1 files changed, 45 insertions, 2 deletions
diff --git a/app/models/compare.rb b/app/models/compare.rb
index 6672d1bf059..05c8fbbcc36 100644
--- a/app/models/compare.rb
+++ b/app/models/compare.rb
@@ -1,5 +1,5 @@
 class Compare
-  delegate :commits, :same, :head, :base, to: :@compare
+  delegate :same, :head, :base, to: :@compare
 
   def self.decorate(compare, project)
     if compare.is_a?(Compare)
@@ -14,10 +14,53 @@ class Compare
     @project = project
   end
 
-  def diff_file_collection(diff_options:, diff_refs: nil)
+  def commits
+    @commits ||= Commit.decorate(@compare.commits, @project)
+  end
+
+  def start_commit
+    return @start_commit if defined?(@start_commit)
+
+    commit = @compare.base
+    @start_commit = commit ? ::Commit.new(commit, @project) : nil
+  end
+
+  def commit
+    return @commit if defined?(@commit)
+
+    commit = @compare.head
+    @commit = commit ? ::Commit.new(commit, @project) : nil
+  end
+  alias_method :head_commit, :commit
+
+  # Used only on emails_on_push_worker.rb
+  def base_commit=(commit)
+    @base_commit = commit
+  end
+
+  def base_commit
+    return @base_commit if defined?(@base_commit)
+
+    @base_commit = if start_commit && commit
+                     @project.merge_base_commit(start_commit.id, commit.id)
+                   else
+                     nil
+                   end
+  end
+
+  # keyword args until we get ride of diff_refs as argument
+  def diff_file_collection(diff_options:, diff_refs: self.diff_refs)
     Gitlab::Diff::FileCollection::Compare.new(@compare,
       project: @project,
       diff_options: diff_options,
       diff_refs: diff_refs)
   end
+
+  def diff_refs
+    @diff_refs ||= Gitlab::Diff::DiffRefs.new(
+      base_sha:  base_commit.try(:sha),
+      start_sha: start_commit.try(:sha),
+      head_sha: commit.try(:sha)
+    )
+  end
 end