Add API endpoints for un/subscribing from/to a label

Closes #15638

1 files changed, 60 insertions, 0 deletions

diff --git a/lib/api/subscriptions.rb b/lib/api/subscriptions.rb
new file mode 100644
index 00000000000..c49e2a21b82
--- /dev/null
+++ b/lib/api/subscriptions.rb
@@ -0,0 +1,60 @@
+module API
+  class Subscriptions < Grape::API
+    before { authenticate! }
+
+    subscribable_types = {
+      'merge_request' => proc { |id| user_project.merge_requests.find(id) },
+      'merge_requests' => proc { |id| user_project.merge_requests.find(id) },
+      'issues' => proc { |id| find_project_issue(id) },
+      'labels' => proc { |id| find_project_label(id) },
+    }
+
+    resource :projects do
+      subscribable_types.each do |type, finder|
+        type_singularized = type.singularize
+        type_id_str = :"#{type_singularized}_id"
+        entity_class = Entities.const_get(type_singularized.camelcase)
+
+        # Subscribe to a resource
+        #
+        # Parameters:
+        #   id (required) - The ID of a project
+        #   subscribable_id (required) - The ID of a resource
+        # Example Request:
+        #   POST /projects/:id/labels/:subscribable_id/subscription
+        #   POST /projects/:id/issues/:subscribable_id/subscription
+        #   POST /projects/:id/merge_requests/:subscribable_id/subscription
+        post ":id/#{type}/:#{type_id_str}/subscription" do
+          resource = instance_exec(params[type_id_str], &finder)
+
+          if resource.subscribed?(current_user)
+            not_modified!
+          else
+            resource.subscribe(current_user)
+            present resource, with: entity_class, current_user: current_user
+          end
+        end
+
+        # Unsubscribe from a resource
+        #
+        # Parameters:
+        #   id (required) - The ID of a project
+        #   subscribable_id (required) - The ID of a resource
+        # Example Request:
+        #   DELETE /projects/:id/labels/:subscribable_id/subscription
+        #   DELETE /projects/:id/issues/:subscribable_id/subscription
+        #   DELETE /projects/:id/merge_requests/:subscribable_id/subscription
+        delete ":id/#{type}/:#{type_id_str}/subscription" do
+          resource = instance_exec(params[type_id_str], &finder)
+
+          if !resource.subscribed?(current_user)
+            not_modified!
+          else
+            resource.unsubscribe(current_user)
+            present resource, with: entity_class, current_user: current_user
+          end
+        end
+      end
+    end
+  end
+end