1 files changed, 96 insertions, 0 deletions
diff --git a/app/services/projects/lfs_pointers/lfs_object_download_list_service.rb b/app/services/projects/lfs_pointers/lfs_object_download_list_service.rb
new file mode 100644
index 00000000000..5ba0f50f2ff
--- /dev/null
+++ b/app/services/projects/lfs_pointers/lfs_object_download_list_service.rb
@@ -0,0 +1,96 @@
+# frozen_string_literal: true
+
+# This service manages the whole worflow of discovering the Lfs files in a
+# repository, linking them to the project and downloading (and linking) the non
+# existent ones.
+module Projects
+  module LfsPointers
+    class LfsObjectDownloadListService < BaseService
+      include Gitlab::Utils::StrongMemoize
+
+      HEAD_REV = 'HEAD'.freeze
+      LFS_ENDPOINT_PATTERN = /^\t?url\s*=\s*(.+)$/.freeze
+      LFS_BATCH_API_ENDPOINT = '/info/lfs/objects/batch'.freeze
+
+      LfsObjectDownloadListError = Class.new(StandardError)
+
+      def execute
+        return [] unless project&.lfs_enabled?
+
+        if external_lfs_endpoint?
+          # If the endpoint host is different from the import_url it means
+          # that the repo is using a third party service for storing the LFS files.
+          # In this case, we have to disable lfs in the project
+          disable_lfs!
+
+          return []
+        end
+
+        # Getting all Lfs pointers already in the database and linking them to the project
+        linked_oids = LfsLinkService.new(project).execute(lfs_pointers_in_repository.keys)
+        # Retrieving those oids not present in the database which we need to download
+        missing_oids = lfs_pointers_in_repository.except(*linked_oids) # rubocop: disable CodeReuse/ActiveRecord
+        # Downloading the required information and gathering it inside a LfsDownloadObject for each oid
+        LfsDownloadLinkListService.new(project, remote_uri: current_endpoint_uri).execute(missing_oids)
+      rescue LfsDownloadLinkListService::DownloadLinksError => e
+        raise LfsObjectDownloadListError, "The LFS objects download list couldn't be imported. Error: #{e.message}"
+      end
+
+      private
+
+      def external_lfs_endpoint?
+        lfsconfig_endpoint_uri && lfsconfig_endpoint_uri.host != import_uri.host
+      end
+
+      def disable_lfs!
+        unless project.update(lfs_enabled: false)
+          raise LfsDownloadLinkListService::DownloadLinksError, "Invalid project state"
+        end
+      end
+
+      # Retrieves all lfs pointers in the repository
+      def lfs_pointers_in_repository
+        @lfs_pointers_in_repository ||= LfsListService.new(project).execute
+      end
+
+      def lfsconfig_endpoint_uri
+        strong_memoize(:lfsconfig_endpoint_uri) do
+          # Retrieveing the blob data from the .lfsconfig file
+          data = project.repository.lfsconfig_for(HEAD_REV)
+          # Parsing the data to retrieve the url
+          parsed_data = data&.match(LFS_ENDPOINT_PATTERN)
+
+          if parsed_data
+            URI.parse(parsed_data[1]).tap do |endpoint|
+              endpoint.user ||= import_uri.user
+              endpoint.password ||= import_uri.password
+            end
+          end
+        end
+      rescue URI::InvalidURIError
+        raise LfsObjectDownloadListError, 'Invalid URL in .lfsconfig file'
+      end
+
+      def import_uri
+        @import_uri ||= URI.parse(project.import_url)
+      rescue URI::InvalidURIError
+        raise LfsObjectDownloadListError, 'Invalid project import URL'
+      end
+
+      def current_endpoint_uri
+        (lfsconfig_endpoint_uri || default_endpoint_uri)
+      end
+
+      # The import url must end with '.git' here we ensure it is
+      def default_endpoint_uri
+        @default_endpoint_uri ||= begin
+          import_uri.dup.tap do |uri|
+            path = uri.path.gsub(%r(/$), '')
+            path += '.git' unless path.ends_with?('.git')
+            uri.path = path + LFS_BATCH_API_ENDPOINT
+          end
+        end
+      end
+    end
+  end
+end