Rewrite Atom generation from stream entries to use Ox instead of Nokogiri (#1124)

* Rewrite Atom generation from stream entries to use Ox instead of Nokogiri::Builder

StreamEntry is now limited to only statuses, which allows some optimization. Removed
extra queries on AccountsController#show. AtomSerializer instead of AtomBuilderHelper
used in AccountsController#show, StreamEntriesController#show, StreamEntryRenderer
and PubSubHubbub::DistributionWorker

PubSubHubbub::DistributionWorker moves n+1 DomainBlock query to PubSubHubbub::DeliveryWorker
instead.

All Salmon slaps that aren't based on StreamEntry still use AtomBuilderHelper and Nokogiri

* All Salmon slaps now use Ox instead of Nokogiri. No touch from status on account

21 files changed, 393 insertions, 262 deletions

diff --git a/Gemfile b/Gemfile
index b5705e9d19f..65bd5eb495b 100644
--- a/Gemfile
+++ b/Gemfile
@@ -34,6 +34,7 @@ gem 'doorkeeper'
 gem 'rabl'
 gem 'rqrcode'
 gem 'twitter-text'
+gem 'ox'
 gem 'oj'
 gem 'hiredis'
 gem 'redis', '~>3.2', require: ['redis', 'redis/connection/hiredis']
diff --git a/Gemfile.lock b/Gemfile.lock
index 408d85ade12..f2a199931f3 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -240,6 +240,7 @@ GEM
       addressable (~> 2.4)
       http (~> 2.0)
       nokogiri (~> 1.6)
+    ox (2.4.11)
     paperclip (5.1.0)
       activemodel (>= 4.2.0)
       activesupport (>= 4.2.0)
@@ -482,6 +483,7 @@ DEPENDENCIES
   nokogiri
   oj
   ostatus2
+  ox
   paperclip (~> 5.1)
   paperclip-av-transcoder
   pg
diff --git a/app/controllers/accounts_controller.rb b/app/controllers/accounts_controller.rb
index dc1aeb5ea5e..619c04be26e 100644
--- a/app/controllers/accounts_controller.rb
+++ b/app/controllers/accounts_controller.rb
@@ -16,7 +16,8 @@ class AccountsController < ApplicationController
       end
 
       format.atom do
-        @entries = @account.stream_entries.order('id desc').where(activity_type: 'Status').where(hidden: false).with_includes.paginate_by_max_id(20, params[:max_id], params[:since_id])
+        @entries = @account.stream_entries.order('id desc').where(hidden: false).with_includes.paginate_by_max_id(20, params[:max_id], params[:since_id])
+        render xml: AtomSerializer.render(AtomSerializer.new.feed(@account, @entries.to_a))
       end
 
       format.activitystreams2
diff --git a/app/controllers/stream_entries_controller.rb b/app/controllers/stream_entries_controller.rb
index de38b360232..469a8c33e2b 100644
--- a/app/controllers/stream_entries_controller.rb
+++ b/app/controllers/stream_entries_controller.rb
@@ -19,7 +19,9 @@ class StreamEntriesController < ApplicationController
         end
       end
 
-      format.atom
+      format.atom do
+        render xml: AtomSerializer.render(AtomSerializer.new.entry(@stream_entry, true))
+      end
     end
   end
 
