Creates references for linked posts after create

app/models/reference.rb

@@ -9,8 +9,17 @@ class Reference < ApplicationRecord
     extend ActiveSupport::Concern
 
     included do
+      after_create :create_references
       has_many :references, as: :source, dependent: :destroy
     end
+
+    def create_references
+      text&.scan(DiasporaFederation::Federation::DiasporaUrlParser::DIASPORA_URL_REGEX)&.each do |author, type, guid|
+        class_name = DiasporaFederation::Entity.entity_class(type).to_s.rpartition("::").last
+        entity = Diaspora::Federation::Mappings.model_class_for(class_name).find_by(guid: guid)
+        references.find_or_create_by(target: entity) if entity.diaspora_handle == author
+      end
+    end
   end
 
   module Target

spec/shared_behaviors/references.rb

@@ -14,6 +14,43 @@ shared_examples_for "a reference source" do
       expect(Reference.where(id: reference.id)).not_to exist
     end
   end
+
+  describe "#create_references" do
+    it "creates a reference for every referenced post after create" do
+      target1 = FactoryGirl.create(:status_message)
+      target2 = FactoryGirl.create(:status_message)
+      text = "Have a look at [this post](diaspora://#{target1.diaspora_handle}/post/#{target1.guid}) and " \
+             "this one too diaspora://#{target2.diaspora_handle}/post/#{target2.guid}."
+
+      post = FactoryGirl.build(described_class.to_s.underscore.to_sym, text: text)
+      post.save
+
+      expect(post.references.map(&:target).map(&:guid)).to match_array([target1, target2].map(&:guid))
+    end
+
+    it "only creates one reference, even when it is referenced twice" do
+      target = FactoryGirl.create(:status_message)
+      text = "Have a look at [this post](diaspora://#{target.diaspora_handle}/post/#{target.guid}) and " \
+             "this one too diaspora://#{target.diaspora_handle}/post/#{target.guid}."
+
+      post = FactoryGirl.build(described_class.to_s.underscore.to_sym, text: text)
+      post.save
+
+      expect(post.references.map(&:target).map(&:guid)).to match_array([target.guid])
+    end
+
+    it "only creates references, when the author of the known entity matches" do
+      target1 = FactoryGirl.create(:status_message)
+      target2 = FactoryGirl.create(:status_message)
+      text = "Have a look at [this post](diaspora://#{target1.diaspora_handle}/post/#{target1.guid}) and " \
+             "this one too diaspora://#{target1.diaspora_handle}/post/#{target2.guid}."
+
+      post = FactoryGirl.build(described_class.to_s.underscore.to_sym, text: text)
+      post.save
+
+      expect(post.references.map(&:target).map(&:guid)).to match_array([target1.guid])
+    end
+  end
 end
 
 shared_examples_for "a reference target" do