Task 8

package.json

@@ -21,19 +21,29 @@
     "test:e2e": "jest --config ./test/jest-e2e.json"
   },
   "dependencies": {
-    "@nestjs/common": "^10.0.3",
+    "@nestjs/common": "^11.1.3",
     "@nestjs/config": "^3.0.0",
-    "@nestjs/core": "^10.0.3",
+    "@nestjs/core": "^11.1.3",
     "@nestjs/jwt": "^10.1.0",
+    "@nestjs/microservices": "^11.1.3",
     "@nestjs/passport": "^10.0.0",
-    "@nestjs/platform-express": "^10.0.3",
+    "@nestjs/platform-express": "^11.1.3",
+    "@nestjs/typeorm": "^11.0.0",
+    "@nestjs/websockets": "^11.1.3",
+    "aws-lambda": "^1.0.7",
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.14.2",
     "helmet": "^7.0.0",
     "passport": "^0.6.0",
     "passport-http": "^0.3.0",
     "passport-jwt": "^4.0.1",
     "passport-local": "^1.0.0",
-    "reflect-metadata": "^0.1.13",
-    "rxjs": "^7.8.1"
+    "pg": "^8.16.0",
+    "reflect-metadata": "^0.1.14",
+    "rxjs": "^7.8.1",
+    "serverless-http": "^3.2.0",
+    "tslib": "^2.8.1",
+    "typeorm": "^0.3.24"
   },
   "devDependencies": {
     "@nestjs/cli": "^10.0.3",

src/app.module.ts

@@ -1,14 +1,32 @@
+/* eslint-disable prettier/prettier */
 import { Module } from '@nestjs/common';
 
 import { AppController } from './app.controller';
-
+import { TypeOrmModule } from '@nestjs/typeorm';
 import { CartModule } from './cart/cart.module';
 import { AuthModule } from './auth/auth.module';
 import { OrderModule } from './order/order.module';
 import { ConfigModule } from '@nestjs/config';
+import { CartItem } from './cart/entity/cart-item.entity';
+import { Cart } from './cart/entity/cart.entity';
 
 @Module({
-  imports: [AuthModule, CartModule, OrderModule, ConfigModule.forRoot()],
+  imports: [
+    AuthModule,
+    CartModule,
+    OrderModule,
+    ConfigModule.forRoot(),
+    TypeOrmModule.forRoot({
+      type: 'postgres',
+      host: process.env.DB_HOST,
+      port: Number(process.env.DB_PORT),
+      username: process.env.DB_USER,
+      password: process.env.DB_PASSWORD,
+      database: process.env.DB_NAME,
+      entities: [Cart, CartItem],
+      synchronize: true, // set to false in production!
+    }),
+  ],
   controllers: [AppController],
   providers: [],
 })

src/cart/cart.controller.ts

@@ -1,3 +1,4 @@
+/* eslint-disable prettier/prettier */
 import {
   Controller,
   Get,

src/cart/cart.module.ts

@@ -1,12 +1,15 @@
+/* eslint-disable prettier/prettier */
 import { Module } from '@nestjs/common';
 
 import { OrderModule } from '../order/order.module';
-
+import { TypeOrmModule } from '@nestjs/typeorm';
 import { CartController } from './cart.controller';
 import { CartService } from './services';
+import { Cart } from './entity/cart.entity';
+import { CartItem } from './entity/cart-item.entity';
 
 @Module({
-  imports: [OrderModule],
+  imports: [OrderModule, TypeOrmModule.forFeature([Cart, CartItem])],
   providers: [CartService],
   controllers: [CartController],
 })

src/cart/entity/cart-item.entity.ts

@@ -0,0 +1,23 @@
+/* eslint-disable prettier/prettier */
+import {
+  Entity, PrimaryGeneratedColumn, Column, ManyToOne
+} from 'typeorm';
+import { Cart } from './cart.entity';
+
+@Entity({ name: 'cart_items' })
+export class CartItem {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  product_id: string;
+
+  @Column('int')
+  count: number;
+
+  @ManyToOne(() => Cart, (cart) => cart.items, {
+    onDelete: 'CASCADE',
+  })
+  cart: Cart;
+}
+

src/cart/entity/cart.entity.ts

@@ -0,0 +1,39 @@
+/* eslint-disable prettier/prettier */
+import {
+  Entity, PrimaryGeneratedColumn, Column, CreateDateColumn,
+  UpdateDateColumn, OneToMany
+} from 'typeorm';
+import { CartItem } from './cart-item.entity';
+
+export enum CartStatuses {
+  OPEN = 'OPEN',
+  ORDERED = 'ORDERED',
+}
+
+@Entity({ name: 'carts' })
+export class Cart {
+  @PrimaryGeneratedColumn('uuid')
+  id: string;
+
+  @Column()
+  user_id: string;
+
+  @Column({
+    type: 'enum',
+    enum: CartStatuses,
+    default: CartStatuses.OPEN,
+  })
+  status: CartStatuses;
+
+  @CreateDateColumn()
+  created_at: Date;
+
+  @UpdateDateColumn()
+  updated_at: Date;
+
+  @OneToMany(() => CartItem, (item) => item.cart, {
+    cascade: true,
+    eager: true,
+  })
+  items: CartItem[];
+}

