Implement diff viewers

1 files changed, 26 insertions, 0 deletions

diff --git a/app/models/diff_viewer/server_side.rb b/app/models/diff_viewer/server_side.rb
new file mode 100644
index 00000000000..aed1a0791b1
--- /dev/null
+++ b/app/models/diff_viewer/server_side.rb
@@ -0,0 +1,26 @@
+module DiffViewer
+  module ServerSide
+    extend ActiveSupport::Concern
+
+    included do
+      self.collapse_limit = 1.megabyte
+      self.size_limit = 5.megabytes
+    end
+
+    def prepare!
+      diff_file.old_blob&.load_all_data!
+      diff_file.new_blob&.load_all_data!
+    end
+
+    def render_error
+      # Files that are not stored in the repository, like LFS files and
+      # build artifacts, can only be rendered using a client-side viewer,
+      # since we do not want to read large amounts of data into memory on the
+      # server side. Client-side viewers use JS and can fetch the file from
+      # `diff_file_blob_raw_path` and `diff_file_old_blob_raw_path` using AJAX.
+      return :server_side_but_stored_externally if diff_file.stored_externally?
+
+      super
+    end
+  end
+end