diff --git a/app/lib/atom_serializer.rb b/app/lib/atom_serializer.rb
new file mode 100644
index 00000000000..21f485c2d37
--- /dev/null
+++ b/app/lib/atom_serializer.rb
@@ -0,0 +1,348 @@
+# frozen_string_literal: true
+
+class AtomSerializer
+  include RoutingHelper
+
+  class << self
+    def render(element)
+      document = Ox::Document.new(version: '1.0')
+      document << element
+      "<?xml version=\"1.0\"?>#{Ox.dump(element)}"
+    end
+  end
+
+  def author(account)
+    author = Ox::Element.new('author')
+
+    uri = TagManager.instance.uri_for(account)
+
+    append_element(author, 'id', uri)
+    append_element(author, 'activity:object-type', TagManager::TYPES[:person])
+    append_element(author, 'uri', uri)
+    append_element(author, 'name', account.username)
+    append_element(author, 'email', account.local? ? "#{account.acct}@#{Rails.configuration.x.local_domain}" : account.acct)
+    append_element(author, 'summary', account.note)
+    append_element(author, 'link', nil, rel: :alternate, type: 'text/html', href: TagManager.instance.url_for(account))
+    append_element(author, 'link', nil, rel: :avatar, type: account.avatar_content_type, 'media:width': 120, 'media:height': 120, href: full_asset_url(account.avatar.url(:original)))
+    append_element(author, 'link', nil, rel: :header, type: account.header_content_type, 'media:width': 700, 'media:height': 335, href: full_asset_url(account.header.url(:original)))
+    append_element(author, 'poco:preferredUsername', account.username)
+    append_element(author, 'poco:displayName', account.display_name) unless account.display_name.blank?
+    append_element(author, 'poco:note', Formatter.instance.simplified_format(account).to_str) unless account.note.blank?
+    append_element(author, 'mastodon:scope', account.locked? ? :private : :public)
+
+    author
+  end
+
+  def feed(account, stream_entries)
+    feed = Ox::Element.new('feed')
+
+    add_namespaces(feed)
+
+    append_element(feed, 'id', account_url(account, format: 'atom'))
+    append_element(feed, 'title', account.display_name)
+    append_element(feed, 'subtitle', account.note)
+    append_element(feed, 'updated', account.updated_at.iso8601)
+    append_element(feed, 'logo', full_asset_url(account.avatar.url(:original)))
+
+    feed << author(account)
+
+    append_element(feed, 'link', nil, rel: :alternate, type: 'text/html', href: TagManager.instance.url_for(account))
+    append_element(feed, 'link', nil, rel: :self, type: 'application/atom+xml', href: account_url(account, format: 'atom'))
+    append_element(feed, 'link', nil, rel: :next, type: 'application/atom+xml', href: account_url(account, format: 'atom', max_id: stream_entries.last.id)) if stream_entries.size == 20
+    append_element(feed, 'link', nil, rel: :hub, href: api_push_url)
+    append_element(feed, 'link', nil, rel: :salmon, href: api_salmon_url(account.id))
+
+    stream_entries.each do |stream_entry|
+      feed << entry(stream_entry)
+    end
+
+    feed
+  end
+
+  def entry(stream_entry, root = false)
+    entry = Ox::Element.new('entry')
+
+    add_namespaces(entry) if root
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(stream_entry.created_at, stream_entry.activity_id, stream_entry.activity_type))
+    append_element(entry, 'published', stream_entry.created_at.iso8601)
+    append_element(entry, 'updated', stream_entry.updated_at.iso8601)
+    append_element(entry, 'title', stream_entry&.status&.title)
+    append_element(entry, 'activity:object-type', TagManager::TYPES[stream_entry.object_type])
+    append_element(entry, 'activity:verb', TagManager::VERBS[stream_entry.verb])
+
+    entry << object(stream_entry.target) if stream_entry.targeted?
+
+    serialize_status_attributes(entry, stream_entry.status) unless stream_entry.status.nil?
+
+    append_element(entry, 'link', nil, rel: :alternate, type: 'text/html', href: account_stream_entry_url(stream_entry.account, stream_entry))
+    append_element(entry, 'link', nil, rel: :self, type: 'application/atom+xml', href: account_stream_entry_url(stream_entry.account, stream_entry, format: 'atom'))
+    append_element(entry, 'thr:in-reply-to', nil, ref: TagManager.instance.uri_for(stream_entry.thread), href: TagManager.instance.url_for(stream_entry.thread)) if stream_entry.threaded?
+
+    entry
+  end
+
+  def object(status)
+    object = Ox::Element.new('activity:object')
+
+    append_element(object, 'id', TagManager.instance.uri_for(status))
+    append_element(object, 'published', status.created_at.iso8601)
+    append_element(object, 'updated', status.updated_at.iso8601)
+    append_element(object, 'title', status.title)
+
+    object << author(status.account)
+
+    append_element(object, 'activity:object-type', TagManager::TYPES[status.object_type])
+    append_element(object, 'activity:verb', TagManager::VERBS[status.verb])
+
+    serialize_status_attributes(object, status)
+
+    append_element(object, 'link', nil, rel: :alternate, type: 'text/html', href: TagManager.instance.url_for(status))
+    append_element(object, 'thr:in-reply-to', nil, ref: TagManager.instance.uri_for(status.thread), href: TagManager.instance.url_for(status.thread)) if status.reply?
+
+    object
+  end
+
+  def follow_salmon(follow)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{follow.account.acct} started following #{follow.target_account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(follow.created_at, follow.id, 'Follow'))
+    append_element(entry, 'title', description)
+    append_element(entry, 'content', description, type: :html)
+
+    entry << author(follow.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:follow])
+
+    object = author(follow.target_account)
+    object.value = 'activity:object'
+
+    entry << object
+    entry
+  end
+
+  def follow_request_salmon(follow_request)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(follow_request.created_at, follow_request.id, 'FollowRequest'))
+    append_element(entry, 'title', "#{follow_request.account.acct} requested to follow #{follow_request.target_account.acct}")
+
+    entry << author(follow_request.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:request_friend])
+
+    object = author(follow_request.target_account)
+    object.value = 'activity:object'
+
+    entry << object
+    entry
+  end
+
+  def authorize_follow_request_salmon(follow_request)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, follow_request.id, 'FollowRequest'))
+    append_element(entry, 'title', "#{follow_request.target_account.acct} authorizes follow request by #{follow_request.account.acct}")
+
+    entry << author(follow_request.target_account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:authorize])
+
+    object = Ox::Element.new('activity:object')
