Send participation after receiving a public post

This is to let the author of the post know, that this pod is interested
in updates about this post.

The sending user is only used to verify that the participation was sent
from this pod, but lets use an admin/podmin account if available.

closes #7708

6 files changed, 125 insertions, 1 deletions

diff --git a/Changelog.md b/Changelog.md
index 7655de013..6ff634234 100644
--- a/Changelog.md
+++ b/Changelog.md
@@ -6,6 +6,7 @@
 * Improve password autocomplete with password managers [#7642](https://github.com/diaspora/diaspora/pull/7642)
 * Remove the limit of participants in private conversations [#7705](https://github.com/diaspora/diaspora/pull/7705)
 * Send blocks to the blocked persons pod for better UX [#7705](https://github.com/diaspora/diaspora/pull/7705)
+* Send a dummy participation on all incoming public posts to increase interaction consistency [#7708](https://github.com/diaspora/diaspora/pull/7708)
 
 ## Bug fixes
 * Fix invite link on the contacts page when the user has no contacts [#7690](https://github.com/diaspora/diaspora/pull/7690)
diff --git a/lib/diaspora/federation/receive.rb b/lib/diaspora/federation/receive.rb
index d4dcea34d..51954db01 100644
--- a/lib/diaspora/federation/receive.rb
+++ b/lib/diaspora/federation/receive.rb
@@ -153,7 +153,7 @@ module Diaspora
             guid:       entity.guid,
             created_at: entity.created_at,
             root_guid:  entity.root_guid
-          )
+          ).tap {|reshare| send_participation_for(reshare) }
         end
       end
 
@@ -193,6 +193,8 @@ module Diaspora
             status_message.photos = save_or_load_photos(entity.photos)
 
             status_message.save!
+
+            send_participation_for(status_message)
           end
         end
       end
@@ -328,6 +330,24 @@ module Diaspora
           end
         end
       end
+
+      private_class_method def self.send_participation_for(post)
+        return unless post.public?
+        user = user_for_participation
+        participation = Participation.new(target: post, author: user.person)
+        Diaspora::Federation::Dispatcher.build(user, participation, subscribers: [post.author]).dispatch
+      rescue => e # rubocop:disable Lint/RescueWithoutErrorClass
+        logger.warn "failed to send participation for post #{post.guid}: #{e.class}: #{e.message}"
+      end
+
+      # Use configured admin account if available,
+      # or use first user with admin role if available,
+      # or use first user who isn't closed
+      private_class_method def self.user_for_participation
+        User.find_by(username: AppConfig.admins.account.to_s) ||
+          Role.admins.first&.person&.owner ||
+          User.where(locked_at: nil).first
+      end
     end
   end
 end
diff --git a/spec/integration/federation/receive_federation_messages_spec.rb b/spec/integration/federation/receive_federation_messages_spec.rb
index c9a67aeb4..b53bc97c1 100644
--- a/spec/integration/federation/receive_federation_messages_spec.rb
+++ b/spec/integration/federation/receive_federation_messages_spec.rb
@@ -116,6 +116,11 @@ describe "Receive federation messages feature" do
           alice, instance_of(Reshare)
         ).and_return(double(create!: true))
 
+        expect(Diaspora::Federation::Dispatcher).to receive(:build) do |_user, participation, _opts|
+          expect(participation.target.guid).to eq(reshare.guid)
+          instance_double(:dispatch)
+        end
+
         post_message(generate_payload(reshare, sender))
 
         expect(Reshare.exists?(root_guid: post.guid)).to be_truthy
diff --git a/spec/integration/federation/shared_receive_stream_items.rb b/spec/integration/federation/shared_receive_stream_items.rb
index 347848e35..1431b9e1a 100644
--- a/spec/integration/federation/shared_receive_stream_items.rb
+++ b/spec/integration/federation/shared_receive_stream_items.rb
@@ -8,6 +8,15 @@ shared_examples_for "messages which are indifferent about sharing fact" do
   it "treats status message receive correctly" do
     entity = Fabricate(:status_message_entity, author: sender_id, public: public)
 
