Track stripe sessions and fulfill purchase status

src/app.module.ts

@@ -1,9 +1,9 @@
 import { Module } from '@nestjs/common';
-import { AccessController } from './access.controller';
-import { UserService } from './user.service';
-import { BuyController } from './buy.controller';
-import { PurchaseService } from './purchase.service';
-import { StripeService } from './stripe.service';
+import { AccessController } from './controller/access.controller';
+import { UserService } from './service/user.service';
+import { BuyController } from './controller/buy.controller';
+import { PurchaseService } from './service/purchase.service';
+import { StripeService } from './service/stripe.service';
 
 @Module({
   imports: [],

src/buy.controller.ts

@@ -1,37 +0,0 @@
-import { Body, Controller, Get, Post, Redirect } from '@nestjs/common';
-import { PurchaseService } from './purchase.service';
-import { UserService } from './user.service';
-import { PurchaseItem } from './dto/purchase-item';
-import { StripeService } from './stripe.service';
-
-@Controller('/buy')
-export class BuyController {
-  constructor(
-    private readonly purchaseService: PurchaseService,
-    private readonly userService: UserService,
-    private readonly stripeService: StripeService
-  ) {}
-
-  @Post('/start')
-  @Redirect()
-  public async startPurchaseFlow(
-    @Body('userId') userId: number,
-    @Body('quantity') quantity: number,
-  ) {
-    const user = this.userService.getUserById(userId);
-    const purchase = this.purchaseService.recordPurchaseStart(
-      user,
-      PurchaseItem.PAELLA,
-      quantity,
-    );
-    const session = await this.stripeService.createStripeSession(purchase);
-    console.log(session);
-    return { url: session.url };
-  }
-
-  @Get('/complete')
-  public complete() {}
-
-  @Get('/cancel')
-  public cancel() {}
-}

src/controller/access.controller.ts

@@ -5,7 +5,7 @@ import {
   Post,
   UnauthorizedException,
 } from '@nestjs/common';
-import { UserService } from './user.service';
+import { UserService } from '../service/user.service';
 
 @Controller('/access')
 export class AccessController {

src/controller/buy.controller.ts

@@ -0,0 +1,47 @@
+import { Body, Controller, Get, Post, Redirect } from '@nestjs/common';
+import { PurchaseService } from '../service/purchase.service';
+import { UserService } from '../service/user.service';
+import { PurchaseItem } from '../dto/purchase-item';
+import { StripeService } from '../service/stripe.service';
+import { PurchaseStatus } from 'src/dto/purchase-status';
+
+@Controller('/buy')
+export class BuyController {
+  constructor(
+    private readonly purchaseService: PurchaseService,
+    private readonly userService: UserService,
+    private readonly stripeService: StripeService,
+  ) {}
+
+  @Post('/start')
+  public async startPurchaseFlow(
+    @Body('userId') userId: number,
+    @Body('quantity') quantity: number,
+  ) {
+    const user = this.userService.getUserById(userId);
+    const purchase = this.purchaseService.recordPurchaseStart(
+      user,
+      PurchaseItem.PAELLA,
+      quantity,
+    );
+    const session = await this.stripeService.createStripeSession(
+      user,
+      purchase,
+    );
+    this.purchaseService.attachStripeSessionToPurchase(session.id, purchase.id);
+    console.log(session);
+    return { url: session.url };
+  }
+
+  @Post('/complete')
+  public async complete(@Body('userId') userId: number) {
+    const user = this.userService.getUserById(userId);
+    const session = await this.stripeService.getStripeSessionForCustomer(user);
+    const isPaid = session.payment_status == 'paid';
+    this.purchaseService.findAndTransitionPurchaseStatus(
+      session.id,
+      isPaid ? PurchaseStatus.COMPLETED : PurchaseStatus.IN_PROGRESS,
+    );
+    return { url: '/signup' };
+  }
+}

src/dto/purchase-status.ts

@@ -1,5 +1,6 @@
 export enum PurchaseStatus {
   CREATED = 'CREATED',
+  IN_PROGRESS = 'IN_PROGRESS',
   COMPLETED = 'COMPLETED',
   FAILED = 'FAILED',
 }

src/dto/purchase.ts

@@ -8,4 +8,5 @@ export class Purchase {
   purchasedProduct: PurchaseItem;
   purchasedUnits: number;
   status: PurchaseStatus;
+  stripeSessionId?: string;
 }

src/main.ts

@@ -1,6 +1,6 @@
 import { NestFactory } from '@nestjs/core';
 import { AppModule } from './app.module';
-import dotenv from 'dotenv'
+import dotenv from 'dotenv';
 
 dotenv.config();
 async function bootstrap() {

src/purchase.service.ts

@@ -1,37 +0,0 @@
-import { Injectable, Logger } from '@nestjs/common';
-import { Purchase } from './dto/purchase';
-import { User } from './dto/user';
-import { PurchaseItem } from './dto/purchase-item';
-import { PurchaseStatus } from './dto/purchase-status';
-
-@Injectable()
-export class PurchaseService {
-  private readonly purchases: Purchase[] = [];
-  private readonly logger = new Logger(PurchaseService.name);
-
-  constructor() {}
-
-  public recordPurchaseStart(
-    user: User,
-    purchasedItem: PurchaseItem,
-    units: number,
-  ): Purchase {
-    this.logger.debug(`Recording purchase for user ID: ${user.id}`);
-    const purchase: Purchase = {
-      id: this.purchases.length,
-      purchasedBy: user,
-      purchasedProduct: purchasedItem,
-      purchasedUnits: units,
-      status: PurchaseStatus.CREATED,
-    };
-    this.purchases.push(purchase);
-    return purchase;
-  }
-
-  public findPurchasesByUser(userId: number): Purchase[] {
-    this.logger.debug(`Searching purchases for user ID: ${userId}`);
-    return this.purchases.filter(
-      (purchase) => (purchase.purchasedBy.id = userId),
-    );
-  }
-}

