1 files changed, 75 insertions, 0 deletions
diff --git a/lib/gitlab/ci/components/instance_path.rb b/lib/gitlab/ci/components/instance_path.rb
new file mode 100644
index 00000000000..010ce57d2a0
--- /dev/null
+++ b/lib/gitlab/ci/components/instance_path.rb
@@ -0,0 +1,75 @@
+# frozen_string_literal: true
+
+module Gitlab
+  module Ci
+    module Components
+      class InstancePath
+        include Gitlab::Utils::StrongMemoize
+
+        def self.match?(address)
+          address.include?('@') && address.start_with?(Settings.gitlab_ci['component_fqdn'])
+        end
+
+        attr_reader :host
+
+        def initialize(address:, content_filename:)
+          @full_path, @version = address.to_s.split('@', 2)
+          @content_filename = content_filename
+          @host = Settings.gitlab_ci['component_fqdn']
+        end
+
+        def fetch_content!(current_user:)
+          return unless project
+          return unless sha
+
+          raise Gitlab::Access::AccessDeniedError unless Ability.allowed?(current_user, :download_code, project)
+
+          project.repository.blob_data_at(sha, project_file_path)
+        end
+
+        def project
+          find_project_by_component_path(instance_path)
+        end
+        strong_memoize_attr :project
+
+        def project_file_path
+          return unless project
+
+          component_dir = instance_path.delete_prefix(project.full_path)
+          File.join(component_dir, @content_filename).delete_prefix('/')
+        end
+
+        # TODO: Add support when version is a released tag and "~latest" moving target
+        def sha
+          return unless project
+
+          project.commit(version)&.id
+        end
+        strong_memoize_attr :sha
+
+        private
+
+        attr_reader :version, :path
+
+        def instance_path
+          @full_path.delete_prefix(host)
+        end
+
+        # Given a path like "my-org/sub-group/the-project/path/to/component"
+        # find the project "my-org/sub-group/the-project" by looking at all possible paths.
+        def find_project_by_component_path(path)
+          possible_paths = [path]
+
+          while index = path.rindex('/') # find index of last `/` in a path
+            possible_paths << (path = path[0..index - 1])
+          end
+
+          # remove shortest path as it is group
+          possible_paths.pop
+
+          ::Project.where_full_path_in(possible_paths).take # rubocop: disable CodeReuse/ActiveRecord
+        end
+      end
+    end
+  end
+end