Encode custom emojis as resolveable objects in ActivityPub (#5243)

* Encode custom emojis as resolveable objects in ActivityPub

* Improve code style

13 files changed, 113 insertions, 42 deletions

diff --git a/app/controllers/accounts_controller.rb b/app/controllers/accounts_controller.rb
index 26ab6636b..75915b337 100644
--- a/app/controllers/accounts_controller.rb
+++ b/app/controllers/accounts_controller.rb
@@ -26,7 +26,10 @@ class AccountsController < ApplicationController
       end
 
       format.json do
-        render json: @account, serializer: ActivityPub::ActorSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+        render json: @account,
+               serializer: ActivityPub::ActorSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
       end
     end
   end
diff --git a/app/controllers/emojis_controller.rb b/app/controllers/emojis_controller.rb
new file mode 100644
index 000000000..a82b9340b
--- /dev/null
+++ b/app/controllers/emojis_controller.rb
@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+class EmojisController < ApplicationController
+  before_action :set_emoji
+
+  def show
+    respond_to do |format|
+      format.json do
+        render json: @emoji,
+               serializer: ActivityPub::EmojiSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
+      end
+    end
+  end
+
+  private
+
+  def set_emoji
+    @emoji = CustomEmoji.local.find(params[:id])
+  end
+end
diff --git a/app/controllers/follower_accounts_controller.rb b/app/controllers/follower_accounts_controller.rb
index 8eb4d2822..399e79665 100644
--- a/app/controllers/follower_accounts_controller.rb
+++ b/app/controllers/follower_accounts_controller.rb
@@ -10,7 +10,10 @@ class FollowerAccountsController < ApplicationController
       format.html
 
       format.json do
-        render json: collection_presenter, serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+        render json: collection_presenter,
+               serializer: ActivityPub::CollectionSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
       end
     end
   end
diff --git a/app/controllers/following_accounts_controller.rb b/app/controllers/following_accounts_controller.rb
index 1ca6f0fe7..1e73d4bd4 100644
--- a/app/controllers/following_accounts_controller.rb
+++ b/app/controllers/following_accounts_controller.rb
@@ -10,7 +10,10 @@ class FollowingAccountsController < ApplicationController
       format.html
 
       format.json do
-        render json: collection_presenter, serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+        render json: collection_presenter,
+               serializer: ActivityPub::CollectionSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
       end
     end
   end
diff --git a/app/controllers/statuses_controller.rb b/app/controllers/statuses_controller.rb
index 65206ea96..e8a360fb5 100644
--- a/app/controllers/statuses_controller.rb
+++ b/app/controllers/statuses_controller.rb
@@ -21,13 +21,19 @@ class StatusesController < ApplicationController
       end
 
       format.json do
-        render json: @status, serializer: ActivityPub::NoteSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+        render json: @status,
+               serializer: ActivityPub::NoteSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
       end
     end
   end
 
   def activity
-    render json: @status, serializer: ActivityPub::ActivitySerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+    render json: @status,
+           serializer: ActivityPub::ActivitySerializer,
+           adapter: ActivityPub::Adapter,
+           content_type: 'application/activity+json'
   end
 
   def embed
diff --git a/app/controllers/tags_controller.rb b/app/controllers/tags_controller.rb
index 3001b2ee3..240ef058a 100644
--- a/app/controllers/tags_controller.rb
+++ b/app/controllers/tags_controller.rb
@@ -12,7 +12,10 @@ class TagsController < ApplicationController
       format.html
 
       format.json do
-        render json: collection_presenter, serializer: ActivityPub::CollectionSerializer, adapter: ActivityPub::Adapter, content_type: 'application/activity+json'
+        render json: collection_presenter,
+               serializer: ActivityPub::CollectionSerializer,
+               adapter: ActivityPub::Adapter,
+               content_type: 'application/activity+json'
       end
     end
   end
diff --git a/app/lib/activitypub/activity/create.rb b/app/lib/activitypub/activity/create.rb
index be656de48..9421a0aa7 100644
--- a/app/lib/activitypub/activity/create.rb
+++ b/app/lib/activitypub/activity/create.rb
@@ -86,15 +86,19 @@ class ActivityPub::Activity::Create < ActivityPub::Activity
   end
 
   def process_emoji(tag, _status)
-    return if tag['name'].blank? || tag['href'].blank?
+    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 if !emoji.nil? || skip_download?
+    return unless emoji.nil? || emoji.updated_at >= updated
 
