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

Closes #15638

7 files changed, 80 insertions, 77 deletions

diff --git a/lib/api/api.rb b/lib/api/api.rb
index 5fd9c30cb42..360fb41a721 100644
--- a/lib/api/api.rb
+++ b/lib/api/api.rb
@@ -57,5 +57,6 @@ module API
     mount ::API::Variables
     mount ::API::Runners
     mount ::API::Licenses
+    mount ::API::Subscriptions
   end
 end
diff --git a/lib/api/entities.rb b/lib/api/entities.rb
index 2870a6a40ef..406f5ea9139 100644
--- a/lib/api/entities.rb
+++ b/lib/api/entities.rb
@@ -307,6 +307,10 @@ module API
     class Label < Grape::Entity
       expose :name, :color, :description
       expose :open_issues_count, :closed_issues_count, :open_merge_requests_count
+
+      expose :subscribed do |label, options|
+        label.subscribed?(options[:current_user])
+      end
     end
 
     class Compare < Grape::Entity
diff --git a/lib/api/helpers.rb b/lib/api/helpers.rb
index 40c967453fb..5e638dbe16a 100644
--- a/lib/api/helpers.rb
+++ b/lib/api/helpers.rb
@@ -95,6 +95,17 @@ module API
       end
     end
 
+    def find_project_label(id)
+      label = user_project.labels.find_by_id(id) || user_project.labels.find_by_title(id)
+      label || not_found!('Label')
+    end
+
+    def find_project_issue(id)
+      issue = user_project.issues.find(id)
+      not_found! unless can?(current_user, :read_issue, issue)
+      issue
+    end
+
     def paginate(relation)
       relation.page(params[:page]).per(params[:per_page].to_i).tap do |data|
         add_pagination_headers(data)
diff --git a/lib/api/issues.rb b/lib/api/issues.rb
index 40928749481..f59a4d6c012 100644
--- a/lib/api/issues.rb
+++ b/lib/api/issues.rb
@@ -103,8 +103,7 @@ module API
       # Example Request:
       #   GET /projects/:id/issues/:issue_id
       get ":id/issues/:issue_id" do
-        @issue = user_project.issues.find(params[:issue_id])
-        not_found! unless can?(current_user, :read_issue, @issue)
+        @issue = find_project_issue(params[:issue_id])
         present @issue, with: Entities::Issue, current_user: current_user
       end
 
@@ -234,42 +233,6 @@ module API
         authorize!(:destroy_issue, issue)
         issue.destroy
       end
-
-      # Subscribes to a project issue
-      #
-      # Parameters:
-      #  id (required)       - The ID of a project
-      #  issue_id (required) - The ID of a project issue
-      # Example Request:
-      #   POST /projects/:id/issues/:issue_id/subscription
-      post ':id/issues/:issue_id/subscription' do
-        issue = user_project.issues.find(params[:issue_id])
-
-        if issue.subscribed?(current_user)
-          not_modified!
-        else
-          issue.toggle_subscription(current_user)
-          present issue, with: Entities::Issue, current_user: current_user
-        end
-      end
-
-      # Unsubscribes from a project issue
-      #
-      # Parameters:
-      #  id (required)       - The ID of a project
-      #  issue_id (required) - The ID of a project issue
-      # Example Request:
-      #   DELETE /projects/:id/issues/:issue_id/subscription
-      delete ':id/issues/:issue_id/subscription' do
-        issue = user_project.issues.find(params[:issue_id])
-
-        if issue.subscribed?(current_user)
-          issue.unsubscribe(current_user)
-          present issue, with: Entities::Issue, current_user: current_user
-        else
-          not_modified!
-        end
-      end
     end
   end
 end
diff --git a/lib/api/labels.rb b/lib/api/labels.rb
index 4af6bef0fa7..c806829d69e 100644
--- a/lib/api/labels.rb
+++ b/lib/api/labels.rb
@@ -11,7 +11,7 @@ module API
       # Example Request:
       #   GET /projects/:id/labels
       get ':id/labels' do
-        present user_project.labels, with: Entities::Label
+        present user_project.labels, with: Entities::Label, current_user: current_user
       end
 
       # Creates a new label
@@ -36,7 +36,7 @@ module API
         label = user_project.labels.create(attrs)
 
         if label.valid?
-          present label, with: Entities::Label
+          present label, with: Entities::Label, current_user: current_user
         else
           render_validation_error!(label)
         end
@@ -90,7 +90,7 @@ module API
         attrs[:name] = attrs.delete(:new_name) if attrs.key?(:new_name)
 
         if label.update(attrs)
-          present label, with: Entities::Label
+          present label, with: Entities::Label, current_user: current_user
         else
           render_validation_error!(label)
         end
diff --git a/lib/api/merge_requests.rb b/lib/api/merge_requests.rb
index 7e78609ecb9..4e7de8867b4 100644
--- a/lib/api/merge_requests.rb
+++ b/lib/api/merge_requests.rb
@@ -327,42 +327,6 @@ module API
           issues = ::Kaminari.paginate_array(merge_request.closes_issues(current_user))
           present paginate(issues), with: Entities::Issue, current_user: current_user
         end
-
-        # Subscribes to a merge request
-        #
-        # Parameters:
-        #  id (required)               - The ID of a project
-        #  merge_request_id (required) - The ID of a merge request
-        # Example Request:
-        #   POST /projects/:id/issues/:merge_request_id/subscription
-        post "#{path}/subscription" do
-          merge_request = user_project.merge_requests.find(params[:merge_request_id])
-
-          if merge_request.subscribed?(current_user)
-            not_modified!
-          else
-            merge_request.toggle_subscription(current_user)
-            present merge_request, with: Entities::MergeRequest, current_user: current_user
-          end
-        end
-
-        # Unsubscribes from a merge request
-        #
-        # Parameters:
-        #  id (required)               - The ID of a project
-        #  merge_request_id (required) - The ID of a merge request
-        # Example Request:
-        #   DELETE /projects/:id/merge_requests/:merge_request_id/subscription
-        delete "#{path}/subscription" do
-          merge_request = user_project.merge_requests.find(params[:merge_request_id])
-
-          if merge_request.subscribed?(current_user)
-            merge_request.unsubscribe(current_user)
-            present merge_request, with: Entities::MergeRequest, current_user: current_user
-          else
-            not_modified!
-          end
-        end
       end
     end
   end
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