feat: Improve subscription workflow

apps/backend/.env.example

@@ -9,8 +9,10 @@ CLIENT_URL=http://localhost:3000
 # Database
 DATABASE_URL="postgresql://postgres:postgres@localhost:5432"
 
-# Stripe 
+# Stripe
 STRIPE_SECRET_KEY=""
+# Webhook signing secret (whsec_...) – use for constructEvent in production
+STRIPE_WEBHOOK_SECRET=""
 
 # TMDB 
 TMDB_ACCESS_TOKEN=

apps/backend/src/adapters/stripe-subscription-provider.ts

@@ -0,0 +1,44 @@
+import { stripe } from '@/adapters/stripe'
+import { SubscriptionAlreadyCanceledError } from '@/domain/errors/subscription-already-canceled-error'
+import type { SubscriptionProvider } from '@/ports/subscription-provider'
+
+async function getCurrentPeriodEnd(providerSubscriptionId: string) {
+  const retrieved = await stripe.subscriptions.retrieve(providerSubscriptionId)
+  const periodEndTimestamp = (
+    retrieved as unknown as { current_period_end: number }
+  ).current_period_end
+  return new Date(periodEndTimestamp * 1000)
+}
+
+async function scheduleCancelAtPeriodEnd(
+  providerSubscriptionId: string,
+  periodEnd: Date
+) {
+  await stripe.subscriptions.update(providerSubscriptionId, {
+    cancel_at: Math.floor(periodEnd.getTime() / 1000),
+    cancel_at_period_end: true,
+  })
+}
+
+async function cancelImmediately(providerSubscriptionId: string) {
+  try {
+    await stripe.subscriptions.cancel(providerSubscriptionId)
+  } catch (error: unknown) {
+    const stripeError = error as { code?: string; message?: string }
+    const isAlreadyCanceled =
+      stripeError.code === 'resource_already_canceled' ||
+      /already canceled|cannot cancel.*canceled/i.test(
+        String(stripeError.message ?? '')
+      )
+    if (isAlreadyCanceled) {
+      throw new SubscriptionAlreadyCanceledError()
+    }
+    throw error
+  }
+}
+
+export const StripeSubscriptionProvider: SubscriptionProvider = {
+  getCurrentPeriodEnd,
+  scheduleCancelAtPeriodEnd,
+  cancelImmediately,
+}

apps/backend/src/config.ts

@@ -26,6 +26,7 @@ function loadServicesEnvs() {
   const schema = z.object({
     RESEND_API_KEY: z.string().optional().default('re_123'),
     STRIPE_SECRET_KEY: z.string().optional().default(''),
+    STRIPE_WEBHOOK_SECRET: z.string().optional().default(''),
     TMDB_ACCESS_TOKEN: z.string(),
   })
 

apps/backend/src/db/migrations/20260130024720_alter_subscriptions_table.sql

@@ -0,0 +1,4 @@
+CREATE TYPE "public"."subscription_provider" AS ENUM('STRIPE', 'APPLE');--> statement-breakpoint
+ALTER TABLE "subscriptions" ADD COLUMN "subscription_provider" "subscription_provider" NOT NULL DEFAULT 'STRIPE';--> statement-breakpoint
+ALTER TABLE "subscriptions" ADD COLUMN "provider_subscription_id" varchar;--> statement-breakpoint
+ALTER TABLE "subscriptions" ADD CONSTRAINT "subscriptions_provider_subscription_id_unique" UNIQUE("provider_subscription_id");