !replied_to_status.nil? && (replied_to_status.account.local? || replied_to_status.account.passive_relationships.exists?)
  end

  def addresses_local_accounts?
    return true if @options[:delivered_to_account_id]

    local_usernames = (as_array(@object['to']) + as_array(@object['cc'])).uniq.select { |uri| ActivityPub::TagManager.instance.local_uri?(uri) }.map { |uri| ActivityPub::TagManager.instance.uri_to_local_id(uri, :username) }

    return false if local_usernames.empty?

    Account.local.where(username: local_usernames).exists?
  end

  def forward_for_reply
    return unless @json['signature'].present? && reply_to_local?
    ActivityPub::RawDistributionWorker.perform_async(Oj.dump(@json), replied_to_status.account_id, [@account.preferred_inbox_url])
  end

  def lock_options
    { redis: Redis.current, key: "create:#{@object['id']}" }
  end
end