File upload UI obeys LFS filters

Uses Lfs::FileModificationHandler to coordinate LFS detection, creation of LfsObject, etc

Caveats:
 1. This isn't used by the multi-file editor / Web IDE
 2. This isn't used on rename. We'd need to be able to download LFS files
    and add them to the commit if they no longer match so not as simple.
 3. We only check the root .gitattributes file, so this should be improved
    to correctly check for nested .gitattributes files in subfolders.

1 files changed, 42 insertions, 0 deletions

diff --git a/app/services/lfs/file_modification_handler.rb b/app/services/lfs/file_modification_handler.rb
new file mode 100644
index 00000000000..fe9091a6e5d
--- /dev/null
+++ b/app/services/lfs/file_modification_handler.rb
@@ -0,0 +1,42 @@
+module Lfs
+  class FileModificationHandler
+    attr_reader :project, :branch_name
+
+    delegate :repository, to: :project
+
+    def initialize(project, branch_name)
+      @project = project
+      @branch_name = branch_name
+    end
+
+    def new_file(file_path, file_content)
+      if project.lfs_enabled? && lfs_file?(file_path)
+        lfs_pointer_file = Gitlab::Git::LfsPointerFile.new(file_content)
+        lfs_object = create_lfs_object!(lfs_pointer_file, file_content)
+        content = lfs_pointer_file.pointer
+
+        success = yield(content)
+
+        link_lfs_object!(lfs_object) if success
+      else
+        yield(file_content)
+      end
+    end
+
+    private
+
+    def lfs_file?(file_path)
+      repository.attributes_at(branch_name, file_path)['filter'] == 'lfs'
+    end
+
+    def create_lfs_object!(lfs_pointer_file, file_content)
+      LfsObject.find_or_create_by(oid: lfs_pointer_file.sha256, size: lfs_pointer_file.size) do |lfs_object|
+        lfs_object.file = CarrierWaveStringFile.new(file_content)
+      end
+    end
+
+    def link_lfs_object!(lfs_object)
+      project.lfs_objects << lfs_object
+    end
+  end
+end