Merge branch 'edit-on-fork' into 'master'

Automatically fork a project when not allowed to edit a file.

Fixes #3215.

To do:

- [ ] Add tests

-----

## "Edit" button on file in a project the user does NOT have write access to

![edit_file](/uploads/7602157420768aef483a6586bba2d164/edit_file.png)

## Clicking will automatically create a fork

![during_fork](/uploads/32f4f5dff9f24ea99522000b0bf881c5/during_fork.png)

## When the fork has been created, the user is returned to the edit page on the original project with a notice

![edit_notice](/uploads/94ed1319404370ff1e9c0d672fb41e03/edit_notice.png)

## The user cannot change the target branch and is informed that editing will start an MR

![edit_footer](/uploads/4da68d4795c7177e575b7c434d16eeae/edit_footer.png)

## Hitting "Commit changes" will commit and start an MR from my fork to the origin project

![Screen_Shot_2015-12-17_at_23.38.08](/uploads/d777a4db6f38a5a1be84031694465bc1/Screen_Shot_2015-12-17_at_23.38.08.png)

-----

## "Create file, "Upload file" and "New directory" buttons in a project the user does NOT have write access to

![new_directory](/uploads/72f556248f30d6652523bbb4be01b3e0/new_directory.png)

## Clicking any of these options will automatically create a fork

![during_fork](/uploads/32f4f5dff9f24ea99522000b0bf881c5/during_fork.png)

## When the fork has been created, the user is returned to the tree page on the original project with a notice

![new_directory_notice](/uploads/a1a3e11308ae0e8f0913fae6813a37ed/new_directory_notice.png)

## Clicking "New directory" again will show the modal. The user cannot change the target branch and is informed that editing will start an MR

![new_dir](/uploads/99ca8cbfb2f70603e352b3fdf67b6281/new_dir.png)

## Hitting "Create directory" will commit and start an MR from my fork to the origin project

![Screen_Shot_2015-12-17_at_23.39.19](/uploads/3713d0235abf831361b803a6198c5bc1/Screen_Shot_2015-12-17_at_23.39.19.png)

cc @dzaporozhets @skyruler

See merge request !2145

1 files changed, 33 insertions, 8 deletions

diff --git a/app/helpers/tree_helper.rb b/app/helpers/tree_helper.rb
index f448dd0ab61..2ad7c80dae0 100644
--- a/app/helpers/tree_helper.rb
+++ b/app/helpers/tree_helper.rb
@@ -50,24 +50,49 @@ module TreeHelper
     project.repository.branch_names.include?(ref)
   end
 
-  def allowed_tree_edit?(project = nil, ref = nil)
+  def can_edit_tree?(project = nil, ref = nil)
     project ||= @project
     ref ||= @ref
+
     return false unless on_top_of_branch?(project, ref)
 
-    can?(current_user, :push_code, project)
+    can?(current_user, :push_code, project) ||
+      (current_user && current_user.already_forked?(project))
   end
 
   def tree_edit_branch(project = @project, ref = @ref)
-    if allowed_tree_edit?(project, ref)
-      if can_push_branch?(project, ref)
-        ref
-      else
-        project.repository.next_patch_branch
-      end
+    return unless can_edit_tree?(project, ref)
+
+    if can_push_branch?(project, ref)
+      ref
+    else
+      project = tree_edit_project(project)
+      project.repository.next_patch_branch
+    end
+  end
+
+  def tree_edit_project(project = @project)
+    if can?(current_user, :push_code, project)
+      project
+    elsif current_user && current_user.already_forked?(project)
+      current_user.fork_of(project)
     end
   end
 
+  def edit_in_new_fork_notice_now
+    "You're not allowed to make changes to this project directly." +
+      " A fork of this project is being created that you can make changes in, so you can submit a merge request."
+  end
+
+  def edit_in_new_fork_notice
+    "You're not allowed to make changes to this project directly." +
+      " A fork of this project has been created that you can make changes in, so you can submit a merge request."
+  end
+
+  def commit_in_fork_help
+    "A new branch will be created in your fork and a new merge request will be started."
+  end
+
   def tree_breadcrumbs(tree, max_links = 2)
     if @path.present?
       part_path = ""