Add button to delete all merged branches

It adds a button to the branches page that the user can use to delete
all the branches that are already merged. This can be used to clean up
all the branches that were forgotten to delete while merging MRs.

Fixes #21076.

1 files changed, 18 insertions, 0 deletions

diff --git a/app/services/delete_merged_branches_service.rb b/app/services/delete_merged_branches_service.rb
new file mode 100644
index 00000000000..8b8deafedb7
--- /dev/null
+++ b/app/services/delete_merged_branches_service.rb
@@ -0,0 +1,18 @@
+require_relative 'base_service'
+
+class DeleteMergedBranchesService < BaseService
+  def async_execute
+    DeleteMergedBranchesWorker.perform_async(project.id, current_user.id)
+  end
+
+  def execute
+    raise Gitlab::Access::AccessDeniedError unless can?(current_user, :push_code, project)
+
+    branches = project.repository.branch_names
+    branches = branches.select { |branch| project.repository.merged_to_root_ref?(branch) }
+
+    branches.each do |branch|
+      DeleteBranchService.new(project, current_user).execute(branch)
+    end
+  end
+end