+    object << author(follow_request.account)
+
+    append_element(object, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(object, 'activity:verb', TagManager::VERBS[:request_friend])
+
+    inner_object = author(follow_request.target_account)
+    inner_object.value = 'activity:object'
+
+    object << inner_object
+    entry  << object
+    entry
+  end
+
+  def reject_follow_request_salmon(follow_request)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, follow_request.id, 'FollowRequest'))
+    append_element(entry, 'title', "#{follow_request.target_account.acct} rejects follow request by #{follow_request.account.acct}")
+
+    entry << author(follow_request.target_account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:reject])
+
+    object = Ox::Element.new('activity:object')
+    object << author(follow_request.account)
+
+    append_element(object, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(object, 'activity:verb', TagManager::VERBS[:request_friend])
+
+    inner_object = author(follow_request.target_account)
+    inner_object.value = 'activity:object'
+
+    object << inner_object
+    entry  << object
+    entry
+  end
+
+  def unfollow_salmon(follow)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{follow.account.acct} is no longer following #{follow.target_account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, follow.id, 'Follow'))
+    append_element(entry, 'title', description)
+    append_element(entry, 'content', description, type: :html)
+
+    entry << author(follow.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:unfollow])
+
+    object = author(follow.target_account)
+    object.value = 'activity:object'
+
+    entry << object
+    entry
+  end
+
+  def block_salmon(block)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{block.account.acct} no longer wishes to interact with #{block.target_account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, block.id, 'Block'))
+    append_element(entry, 'title', description)
+
+    entry << author(block.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:block])
+
+    object = author(block.target_account)
+    object.value = 'activity:object'
+
+    entry << object
+    entry
+  end
+
+  def unblock_salmon(block)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{block.account.acct} no longer blocks #{block.target_account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, block.id, 'Block'))
+    append_element(entry, 'title', description)
+
+    entry << author(block.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:unblock])
+
+    object = author(block.target_account)
+    object.value = 'activity:object'
+
+    entry << object
+    entry
+  end
+
+  def favourite_salmon(favourite)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{favourite.account.acct} favourited a status by #{favourite.status.account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(favourite.created_at, favourite.id, 'Favourite'))
+    append_element(entry, 'title', description)
+    append_element(entry, 'content', description, type: :html)
+
+    entry << author(favourite.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:favorite])
+
+    entry << object(favourite.status)
+
+    append_element(entry, 'thr:in-reply-to', nil, ref: TagManager.instance.uri_for(favourite.status), href: TagManager.instance.url_for(favourite.status))
+
+    entry
+  end
+
+  def unfavourite_salmon(favourite)
+    entry = Ox::Element.new('entry')
+    add_namespaces(entry)
+
+    description = "#{favourite.account.acct} no longer favourites a status by #{favourite.status.account.acct}"
+
+    append_element(entry, 'id', TagManager.instance.unique_tag(Time.now.utc, favourite.id, 'Favourite'))
+    append_element(entry, 'title', description)
+    append_element(entry, 'content', description, type: :html)
+
+    entry << author(favourite.account)
+
+    append_element(entry, 'activity:object-type', TagManager::TYPES[:activity])
+    append_element(entry, 'activity:verb', TagManager::VERBS[:unfavorite])
+
+    entry << object(favourite.status)
+
+    append_element(entry, 'thr:in-reply-to', nil, ref: TagManager.instance.uri_for(favourite.status), href: TagManager.instance.url_for(favourite.status))
+
+    entry
+  end
+
+  private
+
+  def append_element(parent, name, content = nil, attributes = {})
+    element = Ox::Element.new(name)
+    attributes.each { |k, v| element[k] = v.to_s }
+    element << content.to_s unless content.nil?
+    parent  << element
+  end
+
+  def add_namespaces(parent)
+    parent['xmlns']          = TagManager::XMLNS
+    parent['xmlns:thr']      = TagManager::THR_XMLNS
+    parent['xmlns:activity'] = TagManager::AS_XMLNS
+    parent['xmlns:poco']     = TagManager::POCO_XMLNS
+    parent['xmlns:media']    = TagManager::MEDIA_XMLNS
+    parent['xmlns:ostatus']  = TagManager::OS_XMLNS
+    parent['xmlns:mastodon'] = TagManager::MTDN_XMLNS
+  end
+
+  def serialize_status_attributes(entry, status)
+    append_element(entry, 'summary', status.spoiler_text) unless status.spoiler_text.blank?
+    append_element(entry, 'content', Formatter.instance.format(status.reblog? ? status.reblog : status).to_str, type: 'html')
+
+    status.mentions.each do |mentioned|
+      append_element(entry, 'link', nil, rel: :mentioned, 'ostatus:object-type': TagManager::TYPES[:person], href: TagManager.instance.uri_for(mentioned.account))
+    end
+
+    append_element(entry, 'link', nil, rel: :mentioned, 'ostatus:object-type': TagManager::TYPES[:collection], href: TagManager::COLLECTIONS[:public]) if status.public_visibility?
+
+    status.tags.each do |tag|
+      append_element(entry, 'category', nil, term: tag.name)
+    end
+
+    append_element(entry, 'category', nil, term: 'nsfw') if status.sensitive?
+
+    status.media_attachments.each do |media|
+      append_element(entry, 'link', nil, rel: :enclosure, type: media.file_content_type, length: media.file_file_size, href: full_asset_url(media.file.url(:original, false)))
+    end
+
+    append_element(entry, 'mastodon:scope', status.visibility)
+  end
+end
diff --git a/app/lib/tag_manager.rb b/app/lib/tag_manager.rb
index 2a5e7a40953..07b2fb91e01 100644
--- a/app/lib/tag_manager.rb
+++ b/app/lib/tag_manager.rb
@@ -78,6 +78,8 @@ class TagManager
     case target.object_type
     when :person
       account_url(target)
+    when :note, :comment, :activity
+      unique_tag(target.created_at, target.id, 'Status')
     else
       unique_tag(target.stream_entry.created_at, target.stream_entry.activity_id, target.stream_entry.activity_type)
     end
diff --git a/app/models/stream_entry.rb b/app/models/stream_entry.rb
index ae7ae446e9b..8aff5ae0698 100644
--- a/app/models/stream_entry.rb
+++ b/app/models/stream_entry.rb
@@ -5,25 +5,21 @@ class StreamEntry < ApplicationRecord
 
