1 files changed, 30 insertions, 0 deletions
diff --git a/app/assets/javascripts/repository/utils/ref_switcher_utils.js b/app/assets/javascripts/repository/utils/ref_switcher_utils.js
new file mode 100644
index 00000000000..8ff52104c93
--- /dev/null
+++ b/app/assets/javascripts/repository/utils/ref_switcher_utils.js
@@ -0,0 +1,30 @@
+import { joinPaths } from '~/lib/utils/url_utility';
+
+/**
+ * Matches the namespace and target directory/blob in a path
+ * Example: /root/Flight/-/blob/fix/main/test/spec/utils_spec.js
+ * Group 1:  /-/blob
+ * Group 2:  blob
+ * Group 3:  main/test/spec/utils_spec.js
+ */
+const NAMESPACE_TARGET_REGEX = /(\/-\/(blob|tree))\/.*?\/(.*)/;
+
+/**
+ * Generates a ref destination path based on the selected ref and current path.
+ * A user could either be in the project root, a directory on the blob view.
+ * @param {string} projectRootPath - The root path for a project.
+ * @param {string} selectedRef - The selected ref from the ref dropdown.
+ */
+export function generateRefDestinationPath(projectRootPath, selectedRef) {
+  const currentPath = window.location.pathname;
+  let namespace = '/-/tree';
+  let target;
+  const match = NAMESPACE_TARGET_REGEX.exec(currentPath);
+  if (match) {
+    [, namespace, , target] = match;
+  }
+
+  const destinationPath = joinPaths(projectRootPath, namespace, selectedRef, target);
+
+  return `${destinationPath}${window.location.hash}`;
+}