Fix snippets API not working with visibility level

When a restricted visibility level of `private` is set in the instance,
creating a snippet with the `visibility` level would always fail.
This happened because:

1. `params[:visibility]` was a string (e.g. "public")
2. `CreateSnippetService` and `UpdateSnippetService` only looked
   at `params[:visibility_level]`, which was `nil`.

To fix this, we:

1. Make `CreateSnippetService` look at the newly-built
   `snippet.visibility_level`, since the right value is assigned by the
   `VisibilityLevel#visibility=` method.
2. Modify `UpdateSnippetService` to handle both `visibility_level` and
`visibility` parameters.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/66050

4 files changed, 6 insertions, 6 deletions

diff --git a/app/services/base_service.rb b/app/services/base_service.rb
index 3e968c8f707..c39edd5c114 100644
--- a/app/services/base_service.rb
+++ b/app/services/base_service.rb
@@ -44,6 +44,10 @@ class BaseService
     model.errors.add(:visibility_level, "#{level_name} has been restricted by your GitLab administrator")
   end
 
+  def visibility_level
+    params[:visibility].is_a?(String) ? Gitlab::VisibilityLevel.level_value(params[:visibility]) : params[:visibility_level]
+  end
+
   private
 
   def error(message, http_status = nil)
diff --git a/app/services/create_snippet_service.rb b/app/services/create_snippet_service.rb
index 6e5bf823cc7..0aa76df35ba 100644
--- a/app/services/create_snippet_service.rb
+++ b/app/services/create_snippet_service.rb
@@ -12,7 +12,7 @@ class CreateSnippetService < BaseService
                 PersonalSnippet.new(params)
               end
 
-    unless Gitlab::VisibilityLevel.allowed_for?(current_user, params[:visibility_level])
+    unless Gitlab::VisibilityLevel.allowed_for?(current_user, snippet.visibility_level)
       deny_visibility_level(snippet)
       return snippet
     end
diff --git a/app/services/groups/create_service.rb b/app/services/groups/create_service.rb
index e78e5d5fc2c..1dd22d7a3ae 100644
--- a/app/services/groups/create_service.rb
+++ b/app/services/groups/create_service.rb
@@ -68,9 +68,5 @@ module Groups
 
       true
     end
-
-    def visibility_level
-      params[:visibility].present? ? Gitlab::VisibilityLevel.level_value(params[:visibility]) : params[:visibility_level]
-    end
   end
 end
diff --git a/app/services/update_snippet_service.rb b/app/services/update_snippet_service.rb
index 2969c360de5..a294812ef9e 100644
--- a/app/services/update_snippet_service.rb
+++ b/app/services/update_snippet_service.rb
@@ -12,7 +12,7 @@ class UpdateSnippetService < BaseService
 
   def execute
     # check that user is allowed to set specified visibility_level
-    new_visibility = params[:visibility_level]
+    new_visibility = visibility_level
 
     if new_visibility && new_visibility.to_i != snippet.visibility_level
       unless Gitlab::VisibilityLevel.allowed_for?(current_user, new_visibility)