src/service/purchase.service.ts

@@ -0,0 +1,65 @@
+import { Injectable, Logger, NotFoundException } from '@nestjs/common';
+import { Purchase } from 'src/dto/purchase';
+import { PurchaseItem } from 'src/dto/purchase-item';
+import { PurchaseStatus } from 'src/dto/purchase-status';
+import { User } from 'src/dto/user';
+
+@Injectable()
+export class PurchaseService {
+  private readonly purchases: Purchase[] = [];
+  private readonly logger = new Logger(PurchaseService.name);
+
+  constructor() {}
+
+  public recordPurchaseStart(
+    user: User,
+    purchasedItem: PurchaseItem,
+    units: number,
+  ): Purchase {
+    this.logger.debug(`Recording purchase for user ID: ${user.id}`);
+    const purchase: Purchase = {
+      id: this.purchases.length,
+      purchasedBy: user,
+      purchasedProduct: purchasedItem,
+      purchasedUnits: units,
+      status: PurchaseStatus.CREATED,
+    };
+    this.purchases.push(purchase);
+    return purchase;
+  }
+
+  public attachStripeSessionToPurchase(
+    sessionId: string,
+    purchaseId: number,
+  ): void {
+    const purchase = this.purchases.find(
+      (purchase) => purchase.id === purchaseId,
+    );
+    if (!purchase) {
+      throw new NotFoundException();
+    }
+
+    purchase.stripeSessionId = sessionId;
+  }
+
+  public findAndTransitionPurchaseStatus(
+    sessionId: string,
+    purchaseStatus: PurchaseStatus,
+  ) {
+    const purchase = this.purchases.find(
+      (purchase) => purchase.stripeSessionId === sessionId,
+    );
+    if (!purchase) {
+      throw new NotFoundException();
+    }
+
+    purchase.status = purchaseStatus;
+  }
+
+  public findPurchasesByUser(userId: number): Purchase[] {
+    this.logger.debug(`Searching purchases for user ID: ${userId}`);
+    return this.purchases.filter(
+      (purchase) => (purchase.purchasedBy.id = userId),
+    );
+  }
+}

src/service/stripe.service.ts

@@ -0,0 +1,46 @@
+import { Injectable, NotFoundException } from '@nestjs/common';
+import { Purchase } from '../dto/purchase';
+import Stripe from 'stripe';
+import { User } from '../dto/user';
+import { NotFoundError } from 'rxjs';
+
+@Injectable()
+export class StripeService {
+  private readonly stripe: Stripe;
+  private readonly stripeSessions: Map<number, string> = new Map();
+
+  constructor() {
+    const stripePrivateKey = process.env.STRIPE_PRIVATE_KEY!;
+    this.stripe = new Stripe(stripePrivateKey);
+  }
+
+  public async createStripeSession(
+    user: User,
+    purchase: Purchase,
+  ): Promise<Stripe.Response<Stripe.Checkout.Session>> {
+    const session = await this.stripe.checkout.sessions.create({
+      line_items: [
+        {
+          price: 'price_1SWLunBQui1OXGptCHHnBvLX',
+          quantity: purchase.purchasedUnits,
+        },
+      ],
+      mode: 'payment',
+      success_url: 'http://localhost:5173/buy/return',
+      cancel_url: 'http://localhost:5173/buy/return',
+      payment_method_types: ['card', 'paypal'],
+    });
+    this.stripeSessions.set(user.id, session.id);
+    return session;
+  }
+
+  public getStripeSessionForCustomer(
+    user: User,
+  ): Promise<Stripe.Response<Stripe.Checkout.Session>> {
+    const sessionId = this.stripeSessions.get(user.id);
+    if (!sessionId) {
+      throw new NotFoundException();
+    }
+    return this.stripe.checkout.sessions.retrieve(sessionId);
+  }
+}

src/service/user.service.ts

@@ -1,5 +1,5 @@
 import { Injectable, Logger, NotFoundException } from '@nestjs/common';
-import { User } from './dto/user';
+import { User } from 'src/dto/user';
 
 @Injectable()
 export class UserService {

src/stripe.service.ts

@@ -1,28 +0,0 @@
-import { Injectable } from '@nestjs/common';
-import { Purchase } from './dto/purchase';
-import Stripe from 'stripe';
-
-@Injectable()
-export class StripeService {
-  private readonly stripe: Stripe;
-
-  constructor() {
-    const stripePrivateKey = process.env.STRIPE_PRIVATE_KEY!;
-    this.stripe = new Stripe(stripePrivateKey);
-  }
-
-  public createStripeSession(purchase: Purchase): Promise<Stripe.Response<Stripe.Checkout.Session>> {
-    return this.stripe.checkout.sessions.create({
-      line_items: [
-        {
-          price: purchase.purchasedProduct,
-          quantity: purchase.purchasedUnits,
-        },
-      ],
-      mode: 'payment',
-      success_url: 'https://localhost:5173/buy/complete',
-      cancel_url: 'https://localhost:5173/buy/cancel',
-      payment_method_types: ['card'],
-    });
-  }
-}