Make Mentionables work for cross-project refs

Add a note to merge requests and issues when they're mentioned by a
merge request, issue, or commit in another project.

1 files changed, 69 insertions, 4 deletions

diff --git a/app/models/note.rb b/app/models/note.rb
index fa5fdea4eb0..0c1d792ca9a 100644
--- a/app/models/note.rb
+++ b/app/models/note.rb
@@ -70,13 +70,17 @@ class Note < ActiveRecord::Base
       )
     end
 
-    # +noteable+ was referenced from +mentioner+, by including GFM in either +mentioner+'s description or an associated Note.
-    # Create a system Note associated with +noteable+ with a GFM back-reference to +mentioner+.
+    # +noteable+ was referenced from +mentioner+, by including GFM in either
+    # +mentioner+'s description or an associated Note.
+    # Create a system Note associated with +noteable+ with a GFM back-reference
+    # to +mentioner+.
     def create_cross_reference_note(noteable, mentioner, author, project)
+      gfm_reference = mentioner_gfm_ref(noteable, mentioner, project)
+
       note_options = {
         project: project,
         author: author,
-        note: "_mentioned in #{mentioner.gfm_reference}_",
+        note: "_mentioned in #{gfm_reference}_",
         system: true
       }
 
@@ -163,12 +167,73 @@ class Note < ActiveRecord::Base
 
     # Determine whether or not a cross-reference note already exists.
     def cross_reference_exists?(noteable, mentioner)
-      where(noteable_id: noteable.id, system: true, note: "_mentioned in #{mentioner.gfm_reference}_").any?
+      gfm_reference = mentioner_gfm_ref(noteable, mentioner)
+
+      where(['noteable_id = ? and system = ? and note like ?',
+             noteable.id, true, "_mentioned in #{gfm_reference}_"]).any?
     end
 
     def search(query)
       where("note like :query", query: "%#{query}%")
     end
+
+    private
+
+    # Prepend the mentioner's namespaced project path to the GFM reference for
+    # cross-project references.  For same-project references, return the
+    # unmodified GFM reference.
+    def mentioner_gfm_ref(noteable, mentioner, project = nil)
+      if mentioner.is_a?(Commit)
+        if project.nil?
+          return mentioner.gfm_reference.sub('commit ', 'commit %')
+        else
+          mentioning_project = project
+        end
+      else
+        mentioning_project = mentioner.project
+      end
+
+      noteable_project_id = noteable_project_id(noteable, mentioning_project)
+
+      full_gfm_reference(mentioning_project, noteable_project_id, mentioner)
+    end
+
+    # Return the ID of the project that +noteable+ belongs to, or nil if
+    # +noteable+ is a commit and is not part of the project that owns
+    # +mentioner+.
+    def noteable_project_id(noteable, mentioning_project)
+      if noteable.is_a?(Commit)
+        if mentioning_project.repository.commit(noteable.id)
+          # The noteable commit belongs to the mentioner's project
+          mentioning_project.id
+        else
+          nil
+        end
+      else
+        noteable.project.id
+      end
+    end
+
+    # Return the +mentioner+ GFM reference.  If the mentioner and noteable
+    # projects are not the same, add the mentioning project's path to the
+    # returned value.
+    def full_gfm_reference(mentioning_project, noteable_project_id, mentioner)
+      if mentioning_project.id == noteable_project_id
+        mentioner.gfm_reference
+      else
+        if mentioner.is_a?(Commit)
+          mentioner.gfm_reference.sub(
+            /(commit )/,
+            "\\1#{mentioning_project.path_with_namespace}@"
+          )
+        else
+          mentioner.gfm_reference.sub(
+            /(issue |merge request )/,
+            "\\1#{mentioning_project.path_with_namespace}"
+          )
+        end
+      end
+    end
   end
 
   def commit_author