1 files changed, 50 insertions, 29 deletions

diff --git a/lib/gitlab/diff/file.rb b/lib/gitlab/diff/file.rb
index c6bf25b5874..2aef7fdaa35 100644
--- a/lib/gitlab/diff/file.rb
+++ b/lib/gitlab/diff/file.rb
@@ -1,16 +1,17 @@
 module Gitlab
   module Diff
     class File
-      attr_reader :diff, :repository, :diff_refs
+      attr_reader :diff, :repository, :diff_refs, :fallback_diff_refs
 
-      delegate :new_file, :deleted_file, :renamed_file,
-        :old_path, :new_path, :a_mode, :b_mode,
+      delegate :new_file?, :deleted_file?, :renamed_file?,
+        :old_path, :new_path, :a_mode, :b_mode, :mode_changed?,
         :submodule?, :too_large?, :collapsed?, to: :diff, prefix: false
 
-      def initialize(diff, repository:, diff_refs: nil)
+      def initialize(diff, repository:, diff_refs: nil, fallback_diff_refs: nil)
         @diff = diff
         @repository = repository
         @diff_refs = diff_refs
+        @fallback_diff_refs = fallback_diff_refs
       end
 
       def position(line)
@@ -49,24 +50,60 @@ module Gitlab
         line_code(line) if line
       end
 
+      def old_sha
+        diff_refs&.base_sha
+      end
+
+      def new_sha
+        diff_refs&.head_sha
+      end
+
+      def content_sha
+        return old_content_sha if deleted_file?
+        return @content_sha if defined?(@content_sha)
+
+        refs = diff_refs || fallback_diff_refs
+        @content_sha = refs&.head_sha
+      end
+
       def content_commit
-        return unless diff_refs
+        return @content_commit if defined?(@content_commit)
+
+        sha = content_sha
+        @content_commit = repository.commit(sha) if sha
+      end
+
+      def old_content_sha
+        return if new_file?
+        return @old_content_sha if defined?(@old_content_sha)
 
-        repository.commit(deleted_file ? old_ref : new_ref)
+        refs = diff_refs || fallback_diff_refs
+        @old_content_sha = refs&.base_sha
       end
 
       def old_content_commit
-        return unless diff_refs
+        return @old_content_commit if defined?(@old_content_commit)
 
-        repository.commit(old_ref)
+        sha = old_content_sha
+        @old_content_commit = repository.commit(sha) if sha
       end
 
-      def old_ref
-        diff_refs.try(:base_sha)
+      def blob
+        return @blob if defined?(@blob)
+
+        sha = content_sha
+        return @blob = nil unless sha
+
+        repository.blob_at(sha, file_path)
       end
 
-      def new_ref
-        diff_refs.try(:head_sha)
+      def old_blob
+        return @old_blob if defined?(@old_blob)
+
+        sha = old_content_sha
+        return @old_blob = nil unless sha
+
+        @old_blob = repository.blob_at(sha, old_path)
       end
 
       attr_writer :highlighted_diff_lines
@@ -85,10 +122,6 @@ module Gitlab
         @parallel_diff_lines ||= Gitlab::Diff::ParallelDiff.new(self).parallelize
       end
 
-      def mode_changed?
-        a_mode && b_mode && a_mode != b_mode
-      end
-
       def raw_diff
         diff.diff.to_s
       end
@@ -117,20 +150,8 @@ module Gitlab
         diff_lines.count(&:removed?)
       end
 
-      def old_blob(commit = old_content_commit)
-        return unless commit
-
-        repository.blob_at(commit.id, old_path)
-      end
-
-      def blob(commit = content_commit)
-        return unless commit
-
-        repository.blob_at(commit.id, file_path)
-      end
-
       def file_identifier
-        "#{file_path}-#{new_file}-#{deleted_file}-#{renamed_file}"
+        "#{file_path}-#{new_file?}-#{deleted_file?}-#{renamed_file?}"
       end
     end
   end