Collapses directory structure in merge request tree

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53069

1 files changed, 61 insertions, 2 deletions

diff --git a/app/assets/javascripts/diffs/store/utils.js b/app/assets/javascripts/diffs/store/utils.js
index f427367c11e..ada93b570b0 100644
--- a/app/assets/javascripts/diffs/store/utils.js
+++ b/app/assets/javascripts/diffs/store/utils.js
@@ -11,6 +11,7 @@ import {
   MATCH_LINE_TYPE,
   LINES_TO_BE_RENDERED_DIRECTLY,
   MAX_LINES_TO_BE_RENDERED,
+  TREE_TYPE,
 } from '../constants';
 
 export function findDiffFile(files, hash) {
@@ -289,8 +290,63 @@ export function isDiscussionApplicableToLine({ discussion, diffPosition, latestD
   return latestDiff && discussion.active && line_code === discussion.line_code;
 }
 
-export const generateTreeList = files =>
-  files.reduce(
+export const getLowestSingleFolder = folder => {
+  const getFolder = (blob, start = []) =>
+    blob.tree.reduce(
+      (acc, file) => {
+        const shouldGetFolder = file.tree.length === 1 && file.tree[0].type === TREE_TYPE;
+        const currentFileTypeTree = file.type === TREE_TYPE;
+        const path = shouldGetFolder || currentFileTypeTree ? acc.path.concat(file.name) : acc.path;
+        const tree = shouldGetFolder || currentFileTypeTree ? acc.tree.concat(file) : acc.tree;
+
+        if (shouldGetFolder) {
+          const firstFolder = getFolder(file);
+
+          path.push(firstFolder.path);
+          tree.push(...firstFolder.tree);
+        }
+
+        return {
+          ...acc,
+          path,
+          tree,
+        };
+      },
+      { path: start, tree: [] },
+    );
+  const { path, tree } = getFolder(folder, [folder.name]);
+
+  return {
+    path: path.join('/'),
+    treeAcc: tree.length ? tree[tree.length - 1].tree : null,
+  };
+};
+
+export const flattenTree = tree => {
+  const flatten = blobTree =>
+    blobTree.reduce((acc, file) => {
+      const blob = file;
+      let treeToFlatten = blob.tree;
+
+      if (file.type === TREE_TYPE && file.tree.length === 1) {
+        const { treeAcc, path } = getLowestSingleFolder(file);
+
+        if (treeAcc) {
+          blob.name = path;
+          treeToFlatten = flatten(treeAcc);
+        }
+      }
+
+      blob.tree = flatten(treeToFlatten);
+
+      return acc.concat(blob);
+    }, []);
+
+  return flatten(tree);
+};
+
+export const generateTreeList = files => {
+  const { treeEntries, tree } = files.reduce(
     (acc, file) => {
       const split = file.new_path.split('/');
 
@@ -335,6 +391,9 @@ export const generateTreeList = files =>
     { treeEntries: {}, tree: [] },
   );
 
+  return { treeEntries, tree: flattenTree(tree) };
+};
+
 export const getDiffMode = diffFile => {
   const diffModeKey = Object.keys(diffModes).find(key => diffFile[`${key}_file`]);
   return (