Add ActivityPub inbox (#4216)

* Add ActivityPub inbox

* Handle ActivityPub deletes

* Handle ActivityPub creates

* Handle ActivityPub announces

* Stubs for handling all activities that need to be handled

* Add ActivityPub actor resolving

* Handle conversation URI passing in ActivityPub

* Handle content language in ActivityPub

* Send accept header when fetching actor, handle JSON parse errors

* Test for ActivityPub::FetchRemoteAccountService

* Handle public key and icon/image when embedded/as array/as resolvable URI

* Implement ActivityPub::FetchRemoteStatusService

* Add stubs for more interactions

* Undo activities implemented

* Handle out of order activities

* Hook up ActivityPub to ResolveRemoteAccountService, handle
Update Account activities

* Add fragment IDs to all transient activity serializers

* Add tests and fixes

* Add stubs for missing tests

* Add more tests

* Add more tests

11 files changed, 83 insertions, 14 deletions

diff --git a/app/serializers/activitypub/accept_follow_serializer.rb b/app/serializers/activitypub/accept_follow_serializer.rb
index ce900bc78..3e23591a5 100644
--- a/app/serializers/activitypub/accept_follow_serializer.rb
+++ b/app/serializers/activitypub/accept_follow_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::AcceptFollowSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::FollowSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.target_account), '#accepts/follows/', object.id].join
+  end
+
   def type
     'Accept'
   end
diff --git a/app/serializers/activitypub/actor_serializer.rb b/app/serializers/activitypub/actor_serializer.rb
index f5e626d73..8a119603d 100644
--- a/app/serializers/activitypub/actor_serializer.rb
+++ b/app/serializers/activitypub/actor_serializer.rb
@@ -5,10 +5,27 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
 
   attributes :id, :type, :following, :followers,
              :inbox, :outbox, :preferred_username,
-             :name, :summary, :icon, :image
+             :name, :summary, :url
 
   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
+
+  has_one :icon,  serializer: ImageSerializer, if: :avatar_exists?
+  has_one :image, serializer: ImageSerializer, if: :header_exists?
+
   def id
     account_url(object)
   end
@@ -26,7 +43,7 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
   end
 
   def inbox
-    nil
+    account_inbox_url(object)
   end
 
   def outbox
@@ -46,14 +63,26 @@ class ActivityPub::ActorSerializer < ActiveModel::Serializer
   end
 
   def icon
-    full_asset_url(object.avatar.url(:original))
+    object.avatar
   end
 
   def image
-    full_asset_url(object.header.url(:original))
+    object.header
   end
 
   def public_key
     object
   end
+
+  def url
+    short_account_url(object)
+  end
+
+  def avatar_exists?
+    object.avatar.exists?
+  end
+
+  def header_exists?
+    object.header.exists?
+  end
 end
diff --git a/app/serializers/activitypub/block_serializer.rb b/app/serializers/activitypub/block_serializer.rb
index a001b213b..b3bd9f868 100644
--- a/app/serializers/activitypub/block_serializer.rb
+++ b/app/serializers/activitypub/block_serializer.rb
@@ -1,9 +1,13 @@
 # frozen_string_literal: true
 
 class ActivityPub::BlockSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
   attribute :virtual_object, key: :object
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#blocks/', object.id].join
+  end
+
   def type
     'Block'
   end
diff --git a/app/serializers/activitypub/delete_serializer.rb b/app/serializers/activitypub/delete_serializer.rb
index 77098b1b0..b49268d72 100644
--- a/app/serializers/activitypub/delete_serializer.rb
+++ b/app/serializers/activitypub/delete_serializer.rb
@@ -1,9 +1,13 @@
 # frozen_string_literal: true
 
 class ActivityPub::DeleteSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
   attribute :virtual_object, key: :object
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object), '#delete'].join
+  end
+
   def type
     'Delete'
   end
diff --git a/app/serializers/activitypub/follow_serializer.rb b/app/serializers/activitypub/follow_serializer.rb
index 1953a2d7b..86c9992fe 100644
--- a/app/serializers/activitypub/follow_serializer.rb
+++ b/app/serializers/activitypub/follow_serializer.rb
@@ -1,9 +1,13 @@
 # frozen_string_literal: true
 
 class ActivityPub::FollowSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
   attribute :virtual_object, key: :object
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#follows/', object.id].join
+  end
+
   def type
     'Follow'
   end
diff --git a/app/serializers/activitypub/like_serializer.rb b/app/serializers/activitypub/like_serializer.rb
index 4226913f5..c1a7ff6f6 100644
--- a/app/serializers/activitypub/like_serializer.rb
+++ b/app/serializers/activitypub/like_serializer.rb
@@ -1,9 +1,13 @@
 # frozen_string_literal: true
 
 class ActivityPub::LikeSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
   attribute :virtual_object, key: :object
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#likes/', object.id].join
+  end
+
   def type
     'Like'
   end
diff --git a/app/serializers/activitypub/reject_follow_serializer.rb b/app/serializers/activitypub/reject_follow_serializer.rb
index 28584d627..7814f4f57 100644
--- a/app/serializers/activitypub/reject_follow_serializer.rb
+++ b/app/serializers/activitypub/reject_follow_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::RejectFollowSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::FollowSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.target_account), '#rejects/follows/', object.id].join
+  end
+
   def type
     'Reject'
   end
diff --git a/app/serializers/activitypub/undo_block_serializer.rb b/app/serializers/activitypub/undo_block_serializer.rb
index f71faa729..2f43d8402 100644
--- a/app/serializers/activitypub/undo_block_serializer.rb
+++ b/app/serializers/activitypub/undo_block_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::UndoBlockSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::BlockSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#blocks/', object.id, '/undo'].join
+  end
+
   def type
     'Undo'
   end
diff --git a/app/serializers/activitypub/undo_follow_serializer.rb b/app/serializers/activitypub/undo_follow_serializer.rb
index fe91f5f1c..e5b7f143d 100644
--- a/app/serializers/activitypub/undo_follow_serializer.rb
+++ b/app/serializers/activitypub/undo_follow_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::UndoFollowSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::FollowSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#follows/', object.id, '/undo'].join
+  end
+
   def type
     'Undo'
   end
diff --git a/app/serializers/activitypub/undo_like_serializer.rb b/app/serializers/activitypub/undo_like_serializer.rb
index db9cd1d0d..25f4ccaae 100644
--- a/app/serializers/activitypub/undo_like_serializer.rb
+++ b/app/serializers/activitypub/undo_like_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::UndoLikeSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::LikeSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object.account), '#likes/', object.id, '/undo'].join
+  end
+
   def type
     'Undo'
   end
diff --git a/app/serializers/activitypub/update_serializer.rb b/app/serializers/activitypub/update_serializer.rb
index 322305da8..ebc667d96 100644
--- a/app/serializers/activitypub/update_serializer.rb
+++ b/app/serializers/activitypub/update_serializer.rb
@@ -1,10 +1,14 @@
 # frozen_string_literal: true
 
 class ActivityPub::UpdateSerializer < ActiveModel::Serializer
-  attributes :type, :actor
+  attributes :id, :type, :actor
 
   has_one :object, serializer: ActivityPub::ActorSerializer
 
+  def id
+    [ActivityPub::TagManager.instance.uri_for(object), '#updates/', object.updated_at.to_i].join
+  end
+
   def type
     'Update'
   end