Delete webhook services when there are no webhooks left

Else they will show up in the current integration list FOREVAR!

src/github.com/matrix-org/go-neb/database/db.go

@@ -104,6 +104,14 @@ func (d *ServiceDB) LoadService(serviceID string) (service types.Service, err er
 	return
 }
 
+// DeleteService deletes the given service from the database.
+func (d *ServiceDB) DeleteService(serviceID string) (err error) {
+	err = runTransaction(d.db, func(txn *sql.Tx) error {
+		return deleteServiceTxn(txn, serviceID)
+	})
+	return
+}
+
 // LoadServicesForUser loads all the bot services configured for a given user.
 // Returns an empty list if there aren't any services configured.
 func (d *ServiceDB) LoadServicesForUser(serviceUserID string) (services []types.Service, err error) {

src/github.com/matrix-org/go-neb/database/schema.go

@@ -231,6 +231,15 @@ func selectServicesForUserTxn(txn *sql.Tx, userID string) (srvs []types.Service,
 	return
 }
 
+const deleteServiceSQL = `
+DELETE FROM services WHERE service_id = $1
+`
+
+func deleteServiceTxn(txn *sql.Tx, serviceID string) error {
+	_, err := txn.Exec(deleteServiceSQL, serviceID)
+	return err
+}
+
 const insertRealmSQL = `
 INSERT INTO auth_realms(
 	realm_id, realm_type, realm_json, time_added_ms, time_updated_ms

src/github.com/matrix-org/go-neb/services/github/github_webhook.go

@@ -192,6 +192,20 @@ func (s *githubWebhookService) PostRegister(oldService types.Service) {
 			}).Warn("Failed to remove webhook")
 		}
 	}
+
+	// If we are not tracking any repos any more then we are back to square 1 and not doing anything
+	// so remove ourselves from the database. This is safe because this is still within the critical
+	// section for this service.
+	if len(newRepos) == 0 {
+		logger := log.WithFields(log.Fields{
+			"service_type": s.ServiceType(),
+			"service_id":   s.ServiceID(),
+		})
+		logger.Info("Removing service as no webhooks are registered.")
+		if err := database.GetServiceDB().DeleteService(s.ServiceID()); err != nil {
+			logger.WithError(err).Error("Failed to delete service")
+		}
+	}
 }
 
 func (s *githubWebhookService) joinWebhookRooms(client *matrix.Client) error {