-    emoji = CustomEmoji.new(domain: @account.domain, shortcode: shortcode)
-    emoji.image_remote_url = tag['href']
+    emoji ||= CustomEmoji.new(domain: @account.domain, shortcode: shortcode, uri: uri)
+    emoji.image_remote_url = image_url
     emoji.save
   end
 
diff --git a/app/lib/activitypub/tag_manager.rb b/app/lib/activitypub/tag_manager.rb
index 4ec3b8c56..0708713e6 100644
--- a/app/lib/activitypub/tag_manager.rb
+++ b/app/lib/activitypub/tag_manager.rb
@@ -33,6 +33,8 @@ class ActivityPub::TagManager
     when :note, :comment, :activity
       return activity_account_status_url(target.account, target) if target.reblog?
       account_status_url(target.account, target)
+    when :emoji
+      emoji_url(target)
     end
   end
 
diff --git a/app/models/custom_emoji.rb b/app/models/custom_emoji.rb
index 258b50c82..65d9840d5 100644
--- a/app/models/custom_emoji.rb
+++ b/app/models/custom_emoji.rb
@@ -13,6 +13,8 @@
 #  created_at         :datetime         not null
 #  updated_at         :datetime         not null
 #  disabled           :boolean          default(FALSE), not null
+#  uri                :string
+#  image_remote_url   :string
 #
 
 class CustomEmoji < ApplicationRecord
@@ -37,6 +39,10 @@ class CustomEmoji < ApplicationRecord
     domain.nil?
   end
 
+  def object_type
+    :emoji
+  end
+
   class << self
     def from_text(text, domain)
       return [] if text.blank?
diff --git a/app/serializers/activitypub/actor_serializer.rb b/app/serializers/activitypub/actor_serializer.rb
index a11178f5b..896d67115 100644
--- a/app/serializers/activitypub/actor_serializer.rb
+++ b/app/serializers/activitypub/actor_serializer.rb
@@ -10,20 +10,6 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
 
   has_one :public_key, serializer: ActivityPub::PublicKeySerializer
 
-  class ImageSerializer < ActiveModel::Serializer
-    include RoutingHelper
-
-    attributes :type, :url
-
-    def type
-      'Image'
-    end
-
-    def url
-      full_asset_url(object.url(:original))
-    end
-  end
-
   class EndpointsSerializer < ActiveModel::Serializer
     include RoutingHelper
 
@@ -36,8 +22,8 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
 
   has_one :endpoints, serializer: EndpointsSerializer
 
-  has_one :icon,  serializer: ImageSerializer, if: :avatar_exists?
-  has_one :image, serializer: ImageSerializer, if: :header_exists?
+  has_one :icon,  serializer: ActivityPub::ImageSerializer, if: :avatar_exists?
+  has_one :image, serializer: ActivityPub::ImageSerializer, if: :header_exists?
 
   def id
     account_url(object)
diff --git a/app/serializers/activitypub/emoji_serializer.rb b/app/serializers/activitypub/emoji_serializer.rb
new file mode 100644
index 000000000..7b06b1e5d
--- /dev/null
+++ b/app/serializers/activitypub/emoji_serializer.rb
@@ -0,0 +1,29 @@
+# frozen_string_literal: true
+
+class ActivityPub::EmojiSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :id, :type, :name, :updated
+
+  has_one :icon, serializer: ActivityPub::ImageSerializer
+
+  def id
+    ActivityPub::TagManager.instance.uri_for(object)
+  end
+
+  def type
+    'Emoji'
+  end
+
+  def icon
+    object.image
+  end
+
+  def updated
+    object.updated_at.iso8601
+  end
+
+  def name
+    ":#{object.shortcode}:"
+  end
+end
diff --git a/app/serializers/activitypub/image_serializer.rb b/app/serializers/activitypub/image_serializer.rb
new file mode 100644
index 000000000..a015c6b1b
--- /dev/null
+++ b/app/serializers/activitypub/image_serializer.rb
@@ -0,0 +1,19 @@
+# frozen_string_literal: true
+
+class ActivityPub::ImageSerializer < ActiveModel::Serializer
+  include RoutingHelper
+
+  attributes :type, :media_type, :url
+
+  def type
+    'Image'
+  end
+
+  def url
+    full_asset_url(object.url(:original))
+  end
+
+  def media_type
+    object.content_type
+  end
+end
diff --git a/app/serializers/activitypub/note_serializer.rb b/app/serializers/activitypub/note_serializer.rb
index 4dbf6a444..24c39f3c9 100644
--- a/app/serializers/activitypub/note_serializer.rb
+++ b/app/serializers/activitypub/note_serializer.rb
@@ -142,21 +142,6 @@ class ActivityPub::NoteSerializer < ActiveModel::Serializer
     end
   end
 
-  class CustomEmojiSerializer < ActiveModel::Serializer
-    include RoutingHelper
-
-    attributes :type, :href, :name
-
-    def type
-      'Emoji'
-    end
-
-    def href
-      full_asset_url(object.image.url)
-    end
-
-    def name
-      ":#{object.shortcode}:"
-    end
+  class CustomEmojiSerializer < ActivityPub::EmojiSerializer
   end
 end