Refactor BillingEventHandlerService and update SQL permissions

Changed BillingEventHandlerService from a class to a method. Also, the SQL permissions for service_role on public.order_items table have been updated to include insert, update and delete operations. Additionally, made adjustment to configuration values in the billing.sample.config.ts file.

apps/web/supabase/migrations/20221215192558_schema.sql

@@ -1889,7 +1889,7 @@ select
   on table public.order_items to authenticated,
   service_role;
 
-grant insert on table public.order_items to service_role;
+grant insert, update, delete on table public.order_items to service_role;
 
 -- Indexes on the order_items table
 create index ix_order_items_order_id on public.order_items (order_id);

packages/billing/gateway/src/server/services/billing-event-handler/billing-event-handler-provider.ts

@@ -5,16 +5,23 @@ import { Database } from '@kit/supabase/database';
 import { getSupabaseServerActionClient } from '@kit/supabase/server-actions-client';
 
 import { BillingEventHandlerFactoryService } from './billing-event-handler-factory.service';
-import { BillingEventHandlerService } from './billing-event-handler.service';
+import { createBillingEventHandlerService } from './billing-event-handler.service';
+
+// a function that returns a Supabase client
+type ClientProvider = () => ReturnType<typeof getSupabaseServerActionClient>;
+
+// the billing provider from the database
+type BillingProvider = Database['public']['Enums']['billing_provider'];
 
 /**
+ * @name getBillingEventHandlerService
  * @description This function retrieves the billing provider from the database and returns a
  * new instance of the `BillingGatewayService` class. This class is used to interact with the server actions
  * defined in the host application.
  */
 export async function getBillingEventHandlerService(
-  clientProvider: () => ReturnType<typeof getSupabaseServerActionClient>,
-  provider: Database['public']['Enums']['billing_provider'],
+  clientProvider: ClientProvider,
+  provider: BillingProvider,
   config: BillingConfig,
 ) {
   const strategy = await BillingEventHandlerFactoryService.GetProviderStrategy(
@@ -22,5 +29,5 @@ export async function getBillingEventHandlerService(
     config,
   );
 
-  return new BillingEventHandlerService(clientProvider, strategy);
+  return createBillingEventHandlerService(clientProvider, strategy);
 }

packages/billing/gateway/src/server/services/billing-event-handler/billing-event-handler.service.ts

@@ -30,7 +30,24 @@ interface CustomHandlersParams {
   onEvent?: (event: string, data: unknown) => Promise<unknown>;
 }
 
-export class BillingEventHandlerService {
+/**
+ * @name createBillingEventHandlerService
+ * @description Create a new instance of the `BillingEventHandlerService` class
+ * @param clientProvider
+ * @param strategy
+ */
+export function createBillingEventHandlerService(
+  clientProvider: () => SupabaseClient<Database>,
+  strategy: BillingWebhookHandlerService,
+) {
+  return new BillingEventHandlerService(clientProvider, strategy);
+}
+
+/**
+ * @name BillingEventHandlerService
+ * @description This class is used to handle the webhook events from the billing provider
+ */
+class BillingEventHandlerService {
   private readonly namespace = 'billing';
 
   constructor(
@@ -38,6 +55,12 @@ export class BillingEventHandlerService {
     private readonly strategy: BillingWebhookHandlerService,
   ) {}
 
+  /**
+   * @name handleWebhookEvent
+   * @description Handle the webhook event from the billing provider
+   * @param request
+   * @param params
+   */
   async handleWebhookEvent(
     request: Request,
     params: Partial<CustomHandlersParams> = {},