Implement FEP 7888: Part 1 - publish conversation context (#35959)

app/controllers/activitypub/contexts_controller.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+class ActivityPub::ContextsController < ActivityPub::BaseController
+  vary_by -> { 'Signature' if authorized_fetch_mode? }
+
+  before_action :require_account_signature!, if: :authorized_fetch_mode?
+  before_action :set_conversation
+  before_action :set_items
+
+  DESCENDANTS_LIMIT = 60
+
+  def show
+    expires_in 3.minutes, public: public_fetch_mode?
+    render_with_cache json: context_presenter, serializer: ActivityPub::ContextSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+  end
+
+  def items
+    expires_in 3.minutes, public: public_fetch_mode?
+    render_with_cache json: items_collection_presenter, serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+  end
+
+  private
+
+  def account_required?
+    false
+  end
+
+  def set_conversation
+    @conversation = Conversation.local.find(params[:id])
+  end
+
+  def set_items
+    @items = @conversation.statuses.distributable_visibility.paginate_by_min_id(DESCENDANTS_LIMIT, params[:min_id])
+  end
+
+  def context_presenter
+    first_page = ActivityPub::CollectionPresenter.new(
+      id: items_context_url(@conversation, page_params),
+      type: :unordered,
+      part_of: items_context_url(@conversation),
+      next: next_page,
+      items: @items.map { |status| status.local? ? ActivityPub::TagManager.instance.uri_for(status) : status.uri }
+    )
+
+    ActivityPub::ContextPresenter.from_conversation(@conversation).tap do |presenter|
+      presenter.first = first_page
+    end
+  end
+
+  def items_collection_presenter
+    page = ActivityPub::CollectionPresenter.new(
+      id: items_context_url(@conversation, page_params),
+      type: :unordered,
+      part_of: items_context_url(@conversation),
+      next: next_page,
+      items: @items.map { |status| status.local? ? ActivityPub::TagManager.instance.uri_for(status) : status.uri }
+    )
+
+    return page if page_requested?
+
+    ActivityPub::CollectionPresenter.new(
+      id: items_context_url(@conversation),
+      type: :unordered,
+      first: page
+    )
+  end
+
+  def page_requested?
+    truthy_param?(:page)
+  end
+
+  def next_page
+    return nil if @items.size < DESCENDANTS_LIMIT
+
+    items_context_url(@conversation, page: true, min_id: @items.last.id)
+  end
+
+  def page_params
+    params.permit(:page, :min_id)
+  end
+end

app/lib/activitypub/tag_manager.rb

@@ -40,6 +40,8 @@ class ActivityPub::TagManager
     case target.object_type
     when :person
       target.instance_actor? ? instance_actor_url : account_url(target)
+    when :conversation
+      context_url(target)
     when :note, :comment, :activity
       return activity_account_status_url(target.account, target) if target.reblog?
 
@@ -76,6 +78,12 @@ class ActivityPub::TagManager
     activity_account_status_url(target.account, target)
   end
 
+  def context_uri_for(target, page_params = nil)
+    raise ArgumentError, 'target must be a local activity' unless %i(note comment activity).include?(target.object_type) && target.local?
+
+    items_context_url(target.conversation, page_params)
+  end
+
   def replies_uri_for(target, page_params = nil)
     raise ArgumentError, 'target must be a local activity' unless %i(note comment activity).include?(target.object_type) && target.local?
 

app/models/conversation.rb

@@ -4,10 +4,12 @@
 #
 # Table name: conversations
 #
-#  id         :bigint(8)        not null, primary key
-#  uri        :string
-#  created_at :datetime         not null
-#  updated_at :datetime         not null
+#  id                :bigint(8)        not null, primary key
+#  uri               :string
+#  created_at        :datetime         not null
+#  updated_at        :datetime         not null
+#  parent_account_id :bigint(8)
+#  parent_status_id  :bigint(8)
 #
 
 class Conversation < ApplicationRecord
@@ -15,7 +17,24 @@ class Conversation < ApplicationRecord
 
   has_many :statuses, dependent: nil
 
+  belongs_to :parent_status, class_name: 'Status', optional: true, inverse_of: :conversation
+  belongs_to :parent_account, class_name: 'Account', optional: true
+
+  scope :local, -> { where(uri: nil) }
+
+  before_validation :set_parent_account, on: :create
+
   def local?
     uri.nil?
   end
+
+  def object_type
+    :conversation
+  end
+
+  private
+
+  def set_parent_account
+    self.parent_account = parent_status.account if parent_status.present?
+  end
 end

app/models/status.rb

@@ -70,6 +70,8 @@ class Status < ApplicationRecord
     belongs_to :reblog, foreign_key: 'reblog_of_id', inverse_of: :reblogs
   end
 
+  has_one :owned_conversation, class_name: 'Conversation', foreign_key: 'parent_status_id', inverse_of: :parent_status, dependent: nil
+
   has_many :favourites, inverse_of: :status, dependent: :destroy
   has_many :bookmarks, inverse_of: :status, dependent: :destroy
   has_many :reblogs, foreign_key: 'reblog_of_id', class_name: 'Status', inverse_of: :reblog, dependent: :destroy
@@ -442,7 +444,8 @@ class Status < ApplicationRecord
       self.in_reply_to_account_id = carried_over_reply_to_account_id
       self.conversation_id        = thread.conversation_id if conversation_id.nil?
     elsif conversation_id.nil?
-      self.conversation = Conversation.new
+      conversation = build_owned_conversation
+      self.conversation = conversation
     end
   end
 

app/presenters/activitypub/context_presenter.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+class ActivityPub::ContextPresenter < ActiveModelSerializers::Model
+  attributes :id, :type, :attributed_to, :first, :object_type
+
+  class << self
+    def from_conversation(conversation)
+      new.tap do |presenter|
+        presenter.id = ActivityPub::TagManager.instance.uri_for(conversation)
+        presenter.attributed_to = ActivityPub::TagManager.instance.uri_for(conversation.parent_account)
+      end
+    end
+  end
+end

app/serializers/activitypub/context_serializer.rb

@@ -0,0 +1,11 @@
+# frozen_string_literal: true
+
+class ActivityPub::ContextSerializer < ActivityPub::Serializer
+  include RoutingHelper
+
+  attributes :id, :type, :attributed_to, :first
+
+  def type
+    'Collection'
+  end
+end

app/serializers/activitypub/note_serializer.rb

@@ -9,7 +9,7 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
              :in_reply_to, :published, :url,
              :attributed_to, :to, :cc, :sensitive,
              :atom_uri, :in_reply_to_atom_uri,
-             :conversation
+             :conversation, :context
 
   attribute :content
   attribute :content_map, if: :language?
@@ -163,6 +163,12 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
     end
   end
 
+  def context
+    return if object.conversation.nil?
+
+    ActivityPub::TagManager.instance.uri_for(object.conversation)
+  end
+
   def local?
     object.account.local?
   end