Refactor compare and fetch logic

3 files changed, 20 insertions, 12 deletions

diff --git a/app/models/merge_request.rb b/app/models/merge_request.rb
index e32b224eb77..4dcde029efa 100644
--- a/app/models/merge_request.rb
+++ b/app/models/merge_request.rb
@@ -437,4 +437,12 @@ class MergeRequest < ActiveRecord::Base
   def source_sha
     commits.first.sha
   end
+
+  def fetch_ref
+    target_project.repository.fetch_ref(
+      source_project.repository.path_to_repo,
+      "refs/heads/#{source_branch}",
+      "refs/merge-requests/#{id}/head"
+    )
+  end
 end
diff --git a/app/models/merge_request_diff.rb b/app/models/merge_request_diff.rb
index 8a48f78dbd4..6f01a589d1c 100644
--- a/app/models/merge_request_diff.rb
+++ b/app/models/merge_request_diff.rb
@@ -162,20 +162,18 @@ class MergeRequestDiff < ActiveRecord::Base
   def compare_result
     @compare_result ||=
       begin
-        source_sha = merge_request.source_project.commit(source_branch).sha
+        # Update ref if merge request is from fork
+        merge_request.fetch_ref if merge_request.for_fork?
 
-        merge_request.target_project.repository.fetch_ref(
-          merge_request.source_project.repository.path_to_repo,
-          "refs/heads/#{merge_request.source_branch}",
-          "refs/merge-requests/#{merge_request.id}/head"
-        )
+        # Get latest sha of branch from source project
+        source_sha = merge_request.source_project.commit(source_branch).sha
 
-        CompareService.new.execute(
-          merge_request.author,
-          merge_request.target_project,
-          source_sha,
-          merge_request.target_project,
-          merge_request.target_branch,
+        Gitlab::CompareResult.new(
+          Gitlab::Git::Compare.new(
+            merge_request.target_project.repository.raw_repository,
+            merge_request.target_branch,
+            source_sha,
+          )
         )
       end
   end
diff --git a/app/models/repository.rb b/app/models/repository.rb
index 1924e7ee072..41666bd6e38 100644
--- a/app/models/repository.rb
+++ b/app/models/repository.rb
@@ -428,6 +428,8 @@ class Repository
 
     if our_commit && their_commit
       !rugged.merge_commits(our_commit, their_commit).conflicts?
+    else
+      false
     end
   end