ActivityPub delivery (#4566)

* Deliver ActivityPub Like

* Deliver ActivityPub Undo-Like

* Deliver ActivityPub Create/Announce activities

* Deliver ActivityPub creates from mentions

* Deliver ActivityPub Block/Undo-Block

* Deliver ActivityPub Accept/Reject-Follow

* Deliver ActivityPub Undo-Follow

* Deliver ActivityPub Follow

* Deliver ActivityPub Delete activities

Incidentally fix #889

* Adjust BatchedRemoveStatusService for ActivityPub

* Add tests for ActivityPub workers

* Add tests for FollowService

* Add tests for FavouriteService, UnfollowService and PostStatusService

* Add tests for ReblogService, BlockService, UnblockService, ProcessMentionsService

* Add tests for AuthorizeFollowService, RejectFollowService, RemoveStatusService

* Add tests for BatchedRemoveStatusService

* Deliver updates to a local account to ActivityPub followers

* Minor adjustments

4 files changed, 107 insertions, 1 deletions

diff --git a/app/workers/activitypub/delivery_worker.rb b/app/workers/activitypub/delivery_worker.rb
new file mode 100644
index 000000000..cd67b6710
--- /dev/null
+++ b/app/workers/activitypub/delivery_worker.rb
@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+class ActivityPub::DeliveryWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: 'push', retry: 5, dead: false
+
+  HEADERS = { 'Content-Type' => 'application/activity+json' }.freeze
+
+  def perform(json, source_account_id, inbox_url)
+    @json           = json
+    @source_account = Account.find(source_account_id)
+    @inbox_url      = inbox_url
+
+    perform_request
+
+    raise Mastodon::UnexpectedResponseError, @response unless response_successful?
+  rescue => e
+    raise e.class, "Delivery failed for #{inbox_url}: #{e.message}"
+  end
+
+  private
+
+  def build_request
+    request = Request.new(:post, @inbox_url, body: @json)
+    request.on_behalf_of(@source_account, :uri)
+    request.add_headers(HEADERS)
+  end
+
+  def perform_request
+    @response = build_request.perform
+  end
+
+  def response_successful?
+    @response.code > 199 && @response.code < 300
+  end
+end
diff --git a/app/workers/activitypub/distribution_worker.rb b/app/workers/activitypub/distribution_worker.rb
new file mode 100644
index 000000000..004dd25d1
--- /dev/null
+++ b/app/workers/activitypub/distribution_worker.rb
@@ -0,0 +1,38 @@
+# frozen_string_literal: true
+
+class ActivityPub::DistributionWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: 'push'
+
+  def perform(status_id)
+    @status  = Status.find(status_id)
+    @account = @status.account
+
+    return if skip_distribution?
+
+    ActivityPub::DeliveryWorker.push_bulk(inboxes) do |inbox_url|
+      [payload, @account.id, inbox_url]
+    end
+  rescue ActiveRecord::RecordNotFound
+    true
+  end
+
+  private
+
+  def skip_distribution?
+    @status.direct_visibility?
+  end
+
+  def inboxes
+    @inboxes ||= @account.followers.inboxes
+  end
+
+  def payload
+    @payload ||= ActiveModelSerializers::SerializableResource.new(
+      @status,
+      serializer: ActivityPub::ActivitySerializer,
+      adapter: ActivityPub::Adapter
+    ).to_json
+  end
+end
diff --git a/app/workers/activitypub/processing_worker.rb b/app/workers/activitypub/processing_worker.rb
index 7656ab56a..bb9adf64b 100644
--- a/app/workers/activitypub/processing_worker.rb
+++ b/app/workers/activitypub/processing_worker.rb
@@ -6,6 +6,6 @@ class ActivityPub::ProcessingWorker
   sidekiq_options backtrace: true
 
   def perform(account_id, body)
-    ProcessCollectionService.new.call(body, Account.find(account_id))
+    ActivityPub::ProcessCollectionService.new.call(body, Account.find(account_id))
   end
 end
diff --git a/app/workers/activitypub/update_distribution_worker.rb b/app/workers/activitypub/update_distribution_worker.rb
new file mode 100644
index 000000000..f3377dcec
--- /dev/null
+++ b/app/workers/activitypub/update_distribution_worker.rb
@@ -0,0 +1,31 @@
+# frozen_string_literal: true
+
+class ActivityPub::UpdateDistributionWorker
+  include Sidekiq::Worker
+
+  sidekiq_options queue: 'push'
+
+  def perform(account_id)
+    @account = Account.find(account_id)
+
+    ActivityPub::DeliveryWorker.push_bulk(inboxes) do |inbox_url|
+      [payload, @account.id, inbox_url]
+    end
+  rescue ActiveRecord::RecordNotFound
+    true
+  end
+
+  private
+
+  def inboxes
+    @inboxes ||= @account.followers.inboxes
+  end
+
+  def payload
+    @payload ||= ActiveModelSerializers::SerializableResource.new(
+      @account,
+      serializer: ActivityPub::UpdateSerializer,
+      adapter: ActivityPub::Adapter
+    ).to_json
+  end
+end