src/cart/models-rules/index.ts

@@ -1,3 +1,4 @@
+/* eslint-disable prettier/prettier */
 import { CartItem } from '../models';
 
 export function calculateCartTotal(items: CartItem[]): number {

src/cart/models/index.ts

@@ -1,3 +1,4 @@
+/* eslint-disable prettier/prettier */
 export enum CartStatuses {
   OPEN = 'OPEN',
   STATUS = 'STATUS',

src/cart/services/cart.service.ts

@@ -1,62 +1,71 @@
+/* eslint-disable prettier/prettier */
 import { Injectable } from '@nestjs/common';
-import { randomUUID } from 'node:crypto';
-import { Cart, CartStatuses } from '../models';
+import { InjectRepository } from '@nestjs/typeorm';
+import { Repository } from 'typeorm';
+import { Cart, CartStatuses } from '../entity/cart.entity';
+import { CartItem } from '../entity/cart-item.entity';
 import { PutCartPayload } from 'src/order/type';
 
 @Injectable()
 export class CartService {
-  private userCarts: Record<string, Cart> = {};
+  constructor(
+    @InjectRepository(Cart)
+    private readonly cartRepository: Repository<Cart>,
 
-  findByUserId(userId: string): Cart {
-    return this.userCarts[userId];
-  }
+    @InjectRepository(CartItem)
+    private readonly cartItemRepository: Repository<CartItem>,
+  ) {}
 
-  createByUserId(user_id: string): Cart {
-    const timestamp = Date.now();
+  async findByUserId(userId: string): Promise<Cart> {
+    return this.cartRepository.findOne({
+      where: { user_id: userId, status: CartStatuses.OPEN },
+    });
+  }
 
-    const userCart = {
-      id: randomUUID(),
+  async createByUserId(user_id: string): Promise<Cart> {
+    const newCart = this.cartRepository.create({
       user_id,
-      created_at: timestamp,
-      updated_at: timestamp,
       status: CartStatuses.OPEN,
-      items: [],
-    };
-
-    this.userCarts[user_id] = userCart;
-
-    return userCart;
+    });
+    return this.cartRepository.save(newCart);
   }
 
-  findOrCreateByUserId(userId: string): Cart {
-    const userCart = this.findByUserId(userId);
-
-    if (userCart) {
-      return userCart;
+  async findOrCreateByUserId(userId: string): Promise<Cart> {
+    let cart = await this.findByUserId(userId);
+    if (!cart) {
+      cart = await this.createByUserId(userId);
     }
-
-    return this.createByUserId(userId);
+    return cart;
   }
 
-  updateByUserId(userId: string, payload: PutCartPayload): Cart {
-    const userCart = this.findOrCreateByUserId(userId);
+  async updateByUserId(userId: string, payload: PutCartPayload): Promise<Cart> {
+    const cart = await this.findOrCreateByUserId(userId);
 
-    const index = userCart.items.findIndex(
-      ({ product }) => product.id === payload.product.id,
-    );
+    const existingItem = cart.items.find(item => item.product_id === payload.product.id);
 
-    if (index === -1) {
-      userCart.items.push(payload);
-    } else if (payload.count === 0) {
-      userCart.items.splice(index, 1);
-    } else {
-      userCart.items[index] = payload;
+    if (existingItem) {
+      if (payload.count === 0) {
+        await this.cartItemRepository.remove(existingItem);
+      } else {
+        existingItem.count = payload.count;
+        await this.cartItemRepository.save(existingItem);
+      }
+    } else if (payload.count > 0) {
+      const newItem = this.cartItemRepository.create({
+        product_id: payload.product.id,
+        count: payload.count,
+        cart,
+      });
+      await this.cartItemRepository.save(newItem);
     }
 
-    return userCart;
+    return this.findOrCreateByUserId(userId); // to return updated cart with items
   }
 
-  removeByUserId(userId): void {
-    this.userCarts[userId] = null;
+  async removeByUserId(userId: string): Promise<void> {
+    const cart = await this.findByUserId(userId);
+    if (cart) {
+      await this.cartRepository.remove(cart);
+    }
   }
 }

src/main.ts

@@ -1,9 +1,11 @@
 import { NestFactory } from '@nestjs/core';
-
 import helmet from 'helmet';
-
 import { AppModule } from './app.module';
 import { ConfigService } from '@nestjs/config';
+import { Handler } from 'aws-lambda';
+import serverless from 'serverless-http';
+
+let cachedServer: Handler; // Cache the server for better Lambda warm performance
 
 async function bootstrap() {
   const app = await NestFactory.create(AppModule);
@@ -17,8 +19,17 @@ async function bootstrap() {
   });
   app.use(helmet());
 
-  await app.listen(port, () => {
-    console.log('App is running on %s port', port);
-  });
+  await app.init(); // Ensure the app is initialized before exporting as serverless
+
+  console.log('App is ready to be served as a Lambda');
+  return serverless(app.getHttpAdapter().getInstance()); // Return serverless handler
 }
-bootstrap();
+
+// Lambda handler function
+export const handler: Handler = async (event, context) => {
+  if (!cachedServer) {
+    // Only bootstrap the server once (Lambda cold start optimization)
+    cachedServer = await bootstrap();
+  }
+  return cachedServer(event, context); // Proxy event and context to serverless handler
+};