   belongs_to :account, inverse_of: :stream_entries
   belongs_to :activity, polymorphic: true
-
   belongs_to :status, foreign_type: 'Status', foreign_key: 'activity_id', inverse_of: :stream_entry
 
   validates :account, :activity, presence: true
 
-  STATUS_INCLUDES = [:account, :stream_entry, :media_attachments, :tags, mentions: :account, reblog: [:stream_entry, :account, mentions: :account], thread: [:stream_entry, :account]].freeze
+  STATUS_INCLUDES = [:account, :stream_entry, :media_attachments, :tags, mentions: :account, reblog: [:stream_entry, :account, :media_attachments, :tags, mentions: :account], thread: [:stream_entry, :account]].freeze
 
+  default_scope { where(activity_type: 'Status') }
   scope :with_includes, -> { includes(:account, status: STATUS_INCLUDES) }
 
   def object_type
-    if orphaned?
-      :activity
-    else
-      targeted? ? :activity : activity.object_type
-    end
+    orphaned? || targeted? ? :activity : status.object_type
   end
 
   def verb
-    orphaned? ? :delete : activity.verb
+    orphaned? ? :delete : status.verb
   end
 
   def targeted?
@@ -31,15 +27,15 @@ class StreamEntry < ApplicationRecord
   end
 
   def target
-    orphaned? ? nil : activity.target
+    orphaned? ? nil : status.target
   end
 
   def title
-    orphaned? ? nil : activity.title
+    orphaned? ? nil : status.title
   end
 
   def content
-    orphaned? ? nil : activity.content
+    orphaned? ? nil : sta