+    if public
+      expect(Diaspora::Federation::Dispatcher).to receive(:build) do |_user, participation, _opts|
+        expect(participation.target.guid).to eq(entity.guid)
+        instance_double(:dispatch)
+      end
+    else
+      expect(Diaspora::Federation::Dispatcher).not_to receive(:build)
+    end
+
     post_message(generate_payload(entity, sender, recipient), recipient)
 
     expect(StatusMessage.exists?(guid: entity.guid)).to be_truthy
diff --git a/spec/lib/diaspora/federation/receive_spec.rb b/spec/lib/diaspora/federation/receive_spec.rb
index 2c2e7e110..767e67796 100644
--- a/spec/lib/diaspora/federation/receive_spec.rb
+++ b/spec/lib/diaspora/federation/receive_spec.rb
@@ -541,6 +541,10 @@ describe Diaspora::Federation::Receive do
     it_behaves_like "it ignores existing object received twice", Reshare do
       let(:entity) { reshare_entity }
     end
+
+    it_behaves_like "it sends a participation to the author" do
+      let(:entity) { reshare_entity }
+    end
   end
 
   describe ".retraction" do
@@ -766,6 +770,18 @@ describe Diaspora::Federation::Receive do
         expect(status_message.photos.map(&:guid)).to include(photo1.guid, photo2.guid)
         expect(status_message.photos.map(&:text)).to include(received_photo.text, photo2.text)
       end
+
+      it_behaves_like "it sends a participation to the author" do
+        let(:entity) { status_message_entity }
+      end
+
+      it "doesn't send participations for a private post" do
+        status_message_entity = Fabricate(:status_message_entity, author: sender.diaspora_handle, public: false)
+
+        expect(Diaspora::Federation::Dispatcher).not_to receive(:build)
+
+        Diaspora::Federation::Receive.perform(status_message_entity)
+      end
     end
   end
 end
diff --git a/spec/shared_behaviors/receiving.rb b/spec/shared_behaviors/receiving.rb
index 6a563e237..8c2c8da65 100644
--- a/spec/shared_behaviors/receiving.rb
+++ b/spec/shared_behaviors/receiving.rb
@@ -73,3 +73,76 @@ shared_examples_for "it relays relayables" do |klass|
     Diaspora::Federation::Receive.perform(entity)
   end
 end
+
+shared_examples_for "it sends a participation to the author" do
+  it "sends a participation for the post to the author" do
+    dispatcher = double
+    expect(Diaspora::Federation::Dispatcher).to receive(:build) do |user, participation, opts|
+      expect(user).to be_a(User)
+      expect(participation.target.guid).to eq(entity.guid)
+
+      subscribers = opts[:subscribers]
+      expect(subscribers.size).to eq(1)
+      expect(subscribers.first.diaspora_handle).to eq(entity.author)
+
+      dispatcher
+    end
+    expect(dispatcher).to receive(:dispatch)
+
+    Diaspora::Federation::Receive.perform(entity)
+  end
+
+  it "doesn't save the participation in the database" do
+    participation_guid = nil
+    expect(Diaspora::Federation::Dispatcher).to receive(:build) do |_user, participation, _opts|
+      participation_guid = participation.guid
+      instance_double(:dispatch)
+    end
+
+    Diaspora::Federation::Receive.perform(entity)
+
+    expect(Participation.where(guid: participation_guid)).not_to exist
+  end
+
+  it "uses the configured admin as sender for the participation" do
+    AppConfig.admins.account = bob.username
+
+    expect(Diaspora::Federation::Dispatcher).to receive(:build) do |user, _participation, _opts|
+      expect(user.username).to eq(bob.username)
+      instance_double(:dispatch)
+    end
+
+    Diaspora::Federation::Receive.perform(entity)
+  end
+
+  it "uses the first user with an admin role if no admin is configured in the config" do
+    AppConfig.admins.account = nil
+    admin_role = FactoryGirl.create(:role, name: "admin")
+
+    expect(Diaspora::Federation::Dispatcher).to receive(:build) do |user, _participation, _opts|
+      expect(user.username).to eq(admin_role.person.owner.username)
+      instance_double(:dispatch)
+    end
+
+    Diaspora::Federation::Receive.perform(entity)
+  end
+
+  it "uses the first open account if no admin is available" do
+    AppConfig.admins.account = nil
+    expect(Role.admins).to be_empty
+    User.first.close_account!
+
+    expect(Diaspora::Federation::Dispatcher).to receive(:build) do |user, _participation, _opts|
+      expect(user.username).to eq(User.second.username)
+      instance_double(:dispatch)
+    end
+
+    Diaspora::Federation::Receive.perform(entity)
+  end
+
+  it "still receives the entity successfully if there is an error while sending the participation" do
+    expect(Diaspora::Federation::Dispatcher).to receive(:build).and_raise "FooBar"
+
+    Diaspora::Federation::Receive.perform(entity)
+  end
+end